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Home , Acusa, Eucalyptus redunca, Forest protection, World Forestry Congress

Proceedings

of the Fifth World Congress

VOLUME 2

University of Washington, Seattle, Washington United States of America

August 29September 10, 1960

I CONTENTS of VOLUME 2 Page Section II.Genetics and Improvement 675 Session A.Progress in Tree Improvement and Proposals for Inter- national Cooperation 675 Réalisations en matière d'amélioration des arbres et propositions de cooperation internationale Adelantos en el Mejoramiento de Arbolesy Proposiciones para la Cooperación Internacional Session B. 716 Session C. 775 Section III. Protection 833 Session A.Weather and Climate in 833 L'incidence des conditions atmosphériques et du climat sur la con- servation des forêts El Estado del Tiempo y el Clima en Relación con Ia Protección de Bosques Session B. 868 Pathologie forestière Patologla Forestal Session C.Forest Entomology 924 Entomologie des foréts EntomologIa Forestal Session D.Forest Fires 971 Incendies de forêts Incendios de Bosques Section IV.Forest Economics and Policy 1007 Session A.Policy and Economic Problems 1007 Politique forestière et probièmes économiques PolItica Forestal y Problemas Económjcos Session B.Supply, Demand, and Marketing of Forest Products 1048 Approvisionnement, demande et marketing des produits forestiers Oferta, Demanda y Venta de Productos Forestales Session C.Institutional Arrangements for Forestry 1096 Dispositions administratives visant la sylviculture Medidas Forestales Institucionales Session D. How To Achieve Better Management on Small - lands 1137 Comment améliorer l'aménagement des petits terrains boisés Metodos para Mejorar la Administración de Bosques Pequenos Section V. (for Countries With Newly Developed Forestry Programs) 1183 Session A.CriteriaforDeterminingTypes,Size,and Scope of Programs 1183 Critères destinés a determiner le genre, l'envergure et la portée des programmes sylvicoles Criterio para Determinar los Tipos, Amplitudy Alcance de Planes SilvIcolas Session B.Developing Technical Education Programs 1210 Establissement de programmes d'enseignement technique Planes de Desarrollo de Enseñanza Técnica Session C.Enlisting Support and Participation in Forestry by Landowners and the Public 1244 Nécessité de s'assurer le concours et Ia participation du public et des propriétaires terriens en matière de sylviculture Desarrollo del Interés de Terratenientes y del Péblico Respecto a la Necesidad de la Silvicultura Section VI.Forest Products 1277 Session A. Wood:ItsStructureand Physical and Mechanical Properties 1277 Le bois: Sa structure et ses propriétés physiques et mécaniques Madera: Su Estructura y sus Propiedades FIsicas y Mecánicas See page 2063, Volume 3, for index of authors.

II Section II Genetics and Tree Improvement

Session A Progress in Tree Improvement and Proposals For International Cooperation Réalisations en matière d'amélioration des arbres et propositions de cooperation internationale Adelantos en el Mejoramiento de Arboles y Proposiciones para la Cooperación Internacional Progress in Forest Genetics and Tree Improvement

CARL SYRACH LARSEN Director, Arboretet, Horshoim, Denmark

Life, inallits phases, is the dominion of genetics. Our resemble structures or edifices rather more This, in turn, is one of the most powerful natural forces than field cropsstructures which, afterfifty or one and one of the newest sciences of today. The rapid de- hundred years,haveacquiredcertaindefinitechar- velopment of that science has placed in our hands a acteristics. The work of our scientific silviculturist has a valuable instrument which enables us to intervene in and strong resemblance to that of a designing engineer who to influence the capacity for reproduction of and must first analyze the materials at his disposal before he and modify them to our own needs. can use them in what he desires to construct. We face, The uses to which plants and animals may be put, in other words, technical research with a very practical together with the possibilities which we glimpse for their purpose. improvement, have resulted today throughout the world At our disposal, on the one hand, is a large fund of in beautiful gardens, abundant harvests and excellent, knowledge about genetics, botany, and other branches of highly bred domestic animals. Modem tools and imple- biology; on the other, generations of practical experience ments, fertilizers and improved feeding stuffs should by insilviculture.We must unifyallthisfor use in no means be underestimated, but without the improve- forestry without being led to believe that itis a new ments due to genetics, production could not have been abstract science for the gratification of its disciples, how- so enormously increased as has actually been the case. ever charming and fascinating it may seem. A or an must possess those characters It is characteristic for , and, in particular, which make it possible to utilize the improved environ- for ,that a new generation begins with mental conditions. human intervention. Whether the seed is sown from an One of the fundamental rules of genetics is expressed by airplane or the plant is raised in a nursery, it is the alter- the equation: nation of generations passing through our hands. More- over, the entire technical apparatus is equally expensive, Phenotype = Genotype + Environment whether the seeds and plants have good or poor hereditary This means that the final result depends both on the characters. From the moment the seed lies in our hand inherent character of the individual as well as on the until fifty or one hundred years later when the full-grown environment in which it develops. Improved environment tree is felled, each valuable characteristic latent in the usually means a continuous expenditure for fertilizers, seed is at work, free of charge, for the larger economic care or other maintenance, but a better genetic effect return.In an industry run on a long-time plan, it is a is obtainable from a once-for-all expenditure for breeding. satisfying thought that itis possible to isolate so very In silviculture, have greatly improved growth small a part of the production process for closer examina- conditions for trees through planting, determination of tion and treatment. the proportion of different tree species to be used, thin- The necessary living material for raising one hectare flings, etc., but this is no reason for ignoring the pos- of mature forest is a quantity of seed not larger than sibilities offered by genetics for improvement of forest can be held in two hands. The single tree which requires trees. We must be wide awake if we are to increase the both a derrick and a truck for transportation to the saw- returns from our within a reasonable time. mill has developed from a seed which weighed a few grams When agriculturists and horticulturists improve their or a fraction thereof. One can hardly find any other plants by breeding, the start is made with selection and industry where so small a "cog" plays so important a continued with a fascinating puzzle of cross-pollination. part in so large a production. To make the work less difficult, the plants may be dug up It is no new idea, however, among foresters to try to and collected on experimental areas where they can be influence this "cog" in the forestry production.Long studied and worked over at leisure. The problem is quite before the advent of genetics in the early years of the different for the . He is unable to move trees, and present century, there was much discussion in many itis not pleasant for him to picture himself on high, countries on the increased use of seed from the most climbing in the treetops to control pollination. However, valuable forest stands. Experiments with seed from char- this does not mean that he is baffled by the problem. It acteristicallydifferenttreesdemonstratedclearlythe simply indicates that he must try to solve it in other ways. importance of hereditary factors.Due to vague ideas Modern forest has fortunately been able to about these matters, there was little talk of "improve- show theseways,andtheirapplicabilityhas been ment" but much of "genetics" in general. "The Eddy Tree demonstrated by the great use which has been made of Breeding Station" (1925) was the first institution with them in recent years. sufficient courage to acknowledge the term in its true sense. Genetics and Tree Improvement 677 Work along the same lines was done at forest experiment creased growth by selection and controlled pol- stations, and it was included in forest botanical teaching lination. Experiments from the early part of the century, where the importance of the subject had been recognized. now classical, have proved that characters such as branch- However, in the middle thirties great advances were made. ing, forking, and large and small knots are heritable. Favored by the general development and recognition A difference in ability to withstand affects of soil and of the importance of technical research, there have been climate is known to us from ecotypes of the single species established of late years in many parts of the world a developed in nature.Studies of these was included in great number of institutions whose common aim is a study experiments with forest trees more than one hundred of genetics in silviculture and its economic utilization. years ago.However, recently, our knowledge of these Some institutions concentrate on genetics, others on the has been enlarged, for instance, through transplantations more practical sounding "forest tree improvement." The and through the study of drought resistance in . object is the same, and in both cases it is important to From plant pathology we need only to recall white maintain close contact in order to solve the common prob- pine blister rust to realize that this disease is a tempting lem. The separate stages on the way may be seen from subject for the study of genetics in silviculture. A long various aspects according to the temperament of the series of such studies have been successful.So many observer, but by mutual assistance we have made fair successful experiments and convincing demonstrations progress on the way forward. have been made that they leave no doubt that in the future We all know that there are different tree species which increasing attention to genetics will be a part of the fight can be utilized. We also know that in silviculture it is against plant diseases.This means not only attacks of just as important to keep the species separate as it is fungus diseases, but of pests as well. Such studies important to distinguish between the geographical types of are known on white pine in the U.S.A. and Canada, on a single species. Today, we realize that much money has Monterey pine in Australia and New Zealand, and on been wasted and great disappointment caused by moving and in Europe, to name a few examples. natural tree populations, but we also know that the un- The quality of wood was generally accepted in the past fortunate results, to a large extent, were due to a lack to be homogenous and characteristic for the individual of understanding at that time of the necessity of securing tree species. Only of late have studies been made of the seed from the type of tree suited to the climate in ques- variation in the anatomy and chemical composition of the tion. The magnitude of the practical control work today single tree species.It is stimulating to realize that these along these lines indicates the general acknowledgment of studies, though of comparativeshortduration, have the importance of the problem. Today the problem further demonstrated conclusive differences and, like other char- includes a demand for selection of the best stands. acters, these too, must obey the laws of genetics. Here, It has also been demonstrated that in the new genera- again, those laws may be utilized. As an example may be tion we can obtain results which differ depending on which mentioned the length of the wood fibers, the content of tree of the same population of a single geographical type ethereal oils, or of in Heveaall factors econom- has produced the seed used. If the seed from the popula- ically important. Other differences, such as the variation tion as a whole is used and the conditions are similar, found in the shape of wood rays in beech, may possibly the result corresponds to the average of the stand; if we not be of the same direct technical importance, but may collect seed separately from a number of single trees, have an importance in explaining pathological phenomena there are mutual differences. One single tree may have and as an example of progress due to contact between valuable progeny, another, poor progeny. The difference various forms in genetical studies of forest trees. found is solely determined by the control of the mother Knowledge of the cytology of forest trees has also tree. An even more striking difference appears when seed increased, largely through investigations of the chromo- is producd by controlled pollination. some numbers and the discovery of triploid and tetraploid By control of pollination between trees with desirable forms. This leads to the hope of rapid progress in forest heritable factors we are able to obtain an improved tree breeding. Without belittling in any way the contribu- progeny. Moreover, from the time the seed is produced tions made by other scientists, Nilsson-Ehle's now classi- we are able to give the factors better or poorer conditions cal studies on the aspen (Populus tremula) should be for development. If two , one with large and one brought to mind. These are of ever fresh interest, even with small seed, are reciprocally crossed, two portions of though the studies of late years have largely centered on seed are thtained, one with large seed, the other with small mutations. Those sudden discontinuous variations in the seed. Both contain the same mixture of heritable factors hereditary constitution constantly demand further atten- from the maternal and paternal plants, but the larger tionespecially, mutation frequency induced by irradia- amount of reserve nutrients stored in the large seeds tion. gives the plants from this cross a better start. This may be The hybrid larch in Scotland (1915) and the hybrid so pronounced that it cannot fail to be of practical im- pine from Placerville, Calif., U.S.A. (1928) were in- portance.This shows that our observations on the centives to silviculture the world over by showing, by effect of environment cannot begin too early. On the other practical examples, that it is possible to produce and raise hand, an uncritical selection of trees, solely because of artificially, new and better specimens of trees.Itap- their large seeds, will take us too far to the opposite side. peared that heterosis could be utilized in cross-pollination The above example is merely given as a warning to of related species and has been so utilized in numerous proceed carefully.The main point is that it has been series of investigations. Based on the theoretical explana- proved possible within the single species, as well as in tion of this effect, the next stage was inbreeding to find a a single geographically characteristic type, to attain in- possibility for similar results from cross-breeding within

678 Fifth Proceedings pure species or an even more pronounced reaction from This, fortunately, is no longer new, and there is now crossing various species. The experiments were success- progress in the utilization of controlled pollination. When ful, and there are now very promising experiments being this activity has been rationalized by drawing up the made in many places the world over. selected breeding trees, in rows and lines, which trees, This is merely a rough sketch of what has been done thanks to proper grafting and treatment, are small broad in the field of forest genetics and may be summarized as trees producing abundant male and female flowers, every the total of great knowledge gained in a few years. From one will be active and busy. The "cog wheel," the gen- a perception of the character of species from a botanical eration gear, are within reach, and now the experimental point of view and from a distribution according to geo- work and seed production can be started on a large scale. graphical types, we have reached a point where we make Seed storing is another factor of the greatest importance analyses of populations and individuals. At the same time, for the improvement of forest trees.First, because it is we have obtained numerous examples of how hereditary the best way in poor seed years of avoiding the use of characters may be stabilized and utilized in the improve- imported seed which may prove to be a serious danger. ment of forest trees. It is no secret that in the past it was a source of much However, even though the theory for the development damage. It is a pleasant feeling to possess an abundant of the genetics of forest trees may be correct, if it requires stock of the most promising seed. In the future it will be too much time and too much money in its application it of primary importance to distribute such seed grown in will not be used on a large scale. To overcome many of seed gardens, as need and requirement demand. the difficulties, I have, from the beginning, been one of In good seed years it is not only that large quantities those who strongly urge the utilization of vegetative re- of seed are produced, but the seed is of first grade, well production.It is wrong to speak of this as a scienceit pollinated, and well ripened, so that it is eminently suited is a very practical measure, which, in another way, has for storing.Genetic improvement of seed may require been in use for a very long time. Now we must accustom considerable time, but immediate forest tree improvement ourselves to using the method correctly for the advantage may influence the seed quality by securing the use of of our trees.It may then, both in theory and by practical seed from the best stands. For this purpose liberal stor- application of our experience, bring us a long step further. age of "vintage" seed will be valuable. In 1934, when I ventured to publish my first article It is of little interest whether in all the work which has on forest tree breeding, I expressed it thus: "The vegeta- led to the present high standard of forest tree improve- tive propagation, however, should not be undertaken ment, we have been among those who have looked solely for the purpose of future preservation and ex- through a microscope, or with those who handled the perimenting; it should also be made to serve a more grafting knife. We have all contributed to the final result. direct practical purpose, insofar as such graftings and Just as the individual has taken his stand according to cuttings may be planted at specially isolated places (later ability and working conditions, the work itself, in another called seed gardens) and thereby being protected against way, has been subject to diverging influences.In some outside pollination in such a way as to produce seeds from places, government initiative through forest service, state the desired pollination in great quantities." universities, and state forest experimental stations has been Today, more than twenty-five years later, I must admit of decisive importance; in other places, institutions have that it is hardly more than this same subject which has been established in which the scientific staff has been taken my time and my working capacity ever since. given excellent working facilities; in others, again, funds It is a wonderful feeling, when out in the forest with a have been secured for individuals who studied the problem gun, to know that one can shoot a twig off the top of the as a private hobby. These methods may prove equally selected tree and bring it home where it can continue its valuable, and the different forms under which the prob- life as a graft or a cutting. The portion of the tree brought lems have been faced testify to the fascination, vitality, home in this way possesses to the full the same inherited and importance of forest genetics and the improvement characters (genes) as the large tree from which it was of forest trees. shot down. However, it is much more convenient to work Today the question is world wide, and we owe a debt with the "twig" as a source for flowers and pollen, which of gratitude to the organizers of the Fifth World Forestry isthe actual driving factor in the entire large-scale- Congress for giving us the opportunity to discuss matters production unit. of common interest here in Seattle. Vegetative reproduction permits us to conserve first Not much attention was paid to forest genetics at the those trees which we believe to be good breeding trees. conference held in in 1936.Interest for the We can multiply them into as many specimens as we subject was apparent in Helsinki in 1949, and it was on require, and this without changing their hereditary char- the agenda at Dehra Dun in 1954.Since then, new, acters. With our latest knowledge of juvenile and adult valuable contributions have undoubtedly been made, and forms, we can utilize one and the same tree in various we look forward to hearing about them at this conference. ways in the analysis of its hereditary character.With We may rightly rejoice in the development and, in our some trees such as the hevea, and , there is a pos- optimism, have the courage to express wishes for the sibility for economic advantage merely by using selected future; however, it is perhaps reasonable to begin with a trees as clones for continuous vegetative reproduction. warning. By far the most important use of vegetative reproduction, When everything is going well, the danger signal should however, is as a technical aid for continuous pure breed- be hoisted. Too great concentration on a single problem ing. It is in this way that reproduction is most widely used may lead to isolationand that must not happen. We in forest genetics and the improvement of forest trees. are all mere links in a chaina help to, or a further Genetics and Tree Improvement 679 development of,silviculturenot something new and on the best treatment of existing stands and on the choice therefore better.It is silviculture which receives a new of plant material long before we have used it in the crea- tool from us so that forestry may stabilize a contact with tion of new strainsThere is, therefore, good reason to botany, physiology, plant pathology, pedology, entomol- advance and encourage genetics in silviculture by in- ogy, and other branches of natural science. By utilizing creasing the number of forest experiment stations and genetics we can present a better-known, more uniform giving the subject a place on the curriculum where lectures material so that we may all be on the same footing and on forestry are held. expect greater results. Let the planting machines start and let us rationalize As a dream come true I think of having a "phytotron" the work to the greatest extent possible by establishing at my disposal. At present, this is beyond the pecuniary "tree farms" and planting new forests.It is an under- possibilities of silviculture in Denmark, but I hope that taking of enormous importance, but in our eagerness we others here present may have one.It is an expensive must not disregard the fact that in planting we give good affair, but with the material already collected from many and poor plants identical growth conditions and that the sources and presented to demonstrate factors in forest later development of the is determined by the genetics, it is certain to give good returns on the invest- absolutely necessary which are not so well ment.With the help of a specially constructed and adapted for rationalization. We must also realize that equipped greenhouse where the single separate climate it is easier to work with the "good children" than to con- factors can be controlled, our material could be submitted trol an all-too-motley flock. An uncritical selection of to a more exact and especially a quicker analysis than plant material places a great burden on the future.It is the one we must struggle to make without the help of our duty to interfere as early as possible, even before such a "laboratory."Should you be so fortunate one planting. We must take the most suitable "cog wheel" we day as to have such an outstanding implement put at your can to start production.It will only be active at the disposal, you must not forget to invite the silviculturist alternation of generations, and its design and function on a visit. He would not only be shown our progeny make it the ideal tool for sharing in a great and rationally after controlled pollination and the collections of clones planned work. and our seed gardens, but he will wish to know what can It gives a happy feeling when there is a demand for be done in a climate house and other laboratories. We our work or our productsand with the increasing need have nothing to concealon the contrary, we wish to for wood, the future looks bright and full of possibilities demonstrate what can be done. By the closest possible for all of us who have anything to do with forests. We cooperation we would be able to strengthen a closer con- are at the same time on the way to a reorganization of our fidence in the basic principle, "the cog," which is of work. We are leaving behind us the past where "mining" decisive importance for the entire production. nature's accumulated deposits was the order of the day, Through identification with silviculture we strengthen and we are entering a period where utilization of the it and give it greater possibilities.This does not apply forests must be considered as one large, wide-spreading to the main objectthe production of woodalone, it industry.Its beginning is silviculture and in other forms will also give silviculture renewed strength to further the of forestry it passes on through , transportation, establishment of shelterbelts and windbreaks for the pro- sawing, and preparation for sale of many and various tection of settlements and farms. products which are to contribute to the higher standard I come from a country where one hundred to two hun- of living of more and more people.It is to this large dred years ago the lack of forests was keenly felt. By and vital industry that forest genetics must contribute. afforestations we have since more than doubled the forest The possibilities are almost without a limit, and it is up area. For me, this has been an example to illustrate how to those of us who lead the development to serve as the lack of forests can stimulate silviculture, forest genetics, often-mentioned "cog wheel" in the most beneficial way. and the improvement of forest trees.It is even more Just as water in rivers and streams must be tamed by obvious that in other countries, where forests are the engineers before it can be made to work for the benefit basis of a main industry, it is felt to be expedient to sup- of mankind, so genetics, one of the mightiest powers in port forestry by all the means at hand. These two points nature, must be regulated and controlled before it can be of view are given to show the common interest and the utilized. aggregate possibilities.Large and small must work to- The heritable factors, the genes in forest trees, must be gether. Silviculture must enlarge its contact with special- studied intensively, regardless of expense, and "sorted" istsof most different categoriesand in genetics we so that later we can make them work free of cost to possess an excellent instrument to promote international build up the castle of our dreams. relationships. By more comprehensive analyses of tree populations RESUMES and utilization of the results in silviculture, afforestations Pro grès réalisés en matière de génétique forestière et and treatment of the existing forest stands may be made d'amélioration des arbres more effective and rational.Problems such as spacing L'hérédité et le milieu combines donnent une forme definitive of plants, thinnings, evaluation of the severity of attacks a tout ce qui est anime. Ii est inutile de discuter de l'importance of fungi and insect pests, etc., are also part of the work. relative des deux facteurs dans la formation de l'individu:ils For many of us the primary object of our efforts is to raise sont comme un couple bien assorti, ou bien, comme deux jambes avancant ensemble en partenairessurIavoie du bien-être trees of better qualityand in many cases this now seems commun. possible. In doing this we must not overlook the fact that Nous n'abordons pas le domaine de la génétique forestière many an analysis can give silviculture valuable guidance etdel'améliorationdesarbresdesforêtsdansl'intention

680 Fifth World Forestry Congress Proceedings d'introduire quelque nouvelle "invention" ou bien de préférer cada factor en esta formación comdn del individuo. Son como quelque chose de nouveau a l'expérience infiniment variée en una pareja bien avenida o un par de piernas avanzandojunta- sylviculture, des générations qui nous ont précédés. mente por el camino del provecho comdn. Et bien que nous reconnaissions que le niveau de Ia sylvicul- Si entramos en el dominio de lagenética forestal y del ture soit au point le plus haut grace a l'utilisation du milieu, mejoramiento de los árboles del bosque, no es para introducir iiy a mainte raison de temr également compte de l'autre ningdn nuevo invento, o para preferir alguna novedad frente a partenaire. Certains d'entre nous semblent croire que la sylvi- la multiple experiencia en silvicultura de las generaciones pasadas. culturea tout bonnement avancé clopin-clopant, que l'on a Sin embargo, aunque reconozcamos que el nivel de la silvi- abuse de l'un des partenaires,le milieu, lequel a tralné une cultura es más alto que nunca, porque se han tenido en cuenta part trop importante de la charge, ce qui a fait que l'autre, losfactores ambientales, hay razones suficientes para tomar c'est-à-dire la génétique, n'a pu maintenir la cadence qu'avec también en consideración al otro factor. Algunos entre noso- difficulté. tros creen que Ia silvicultura ha desmerecido un tanto, porque On n'a jamais manqué de preuves de l'importance de la este dnico factor, el medio ambiente, ha sido forzado tanto y génétique en sylviculture, comme le montrent les longues series ha arrastrado una carga tan pesada, que ha sido difleil para el otro d'expdriences faites en de nombreux pays et remontant assez factor, Ia genética, mantener el mismo paso. loin. Ce qui est plutôt étonnant, c'est que, dans les écrits traitant de cc sujet et remontant si loin en arrière, on puisse rencontrer No han faltado nunca pruebas de la importancia de Ia ge- des projets d'utilisation de la génétique en sylviculture qui n'aient nética en silvicultura, como lo demuestran largasseries de jamais été réalisés. experimentos en varios paises y desde fecha antigua. Lo que Du domaine de Ia sylviculture, nous avons jeté des regards es más de extraflar es que la bibliografIa sobre lamateria sea admiratifs vers l' et l', oi Ia génétique tan antigua y que en esta literatura encontremos muchos planes a donné des fruits plus abondants. Mais les méthodes utilisées para utilizar la genética en silvicultura, que no se hanilevado nous ont rendu aveugles et nous ont fait croire d'abord qu'elles a cabo. étaient les seules possibles. Finalement, nous avons rompu avec Desde el campo de la silvicultura miramos con admiración a elles et avons suivi notre chemin a nous, avec une nouvelle corn- la agricultura y horticultura, donde la genética ha dado cose- binaisonla formation végétaletelle qu'on Ia connait depuis chas más abundantes. Los métodos usados nos habIan deslurn- des temps très reculés, combinée aux plus récents résultats de brado y nos habIan hecho creer al principio que eran los dnicos La génétique. posibles. Al final hemos cambiado de punto de vista y hemos En utilisant Ia reproduction végétative sous forme de greffe emprendido nuestro propio carnino con una nueva combinación- de boutures,etc.,on peut inclure tout arbre sélectionnéet La formación vegetativa, tal como se conoce desde los tiempos exceptionnel dans notre analyse de ses facteurs héréditaires et antiguos, junto con los resultados mds recientes de la ciencia l'utiliser pour lesgénérations a venir. La multiplication con- genética. tinuelled'individussélectionnésnous permet d'augmenterla Utilizando la reproducción vegetativa en forma de injertos de quantité de semences et par la pose convenable de greffes dans rarnitos, yemas y ramos, etc., es posible incluir cualquier árbol ce qu'on appelle des jardins a semence, nous sommes aussitôt en seleccionado y excepcional en nuestro análisis de los factores mesure, par la pollinisation artificielle, de produire des semen- hereditarios y utilizarlo para futuras generaciones. La multi- ces dans les quantités désirées. plicación continuada de individuos selectos nos permite aumentar Les plantes herbacées, donnant des semences chaque année, Ia cantidad de semilla y La adecuada aplicación de injertos en ou tous les deux ans, ont donné aux agriculteurs l'idée d'amé- los llamados jardines productores de sernilla, nos ponen pronto liorer la culture en utilisant l'alternance fréquente des générations; en situación de producir semillas en la cantidaddeseada por mais comme pour les arbres il faut cinquante ou cent am pour medio de la polinización controlada. une seule génération, l'optimisme des sylviculteurs a diminué Las plantas herbáceas, que producen semilla anualmente o en ce qui concerne cette méthode. cada dos anos, han estimulado a los agricultores a mejorar Ia Cependant, en utilisantIapropagation végétative,lesylvi- especie, utilizando frecuentes alternaciones de generaciones; pero culteur peut maintenir,multiplieretutiliserde touteautre el método ha enfriado ci entusiasmo de los silvicultores, puesto manière de beaux specimens d'arbres en vue de la reproduction, que se necesitan cincuenta o cien años para una generaciónde pour autant qu'il trouve avantage a le faire.L'agriculteur ne peut agir ainsi: ses plantes meurent dans l'espace d'un ou deux árboles. ans. Sin embargo, usando la reproducción vegetativa ci silvicultor es Cette méthode combinant l'aptitude avec certains des der- capaz demantener,multiplicar yutilizar deotros modos, fliersrésultats de lagénétique, présente des avantages par- árboles valiosos para la reproducción, mientras resulte ventajoso. ticulièrement importants dans l'hétérosis.Son importance dam El agricultor no puede hacer ésto. Sus plantas mueren a! cabo de Ia pathologie des plantes et l'entomologie eat soulignée de la uno o dos aflos. même facon. On exprime l'espoir que des "serres climatisées" El método ofrece ventajasparticularmente grandes en la seront utilisées en sylviculture pour la culture des arbres et que heterosis, combinando la habilidad y otros de los resultados l'emmagasinage des semences sera encore amélioré. más recientes de la genética. Se insiste asimismo en su im- Vu queIagénétiqueaffectelesphénomènesbiologiques portancia para La patologia de las plantas y la entomologIa. fondamentaux, elle devrait être considérée comme une des meil- Se espera que se usen en silvicultura "invernáculos clirnatiza- Leures voies pour établir des contacts internationaux. dos," para Ia reproducción de las plantas y que se desarrolle En revenant a notre point de départle milieu et l'hérédité- el almacenamiento de las semillas. on ne devrait pas oublier qu'un meilleur milieu depend en général Puesto que la genética afecta a los fenómenos bioiógicos de "dépenses courantes" continuelles et que des possibilités géné- básicos, debe ser considerada como uno de los mejores medios tiques accrues sont concentrées dans les processus de propagation. Dans le cycle entier parcouru par les forêts, le changement de para hacer contactos internacionales. génération, c'est-à-dire Ia naissance d'un nouvel arbre est d'une Si volvemos a nuestro punto de partidaherencia y medio durée très courte et est un bon objet pour la rationalisation. Les ambienteno debemos olvidarelhecho de que un medio genes inhérents aux semences travaillent gratuitement en temps arnbiente mejor depende de "gastos de explotación" constantes utile, tandis que nous, d'autre part, par une utilisation peu judi- y que el aumento de las posibilidades genéticas se concentra en cieuse des semences, nous hypothéquons l'avenir. la reproducción. En Ia rotación completa del bosque, el cambio de generación, es decir la reproducción, es de muy pequefia Pro gresos en Genética Forestal y Mejoramiento de los duración y es un objeto adecuado para Ia racionalización.El Arboles gene incluIdo en la semilla trabaja libre de impedimentos a La herencia y el medio ambiente, juntos, dan forma definitiva su debido tiempo, mientras que nosotros, por otra parte, con a todo lo viviente. Es indtil discutir la importancia relativa de un uso sin crItica de la semilla, acumulamos cargas para elfuturo.

Genetics and Tree Improvement 681 Propositions pour faciliter l'échange du materiel de plantation

GIAc0MO PIccARoLo Direttore, Istituto Nazionale per Piante de Legno, Turin, Italie

Nous avons acceptélaproposition detraiterce definitions des objets, pour contrôler et désinfecter le problème, mais non pas avec l'intention d'apporter une materiel qui fait l'objet de l'échange. contribution decisive a cette question déjà discutée au Ii nous semble plus urgent pour le moment, de parvenir cours de précédents congrès forestiers, et qui demeure a un échange commode et rapide de materiel. encore en suspens, a certains égards. Bien que cela soit presque superfiu, établissons tout Durant le XIe congrès de 1'Union Internationale des d'abord la distinction entre ce qu'on définit comme le Instituts de recherches forestières, qui s'est tenu a , materiel de plantation a demeure pour la pratique normale M. J. Macdonald (Angleterre), qui avait suivi les travaux du reboisement, et ce qu'on définit comme = le materiel relatifs aux essais des semences a Dublin, déclarait que de plantation destine a la recherche scientifique et a l'accord avait été a peu près atteint sur tous les points; l'expérimentation pratique. cependant, la principale question non résolue, était la Ii s'agit évidemment dans le premier cas de grandes definition du mot "semence pure." A cet effet, on avait quantitéset l'échange relève du commerce.Dans le décidé d'adopter pour les échanges internationaux des deuxième cas, au contraire, II s'agit de quantités limitées, semences,laméthoded'essaidite"rapide"(quick et l'échange s'effectue en dehors de toute speculation method) de préférence a la méthode dite "rigoureuse" commerciale. (thorough method). Une autre question importante fut Cette distinction faite, précisons que, pour le but que celle d'inclure dans la règlementation une description des nous nous proposons, nous nous référerons exciusivement méthodes rapides de germination des semences dures ou aux échanges de materiel destine a la recherche scientifi- a germination retardée. que ou a l'expérimentation pratique contrôlée, effectués Au cours de la même reunion, M. H. van Vioten par des instituts, organismes ou chercheurs qualifies. déclarait que ce qu'on demandait au Conseil,c'était L'utilité générale des echanges internationaux du ma- d'approuver une nouvelle règlementation concernant les tériel de recherche et d'expérimentation, tel que semences, essais de semences sur Ia base desquels seraient faits les pollens, branches a fleurs a faire éclore, scions et boutures, echanges internationaux de semences des espèces fore- n'aurait pas non plus besoin d'éclaircissements ni de stières; exprimait l'espoir que la FAO se chargerait de ces confirmation. Toutefois, pour mieux souligner la nécessité fonctions. d'en schématiser le développement, nous nous permettons M. Guillebaud, a son tour,fit des voeux pour que d'attirer l'attention en faisant une breve énumération de l'UnionInternationaledesInstitutsderecherches quelques-uns des principaux buts pour lesquels ii est utile forestières se maintienne en contact étroit avec l'Associa- et méme nécessaire d'effectuer les operations projetées en tioninternationaled'essaide semencesetque des temps opportun. spécialistespourlesessaisdesemencesd'espèces L'introduction des semences se pose comme premiere forestières soient invites a participer aux travaux des phase des essais d'acclimatation d'espèces nouvelles reunions ultérieures. dont la culture est desirable. Les semences sont le materiel de propagation le plus commode et le plus Nous ne voulons pas, par contre, nous engager dans sflr, le mieux contrôlable, et celui qui se soumet le l'étude des développements successifs de ces initiatives, mieux au traitement de désinfection propre a éviter même si elles font partie de la contribution que des l'introduction des maladies.Bien entendu, l'emploi spécialistes en la matière ont donné et donnent encore a de ce materiel est soumis aussi a certaines exigences la solution d'importants aspects du problème. saisonnières, aussi bien pour une bonne réussite que A la lumière de l'experience acquise au cours de longues pour éviter les pertes de temps. années de travail, avec un intérét particulier pour tout ce Le pollen et les branches fleurs dont on cherche a qui a trait en particulier aux échanges de semences, de obtenir l'éclosionafin de pouvoir, a partir de là, pollens, et de boutures, nous voudrions exposer ici quel- executer les croisements, representent deux moyens ques vues limitées a la question des operations de transfert permettant d'agrandir le champ des hybridations les proprement dit du materiel. plus intéressantes et de les accélérer. Par ces moyens, Aussi ne nous attarderons-nous pas a approfondir les la gdnétique appliquée a fourni, et fournit encore, les problèmes scientifiques auxquels les dchanges pourront résultats les plus brilants et d'une grande importance donner lieu, pas plus que nous ne nous sommes attardés pour tous les pays. sur les moyens et les modalités selon lesquels le materiel Dans ce cas aussi, tout contretemps peut nous amener devrait étre préparé, cette question étant du ressort des adesdéphasagesqui peuvent compromettrela spécialistes qui pourront proposer et discuter les normes recherche, ou du moms nous amener a de notables concemant les procédés les plus appropriés a établir les retards dans les résultats.

682 Fifth World Forestry Congress Proceedings 3.Les scions et les boutures, enfin, se prêtent a deux L'accélération des échanges presuppose deux mesures formes de recherches. L'une est encore l'introduction préalables: de nouvelles espèces a acclimater et a experimenter, Connaitre et énumérer les pays et leurs respectils et représente le moyen le plus direct, qui favorise le Institutsqualifiés---qui désirent entrer en contact pays dans lequel on procède a l'introduction. L'autre pour instaurer des rapports de collaboration sur des est la distribution sur une vaste échelle a de nombreux schémas méthodiques et constructifs. chercheurs et expérimentateurs, du materiel dont le Diffuser les connaissances relatives au materiel dont pays d'origine fait l'étude et l'essai, et pour lequel ii chacun dispose,qu'ils'agissed'un materiel déjà recourt a la collaboration compétente d'autres pays sélectionné, ou d'un materiel encore dans la phase que ces résultats peuvent intéresser. Ce dernier pro- d'essai ainsi que celles relatives aux problèmes pour cédé est celui qui a été largement employé par l'Institut lesquels les intéressés désirent instituer la collabora- d'expérimentation pour la populiculture de Casale tion. Monferratoafind'accélérerlaconfirmationdes L'initiative personelle fait deja beaucoup dans ce do- résultats obtenus et des caractéristiques établies par la maine, et nous pourrions citer les très nombreux échanges constitution de nouveaux clones dans le domaine de de ce genre qui se pratiquent déjà en Europe et dans la populiculture. d'autrescontinents.Nous saisissonsici l'occasion de Les essais longuement répdtés dans un même milieu, rappeler la collaboration que nous menons avec des même s'ils sont exécutés soigneusement et menés selon chercheurs des Etats-Unisle Professeur Schreiner, le unerigoureuse méthodestatistique,n'aurontqu'une Professeur Scott Pauley, M. Mac Gowin, M. Stauffer et signification relative a ce qui s'est produit dans ces lieux et du Canadale Professur Heimburger, M. Nordin, pour limitée a cette période de temps. Pour parvenir a des ne citer que quelques noms. conclusionsplussatisfaisantes,IIfaudraitprolonger Mais, comme nous l'avons dit, tout cela se fait par l'expérimentation pendant de longues périodes de temps, initiatives personnelles et souvent, par consequent, au notamment en raison des facteurs de variation qui, comme milieu de difficultés et de retards qui nuisent au succès et par exemple les vicissitudes saisonnières, ne peuvent pas a Ia bonne marche des experimentations. L'Union Inter- toujours être reproduits artificiellement. nationale des Instituts de recherches forestières, ou mieux Par contre, par une large distribution du materiel a la section forestière de la FAO, pourraient fort bien pour- l'essai, non seulement dans le pays d'origine, mais encore voir a la tâche de dresser et tenir a jour les listes des auprès des expérimentateurs d'autres pays, on pourrait Instituts retenus capables de donner une sure garantie obtenir des relevés plus nombreux, grace a un champ d'un régulier développement des échanges en observant d'enquêtes plus vaste, ce qui permettrait de parvenir, dans les normes génerales qui seraient établies, avec le souci une période de temps appréciablement plus courte, a des d'abréger les formalités administratives et bureaucratiques, conclusions plus convaincantes, pour passer ensuite a aussi bien pour faciliter les échanges que pour Ia defense l'exécution pratique. Ce gain de temps est aussi de la phytosanitaire. plus grande importance pratique, car étant donné les La phase Ia plus delicate, cela va sans dire, est celle variations sensibles des besoins, de la technique, des ap- qui a trait au déroulement des echanges,c'est-à-dire plications industrielles d'aujourd'hui, il pourrait se faire l'expédition et le retrait du materiel, en évitant les con- qu'une fois les buts de la selection atteints, ceux-ci ne tretemps, les immobilisations qui paralysent les initiatives. correspondent plus aux nouvelles exigences du moment, En particulier,lemateriel périssableestsujet, pour aux nouvelles situations industrielles et commerciales. diverses raisons, aux pertes, aux dommages, ou bien aux Et ainsi,le long travail accompli pourrait devenir retards. inutilisable. Ce ne sont naturellement plus les moyens de trans- Des considerations analogues sur la nécessité d'étendre port qui font défaut, car le problème en ce sens est par- rapidement l'expérimentation auprès de nombreux pays faitement résolu. nous sont suggérées aussi en vue de determiner les possi- Nous reconnaissons que toute nation a le droit de se bilités de constituer de nouveaux types de plantes suf- protéger contre l'éventuelle introduction d'agents parasites fisamment adaptables a des milieux divers.Sans aucun de nature variée, et nous connaissons fort bien les dan- doute,les techniques de culture ont fait de notables gers qui existent.C'est pourquoien se rapportant a la progrès, de sorte que l'homme peut même intervenir dans distinction déjà faite entre le materiel de propagation a certaines limites pour modifier plusieurs facteurs, soit en employer dans la grande culture et le materiel a propager mettant a profit les lois de la nature, soit en employant des dans les limites de l'expérimentationil ressort que, pour moyens artificiels.Toutefois,iisera toujours utile de le premier qui demande presque touj ours l'expédition de retenir, parmi les facteurs de selection, la nécessité d'avoir grandesquantités,l'applicationdesdispositionsque des espèces ligneuses qui possèdent un notable degré chaque pays a pris pour sa protection est absolument d'adaptation a des miieux divers. nécessaire, et que, par consequent, les formalitCs et les Pour pouvoir arriver plus vite,et surtout avec plus interventions requises par les autorités spécialisées sont de certitude, a cette caractéristique, il est bien entendu indispensables. très utile de multiplier les essais sur les nouvelles variétés, Par contre, pour le materiel de recherche et d'expé- les nouvelles espèces, les nouveaux "cultivars", les nou- rimentationsemences, pollens, branches a fleurs pour veaux clones, etc. non seulement dans les pays d'origine, les hybridations (flowering branches for breeding), racines mais encore dans d'autres pays. D'oü la grande utiité et parties de racines, bourgeons, scions, bouturesil est de pouvoir assurer un échange rapide et commode du nécessaire d'éviter les difficultés qui se prdsentent a chaque materiel experimental. passage de frontière. En effet, ces obstacles, comme nous

Genetics and Tree Improvement 683 l'avons dit, ont été établis pour assurer Ia surveillance qui non convenables et par un personnel qui n'est pas tou- est nécessaire pour les grandes quantités destinées a la jours competent, peuvent presenter des risques. grande culture. Par cc moyen, on excluerait les envois aux organis- En raison de ces obstacles, ii n'est pas toujours possi- mes centraux des différents pays, toujours pour éviter que ble de suivre et de verifier le materiel sur les lieux de ne se produisent les dommages mentionnés précédem- destination au cours de l'emploi et a travers les phases de ment. laculture,et par consequent, un contrôlesanitaire Dc fait, des echanges, plus ou moms aléatoires, ont ultérieur devient alors difficile. déjà pour de trèspetitesquantités,et pour certain Dans Ic cas du materiel scientifique, par contre, étant materiel (pollen, semences, boutures), et les scrupules donné la nature du materiel et les faiblesquantités exercés par les Instituts de recherche ont prouvé qu'on employeesla surveillance et le contrôle de la prépara- peut faire confiance a cette procedure. tion et des traitements, de l'emploi et des développements Certains pays, comme les Etats-Unis, le Canada, pour successifs, deviennent notablement plus aisés. On pour- recevoir le materiel, se chargent d'envoyer au prdalable rait éviter ainsi l'introduction et le développement des aux pays expéditeurs des étiquettes spéciales a appliquer maladies,l'envoiétaitfaitdirectementdel'Institut sur les envois et y joignent des formulaires pour les expéditeural'Institutdestinataire,qui observeraient declarations phytopathologiques qui constituent le laisser- l'engagement réciproque d'adopter des mesures de pré- passer pour les pays destinataires. Mais il semblerait que caution bien établies aussi bien au depart qu'à l'arrivée. même cette mesure n'ait pas toujours été suffisante, et Nous avons voulu considérer avant tout la possibilité des dispositions plus générales et plus strictes a faire con- d'uri échange par l'intermédiaire d'une sorte de "clearing- naItre aux organisations douanières et phytosanitaires house."Celui-ciprésenteraitsansaucun doutedes instaliées aux frontières de tous les pays qui voudraient avantages et surtout celui d'assurer le respect des con- se soumettre a cette convention particulière,seraient trôles et des traitements de désinfection, en fournissant peut-être nécessaires. une veritable garantie aux intéressés,et en tout cas Vu les avantages et les inconvénients que présentent les pourrait éventuellement s'avérer utile pour les grands différents systèmes,il semblerait opportun de faire les échanges commerciaux, qui toutefois ne sont pas con- propositions suivantes pour faciliter l'échange direct du sidérés dans la présente étude. materiel destine a l'expérimentation, entre les Instituts Mais, en suivant ce système, nous nous heurterions ou, en tous cas, entre organismes officiellement reconnus toujours a des transports supplCmentaires,a d'autres auprès des pays interesses. pratiques bureaucratiquesetadministratives,a l'éven- Une foisconstituéel'organisationinternationale, tualité d'arrêts inopportuns, a des mises en quarantaine par exemple auprès de la section forestière de la F.A.O. dans des conditions ambiantes qui ne seraient pas tou- les ministères compétents des différents pays adherents jours celles du pays expéditeur, ni celles du pays destina- devraient chacun lui communiquer les listes tenues a jour taire.Chacun peut alors se rendre compte a quel point des Instituts qui peuvent être en mesure de satisfaire aux pourrait être compromis le succès d'initiatives du plus exigences de la protection phytosanitaire, relatives aux haut intérêtetd'une grande portée pour l'économie échanges directs dans un but scientifiquede semences, même des pays intéressés. pollens, branches a fleurs (flowering branches for breed- D'autre part, un "clearing-house" ne supprimerait pas ing) racines et parties de racines, bourgeons, boutures et complètement les obstacles qui se posent a la frontière de scions, a l'exclusion de toute formalité douanièrepour chaque pays, sinon en faisant intervenir d'autres accords desquantitésqui ne dépassent pas leslimitesdes particuliers pour éviter que les envois ne subissent de recherches et des experimentations a accomplir. nouveau Ia longue série d'arrêts et de verifications qui A son tour, cette organisation internationale devrait reproduiraient les mêmes inconvénients. assurer la communication de ces listes aux autres nations, L'CchangedirectentrelesdifférentsInstituts,qui de manière a leur faire connaitre les matériels disponibles seraient homologués par une organisation internationale pour les espèces qui les intéressent, et les mettre au crëée a cet effet, sans aucun doute pourrait presenter courant des problèmes étudiés. d'évidents avantages de rapidité et d'opportunité, qui con- La même organisation internationale devrait assurer tribueraient a la bonne execution des recherches et des l'élaboration des règles selon lesquelles on doit procéder experimentations projetées. pour preparer le materiel pour les expeditions, afin qu'il La garantie fournie par le "clearing-house" a propos puisse parvenir en bon état, scion le type du materiel, les de l'exécution des operations de désinfection, de misc en distances, les moyens de transportct afin qu'on puisse quarantaine, devrait être remplacée par le formel engage- executer les operations de désinfection qui s'imposent. Des ment, de la part de chaque Institut, d'exécuter les vérifica- mesures de precaution analogues, surtout pour éviter tions et les operations phytosanitaires analogues, aussi l'introduction d'agents parasites, devraient étre suggérées bien au depart qu'à l'arrivée, en fournissant au préalable pour la reception a l'arrivée. la preuve de posséder l'équipement nécessaire aces Les Instituts expéditeurs et les Instituts destinataires operations et en assumant la responsabilité de la bonne devraient s'engager a observer scrupuleusement les règle- execution de celles-ci. ments susdits et toute autre regie établie par l'organisation La garantie de la competence des Instituts constitue internationale, en prenant la responsabilité des incon- done la base de la confiance qu'on devrait mettre dans vénients qui pourraient survenir par leur faute dans ce système d'echange direct.Sur cette base, on devrait l'application des normes en question. abolir toute formalité douanière, toute manipulation des La preparation des envois, en pius des avis néces- emballages, manipulations qui, faites dans des milieux saires a la protection et a ia conservation du materiel 684 Fifth World Forestry Congress Proceedings pendant le voyage, devrait comporter des étiquettes et des pas examine cc qui a trait aux règles qui devront néces- emballages ayant des caractéristiques typiques et uni- sairement faire partie d'une règlementation generale, con- formes, permettant une rapide identification. cernant l'équipement dont lesInstitutsautorisés aux Les envois devraient toujours être accompagnés d'un échanges directs devront étre munis, ni aux règles a fixer formulaire standard, fourni par l'organisation interna- pour la désinfection au depart et a l'arrivde. tionale, attestant la provenance et la nature du materiel Nous n'avons done pas spéciflé cc qui a trait aux expédié. engagements et aux garanties réciproques. L'organisation internationale devrait aussi fournir- Tout cela devra faire l'objet de tractations de la part contre remboursementles étiquettes en question,les d'une commission de spécialistes nommés a cet effet. emballages(enveloppes,boItes,feuilles,toiles-sachets, etc.) et des cachets-types de modèle et de couleur unique, RESUMES aux inscriptions bien visibles, et la declaration du contenu: Proposals for Facilitatingthe Exchange of Breeding "materiel scientifique périssable qui voyage en franchise Material de douane et de formalités phytopathologiques, a faire Firstly, in making proposals for facilitating the exchange of passer sans ouvrir, selon la convention internationale .. breeding material, a distinction is made between material for (citer les extraits du règlement qui s'y rapportent). large-scale cultivation and material for scientific research and Nous avons tenté de donner au sujet qu'on nous a con- experimentation. The author confines himself to the latter. Having considered two possible types of exchange, one through flé,un développementcorrespondantal'expérience a clearing house, and the other on the basis of direct exchange acquise durant plusieurs années de travail, travail qui between qualified institutions, he thinks that the direct exchange nous a convaincus de l'utilité, et même de la nécessité system would be more reliable for practical and scientific purposes. de faciliter les échanges internationaux du materiel de In this connection, he outlines briefly the standards and means whereby the organization could be established, after the institu- recherche pour l'acclimatation, la selection, et l'améliora- tions had been accepted and recognized by a central agency under tion des espèces ligneuses. Nous ne nous cachons pas the FAO Forestry Service. que pour réaliser ce que nous avons suggéré,iisera nécessaire de surmonter de considérables difficultés, mais Proposiciones para Facilitar el Canje de Material de les avantages qui peuvent en denver, a notre avis, doivent Cultivos inciter a aifronter celles-ci. Como es lógico, para presentar proposiciones respecto a facili- Le système propose, comme nous l'avons dit, est fondé tar el canje de material de cultivos, es necesario establecer la sur l'honnêteté qui doit être implicite dans la nature diferencia entre el material para grandes cultivos y el material même des organismes appelés a le faire naItre.D'autre para investigaciones cientIficas y experimentos.El autor trata preferentemente este Cltimo aspecto. part, cc système peut presenter l'avantage de fournir une Habiendo considerado dos posibilidades de canje, una por assurance veritable du materiel échangé en ce qui concerne intermedio de un "centro de distribución" creado al efecto y la l'identité des variétés, des espèces, des "cultivars" et des otra a base del canje directo entre los institutos interesados, juzga clones (contrôle varietal), cc qui est un élément d'intérét más seguro, para fines prácticos y cientIficos, el canje directo. Al respecto, presenta un pequeño plan de normas y métodos segim considerable, comme l'ont démontré les travaux de la los cuales se puede constituir el organismo central después que se Commission Internationale du Peuplier. hayan reconocido y conceptuado los institutos por un órgano Comme nous l'avons indique au debut, nous n'avons central bajo Ia dirección del Servicio Forestal de la FAO.

Problems and Proposals for International Forest Tree Seed Certification

ERNEST ROHMEDER Direktor, Institut für Forstsamenkunde and Fflanzenzflchtung, Munich, Germany

Introduction it is necessary to import seed until the newly grown trees Today forest seed often will be shipped from one have reached maturity and will be able to supply sufficient country into another. The reasons for such a shipment or seed. exchange of seed may be: The quality of each seed lot being shipped from one Growing tests of a tree species out of its distribution country into another should be covered by certificates. district, often even in other continents; The characteristics of a seed lot may be evaluated from Growing tests of local breeds of a special tree species two principally different points of view: in a foreign country; The genetic value may be declared most clearly by Provenance growing tests; a provenance description, provided the seed in question Forestry growing of a new, imported tree species as is not a cultivated variety of a tree species with genetic soon as the cultivation of that new species seems to be certificates. established in a special district.For the latter purpose, The somatic value of a seed, the temporary condi- Genetics and Tree Improvement 685 tion, will be shown by the reports of the seed testing within a stand in most cases will be fertilized by pollen stations. of the surrounding trees, this fact will effect an isolation. Last, but not least, the identification of a seed lot will be The isolation effect will be increased if a stand of trees is most important. Even though there are certificates for composed of only a few trees and if other trees of the provenance and conditions (e.g., purity and germination) same species are far off.While climate selection and for a certain seed lot, there is not always a satisfactory isolation will constrict the gene constituent, the spectrum guarantee for the last receiver of the seed that he will of genes will be enlarged a little by immigration and really get that seed certified by the one who harvested it. mutation. In every case for the future it is necessary to pay more attention than today to the diversity of gene The Genetic Value of a Seed Lot (Provenance Question) components of individual stands and to require the most The results of forestry provenance research, based on exact provenance designation for each seed, especially for international cooperation and on the work of many seed used for experiments. Only in that way does it seem countries for 60 years, produced the universal acknowl- to be possible to get seed again with approximately cor- edgement thatthe provenance questionisofgreat responding gene factors from the same stand which economic importance. previously resulted in exceptionally good plantation. Com- A certificate showing the genetic value of a seed lot plete agreement of gene factors is not to be expected shall report the tree species, packing manner, designation, though, if the same stand is harvested at several times, harvest time, a characterization of the place where the because not the same trees fructify every year, and the seed has been harvested, the stand, and, if harvested supply of pollen will vary in quantity and quality from from a single tree, a description of that tree. year to year. The general designation of a seed lot must show the Therefore,itisnecessary to designate the district, tree species by its popular Latin name, author's name community, etc., in addition to the provenance country, included, in order to prevent a confusion of synonyms, the governmental forestry administration which inspects and by its common name as used in the language of the the forest, and the name of the owner of the forest. The country of origin. Furthermore, it must show details of the place of harvesting is designated by name of the local manner of packing (e.g., tins, linen sacks, etc.), the weight forest, or, if the seed has been harvested from stands, by of the seed lot, and the harvest time. For the latter it is the next higher unit of area (district, forestry adminis- not sufficient to have only the year of harvest, because tration, etc.). with tree species being harvested from autumn to spring, The place of harvesting will be approximately, if not the year alone does not properly designate the time of exactly, fixed by its longitude and latitude.Absolutely harvestingTherefore, in this case it seems to be neces- necessary is the designation of height above sea level (if sary to add the harvesting month (e.g., Nov. 1952) or to possible, with its lower and upper limits) demand a designation by two years (1952/53).If the The exposition may be designated by the aspects (N., seed is to be shipped under seal, the manner of sealing is NE., E., etc.); the slope, by remarks such as "level," to be reported. "slight," "steep," "very steep," or by reporting degrees The place where the seed has been harvested is to be or percentages. To be desired are remarks on the geologi- described as exactly and as completely as possible. The cal origin of the parent rocks, type of soil, and forest forestry seed laws or harvesting instructions of some sociological association, if known. countries, or the trade custom in many cases, feel satis- If possible, a map on which the place of harvesting is fied with a provenance statement of wide districts with marked should be added to the provenance certificate. approximately equivalent climate and sites.If such prov- If the seed lot has been harvested from only one stand enance districts include several square kilometers or even the characteristics of the stand should be designated as several hundred square kilometers, special breeds on the accurately as possible. In the case of uneven-aged stands, smallest habitats have been developed by selection of the age should be reported as the average age, and the site and climate in a thousand years' time. But although upper and lower limiting values should be given. Most the climate conditions may be as uniform as possible, important seems to be the designation of the origin of various stands of trees of a uniform growing district may the stand being harvested, i.e., if it is indigenous, prob- strongly differ one from another within their gene com- ably indigenous, unknown, or introduced. The climatic ponents and may, therefore,show largedifferences, selection of the stand can have become completely effec- hereditarily caused, among their growth capacities. Prov- tive only in indigenous stands, while in the other extreme enance tests of the last years, in which several stands of case, by introducing a provenance foreign to the stand, a the same tree species have been harvested and their seed selection by climatic factors will work out only slightly has been grown in test plots, have confirmed that fact in the first generation, because extreme climates, such as that such differences are also to be expected in narrow extreme frost during the winter or extreme dryness dur- districts with nearly uniform climate.Investigations of ing the summer, often occur only once in a number of the young scienceof population genetics have also years and not regularly. In case of doubt, the origin of revealed this genetic differentiation among different stands the stand should be reported as "unknown" or "uncer- in the same growth regions; because in the distribution of tain." In some cases, the question of origin will be some- genes, besides climatic selection, some other factors are what elucidated by remarks on the mixture of tree species active, such as chance happenings concerning the dis- and establishment. Well mixed and naturally rejuvenated tribution of types when the area was first covered by stands are a sign of a natural, original forest, while the trees (predominance of more or less productive types), provenance question in artificially grown monocultures isolation,immigration, and mutation.Since the trees is always to be examined very exactly.In mixtures of

686 Fifth World Forestry Congress Proceedings tree species the percentages of the volumes of the con- forestry commissions, issue the certificates.Sometimes tributing species are to be reported in addition to descrip- the owner of the forest or his agentespecially if suitably tive remarks such as "pure stand" or "mixed stand." instructedmay be allowed to issue certificates if they For origin of stand,designations such as "natural are later confirmed by the forestry authorities. rejuvenation," "seed," "plantation," "mostly seed, some- On principle, only one uniform certificate form should what improved by planting," etc., are sufficient. be used all over the world for that purpose. FAO-Rome, While density may be designated by descriptive terms in 1952, proposed such a form (FAO 52/10/6055) and such as "dense," "normal," "light," "sparse," or "spotty," recommended it to its members. In my opinion, it is the the stocking density should be expressed as a percentage task of this Congress to decide on a uniform provenance of the volume of full stocking. certificate, e.g., we should improve or enlarge the FAO The growth capacity of the stand being harvested form. The author of this report has outlined such a form should be reported only exceptionally by such general (based on the FAO form and the provenance certificates terms as "very good," "good," "average," or "bad"; the used in Switzerland) that has been attached to the Con- site class indication yield according to clearly defined yield gress documents.Perhaps it will serve as a guide for tables is preferred. In addition, it may be recommended the adoption of a uniform form. that the average height be reported, because this, in con- lit seems to be rather difficult to estimate the cost of a nection with the age, makes it possible to correlate it with proper certification of seed provenance. Costs will differ other yield table data. with the intensity of forestry. In one country there are Desired, but not absolutely necessary, are statements good stand descriptions of all the forests being harvested of the averages of stem quality and crown structure. and these are available to the forestry authorities.In Finally, a statement would be desirable concerning the this case, the issuance of a provenance certificate needs number of trees from which the whole lot, not only the less than an hour of work. But if these descriptions are portion delivered, has been harvested.Theoretical con- not available and must be collected on the spot, up to a siderations of population genetics lead to the expectation day's work may be needed, depending upon the terrain of inbreeding depressions and yield reductions in the F2 and the circumstances of accessibility. generations, when the number of harvested trees is very If all countries of the world with regulated forestry small.This danger existsespecially with smalltest would certify the provenance of seed by a uniform form, plantings.If, of a particular seed, only 0.5 kg. or less is and if these certificates of each country were approved wanted and there is no greater need of it, it is possible to by all others, then, in my opinion, there would be no need fulfill the demand of the buyer by harvesting only one of a central certification authority, as may be suggested tree. In this case all plants grown from that seed supply by others. are half-brothers and half-sisters or perhaps full ones. Certain tasks of coordination and development of such They all have the same mother and some (in an extreme a procedure might be taken over by the forestry branch case, perhaps all), the same father. By such inbreeding of FAO. the proportion of heterozygotes will be decreased, and that of homozygotes will become increased. But inbreed- The Somatic Value of Seed (Evaluation of ing damages may also occur in the following generations. Temporary Conditions) With these considerations, one shall be obliged to pay The evaluation of the temporary conditions of forest more attention in the future to the question of how many seed is much more simple than the provenance certificate, trees of a stand have been harvested. because in this case we already have international cooper- If a seed lot has been harvested not only from one ation on official seed testing and there are well established stand of trees but from several, the provenance certificate testing methods. may show the same statements that are necessary for the Most of the seed testing stations of the world, which harvesting of a single stand, but the statements (age, are also testing forest seed, are joined in the "Inter- height above sea level, density, growth, etc.) in these national Seed Testing Association" (ISTA). The "Inter- cases will show variations greater than in the case of a nationalRulesforSeedTesting"arerevisedand single stand. completed every third year by the meetings of the associa- For scientific purposes, e.g., progeny tests, but not for tion, e.g., 1953 at Dublin, 1956 at Paris, and 1959 at purposes of practical forestry,it may sometimes occur Oslo.Especially with respect to the testing of forest that seed is harvested from a single tree only.In such seeds, the rules have been completed and revised at the cases, the characteristics of the stand being harvested last three meetings. We are very much obliged to Mr. apply to the individual.Age, height, breast-high diam- Holmes, chairman of the ISTA Forest Seeds Committee, eter, trunk- and crown-qualities, ramification, bark, etc., for his careful and strenuous management of this enter- shall be designated as far as possible by figures, otherwise prise. by evaluating remarks. The most important tests of the temporary conditions In order to secure the best possible provenance descrip- of forest seeds are purity and germination tests.The tion the following question is to be answered: Who is to buyer and consumer of a seed lot likes to get, in a unit of issue the provenance certificates?This question cannot weight, a percentage of full seeds as high as possible and properly be answered for all cases, because forests are of inert matter as low as possible. The full seeds also cultivated with different intensities by the several countries should germinate with a high percentage. Each germi- of the world, and some other conditions may also be nation test needs also a purity test; in that way both impossible to be satisfied. Normally, we must try to have characteristics are always tested together. In the germi- the governmental forestry authorities,i.e.,theofficial nation tests, not only the number of seeds germinating Genetics and Tree Improvement 687 during a stated test period will be important but also the certificate of temporary conditions issued by the official percentage of those germinating rapidly. This percentage seed testing station and wifi ship that seed under seal will be determined for each seed species at the first directly to the consumer, then the problem is solved in account.The resultiscalled germination speed.Of an ideal manner. these rapidly germinating seedlings the percentage of But if the seed is traded several times, especially from those dying is lower and the percentage of survivors seller to buyer, then the problem of identification occurs higher than in the case of late germinating seedlings. For and will be difficult to solve. It is not intended to insinu- several species, it has been proved that the early germi- ate that the seed trade likes to cheat, but during the course nating seedlings produce taller plants in the first year of exchange, mistakes may occur which possibly may be- than the late germinating ones, but in the following years come most unpleasant to the forest owner. Although if this advantage of height may be lost again. the seed trade, in its own interest, will take care that the On the germinability (including the germination speed) seed supplied wifi be correctly identified,it must be depends the sowing density and the seedling production estimated that there is a low percentage of outsiders who, to be expected under average conditions of soil and in special cases, may be induced to exchange or mis- climate. represent seed. The following example may show that: Seeds of some species are too slow and difficult to If, within a seed year, only a small amount of seed of a germinate in order to be tested in an economically practi- special species could have been harvested from provenance cal time. In such cases it is possible to give an approxi- district "A," and if that seed were to be wanted urgently mate prediction by using the tetrazolium test, as a bio- by the owners of a forest, and, at the same time, in district chemical rapid test. For these rapid tests the international "B" there is a large surplus of seed of that species, rules for seed testing also contain instructions for cer- rather difficult to be marketed, a not very honorable seed tain tree seeds. The development of these tests will be a dealer may be enticed tosell the abundant seed of special task of the seed testing stations as a substitute for provenance "B" as being of provenance "A." germination tests of long duration. The best way to prevent exchange and fraud during Besides the testing for purity and germination, other seed tradingis by uninterrupted supervision of seed conditions of seeds may be tested, such as the weight of harvesting and processing. But often, uninterrupted con- 1,000 seeds (most important to provenance control) or trol may be too expensive to be economically justified. the number of seeds in a unit of weight, and with it the In some countries it is prescribed by law or custom minimum number of seedlings in1kg. of seed, to be that forest seeds from stands that are acknowledged or agreed upon under paid cultivation contracts. The deter- approved for collection are to be harvested only under mination of moisture content is necessary if the seed is supervision. The weight of the seed crop yield is measured to be stored over several years. at the first collecting place. But after this process there In testing forest seeds for the international seed ex- is a period (with the cones of conifers, until extraction; change and trade, two different certificate forms are with the fruits of broadleaves, for drying and lowering available. An orange one is to be used if testing is done of moisture content) where a constant supervision will be by the seed testing station itself or by an official testing practically impossible.After extraction, removing the agency authorized by the station.Testing is to be done wings, and of the seeds of conifers, a second step according to the principles laid down in the international of control may be inserted by testing the relation between rules for seed testing. The orange certificate establishes the quantity of seed and that of cones. But because the the connection between the results of the analysis and crop yield from 50 kg. of cones varies between wide the authority to which it refers. A blue certificate is to be limits of sometimes more than 100 percent (with Pinus used in cases where the sender carried out the testing. sylvestris L. between 0.6 and 1.2 kg.; with Picea abies L. The results of the analysis, therefore, refer only to the Karst. between 0.8 and 2.6 kg.), an approximative ex- sample being tested.Since we already have international amination is possible, but not an absolutely reliable one. certificates which have been introduced and agreed upon, After extracting, removing the wings, and cleaning of there seems to be no need of new certificate forms. From the seeds of conifers, further identification of the seeds thispoint of view also,thecertificate form (FAO is made possible by technical means such as sealing or 52/10/6056), suggested in 1952 to cover quality, seems staining. to be superfluous. If the circle of buyers is known when the processing of the seed has been done, the whole lot can be divided The Identification of Seed into the portions wanted by the buyers and put into con- With the questions of certifying provenance and quality tainers(tins, sacks, etc.). To each portion, copies or there is combined another one, namely, the identification photostats of the provenance and quality certificates may of seed. In other words: What about the guarantee that be added, or at least a check number will be given before the consumer of seed really gets from the producer that the containers are closed and sealed by the supervisor. the actual seed lot offered by the latter is covered with There are more difficultiesif the circle of buyers is provenance and quality certificates? unknown, because, in thesecases,the portions into This problem is solved easier and more certainly if the which the whole seed lot is to be divided are also un- way between the seed grower, seed processing, and the known. Iere it is only possible to divide the whole seed seed consumer is a short one.If the owner of the seed, lot into several portions, the weight of each to be de- having harvested the seed from a certain stand and having termined by the lowest weight expected for delivery. processed it personally, has a certificate of provenance In the case just mentioned, another technical device issued by the governmental forestry authorities and a until now not used on forest seedsthe staining of seeds,

688 Fifth World Forestry Congress Proceedings is used in some conifers, the wings of which have not been removed.Form may be favorable. Today, seed staining that it countriesonly for a few speciesof imported seed, and color of the wings are so typical for each tree especially clover, alfalfa, beets, and grasses. By staining is possible to separate a mixture into lotsfrom single trees, seeds, it is intended to distinguish between imported, i.e., if samples from the single trees are available.If one were foreign seed and home-produced seed. For the staining, engaged in such examinations more intensely, without any eosin, fuchsin, safranin, polishing red, etc., are mostly doubt it would be possible to develop methodssuitable used, dissolved in water or methylated spirits. Only Nor- for the identification of seeds. way prescribes staining for all importedseed of species RESUMES of Picea and Pinus (except Pinus cembra and Pinus Problèmes et recommandations portant surl'établisse- cern bra sibirica).For us here, a staining system for qualité pour les horticultural seeds developed in Sweden may serve as an ment d'un certificat international de example. This method, using clearly defined color tones semences d'essences forestières known only to the approving authority, makes it possible S'il est nécessaire de procéder a une transactioncommerciale to ensure the identification of a seed lot on its wayfrom ou a un échange de semencesd'essences forestières entre deux pays, la qualité de celles-ci devrait êtregarantie par des certificats the testing office to the contents of the smallest paper aussi exacts et détaillés que possible.Afin d'estimer Ia qualité bags filled with seeds and sold across the counter and de la semence, on doit pouvoir se baser defacon precise sur sa back again. valeur génétique (provenance) et sur sa valeur somatique(condi- tions temporaires). Une description systématiqueservirait a identi- On this basis, guarantee could be given that the con- fier la semence en question et permettrait de s'assurer queIa sumer of forest seed will get exactly that provenanceand semence délivrée est conforme en touspoints a celle offerte et seed lot that has been approved by the supervising officer garantie par le certificat. when processing has been done and that has been covered Le certificat de valeur génétique doit porter ladescription de la semence selon la declaration de l'expéditeur, donnerle nom by certificates. For that purpose, the supervisor should latin et le nom commun de l'espèce, la nature de l'emballage,la have a set of different colors (about 5 to 10 color tones). saison et le lieu de la récolte.Ii doit indiquer le nombre d'arbres The several seed lots could be stained with one, two, or sur lesquels les semences ont été récoltées, oubien si elles provien- three, etc., up to ten different colors in such a way that nent d'un seul arbre.La présente conference devrait conclure qu'une seule et même formule de certificat devraitêtre employee the seed lot could be divided into suitable portions and dans le monde entier; une recommandation a cesujet est faite each portion separately stained with the desired color plus loin. tone. If staining has been done, the seed lot must bewell Connaissant la génétique des peuplements d'oii proviennentles mixed and made homogeneous again.The controlling semences, il y a lieu de considérer queles peuplements, tout en croissant dans une region de même climat, peuventpresenter des officer would send a small sample to a seed supervising differences en ce qui concerne leurs éléments génétiques.Par authority, e.g., to an official seed testing station. The key consequent, on doits'efforcer d'obtenir une description aussi of color tones of each seed lot is known not only to the détaillée que possible des peuplements d'arbres surlesquels les supervisor but also to the seed testing station so that an semences ont été récoltées, afin d'éviterles imprécisions quant a examination is possible at any time. At first view, this leur origine, étant donné l'étendue plus oumoms grande de la region oü les semences ont été récoltées. method seems to be complicated but it will be absolutely Les qualités les plus importantes, telles que lapureté et le reliable; with suitable equipment, it may be executed under pouvoir germinatif, la teneur en eau, le poids de Ia semence,etc., economically tolerable cost. doivent être vérifiées et indiquées de facon precise etuniforme par les stations officielles d'essais de semences.Les stations d'essais The official seed testing stations may contribute also to de semences de nombreux pays font partie del"Association the identification of seeds by using their normal testing Internationale d'Essais de Semences," et elles procèdent auxessais methods. For instance, the weights of 1,000 seed lots and de semences selon des règles uniformes etbien définies. Certains the percentages of purity of several portions of a uniform certificats ont déjà été adoptés par différents pays, pourindiquer les résultats de ces analyses.Si la semence a été échantillonnée seed lot must be within the allowed tolerances. If such is par la station même ou par unorganisme d'échantillonnage not the case, then either the whole lot has been equalized autorisé, le certificat est de couleur orange;ilest de couleur insufficiently or an exchange of seed is to be suspected. bleue si l'echantillonnage n'a pas étd effectuéofficiellement. The more several portions differ from one another, the Iiserait beaucoup plusfacile degarantir que lelot de semences livrées est conforme al'échantillon offert s'il y avait more a suspicion is justified that the samples beingtested moms d'intermédiaires entre le pépiniériste et l'acheteur.Si la are not uniform. semence passe par plusieurs mains,la garantie d'identification devient plus difficile et problématique. Lespossibilités d'une telle Going beyond the normal seed testing methods of today, garantie dependent du contrôle qui, dans bien des casn'est pas seed testing could contribute to the identification of seeds sans défauts, étant donné lesfrais élevés de la conservation, et by many other especially morphological examinations. For de la coloration des semences (au moyend'un système secret de instance, by using sets of sieves it is possible to graduate différents tons), de la comparaison des résultats desessais de samples into groups with different minimum widths of the semences et du développement denouvelles méthodes d'essais seeds. The percental distribution of the groups received sp ciaux (examen des structuresanatorniques). by sieving will characterize a certain seed lot.In a Problemas y Pro puestas para la CertificaciónInternacional similar way it is possible to examine the weights of the de Semillas Forestales single seeds of a sample and to put seeds with uniform Cuando haya necesidad de vender o enviar enintercambio weights into groups. Also, in this way one will get char- semillas a otro pals, la calidad de éstas deberia estargarantizada acteristic distribution patterns of certain seed lots. More por un certificado tan exacto y biendocumentado como fuere exact examinations of the characteristics of form and posible. Para evaluar Ia calidad, es necesariodeterminar el valor genético (origen) y el valor somático (condicionesactuales). color, e.g., the relation of length to width, curvature, sulci Con el establecimiento de un programadefinido serIa posible of the testa, and color tones, give further possibilities of garantizar que la semilla entregada sea idéntica a laofrecida y determining thecharacteristics of a certain seed lot. que Ileve un certificado de dichagarantla. Rather easy to be identified in this way are seeds of El certificado de valor genético deberá probar que lasemilla Genetics and Tree Improvement 689 es tal cual la garantiza ci que la envIa y deberá incluir el Algunas estaciones de diversos paIses pertenecen a la "Asociación nombre latino y el vulgar de las especies, la forma de envase, Internacional para el Análisis de Semillas" y examinan el material fecha de recolecta y el lugar donde se recolectó. Asimismo, se conforme a reglas ya establecidas y uniformes. Ya existen certi- indicarán los árboles y si provienen de un solo árbol, se indicarán ficadosinternacionalmentereconocidosparainformardel debidamente sus caracterIsticas en un informe sobre el particular. resultado de los análisis. Hay un modelo color naranja que se Este congreso deberIa adoptar una resolución en el sentido de usa cuando la semilla ha sido analizada por la estación o por un que se use un certificado que sea uniforme en ci mundo entero y a laboratorio autorizado para el caso y otro azul usado cuando continuación Se propone un modelo. no se ha hecho análisis alguno. Sobre Ia base de conocimientos de genética debe darse por Es mucho más fácil garantizar que las semillas suministradas sentado que el material arbóreo, aunque crezca en un distrito de corresponden exactamente al lote ofrecido cuando el suministro clima uniforme, puede diferir de una planta a otra dentro de es más directo del productor al consumidor. Pero cuando las sus componentes genéticos. Por lo tanto, conviene obtener una semillas pasan por varias tnanos, la garantla de identificación designación exacta del material que se recolecte teniendo en es más difIcil y problemática. Las posibilidades de tal garantla cuenta, dentro de lo posible, el hecho de que éste puede provenir dependen de la vigilancia que se ejerza, que algunas veces suele ser de un distrito de suministro más o menos extenso. imperfecta cuando es necesario economizar en los gastos, en lo Las caracterIsticas de mayor importancia, como lo son la referente al sellado y al teñido (con un sistema secreto de colores) pureza y germinación o el contenido de humedad, peso de la de las semillas, y a la comparación de los resultados del análisis semilla, etc., deben analizarse y certificarse de manera seme- y de otros nuevos análisis de semillas que deben perfeccionarse, jante enel informe de lasestacionesanalizadorasoficiales. como por ejemplo, ci de estructuras anatómicas.

Problems and Proposals for International Certification of Tree Seed Origin and Stand Quality With Particular Reference to Western North American Species

LEO A. ISAAC Collaborator Pacific Northwest Forest and Range Experiment Station, Forest Service, U. S. Department of Agriculture, Portland, Oregon, U.S.A.

Foresters of western North America are happy to know absolute integrity are more essential than in the procur- that our trees are producing good forests in many parts ing of forest tree seed. And since seed is an important of the world. We pray that they may contribute a little item in international trade it is fitting that seed certifica- toward the bond of good fellowship between the foresters tion for foreign shipment should be discussed at this, our and peoples of many lands. But if our trees are to do this, 5th World Forestry Congress. the seed we send out to other countries must not only In the gradual transition from wild forests to managed be good, but must be carefully selected for planting in a stands here in America and throughout the civilized given climate. world, there has been an awakening toward forest tree Some countries have improved their entire way of life improvement, or at least toward the procurement of seed through the careful importation of tree seed and the from the right climate and the best wild stands or trees. establishment of new forests (8) *; other countries have There is every reason to believe, and considerable proof improved their existing forests by the importation of bet- isalready available, that similar improvement can be ter tree species or better strains (17). For that reason, made with forest trees, as has been made with fruit trees, the FAO of the has proceeded to act as a berries, grains, grasses, and all wild, growing things. clearinghouse for tree seed, and they have asked the The first problem of tree improvement, already quite different countries to provide certification as to both well solved in some countries, is to classify the wild forest quality and point of origin (4) of tree seed. stands, identify the better wild strains, and to locate and register the best strains and best individual trees (1, 2, Background Information 13, 20, 21). The second problem is to make sure that the Some further explanation is due to the members of best quality seed obtainable is consistently made available this Congress who come from countries that have not as for purposes. And to accomplish this we yet embarked on an active program of tree improvement must have tree seed certification (3, 4, 5). or the importation of better tree species from other lands. A lifetime is required to grow a forest, and if the What is Certification of Tree Seed? wrong seed is used, it may not be discovered until it is Tree seed certification means more than mere germina- too late to change. Therefore, there is no place in the tion percent, purity, and size of seed. It must first include entire economic orbusiness world where careand verification of point of origin (or climate), because a single species of tree may occur all the way from sea level *Numbers in parentheses denote the references listed at the end to timberline on the mountain, or from a mild humid of this paper. coast climate to a cold semiarid windswept ridge. A

690 Fifth World Forestry Congress Proceedings single strain, when moved from one climatic environment What Must We Certify? to another very different one, may survive but it will Let us face some facts. How much tree seed is pro- not produce a satisfactory or profitable forest (9, 17). duced, where does it come from, what should be the Many of the failures of our forest trees in other countries can be directly traced to seed from the wrong climatic future trend, and what certification can we provide? zone.Certification procedure, therefore, must first con- Accurate figures are not available, but it is probable sider climate or point of origin, and should then consider that thousands of pounds of western tree seed are col- tree form and growth rate, and it may consider wood lected for export every year. A similar sizable quantity quality, and resistance to drought, disease, and insect and is collected for domestic use. animal attack. Practically all of our seed is now collected from average The Scandinavian countries and the British Isles (1, 2, or better natural wild stands or young stands that repro- 13) have divided their forests into fairly well-defined duced naturally after one cutting; most seed will continue zones according to stand quality and climate, and such to come from these native stands for the next decade or certification as can be done for wild seed is performed on two. Although they are being considered for the purpose, a voluntary basis by recognized associations (20, 21); in these average quality natural stands do not lend them- addition, many seed orchards or seed collection areas have selves readily for registration as seed collection areas. been developed from registered planting stock, and seed Under normal conditions, good seed crops occur from two is certified accordingly (21). Central and some Southern to seven years apart, and cones cannot be collected European countries have Seed Certification laws and regularly from year to year from the same stand (9). require registration of seed collection stands, and inspec- Under the laws of Germany and some other countries, tion and labeling of seed for sale. In America we have as these seeds could not be marketed because they are not yet only the general British Columbia "Forest Act" collected from registered stands. For the same reason, all Regulation on picking tree cones, and the U. S. Customs our seed would be classed as substandard by the new seed export sanitation inspection. Two States (Georgia and law of our own State of Georgia (5). This would be a South Carolina) have well-worked-out tree seed certifica- completelyfalseclassificationfor our western seeds tion laws (7), other States such as New York, Wisconsin, because most of the seeds are not substandard or inferior Michigan, and South Dakota are partially covered, but in any way. There is no evidence whatever that some of so far as I could learn, the remaining States have none. our best wild strains are not as good as, or even better There is, however, some reliable dealer guarantee (15) than, strains or registered stands that will be developed available, but, as yet, there is no other worthwhile tree in the next 10 to 20 years. seed certification for foreign trade. Geneticists and other tree improvement men in western North America are at work selecting and registering plus Certification of Western North American Tree Seeds trees and superior stands, they are crossbreeding and I have been asked to make special reference to tree grafting scions from superior trees to produce planting seeds of western North American species in my discussion stock for seed orchards (6, 10, 11, 22). In spite of all of of certification (3) of tree seed. this activity, probably less than a hatful of seed is now By chance or otherwise, western North America has produced in a year that can truthfully be classed as cer- been blessed with a large number of the world's most tified seed from progeny-tested parent trees.It will be 10 desirable forest tree species.They have been tested in to 20 years or more before an appreciable amount of arboretums and field in comparison with the such seed is available in western North America. best forest trees from all over the world (18), and west- The nearest approach to superior wild seed comes from ern American foresters, as yet, have found no tree that carefully selected superior wild strains. These strains are they are ready to substitute for their own good native now being eagerly sought out, and in some of them the species. inferior individual trees (bad pollen parents) have been Furthermore, western American trees have shown removed to provide seed from superior parents only. A phenomenal results in foreign lands, producing quicker little of this seed will soon be available, but it will be and better forests than native species.Examples are: produced in slowly increasing amounts.It will be the Monterey (Pinus radiata D. Don) and ponderosa pine nearest approach to improved seed availablein any (Pinus ponderosa Laws.), planted all across the southern quantity for some years to come. Its claim for improve- hemisphere;alsoDouglas-fir(Pseudotsugamenziesii ment rests oniy in the fact that it is produced by the best (Mirb.) Franco), Sitka spruce (Picea sitchensis (Bong.) individuals of a superior stand of native non-progeny- Carr.), western hemlock ( heterophylla(Raf.) tested trees. Sarg.), grand fir (A bies grandis (Dougl.) Lindl.), noble The logical and practical approach to the problem in fir (Abies procera Rehd.), lodgepole pine (Pinus contorta the Northwest today is to provide a verification of point of Dougl.), and Port-Orford-cedar(Chamaecyparis law- origin and a quality certification that can be applied to soniana (A. Murr.)Parl.), now used successfully in the good wild seed that is available now, and will consti- European countries (14). The export of these, in num- tute most of the seed marketed in the next decade or two. ber of seeds, far exceeds the export of all other American At the same time, provision must be made to register and tree seeds combined. Successful use of these western trees certify the seed from more improved parentage when it depends on care in selection of seed. Except for red becomes available.Provision should also be made for (A inus rubra Bong.), only coniferous forest tree seed is registration and certification for plus trees and superior collected for export in western North America; therefore, strains(10, 11), and every encouragement should be this discussion will be confined to coniferous seed. given to all forms of tree improvement. But to provide

Genetics and Tree Improvement 691 certification for highly improved, now non-existent seed, orchard developed by rooting clones, nursery and at the same time degrade or neglect the seed that will selectionofplusseedlings,or any other be produced and marketed in the next 10 to 20 years, process. But the developmentprocedure must be recorded. would be sheer folly. resulting from A broad classification that would provide for a separate Possible changes in grade standards improvement processes and certainparallels between certification for the seed from wild stands, and also one standard and geneti- for the seed from artificially developed stands, seems to grades must be recognized in both be the logical solution for certification of western species cally improved classes. at the present time. Unless a clear distinction ismade If a "standard" young seed area wererogued and all between seed from natural wild native trees and seed inferior parent trees removed, including anisolation strip, from genetically improved trees, there will always be con- the "standard" area would automaticallybecome a "stand- fusion in the mind of the seed buyer, particularly in ard-plus" seed collection area.Similarly, if a "standard- superior" area were rogued it would become a"standard- foreign countries.It is true that some strains of wild be eligible for seed will parallel the improved seed in qualifications, as superior-plus" area. Both areas would then will be explained later, but at least the buyer willknow registration. In the "genetically improved"classification, Grade B exactly what he is getting. Seed from native trees should eventually progeny be known as"standard,"and seed fromartificially group, if the parent plus trees were tested and the inferior parent treesremoved from the improvedstandsshouldbe knownas"genetically automatically advance to improved." seed orchard, the area would the Grade A class. and specifi- A Workable Classification of Seed for Certification Normally, rules, requirements, procedures, cations for seed certification are set upby law or by a The grade classifications for seed certification that I designated certification authority, but for abetter under- would suggest are as follows: standing of these suggested grades forcertification, some explanation and discussion is necessary atthis time. Suggested Grades for Standard Seed Standard seed is seed from native wild stands of all Squirrel-Collecte4 Seeds ages, some of which may be fromselected strains, and At this point there should be somemention of cone some of which may be from young,wild stands improved collection from squirrel caches. Much tothe surprise of by removal of poor parent trees. Most seedmarketed now foresters from other parts of theworld, a large portion and in the immediate future will come from thesestands. of the cones collected in westernNorth America are cut Suggested grades for the wild seed are as follows: from thetreesby wildsquirrels(Douglassquirrel, Grade 1."Standard," seed from good native stands at a Sciurus douglasii). The cones areeither picked up from known or recorded point of origin (climate, the ground as they fall, or aretaken from squirrel caches soil, elevation, site class, etc.). where cones are placed for thesquirrels' winter food. Grade 2."Standard-superior,"seedfromrecognized Objection to squirrel-collected coneshas been voiced for superior strains of native stands. These areas fear that they may be collected tooearly. However, it may be registered with the certifying agency. develops that although cones are cutfor food while green, Grade 3."Standard-plus," seed from young, wild stands very few are cut for storagebefore they are ripe.It has where inferior parent trees have been removed. also been discovered that considerableripening of seed These areas will be registered with the certi- takes place after the cones are placedin the squirrel cache. fying agency. Sometimes immature cones areeliminated as the cones are picked up, or lightseeds are blown out in a thorough Suggested Grades for Genetically Improved Seed cleaning process, so thatsquirrel-collected cones usually This is seed from seed orchards or seed collection areas produce high grade seed.One other pointcollection where parent trees have been developed or improvedby of cones from exceptionally fine,large, old-growth trees testing, cross polli- (200 to 250 feet tall) would bepractically impossible, some genetic process such as progeny for the cone- nation, grafting, or selection. Such work is nowunder way particularly during lean years, if it were not (22),israpidly increasing, andishighlydesirable. cutting squirrels. Therefore, provision must be made for the certification of this improved seed as rapidly as it becomesavailable. Collection and Handling of Wild Seed Grade A. "Genetically Improved," seed from aseed Normally, for (Grade 1) "Standard" seed,the cone orchard developed from grafted or rooted collection in a limited vicinity is done bylocal residents stockof15or more progeny-tested plus and brought into a cone collectiondepot that is in charge ("elite") trees. of a cone buyer. If the seed is to becertified it is his duty Grade B. "Genetically Improved," seed from aseed to see that cones are collectedfrom acceptable stands and orchard developed from grafted or rooted are properly tagged. stock from 15 or more non-progeny-tested Keeping in mind that wild seed willconstitute most of plus trees. the seed marketed in the next 10 to20 years, a summary Grade C. "Genetically Improved," seed from aseed of field requirements for certified"Standard Seed" would orchard developed from seed of many hand- be: Collection from an average orbetter stand, in an pollinated plus trees. acceptable seed zone where reasonablyclose weather Grade D. "Genetically Improved," seed from aseed records are available and generalsoil conditions and Proceedings 692 Fifth World Forestry Congress elevation are recorded.Cones must be ripe, collection Seed Processing area named, and containers tagged and dated when brought in to a cone depot. Also, cones must be handled After the field details have been worked out and the to the satisfaction of the certification officer from the time cones properly tagged, they must be transported and of picking until delivered to the drying shed or extracting dried, and the seed extracted and stored according to the plant. rules of the certifying agency.Normally, seed dealers Collection areas and handling and tagging opera- who willrequestseed certificationservicewill have tions are subject to inspection at any time by the certify- registered acceptable seed extracting or processing plants, ing officer. but seed can be certified from smaller plants or can be Superior Strains of Wild Seed extracted by hand, if it is handled according to established rules, and to the satisfaction of the certifying officer. Throughout the virgin forests of the world and especially On the one hand, we ask ourselves "What is available in western North America, there are patches of timber of for certification?" Obviously we cannot certify as to quali- varying sizes where the trees are superior to neighboring ties we do not have records of, or cannot obtain them on stands, and better trees than experienced foresters would short notice. On the other hand, we ask "What minimum expect to find at a given site, elevation, and climate. Such qualifications for certification will be demanded by other stands have become known as "superior strains" (6, 9, nations for foreign export?" This, no doubt will have to be 10). Just how they developed is as yet unknown, but it worked out through the FAO of the United Nations or has been shown that they possess superior hereditary some other international body. characteristics that will be apparent in their progeny (10, 11). A register will be set up for such stands so that How Shall Seed be Certified for Foreign Export? they can be duly registered as seed collecting areas. Seed Great quantities of native western North American collected from such areas can then becertifiedas tree seed is exported to foreign lands each year, but as yet "Standard-Superior" seed. no satisfactory method of certification has been developed for it.Proposed methods of certification are as follows: Improving a Wild Stand for Seed Collection The passage of a Federal tree seed certification law Within any average indigenous forest stand there will that would require verification of origin of seed from be a wide range of individual tree quality with regard to wild trees, and the inspection and registration of form, growth rate, and resistance to disease and . other stands, followed by the field inspection for Ifall slow-growing, poorly formed and diseased trees seed crops and the testing and marking of seed. (bad pollen parents) are removed from such a stand, it Germany, some other countries, and some of our is certain to bring about some improvement in the quality own States have such laws. of the seedprovided that stand is flanked on all sides The passage of similar seed certification laws by in- by adequate isolation strips.Seed from such areas, if dividualStates.Georgia, South Carolina, New properly registered, can be certified as "Standard-plus" York, and South Dakota now have such laws. seed. Certification by the International Crop Improvement What constitutesadequateisolationhas not been Association that now certifies a number of agri- determined for all the varied field conditionsor for dif- cultural field crop seeds (12).It recommends a ferent species, but this will be done as the work progresses procedure similar to No. 1. and conditions demand. Normally, in a continuousyoung, Certification by an approved professional non-profit natural stand of the same species, a strip 300 to 500 feet tree seed certification authority such as is used by wide, with inferior trees removed, would be consideredan Scotland and several Scandinavian countries. adequate isolation strip to protect the improved seed col- Some comments should be made regarding each of the lection area in question from an inferiorsource of pollen. above proposals in order that they may be better under- At the present time, information is available only for stood. the certification of "Standard" seed (Grade 1, 2 and 3), A special Federal seed certification law would neces- as to the point of origin, germination percent, purity, and sitate setting up another new and costly national seed moisture content.Some information is available as to certification agency.It would be difficult to frame such what constitutes a plus tree and a superior strain for a law that would be flexible enough to meet the varied Douglas-fir and white pine (6, 10, 11). But beforemore conditions of the entire nation. A general law requiring complete certification can be made, it will benecessary that all tree seed be certified for sale would meet opposi- todefineterms, work out procedures, and establish tion both from the dealers and the largest users in the standards as to what constitutes a plus tree, elite tree, Western States; this includes some large companies, superior strain,adequate isolation strip, progeny test, western regions of some U.S. Government agencies, and resistance to disease, etc. For these things,we can at the some of the States. They prefer to buy seed on bids and demand in the bid what quality they want and where the present time only rely on the judgment and training of the seed must come from, and thereby avoid the cost and forester or scientist in charge. These details will have to bother of certification. be worked out in collaboration with the Western Forest The above objections would hold true for individual Genetics Association and other organizations.At the State laws in most of the Western States that required that present time, no seed orchards from progeny-tested trees all seed be certified for sale. A State law may function are ready for registration or seed certification, but several perfectly within a State like Georgia but would be ques- are in the process of development. tionable for foreign export, because the laws of each State

Genetics and Tree Improvement 693 would differ from the next and some States would not and Conservation Association or some similar organiza- bother to pass such a law at all. tion, that represents the 11 Western States and Canada The International Crop Improvement Association has and includes all agencies interested in Forestry, could be been suggested as a certifying agency for tree seed. They induced to sponsor the seed certification authority,it are represented in many States and Canada by member would automatically form an advisory body that would associations; in other States their work is carried on by represent all forest agencies. the Agricultural Extension Service or by the State Agricul- The seedcertificationauthority membership could tural Departments. This organization has been certifying then be set up to include regular members and support- seed of certain farm crops for years, but they are not ing members. The supporting members would be seed equipped with the forestry-trained personnel to certify dealers or those offering seed for certification as to origin wild tree seeds.Tree seed must first be verified as to and soundness. For all such seed offered for certification point of origin.Then a highly trained forester will be a fiat fee would be charged. This wouldconstitute the required to recognize and describe parent trees and stands primary support of the "Authority." For all additional and provide for necessary inspection and registration.It services, a special scale of charges would be set up as is is also probable that in many States there would not be now done in the State of Georgia. enough tree seed business to justify having this organiza- The Western Pine Association and the West Coast tion hire the required personnel to do the job. Lumbermen's Association are now supported by a fiat fee per thousand board feet of lumber produced, and A Suggested Independent Seed Certification there is no reason why the seed certification authority Authority for Western American Species could not be similarly supported by a fiat fee per pound of seed produced and offered for sale. The most logical solution for the Western States and Once established, the board of directors of this certifi- Canada, for the certification of tree seed, both for domestic cation authority could be authorized to hire facilitating use and foreign export, would be one, single, independent, personnel and set up a scale of charges for such services non-profit, tree seed certification organization for western as are requested from them, such as theapproval and North America, like the Scottish Forest Tree Seed Associa- registration of plus trees, superior strains, seed orchards, tion, or like similar independent professional associations special collection areas, inspection of collection areas, thatcertifytreeseed insome of the Scandinavian transportation facilities and extracting plants where seed countries. The association would cover roughly the same area as occupied by the ponderosa pine region and the certification will be requested, and the final certification Douglas-fir region (14), and incidentally, the same ter- of seed. ritory as is served by the Western Forestry and Conserva- The association would be equipped to make a broad tion Association, the Western Forest Genetics Association classification of stands divided into climatic belts for and several other professional organizations. seed collection (11); from these, all known unfavorable seed collection areas would be eliminated. The association The organization could be incorporated as "The West- would then proceed to furnish uniform labels for cone ern Forest Seed Authority" and its use would be not collection, extraction, and seed storage, and uniform out- compulsory but voluntary for those who wished to avail lines for certification. themselves of the service; those who had a need for Minimum requirements for germination percent and seed certification and were willing to pay for iteither purity for different species, and acceptable standard pro- the seed dealer or buyer.To function properly, the cedure for germination tests have already been established controlling body of this organization must include both by the Northwest Tree Seed Committee (16). Adequate the seed dealers and the seed users, and, in addition, facilities for making germination tests are available at the must include those who are interested in tree improve- seed laboratories of different agricultural colleges. ment. Those who can and will produce seed of superior This professional, non-political organization, if estab- quality must be provided with facilities to register it as lished, would most likely set up rules, regulations, and such, in order that they may be paid for their effort, and procedures that would be uniform and effective and at the buyers can be assured of what they are getting. same time fair to both the producersand buyers of I would suggest that the organization be governed by a western tree seed in this and other countries. Also, when board of directors made up of seven memberstwo from improved seed is produced it can be registered as such, the Forest Seed Dealers Association, one from the West- so that the producer can expect abetter price and the ern Forest Tree Seed Committee, one from the U.S. buyer can be assured of a better seed. Forest Service or Bureau of Land Management, one In order that any system of seed certification for from the State Forester's Office of a participating State, export purposes may help to produce better forests in and two from the forest industry. They should form the foreign lands, complete cooperation on the part of the nucleus of an advisory committee or advisory board foreign buyer is necessary. A request for seed from a which would include members from the Western Forest general locality is not enough, because in our western Genetics Association,Society of American Foresters, country one may go from a good stand to a poor one or Canadian Institute of Forestry, Western Forestry and from sea level to timberline in a very short distance.If Conservation Association, Industrial Forestry Association, a buyer cannot name a specificlocality or stand from Western Forest Nurserymen's Association, Western Pine which seed is wanted, then the safest procedure is to give Association, and representatives from forestry colleges pertinent climatic data for the contemplated planting and State Forest Services. site,namely,averageannualtemperature,absolute If an established organization like the Western Forestry minimum temperature, annual rainfall, and rainfall during

694 Fifth World Forestry Congress Proceedings the summer months. Records of relative humidity, alti- Rocky Mountain and Pacific Coast States and British Columbia. tude, latitude, and longitude are also helpful. With this Forest Genetics Research Foundation. University of California, information at hand, the American seed dealer can go a Berkeley, California. long way toward certifying seed for a specific planting site in any country. RESUMES Seeds from our fine northwest forests can then be La certification internationale des graines forestières quani furnished to foresters of other lands with more assurance a l'origine et a la qualité en ce qui concerne en than ever that they will produce equally good forests particulier les essences de l'ouest de l'Amerique du in their own country. Nord Les peuplements naturels d'essences indigènes de l'ouest de References l'Amérique du Nord renferment plusieurs des essences forestières les plus remarquables du monde. Un grand nombre d'entre elles Anderson, M. L. and Fairbairn, W. A., 1955. Division of produisent déjà des forêts de qualité supérieure a l'étranger. Scotland into climatic sub-regions as an aid to silviculture. Mais il y a eu également des échecs. Bulletin No. 1. University of Edinburgh Forestry, Edinburgh, Scotland. Les essais qui ont été effectués et qui se poursuiventen Europe Austin, Toralf, 1959. Seed supply in Norwegian forestry. montrent déjà de facon concluante que le succès de nos essences Reprint: XII International Seed Testing Convention, Oslo. De- dans d'autres pays depend du soin avec lequel est opérée la partment of Agriculture, Forestry Directorate, Oslo, Norway. selection des semences, lesquelles doivent provenir de souches génétiques indigènes de bonne qualité, croissant dans lazone Baldwin, H. I., 1942. Forest tree seed of the north temperate climatique appropriée. regions, with special reference to North America. Waltham, Autrement dit, pour les plus grandes Mass, Chron. Bot. chances de succès, le climat de la region d'oà provient la semence doit autant que possible correspondre a celui du lieu oil ellesera and Holmes, H. D. 1955. Handling forest plantée. tree seed. United Nations Food and Agriculture Organization, Rome, Italy, Forestry Development Paper No. 4. L'Organisation des Nations Unies pour l'Alimentation et l'Agri- Barber, John C., and Darby, Stanford P., 1959. Georgia's culture et certains pays étrangers ont demandé Ia certification des seed certification program. Jour. Forestry Vol. 57, No. 2. Page grainesforestières quant a l'origine et a la qualité.Quelles 125. mesures devons-nous prendre en vue de la certification de nos Duffield,J. W., 1955. Selecting plus trees for our seed sernences pour l'exportation a l'étranger?C'est là le problème orchards. Industrial Forestry Association, Portland, Oregon. qu'il nous faut résoudre. Aucune réglementation générale n'existe Georgia Crop Improvement Association, 1958. Certification encore pour l'ensernble de la region.Certains états ont établi standards for forest tree seed. 310 Hoke Smith Annex, Athens, leur propre legislation en Ia matière; mais il n'est pas certain Georgia. que tous les états en adopteront éventuellement d'analogues, ou qu'elles seront suffisamment uniformes pour répondre aux besoins Hinds, H. V., and Reid, J. S., 1957. Forest trees and timber de l'exportation. of New Zealand.GovernmentPrinter,Wellington, New Zealand. Lessemencesdesessencesouest-américainesproviennent Isaac, Leo A., 1949. Better Douglas-fir forests from better actuellement en majeure partie de peuplements spontanés d'es- seed. University of Washington Press. Seattle, Wash. sences indigènes; mais on procède maintenant a la selection et a ,1955.Tentative guides for the selection of la reproduction de souches améliorées, au titre d'un programme plus trees and superior stands in Douglas-fir.Research Note bien concu visant a l'amélioration des essences forestières.II 122, Pacific Northwest Forest and Range Experiment Station, faut en consequence établir une classification distincte pour les U. S. Department of Agriculture, Forest Service, Portland, souches génétiques provenant de sujets indigènes sauvages et une Oregon. autre pour les souches génétiquement améliorées, au fur et a ,1955. A proposed plus tree register for the mesure qu'elles sont mises au point et peuvent être utilisées. Pacific Northwest. Pacific Northwest Forest and Range Ex- Etant donné que l'habitat d'un grand nombre d'essences im- periment Station, U. S. Department of Agriculture, Forest Serv- portantes de notre region ouest s'étend de Ia Colombie britannique ice, Portland, Oregon. au Mexique, il semble qu'un seul système de certification uniforme International Crop Improvement Association, 1959. Mini- pour l'ensemble de cette zone soit préférable a un essai de certifi- mum seed certification standards. Publication No. 19, 310 Hoke cation distincte pour chaque état. Smith Annex, Athens, Georgia. La certification des graines forestières ne comprend pas seule- Lindquist, Bertel, 1948. Genetics in Swedish forestry prac- ment l'essai des semences, comme c'est le cas pour la plupart tice. SvenskaSkogsvardsforeningens Forlag. Stockholm, des semences agricoleselle comprend l'évaluation des peuple- Sweden. ments spontanés quant a la "qualité de l'emplacement," la "qualité Little, Elbert L., Jr., 1953. Check list of native and natural- de la souche génétique" et la "qualité de l'arbre," et aussi Ia ized trees. Agriculture Handbook No. 4, U. S. Department of tolerance climatique. Parallèlement a ces operations, on procède Agriculture, Forest Service, Washington, D. C. ensuite a une evaluation des arbres et des peuplements génétique- Manning Seed Company, 1954. Tree seeds from the Pacific ment améliorés au fur et a mesure de leur mise au point. En Coast. Roy, Washington. consequence, la formation et les procedures requises pour Ia Northwest Forest Tree Seed Committee, Oregon State Col- certification des semences agricoles ne peuvent guère s'appliquer lege, 1959. Rules for service testing forest tree seed of the aux graines forestières. Une formation trIs poussée en mature Pacific Northwest. Miscellaneous Paper 83, Agricultural Ex- de sylviculture et d'amélioration génétique est indispensable. periment Station, Oregon State College, Corvallis, Oregon. Nous proposons en consequence l'établissement d'un organisme Schober, Dr. R., 1959.Ergebnisse von DouglasienPro- indépendant a huts non lucratifs qui serait chargé de la certifica- venienzversucheninDeutschland, Halland und Danemark. tion des graines forestières en provenance de l'ouest de l'Amérique Allgemeine Forstzeitschrift, MUnchen, Germany. du Nord.Cet organisme fonctionnerait sous les auspices des Silen, Roy R., 1959. The Wind River arboretum. Research acheteursetdes vendeurs de graines forestièreset aussi des Paper 33, Pacific Northwest Forest and Range Experiment Sta- diverses institutions et associations s'intéressant a la sylviculture tion, U. S. Department of Agriculture, Forest Service, Portland, et a l'amélioration des souches génétiques. Oregon. Nous proposons enfinet ce n'est pas là le moms important- Streyffert, Dr. Thorsten, 1958. Forestry in Sweden. Oregon que l'on procéde a une classification séparée des semences issues State College Press. Corvallis, Oregon. d'essences indigènes spontanées et des semences génétiquement The Scottish Forest Tree Seed Association, 1957. Members améliorées;cetteseparation estnécessaire pour permettre la Handbook. 25 Drumsheugh Gardens, Edinburgh 3, Scotland. verification de l'origine et la certification de la qualité des semences The Society for Practical Forest Improvement, Uppsala, naturelles qui seront vendues ou utilisées au cours des 10 on 20 Sweden. 1956. Pine seed orchards of S.C.A. Svenska Cellulosa, années a venir; cela rendra possible également l'enregistrement et Akliebolaget Sundsvall, Sweden. la certification des semences génétiquement améliorées au fur Wyckoff, Stephen N. 1958. Forest Genetics research in the et a mesure de leur production.

Genetics and Tree Improvement 695 La legislation existant actuellement dans les divers états, comme Como el campo de cultivo de muchas de nuestras especies celle qui est envisagée, couvre la semence améliorée, mais ne occidentales más importantes se extiende por los estados del renferme pas de disposition adequate pour la semence naturelle des oeste, desde la Columbia Británica hasta Mexico, parecemás essences indigènes.Ii nous faut éviter cette même erreur en ce conveniente adoitar una clasificación uniforme para toda la qui concerne nos essences de l'Ouest, étant donné que pendant les region más bien que intentarla clasificación de lasemilla 10 ou 20 ans a venir, nous n'aurons que de la semence naturelle separadamente por estados. a offrir a la vente. La certificación de la semilla de árbol significa algo más que el Lorsqu'un système pratique de certification aura été mis au simple ensayo de la semilla misina, como suele hacerse con point, les sylviculteurs de l'ouest de l'Amérique du Nord pourront muchas de las semillas de los cultivos agricolas. En realidad, exporter nos graines forestières a l'étranger en étant raisonnable- significa la clasificación de los árboles de bosques silvestres en lo ment certains qu'elles y produiront d'aussi bonnes forêts que dans referente a "calidad de sitio," "clase," "calidad" individual del leur contrée d'origine. árbol y también tolerancia climática. Después deberá haber una clasificación paralela para los árboles genéticamente mejorados y Problemas y Proposiciones para la Certificación Inter- para los bosques a medida que vayan desarrollándose.Por lo nacional del Origen de Semillas y de sus Cualidades tanto, el adiestramiento y los procedimientos empleados enla certificación de semillas de cosechas agrIcolas no pueden ser de Germinación, con Ref erencia Especial alas aplicados fácilmente a las semillas de árboles. Para esto iiltimo se Especies Indigenas del Occidente de la America requiere un alto grado de conocimientos en materia de silvicijltura Sep tentrional y mejoras de árboles. El occidente de la America Septentrional tiene en sus bosques Por lo tanto, se propone el establecimiento de una oficina inde- silvestres algunas de las mejores especies de árboles forestales del pendiente, sin motivos de lucro, que certifique las semillas de los mundo. Muchas de estas especies están produciendo ya bosques árboles forestales del occidente de Ia America Septentrional y que superiores en paIsesextranjeros.También se ban registrado dicha entidad sea sostenida igualmente por los compradores y algunos fracasos. vendedores de semillas de árboles y por las diversas oficinas y Losexperimentoshechos en Europa(algunosnoestán asociaciones interesadas en la silvicultura y en el mejoramiento terminados todavIa) han probado ya, sin género de dudas, que el de árboles. buen éxito de nuestras especies en otros paIses depende de la Y por tiltimo, aunque no menos importante, que se establezca cuidadosa selección que se haga de las semillas de nuestras clases una clasificación separada para Ia semillasilvestre nativa y otra indIgenas en la zona climática correspondiente. En otras palabras, para la genéticamente mejorada.Esto va a ser necesario para el clima de donde proviene la semilla debe ser igual, en todo lo poder dar alguna verificación del origen y certificación de calidad posible, al del lugar en que va a plantarse, para asegurar asI en el caso de la semilla silvestre que seavendida y usada durante buenos resultados. los próximos diez o veinte años. Al mismo tiempo, sedispondrá La Organización para la Alimentación y Ia Agricultura de las de medios para certificar y registrar Ia semilla genéticamente Naciones Unidas y algunos paises han pedido Ia certificación del mejorada con la misma rapidez que ésta vaya produciéndose. origen de las semillas de árboles. El problema consiste en deter- Las leyes existentes en los estados y otras que se proyectan, minar lo que puede hacerse para certificar las semillas destinadas incluyen disposiciones referentes alasemilla mejorada pero a la exportación. Hasta ahora no existen reglamentos aplicables no tienen medidas adecuadas para lasemilla silvestre nativa. en todas las regiones. Algunos estados de nuestro pals han legis- Debemos impedir que se cometa esta misma equivocación enel lado para la certificación, pero es dudoso que todos lleguen a caso de nuestras especies occidentales porquedurante una o dos legislar o que, de hacerlo, resultasen lo suficientemente uniformes décadas no vamos a tener nada más que semillas silvestres nativas pamsatisfacer los requisitos de exportación al extranjero. que ofrecer a la yenta. Prácticamente, casi toda la semilla de árboles de la America Una vez que se hayan establecido procedimientos prácticosde Septentrional proviene de los bosques virgenes; pero se ha formu- certificación, los silvicultores del occidente de la America Sep- lado un excelente plan para Ia selección y desarrollo de clases tentrional podrán exportar nuestras semillas de árboles a los paIses mejoradas. Por lo tanto, será necesario establecer una clasificaci6n separada para lasclases silvestres indigenas y otras para las extranjeros con alguna seguridad de que han de producir en genéticamente mejoradas, a medida que estas ditimas vayan des- ellos bosques tan buenos como los que produjeron en susuelo sarrollándose y se hallen disponibles para su utilización. nativo.

696 Fifth World Forestry Congress Proceedings SPECIAL PAPERS

La Interdependencia de la Taxonomi'a y la Botánica Forestal

MARIA BUCHINGER Dirección de Investigaciones Forestales, Administracjón Nacional de Bosques, , Repáblica

La taxonomIa, que se ocupa de la clasificación de las ferum L. fil. y las rubiáceas Coutarea hexandra (Jacq.) plantas, es una rama de la botánica pura que estudiaesos Schum. y Pognonopus tubulosus (DC.) Schum. Mientras organismos desde un punto de vista teórico. Por su parte, que es muy frecuente que diferentes plantas reciban el Ia botánica forestal es una ciencia aplicada que tieneen mismo nombre vulgar, suele ocurrir también que una cuenta los Ilamados problemas prácticos que se presentan especie con amplia area de distribución sea denominada al tratar la utilización de los árboles y sus maderas. por los pobladores de dicha region en forma diversa. Asi Como es lógico, los conceptos básicos de la botánica "timbó," "timbó colorado," "pacará," "oreja del negro," pura y aplicada son inevitablemente los mismos, y, deben "timbó cedro," "timbó poitá" y "cambá camby" son ser respetados por todos, como se los respeta en otras designaciones que el mismo árbol recibe en distintas ciencias. A qué contador se le ocurrió jamás modificar regiones de nuestro pals.Como otro ejemplo puede las operaciones básicas de las matemáticas o qué industria citarse el nombre vulgar "pino tea" que en America del no se sustenta sobre leyes fIsicas o quImicas? Desgra- Norte se refiere a Pin us echinata Miller, mientras que en ciadamente no podemos hablar de una misma concor- America del Sur significa todos los pinos resinosos. dancia en nuestro campo de acción.Por el contrario, Aprovechando esta confusion es frecuente que corner- parece que se han formado dos grupos, uno el de los ciantes e industriales vendan la misma madera bajo di- forestales y otro el de los sistemáticos que representan ferentes nombres.En una oportunidad pudirnos ver intereses aparentemente diferentes y por lo tanto se tra- como de un mismo rollizo se sacaban en un aserradero tan como seres civilizadamente hostiles que procuran maderas que liegaban al comercio como "cedro blanco," imponer su voluntad el uno sobreelotro,sea por "cedro rosado "y" cedro rojo." Suele ocurrir también, lo acuerdos o sea por la fuerza, es decir no respetando las que es más grave, que reemplacen especies económica- leyes botánicas.Estos desacuerdos, como en todos los mente muy valiosas por otras del mismo nombre vulgar órdenes de la vida,se basan, o pueden basarse, en pero de caracterlsticas madereras inferiores.Si se trata intereses contrarios, o en la falta de comprensidn del de piezas de máquinas o maderas de construcciOn, utili- punto de vista del adversario. Como no cabe la menor zar una madera por otra puede llevar, y desgraciadamente duda de que los intereses de los forestales y taxonomistas ya ha llevado, a serios accidentes, pero aun en casos no puede ser adversos, queda como raIz del malentendido donde el cambio no tiene mayores consecuencias, por la falta de comprensión entre los dos grupos. ejemplo en muebles o mangos de herramientas, Ia sus- Uno de los problemas más discutidos es el de la titución de una madera por otra puede acarrear toda denominación de los árboles forestales. A pesar de haber clase de inconvenientes. Es entonces una falta lamenta- aprendido en las escuelas primarias, que los nombres sir- ble, que en publicaciones del ambiente forestal se utilice yen para designar a los objetos y a sus cualidades para nombres vulgares sin aclarar la correspondiente identifica- hacerlos conocer y distinguir de otras cosas, estamos ción cientlfica.Seria muy importante imponer, que en aplicando muchas veces nombres sin este criterio. Nom- todas las publicaciones, no sOlo en lastécnicas,sino bres vulgares como el de "palo blanco" o "palo santo" especialmente en las de divulgaciOn y que se dirigen a no sirven para conocer o distinguir una especie sino para técnicos no especializados en botánica, figure el válido confundir varias, ya que se los aplica a árboles con muy nombre cientifico de las especies tratadas. diferentes rasgos que se asemejan por su madera blanca Una de las razones por Ia cual los forestales tarden en o por ser utilizados durante las ceremonias religiosas por aceptar esta norma es Ia aparente inestabilidad de los nombres.Es cierto que a raiz de intensivos estudios tener la corteza, el leño o los frutos aromáticos. Pero aun botánicos que se han realizado en las ültimas décadas y nombres que no se refieren a ninguna caracterIstica de la en acuerdo con las Leyes Intemnacionales de Nomencla- planta pueden ser fuentes de confusiones. En la Argen- tura muchos cambios eran inevitables.AsI es que un tina, por ejemplo, con la palabra "quina" se designa gran nflmero de árboles forestales apareció con una nueva árboles tan diferentes como la ramnácea Colletia ferox designaciOncientifica.Considerando los métodos de Gill. ex Hook. et Am. la leguminosa Myroxylon perui- trabajo de los botánicos en siglos pasados no nos puede

Genetics and Tree Improvement 697 extrañar que son justamente las plantas ieñosas que su- adecuado? Vivimos en un siglo en ci que no sOlo las frieron modificaciones en su clasificación. En la mayo- universidades y museos europeos tienen sus botánicos, sino rIa de los casos los sistemáticos han confeccionado la que cada pals del mundo los posee ylos naturalistas descripción original a base de material de herbario al pueden realizar muy buenos trabajos "in situ" y sus cual se agregó a veces anotaciones de los coleccionistas, exhaustivasmonografiaslocales contribuyen a hacer que, por su parte, no eran botánicos. Nosotros, que somos posibie a los especialistas la preparaciOn de monograflas botánicos y forestales sabemos qué poco aconsejable es generales.Es evidente entonces la necesidad de una este procedimiento. En árboles y arbustos una serie de estrecha colaboraciOn entre los sistemáticos de todo ci caracterIsticasde lasinflorescencias y hojas(forma, mundo y una coordinación de su trabajo. En ci caso de dimension, pubescencia) dependen en gran parte de su tratarse de plantas leñosas, es menester que losforestales ubicación en el árboi y, en consecuencia, las mismas se ayuden a los taxonomistas.Richards observa en ci halian sujetas a fluctuaciones, como también ci tamaño prefacio de su obra The Tropical Rain Forest que: "In my del fruto puede depender de la edad del árbol. La forma travels I have been impressed by the large amount of bioiógica y hábito de una pianta son caracterIsticas de valuable ecological information which exists unpublished suma importancia taxonOmica.Existensin embargo in the minds and notebooks of foresters and buried in descripciones que no tienen en cuenta estos datos o lo departmental reports." expresan por falta de informaciones precisas enforma Pero no son sOlo datos ecolOgicos y fenolOgicos que se dudosa que con frecuencia induce a confusiones. Lo encuentran en la mente y los archivos de los forestales, mismo puede decirse de otrascaracterIsticascitadas son frecuentemente observaciones muy valiosas parade- relativas a diversos órganos ausentes o inmaduros en el finir ci taxon que corresponde a cierto grupo de plantas. material utilizado para efectuar la diagnosis.Son esas Una de las causas de la inestabiidad en la nomenclatura deficiencias que no han ocurrido solo en el siglo pasado, esque los botánicos discutenciertascaracterlsticas, aun en nuestros dIas leemos en descripcionesoriginales mientras unos les atribuyen valor genérico otros las con- frases como las siguientes: "Arbol vel frutex' sideran solamente como especIficas o atmde menor bacca (immatura)cr.2 ," o "Frutex' categorIa.Es en el habitat que se evidencian bien los Fructus maturi desunt in specimen nostro." rasgos de valor especIfico.Por ejemplo Tabebuia aye- Existendescripcionesgenéricasbasadasexciusiva- llanedae Lor. cx Griseb. y Tabebuia ipe(Mart. cx mente en las fibres masculinas o femeninas de árboles Schum.) Stand. son considerados por todos los botánicos dioicas; en consecuencia es muy grande ci némero de los que han visto los árboles en pie como dos especies nombres que pasan a la sinonimia cuando se realiza un diferentes, mientras que los que han tratado sOlo con estudio intensivo de un grupo de plantas. Cuando con un material de herbario las aceptan como variedades. Las colega prepare la monografIa de las Meliáceas formas péndulas de los árboies se pueden apreciar también nos causó cierta gracia coleccionar 3"diferentes" especies solo en ci campo. de Guarea del mismo arbolito. Para evitar futuros in- Los árboles cuitivados dan lugar frecuentemente a convenientes de esta Indole y sobre todo la creación de discrepancias entre los diferentes autores, ya que muchas nombres inétiles, hice una propuesta en ci sentido de que veces las especies o variedades dcberlan serconsideradas Ia descripción de un nuevo taxón para tener validez debe simpies formas. Las subsiguientes revisiones traen cam- ser completa, abarcando las caracterIsticas detodos los bios y nuevas combinaciones que atentan contra la csta- Organos en estado adecuado de evolución, inciuyendo biidad de nombres cientificos.Serla ilusorio entonces por supuesto los de individuos de ambos sexos en caso aceptar la conservaciOn de nombres si esta conservaciOn de ser dioico. Mi propuesta fue aceptada por los botánicos no protege al mismo tiempo contra ci cambio de rango. forestales argentinos y publicada en Taxon(VI, 7:195- Por ejemplo, conservar ci nombre Populus tremula L. 197, 1957).Esta sugerencia tuvo un eco muy desfavo- como se lo ha propuesto en ci Congreso de Oxford, no rable en los cIrculos de taxonomistas; ci Doctor Bullock, significa que ia misma planta no pueda ser ilamada por ejemplo, a pesar de constar en su nota enTaxon Tremula vulgaris Opiz. si se la pasa a otro género. La (VIII, 4:111, 1959)que: "Further objections to epitheta conservación de nombres especlficos, como ya lo hemos conservanda have been given convincingly by Maria expresado en varias oportunidades es irrealizabie y no Buchinger" agrega "The consequent proposal is, however, ileva a la estabiiidad tan dcseada por forestales y taxo- too subjective to lead to stability, whilst its retroactive nomistas. Lo que es factible es rechazar nombres oscuros, effect would be disastrous." Su opinion fue evidentemente propuesta ésta quc hizo, y por cuya implantaciOn iucha compartida por la mayorla de los botánicos en ci congreso tan valientemente, el botánico forestal Elbert L. Little de Montreal ya que derrotaron mi propuesta con219 Jr. Por lo demás ci tmnico camino hacia la estabiizaciOn votos en contra y 5 a favor.Sistemáticos, que son de los nombres cientIficos de los árboles forestales es la amigos personales, me han pedido retirar esta propuesta realización de buenos y muy compietos estudios botánicos. que han calificado de absurda ya que es muydifIcil que el Estos no pueden limitarse a ciertos rasgos morfolOgicos botánico que describe una nueva especie disponga de un que liaman la atención del investigador, pero que ensi material tan completo como nosotros lo exigimos. son insuficientes para una diagnosis. Citamos ci ejcmpio Por nuestra parte no vemos razón alguna por la cual de las especies del género Coccoloba cuyas fibres no haya que apresurarse en dar nombre a una planta de la figuran en la mayorla de las descripciones originales ya que se conoce iinicamente un fragmento. NoserIa mejor que Lindau mencionó que son siempre hermafroditas y publicar los datos refiriéndose a una posible novedad y de una monotonla cansadora.Sin embargo, pudimos observar más detalles sobre la misma o voiver a colec- comprobar que entra las siete especies representadas en cionarla cuando se encuentre en un estado de desarrollo la flora argentina hay, además de las con fibres netamente

698 Fifth World Forestry Congress Proceedings hermafroditas, plantas dioicas y polIgamas. Para apreciar of insufficient herbarium samples. This adds to the reigning con- bien el valor sistemático de los rasgos morfológicoses fusion in nomenclature. Stability would not be promoted by the conservation of specific names, as this would mean sometimes menester observar los caracteres silvIcolas, el area de dis- to maintain erroneous denominations. Names, little-used in the tribución, la adaptabilidad a diferentes ambientesy la past, should be discarded, as proposed by Dr. Little. Future tolerancia de las plantas. ëonfusions can be avoided by requiring that the description of En una reunion de forestales es suplerfiuo mencionar a new taxon should be complete and include the characters of all organs in an adequate state of development, and of both sexes la importancia de los estudios anatómicos de la madera if the plant is dioecious. pero tenemos que subrayar especialmente el gran valor The foresters possess important ecological and phenological que tiene Ia anatomIa comparativa para resolver delicados data, their field observations help to verify the systematic value problemas sistemáticos. La genéticaes un campo en el of certain characteristics, and the studies of populations are cual las observaciones de los forestales pueden ilegar important for genetic interpretations. If all these data would not a stay buried in departmental reports but be made available through ser muy iitiles a los taxonomistas. AquI nos referimos publication to taxonomists, whose major concernistheac- especialmente a los estudios de las poblacionesque es cumulation of adequate information, the indisputable definition trabajo de rutina en nuestro ambientey que pueden and ranking of all woody plants could then be achieved by proporcionar interesantes datos sobre el dinamismo de las mutual effort. variaciones, la sobrevivencia y las migraciones, facilitan- L'interdépendance de la taxinomie et de la botanique do asI la comprensión y delimitación de entes taxonómicos. forestière En el Congreso Internacional de Botánica del afio Une des preoccupations principales du dernier Congrès de pasado el Doctor Gilmour, presidente de la Comisión Botanique fut de prendre des mesures ayant pour objet d'assurer para Estabilización expresó:"I was convinced that,if lastabilisation de Ia nomenclature botanique et de contribuer some definite steps towards stabilization could be taken ainsi a améliorer les relations entre taxinomistes et autres per- by the Section at Montreal, it would bea major contribu- sonnes utilisant les noms de plantes. Nous estimons que les contacts entre deux branches de la tion towards better relations between taxonomists and même science ne peuvent être rien moms qu'excellents, étant other users of plant names." donné que leurs concepts fondamentaux sont les mêmes,et Nosotros no consideramos que las relacionesentre qu'il y va de l'intérêt commun des forestiers comme des taxi- taxonomistas y forestales tendrIan que nomistes qu'ils soient clairs et bien définis. ser mejores, sino Pour arriver a la meilleure classification possible, il est indis- decididamente buenas, basadas en un completo acuerdo. pensable de posséder toutes les donnëes se référant a un certain Para ilegar a éste, insistimos, debemos exigir ubicación groupe de végétaux, y compris leur rapport du point de vue y definición indiscutible de las plantas leñosas. Nadie se génétique et leur distribution géographique.Iiest evident en opondrá a aprender algunos nuevos nombres consequence qu'aucune plante ligneuse ne peut être caractérisée para re- a l'aide d'un fragment incomplet, et cependant ii arrive fréquem- emplazar a los que estamos acostumbradosa utilizar, ment dans les musées que l'on entreprenne de décrire des plantes pero estos cambios deben ser indiscutiblemente inevitables en se basant sur des specimens d'herbier inadéquats. Ceci ajoute y definitivos. encore a la confusion qui règne dans la nomenclature, confusion qui ne peut être éliminée si l'on conserve les noms actuels des RESUMES diverses espèces, étant donné que cela reviendrait dans certains cas a maintenir des denominations erronées. Les noms peu The Interdependence of and Forest Botany usités doivent étre rejetés comme le propose le Dr. Little,Afin One of the main preoccupations of the last Botanical Congress d'éviter a l'avenir toute confusion, ilest indispensable que la was to take some definite steps towards stabilization in nomencla- description d'un nouveau specimen soit complete et renferme les ture so as to contribute towards better relations beweentaxon- caractéristiques de tous les organes a un stade d'évolution ap- omists and other users of plant names. proprié, y compris la description de chaque sexe s'il s'agit d'une plante dioIque. We consider that there can be no better relations betweentwo Les sylviculteurs possèdent d'importantes données écologiques et branches of the same science but only complete understanding phénologiques. Leurs observations in situ peuvent fréquemment as their basic concepts are the same. It is the common interest aider a verifier la valeur systématique de certaines caractéristiques, of both foresters and taxonomists that these concepts shouldbe et les etudes auxquelles ils se livrent en matière de phytosociologie clear and well defined. sont de la plus haute importance pour l'interprétation des donnëes To reach the best classification possible, all data concerning génétiques. Si tous les renseignements qui s'accumulent ainsi dans a particular plant group should be available, including the inter- les archives des services forestiers sans être publiés étaient mis a relationship of its members and their geographical distribution. Ia disposition des taxinomistes, dont le principal souci consiste a It is quite evident that no woody plantcan be effectively charac- recueillir des renseignements adéquats, il serait possible de parve- terized from an incomplete fragment, yet itis quite frequent nir, grace a la mise en commun de tous les efforts, a une that museum workers describe and name plants throughthe use definition et a un classement irréfutables des plantes ligneuses.

Genetics and Tree improvement 699 Labor de Mejora de Populus Realizada en España

JOSE ELORRIETA Jefe de Ia Sección de Experiencias, de Repoblaciones del Instituto Forestal de Madrid, Madrid, España

La labor de mejora del chopo realizada en Espana por y copa abierta de fuertes ramas, pero sufuste, propende los cultivadores particulares y los Servicios Forestales en lo a ser más 0 menos sinuOSO. que va de siglo es importante y ñltimamente elInstituto Como se ye, la experiencia secular de los piantadores Forestal de Investigaciones y Experiencias ha intensificado catalanes, ha permitido seleccionar dos clones de Populus esta labor con la importación de los clones más destacados x euramericana importados deFrancia, "Canada blanco" de Europa y semillas de Populus de Norteamérica junto femenino y "Canada negro" masculino que es de tipo con losinteresantesôruzamientosartificialesdesus "robusta" y dos clones espontáneos de orillas del Ter y distintas Secciones que viene realizando. del Tordera, denominados respectivamente "Bordils" y En las provincias de Gerona y Granada, donde se viene "Poncella," el primero de tipo erguido piramidal abierto, aplicando el cultivo intensivo del chopo con asociación originado a! parecer por cruzamiento de algün ejemplar de plantas agrIcolas en la primera fase de su desarrollo, de P. x euramericana con el P. nigra L. v. itálica y el es de singular interés la mejora de Populusdesarrollada segundo, producto del cruzamiento de dos tiposin- por los particulares ya que se obtienen producciones muy dIgenas de P. nigra L. es de copa fusiforme amplia. En elevadas de 20 a 40 metros cübicos por hectárea y año, las plantaciones intensivas de Gerona, con labores del en turnos extraordinariamente cortos de 10 a 16 años. suelo, cultivos intercalares de plantas agrIcolas y riegos, clones por el Las primeras plantaciones regulares de Gerona, en las se emplean actualmente los tres primeros siguienteórdendepreferencia:"Canadablanco," riberas del Ter, Tordera y sus afluentes, datan de mediados "Bordils" y "Canada negro." Para los cultivos de secano del siglo pasado y en un principio, plantaron, como es y terrenos compactos o pobres, seemplea casi exciusiva- natural, el chopo negro comün, pero pronto, los cultiva- mente el "Poncella." Solo cuando los terrenos de secano dores más avisados de "Bordils" descubrieron en las on- son buenos y el subsuelo es fresco seutiiza el "Bordils." ilas del rIo Ter un chopo espontáneo de porte erguido que En Granada, sus apretadas y magnIficas choperas se sobresalIaporsus buenos crecimientos y excelente extienden principairnente por las orilas del rIo Genii. Es adaptación a los suelos profundos y nicos de aquella donde los cultiva- comarca,multiplicándosesusplantaciones con ritmo en esta gran masa de 3.500 hectáreas, creciente en años sucesivos, por la buena calidad de su dores granadinos han realizado una meritIsima labor de selección y actualmente, están constituidas estas choperas madera que es fácil de trabajar. sobre la base casi exciusiva de dos clones titulados A finaldel siglose introdujo de Francia el don "Blanquillo" y "Negnito de Granada," que se disponen en "Carolino" que se difundió rápidamente, desplazando a! plantaciones regulares de cada uno de ellos, muy densas "Bordils" en las tierras bajas, más calientes, frescas y y con ejemplares aislados de otro dondenominado sueltas, por su desarrollo rapidIsimo, tanto en altura como en diámetro, pero años de fuertes heladas le afectaron "Chopa." gravemente y un hongo parásito (Pleococcum populneum) El titulado "Blanquillo de Granada" es Ull don mascu- que al principio se localizó en las heridas depodas y lino, ilamado también "Castellano" y se trata de una fendas de heladura, adquirió en el perIodo 1910-15 forma erecta del Populus nigra, menos fastigiado queel carácter epidémico y diezmó las jóvenes plantaciones de "lombando comün"(P.nigrav.itálica)oniginado "Carolino," por lo que perdió 'ste don el favor püblico y pnobablemente por cruzamiento natural de nuestro chopo negro comün con el "lombardo." Comorecibe también volvió a plantarse de nuevo el "Bordils." Ia denominaciOn de "Castellano," acaso proceda delas A partir de 1920 adquinieron gran auge las planta- riberas del Duero o de alguno de sus afluentes. Este don ciones con "Chopos canadienses" que se importaron de por su gran crecimiento, cortezalisa los primeroS aflos y Francia y actualmente son dos clones, titulados "Canada condiciones tecnolOgicas de la madera, supera con mucho blanco" y "Canada negro," los preferidos para la planta- a su progenitor el chopolombando. ción en suelos ricos, profundos y frescos, dadas sus El "Negnito de Granada" es un don euramericano, mayores producciones y la excelente calidad de sus tarnbién masculino de tipo "robusta" que presenta en la aprovechamientos. Vega Granadina un gnan desanrollo y se destaca porla En los terrenos de secano y en los suelos más corn- uniformidad de sus plantaciones y limpieza y rectitud de pactos y pobres se emplea con preferencia el don indIgena sus fustes, pero en los suelos que no sonricos y de buena denominado "Poncella" que surgió espontaneamente a ca!idad !e supena en producciOn el "Blanquillo." orifias del Tordera y es un Populus nigra masculino, de El tender don, la "Chopa," es unhIbrido femenino corteza blanca y lisa que se desarrolla con tronco robusto originado probablemente por cruzamiento delPopulus

700 Fifth World Forestry Congress Proceedings nigra con el P. deltoides cv. "Carolin,"cuyos crecimientos tábrico y Ia alta cotización que alcanzan sus rollos de más son los máximos alcanzados en Granada por el chopo, de 40 centImetros de diámetro para la fabricación de pero ofrece en su desarrollo un acentuado foto-tropismo, tableros contrachapeados. que se acusa en sus fustes más o menos sinuososy, por Sin duda, el difIcil arraigamiento de la estaquila del otra parte, arraiga con dificultad de estacón, observándose "Carolino," su menor resistencia al frIo, la fragilidadque años de grandes pérdidas en su plantaciónen contraste demuestra contra el viento y la enfermedad quecon con otras de porcentaje menor. Estas son las causas por carácter epidémico le atacó en el Litoral Mediterráneo, las que el cultivador granadino nose ha decidido, hasta han impedido su mayor difusión en España, a pesar de la el presente, a plantar Ia "Chopa" sinoen ejemplares demanda tan grande que tiene para la industria del aislados en el interior de las masas de "Negrito"o "Blan- desenrollo. quillo." La importancia de Ia mejora realizada por los Servicios Forestales, en lo que vá de siglo, no ofrece duda, ya que Servicios Forestales se ha logrado la propagación por toda España de los tipos Los Distritos Forestales vienen cultivando los chopos femeninos de P. x euramericana, conocidos comunmente en sus viveros centrales junto con otras especies frondosas con ci nombre de "Canadienses," de "Pinseque" en Ara- desde su creación, distribuyéndolos entre particularesa gón y de "virginiana" en Madrid, cuyas plantaciones precio de coste para el fomento del arbolado. Al prin- sobre terrenos frescos y fértiles se desarrollan con un cipio solo se empleaba el chopo "lombardo" (Populus vigor y crecimiento superior a las del "lombardo," aunque v.itálica) pero a! conocerse las grandes producciones en sus cultivos no pueda subir tanto en montana, porque logradas sobre terrenos frescosy fértiles con las primeras le afectan más los frIos. También permitieron establecer plantacionesdel "Canadiense," se iniciósu cultivo a ci cultivo del valioso "Carolino" en el Litoral Cantábrico. partir de1920,sin abandonar el"lombardo," cuya demanda por los particulares seguIa siendo grande hasta Mejora dcl Chopo por el Instituto Forestal bien recientemente. La mejora emprendida por ci Instituto Forestal se está También losServicios Forestales de las Confedera- llevando a efecto por dos métodos: (1) Importación de ciones Hidrográficas, desde su fundación, han venido los clones considerados de máximo interés en Europa empleando estos mismos chopos congran éxito en la para su selección, multiplicación y distribución; y (2) defensa de los terrenos de ribera. Mejora directa por cruzamientos interseccionales e intra- De éste modo y con suma rapidezse logró extender seccionales entre chopos de ambos sexos bien selecciona- por toda España el cultivo de los "Chopos canadienses," dos. que en suelos profundos, sueltos y frescos o de regadIo, Solo daremos cuenta aquI de los primeros resultados superaban al "lombardo" por el volümen desu produc- obtenidos por el primer método ya que Ia mejora directa, ción, condiciones tecnológicas de Ia maderay mayor por su importancia, será tratada por ci Jefe de la Sección resistencia a las enfermedades de laroya. de GenétIca. Los "Chopos Canadienses" que los Distritosy Con- En 1947 se importaron de Wagening en los siguientes federaciones han multiplicadoen gran escala, son por 10 clones: Serotina, Serotina erecta, Regenerata, Geirica, regla general femeninos y del tipo Populusx euramericana Marylandica, Robusta, Deltoides missouriensis, Oxford, cI."virginiana."Es posible que existan varios clones, y Berolinensis y al año siguiente se importaron aunque aparenten ser el mismo, pués con independencia del Instituto de Popuiicultura de Casale Monferrato los de la primera introducción del "Canadiense"de Francia, clones italianos: 1-154, 1-214, 1-262, 1-455, 1-488, un posteriormente los Servicios Forestales de las provincias derivado del "Blanco de Cercenasco" y dos dci Populus limItrofes pudieron haber adquirido otros clones deP. x nigra. En 1949 importamos de Alemania los clones que euramericana.Nosotros mismos multiplicamos en los el Profesor W. Wettstein habIa reunido en su colecciOn viveros de Vizcaya en 1923 los clones "Raberdeaublan- en nümero de 30 y para completar la lista, ya extensa del co" y "Raberdeau negro," cuyas primeras estaquillas Instituto se importaron de Versalles 30 más especies y importamos de Francia y por aquella época, IaPapelera clones de la ColecciOn Lanterne. Finalmente en 1950 y Española importó un don "Canadiense" de Italiay se en ci 51 recibimos por envIos aéreos de los Profesores distribuyeron,entreparticulares y ServiciosOficiales, Genetistas S. Pauley de Nortearnérica y Heimburger del estaquillas procedentes de los viveros de dicha Entidad. Canada, semillas de las Secciones Aigeiros y Leuce. Dc Pero es más, en visitas a los viveros centrales de Va- Ia siembra de estos envIos hemos iogrado ejemplares muy lladolid y de Asturias, pudimos comprobar la existencia interesantes de P. deltoides procedentes de Dakota del de ejemplares euramericanos adultos (30-40años) de Norte y del Sur, Kansas y Colorado, asI como P. fre- tipo "serotina" que son masculinosy en la misma provin- montii, sargentii y wislizenii, de la zona Occidental y los cia de Madrid se pueden distinguir "Canadienses"mas- temblones americanos P. tremuloides y P. grandidentata culinos de la misma época. Sin duda, estos tipos "sero- que vienen siendo utilizados por Ia Sección de Genética tinas" no prosperarIan en sus primeras plantacionescon en sus cruzamientos artificiales. tanto éxito como los "virginianas" y se desistió desu Entre los clones de esta colecciOn numerosa se han ido empleo. Por el contrario el "Carolino,"don masculino seleccionando y multiplicando los que mejor se adaptaban de Populus deltoides que fracasó en el Centroy Sur de al clima de Madrid y en las tres campañas de 1957, 58 y Espafla, después de su primer éxito inicial, sin embargo, 59, se han podido distribuir entre Servicios Oficiales y se sigue multiplicando en los viveros forestales de San- particulares aproximadamente dos millones de estaquillas tander y Guipüzcoa, por los buenos resultadosque se y 5.000 estacones de los siguientes clones seleccionados: vienen obteniendo con sus plantacionesen el Litoral Can- 1-214, 1-455, 1-262, 1-154, "Robusta," Populus deltoides

Genetics and Tree Improvement 701 du ci. missouriensis, P. x euramericana Bayer de Lianura y L'oeuvre réaliséeen Espagne pour l'amélioration de Montafla, y P. x euramericana (Dolomiten) y ci P. x peuplier euramericana cv. "Campeador" obtenido por la Sección L'oeuvre que les sylviculteurs privés et lesServices forestiers ont réalisée en Espagne depuis le debut dusiècle pour l'améliora- de Genética. La experiencia de los balsamIferos está en tion du peuplier est considerable, et elle a encoreCté intensifiée su iniciación. dernièrement, d'unepart,grace a l'importation par l'Institut forestier de recherches et d'expériences de clonessélectionnés RESUMES d'Europe et de graines du Populus Nord-Américaifl, etd'autre Work Carried Out in Spain to Improve the Populus part, grace aux intéressants croisementsartificiels de ses différentes variétés qui sont actuellement réalisés a l'Institut. The work done in the twentieth century in Spain byprivate Les sylviculteurs des provinces de Gérone et deGrenade obtien- growers and the Forest Services to improve thepoplar is signifi- nent, dans leurs cultures intensives, desproductions importantes, cant, and recently the Forestry Research and ExperimentInsti- représentant 30 a 40 metres cubes a l'hectare avecdes rotations tute has intensified this work, importing the best clonesfrom courtes de 10 a 16 ans. Les clonesutilisés sur terres irriguées Europe and Populus seeds from the United States,together with pour la culture sont les "Canadablanco", "Bordils" et "Canada the interesting artificial crosses of various poplar speciesthat are negro" dans la province de Gérone, et "Blanquillo"et "Negrito", being made. additionnées d'une petite proportion de "Chopa" danscelle de Private growers in Gerona and Granada areobtaining in Grenade. Sur les terrains øü l'irrigation fait défaut, onutilise des intensive operations heavy yields of 30 to 40 cubic meters per clones nommés "Poncella" et "Blanquillo". hectare a year with short rotations of 10 to 16 years.The clones and black Les Services forestiers ont multiplié, dansleurs cultures rive- used on irrigated lands are white Canadian, Bordils, raines, les plantations de "peuplierscanadiens" féminins du type Canadian in Gerona, and "Blanquillo" and "Negrito,"with small "Virginiana", dont le rendement et la rusticité se sontavérés amounts of "Chopa," in Granada. On unirrigatedlands, "Poncella" littoral Nord, il y a is being used in Gerona and "Blanquillo" in Granada. exceflents dans le centre de I'Espagne. Sur le plantings of predominance des plantations de "Carolina", enraison de la The Forest Services have increased their river bank qualité de son bois ainsi que de son hon rendement. female Canadian poplars of the Virginia variety in CentralSpain, dernières which variety has been hardy and has given excellent yields.On L'Institut forestier a distribué, au cours de ces trois predominate années, deux millions d'épis provenant surtout desclones 1-214, the Northern coast, plantings of Carolina poplar 1-455, 1-212, 1-154, "Blanco de Cencenasco,""Robusta," "Mis- because of the quality of the wood and good yield. souriensis," "Dolomiten," "Bayer A," "Bayer B," et lePopulus In the past three years the Forestry Institute has distributed two Sectionde 1-212,1-154, euramericanacv."Campeador,"obtenuparla millionslips,chieflyofclones1-214,1-455, génétique. Parmi les graines reçues du Professeur S.Pauley, on "Blanco de Cercenasco," "Robusta," "Missouriensis," "Dolomiten," développement, des "Bayer A," "Bayer B," and Populus euramericana cv. "Campea- cultive, avec de bons résultats quant a leur Samples of the seeds exemplaires de P. deltoides provenant du Colorado, duKansas, du dor," obtained by the Genetics Section. Dakota du Nord et du Dakota du Sud, ainsi quedes exemplaires received from Professor S. Pauley of P. deltoides from Colorado, qui d'ores et déjà aswellasof de P. sargentii, P. fremontii et P. wislizenii, Kansas, North Dakota, and South Dakota, fleurissent bien et qui sont utilisés par la Section degénétique pour P. sargentii, P. fremontii, and P. wislizenii, are coming alongwell, peupliers de variétés are flowering, and being used by theGenetics Section in crossings sescroisementsartificielsavec d'autres with other poplars of the Aigeiros and Leuce species. Aigeiros et Leuce.

Tendencia Actual del Cultivodel Chopo

FERNANDO JAIME FANLO Jefe de la Brigada de Teruel del PatrimonioForestal del Estado, Espaha

desde mamente, principalmente por ciInstitutoForestal de El cultivo del chopo es tradicional en España Investigaciones y Experiencias, con laobtención de hace variossiglos,utilizado principaimente en planta- cultivados ciones lineales con fines de embeilecimiento yobtención hIbridos artificiales y la selección de clones rurales anteriormente ya en España, se han mejorado engeneral de madera para usos domésticos, construcciones las condiciones de cultivo en España de una manera muy y calefacción. Fué en el tultimo siglo cuando al mejorar el sistemade intensa en estos ñltimos veinte años. La actuación de la Administraciónforestal espaflola, comunicaciones se establecieron los cultivos en masas que 1941, sobre quedan localizados en España en cuatro zonas principales: aplicando la Ley del 18 de Octubre de repoblación de riberas de rIos y arroyos, hadado un gran provincias de Gerona y Barcelona (Vailes del Ter y especie como a Tordera); provincias casteilanas y leonesas en elValle empuje tanto a la repoblación con esta del Duero; provincias aragonesas, Rioja y Navarra; y las técnicas de su cultivo. Granada en el Valle del Genii. La citada Ley, adjudica alPatrimonio Forestal del por ñltimo, provincia de Estado, organismo encargado de laadministración y La utilización de hIbridos euramericanosposiblemente inundables importados de Francia,mejoró considerablementela gestión de los montes del Estado, los terrenos de los rIos que quedan cubiertos por lasavenidas ordi- producción de estas primitivas piantaciones, pero para coinciden estas superficies con las zonas mar- cada una de estas regiones los cuitivadoresadaptaron ia narias: tédnica de plantación a las demandas de losmercados ginales entre los cauces ordinarios y loscultivos agrIcolas permafleflteS. locales que en grandes lIneas son: gruesosdiámetros en sus dimen- Con ello se ha logrado recuperar zonas que por Gerona y Valle del Duero y maderas de pequeñas caracterIsticas son muy aptas para ci cultivodel chopo. siones en Granada y Valle del Ebro. tienen en su Paralelamente a las mejoras genéticas reaiizadasülti- pués quedan periódicamente inundadas, Fifth World Forestry CongressProceedings 702 mayorIa capas freáticas altas o hay posibilidades de riego, suelo como principales cuidados culturales adecuados,es tratándose de conseguir, y habiéndose logradoya en decir: en la práctica de una selvicultura intensivay de muchos casos, una estabilidad de loscauces cuya divaga- detalle. ción produce serios trastornosen las fincas colindantes con los rIos. RESUMES La longitud de los rIos españolesse estima en 60.000 Present Trends in the Growing of Black Poplars kms para los rIos principalesy 40.000 para sus afluentes; en una primera aproximación, las superficies de las riberas For several centuries the black poplar had beengrown in Spain by lineal planting, but in the 19th century the growingen inundables en las avenidas ordinarias,se fija en 80.000 masse was begun in four regions: in the Ter and Tordera valleys ha., con posibilidad de repoblación deunas 50.000 ha., in Gerona and Barcelona; on the Duero basin in Castille and especialmente a medida que se va realizando el plan Leon; in the Ebro Valley in AragOn, Rioja and Navarre; and general de obras hidráulicas y construcción de embalses. along the banks of the Genil River in Granada. The growers adapted their planting techniques to the demands Hasta el momento actual por el Patrimonio Forestal del of the local markets: large-size trees in Gerona and in the Duero Estado y dentro del plan general de repoblacionesse ha Valley, and small-size trees in Granada and in the Ebro Valley. prestado atención especial a esta clase de trabajos, pri- Use of Europeo-American hybrids and the hybrids produced mero con la delimitación de las zonas ribereñas, sobrepa- by the Forestry Institute have improved the cultivation in recent sando de 14.000 ha. las que se consideran years. como riberas, The Law of October 18, 1941 awarded to the State Forest especialmente en los RIos Ebro, Duero, Guadalquiviry Service the flood lands near rivers which are submerged at en sus afluentes, y habiéndose logrado Ia repoblación de ordinary high-water level. This resulted in the recovery of land 5.000 ha. sobre estos terrenosya delimitados. very suitable for poplar growing and, in many cases, in the stabilization of the river beds.The flood land submerged at Las repoblaciones que se están efectuandose acorn- ordinary high-water level amounts to 80,000 hectares, 50,000 of pañan con las consiguientes obras de defensay fijación which are suitable for planting. The State Forest Service has de cauces, pero en especial con un sistema de reticulado already mapped out 14,000 hectares and planted 5,000 hectares, sobre el terreno para lograr que se depositenen épocas supplementing the planting with work on the river beds and with de avenidas de aguas turbias los lodos a system of mesh nets spread over the land so that, when the y limos que forman flood waters are silty, the silt will settle, enrich the soil, and raise un suelo apropiado para el cultivo del chopo, consiguiendo the height of the banks además con ello elevar el nivel de la ribera sobre elcauce The example of the Forest Service has had repercussions on dando a este mayor superficie mojaday disminuyendo por private plantations and has brought about an increase in the lo tanto los riesgos de avenidasy daflos consecuentes. spacing between the trees and a more frequent use of selected clones.Inasmuch as small timber is easily marketed in some En los trabajos de la Administración Forestal española provinces of Spain, it will be difficult to achieve in the growing se emplean ya técnicas de plantación más espaciadas, con of black poplars a trend toward the general production of large tendenciaa producir maderas de gruesos diámetros, trees. utilizando, además de diversos clones españoles, otros extranjeros. Tendance actuelle dans la culture du peuplier noir Se presta, como es lógico, la debida atencióna los En Espagne, le peuplier noir estcultivé en ligne depuis cuidados culturales de estas repoblaciones, especialmente plusieurs siècles, mais c'est seulement au XIXème siècle que la culture en massifs a été entreprise dans quatre zones: les vallées en podas y lucha contra insectos, que, por las condiciones du Ter et de la Tordera dans les provinces de Gérone et de climáticas de España, atacan con preferenciaa las re- Barcelone; le bassin du Douro dans celles de Castille et de Leon; poblaciones en tanto que son limitadas las enfermedades Ia vallée de l'Ebre en Aragon, dans la Rioja et en Navarre; et causadas por hongos, más bien propias de paIsescon les berges du Genil dans la province de Grenade. latitudes superiores a la de España. Les planteurs ont adapté leurs méthodes de plantation aux exigences des marches beaux: gros diamètres dans Ia province de Esta actuación de Ia Administración Forestal española Gérone et dans la Vallée du Douro et bois de petites dimensions va teniendo su repercusión sobre las plantaciones que dans la province de Grenade et la Vallée de l'Ebre. efectüan los particulares, tanto lograndoque se aumente Au cours des dernières années, les cultures ont £te améliorées grace a l'utilisation des hybrides euro-américains et de ceux el espaciamiento, como que éstos utilicencon mayor qu'a obtenus l'Institut forestier. frecuencia clones selectos. En vertu de la Loi du 18 octobre 1941, les terrains inondables No se ha liegado todavIa a conseguir deuna manera des vallées, qui sont submerges par les crues subites ordinaires, general que el cultivo del chopose oriente hacia la produc- font partie du Domaine de 1'Etat; grace a quoi on a récupéré ción de maderas de grandes diámetros, des zones très favorables a la culture du peuplier noir, et en même por cuanto en temps, dans bien des cas, on en a tire le bénéfice supplémentaire algunas provincias españolas las maderas de pequeñas de la stabilisation des lits. La surface des berges inondables par dimensiones tienen mi gran arraigocomo consecuencia de les crues subites ordinaires représente 80.000 hectares, dont 50.000 su utilidad para construcciones, pero si es cierto que estas se prêtent a Ia plantation. Le Domaine forestier de l'Etat a maderas de pequenas dimensiones tienen cada déjà délimité 14.000 hectares, dont 5.000 ont été plantés, ces vez un plantations étant accompagnées de travaux réalisés dans les lits valor comercial más pequeflo. Por ellose ha logrado un et de l'application au terrain d'un système d'engrillagement, de interés muy marcado por parte de los plantadorespor manière qu'aux époques de crues subites, borsque les eaux sont conocer cada vez con mayor precision cuales son las boueuses, le limon se depose sur le sob qu'il améliore, et sur les directrices que han de seguir para obtener los mejores berges dont il élève le niveau. L'exemple donné par l'Administration forestière s'est rdpercuté resultados económicos, que indudablemente han deser sur les plantations privées, ce qui a permis d'obtenir, de leurs las que ya hace algün tiempo siguen elresto de los paIses propriétaires, un espacement plus grand et une utilisation plus fré- del Oeste de Europa y que pueden resumirse,para el quente de clones sélectionnés. Le bois de petites dimensions chopo, en la selección de clones degran rendimiento y étant d'une vente facile dans certaines provinces espagnoles,ii resistentes a enfermedades, la ampliación del espacia- est difficile d'obtenir que la culture du peuplier noir s'oriente, d'une facon générale,versIaproduction de bois de grand miento, en dar al arbolado las podas, riegosy cultivo del diamètre.

Genetics and Tree Improvement 703 Estudios de Mejora delChopo

FLORENTINO MARTINEZ MATA Jefe de la Sección de Genética del InstitutoForestal de Madrid, Madrid, España

przewalskii Maxim., que Anotamos algunas observaciones sobre los crucesde simoni fastigiata Schneid. y P. reanudan pronto en primavera suactividad vegetativa, con Populus que hemos realizado en el InstitutoForestal. injertadas. Además, para Disponemos de tres invernaderos con un totalde 7 algün adelanto sobre las püas las ramasflorIferas femeninas de la SecciónLeuce, compartimentos, en cada uno de los cuales se hautilizado empleamos brinzales de un añode P. grandidentata una sola clase de polen. Michx. y para Aigeiros plantitasde estaquilla, también El polen de Pop ulus tremula se recogió el 4 deFebrero de un año, de P. nigra var. giganteaHort. DispusimoS en árboles criados en los viverosdel Instituto, nacidos de injertos para cada tipo polinizado.El semillas recibidas del Pirineo de Lérida y de laSierra de como mInimo de seis brinzales de año, por la recogió trabajo es más fácil con los Guadarrama (Madrid); el de P. tremuloides se mayor igualdad entre losdiámetros de püa y patrOn, pero el 12 de Febrero en árboles criados en losviveros del sOlo se puedan injertar el no hemos encontrado exacto que Instituto, de semillas recibidas de America del Norte; chopos de acuerdo con la serie deBogdanov (tembiones- de P. alba el 14 de Febrero en el Parquedel Retiro biancos_deltoides_balsamIferos), que predicemalos (Madrid); el de P. bolleana, el 20 de Febrero en el Parque resultados para los injertos de blancos otemblones en de la Ciudad Universitaria de Madrid; el de P.nigra el 1 de Marzo en Aranjuez y ci 15 de Marzo en ci Parquedel baisamIferos. el 13 de El polen se aplica con unpulverizador de boquilla Retiro; el de P. deltoides cv. "Carolin" el 4 y fina, pués el exceso de polen nofavorece la fecundación, Marzo en Aranjuez, y el polen de P. deltoidesmonilif era fibres viveros del Instituto, nacidos de y se repite variosdIas la operación sobre las en árboles criados en los sucesivamente abiertas en cada rama. semillas recibidas de Dakota del Norte. varios amentos y Las ramas fiorIferas masculinas se cortaron entodas Como cada rama florIfera ileva adelantadas en éstos muchas cápsulas, cada unade las cuales rinde en las especies citadas con yemas bastante aigunas variedades de Aigeiros másde cincuenta semillas, su desarrollo, de modo que,colocadas en agua, en habita- obtener en cruces intrasec- del laboratorio cuya temperatura se mantenIa bastan pocos injertos para ciones cionaies miles de semillas viabies. aproximadamente a 20°C., diseminaban en un plazode medida que maduran y se veinticuatro a setenta y dos horas. Las semifias se recogen a polen de siembran diariamente en macetas dedos a tres pulgadas, Como ensayo se realizaron fertilizaciones con iienas con una mezcla de tierraordinaria del vivero, Populus alba, bolleana, nigra y deltoides cv."Carolin" Germinan en veinticuatro a cuarenta y del año anterior, conservado en frigorIfico, en tubosde arena y mantillo. frecuentes en Aunque selograron ocho horas, y mejor en dIas luminosos, muy ensayos concierreparafinado. Madrid. No se ha presentado casoaiguno de "damping- semillas maduras en pequeiia cantidad este polen viejo no off," enfermedad que en ci Nortede Europa y America tenIa valor práctico. exige desinfecciones del suelo antesde la siembra. Wettstein aplicó a los chopos el sistema ideado para Cuando las piantas tienen de cuatro aseis hojas, se los sauces, que consiste en colocar en cubos de agua, enel centImetrOS invernadero, ramas durmientes con yemas de for, queal traspiantan al vivero a distancias de cuarenta en cuadro. abrirse se polinizan artificialmente, y silos frutos sonde estudios sucesivos, pués ci maduración rápida, no necesitan para liegar a sazón otro Este material será objeto de porte y crecimiento de lasplantitas durante un año en alimento. Este método se ha perfeccionado conel injerto forzosamente larga, de vaso, que por un injerto lateral une al patron lapüa, vivero es poca base para la selecciOn, pués no se conocen correlaciones entrelos caracteres (rama florifera femenina con yemas durmientes),dejando acelerar la selec- libre ci extremo inferior de ésta, introducido en un vaso juveniles y adultos de los Populus, para con agua que se renueva diariamente.De éste modo se ción de ios hIbridos. semillas que maduren Nuestros cruces de Aigeiros tienen pormeta la maxima asegura el éxito aunque se trate de regadIo, condiciones más lentamente. producción en terrenos fértiles y de Las hibridaciones en invernadero no soloevitan las que reducen bastante suarea en Espaha. molestias de la escalada a los árboles para aislamiento y La capacidad de adaptaciónai suelo de los chopos de polinización de cada inflorescencia, sino que permiten la Sección Leuce, blancos y temblones europeos yamen- realizar cruzamientos entre árboles situados agrandes canos, permite pensar en sucultivo sin riego en la zona distancias o que no florecen al mismo tiempo,pués se forestaldela España hümeda y encombinaciofleS pueden forzar las ramas masculinas o femeninas para ventajosas de cruces interseccionales, ointraseccionales con la Sección Aigeiros, quesuministren productos menos lograr el sincronismo de la floración. del sueio. Para todas las especies utilizamos patrones dePopulus exigentes en agua y en fertilidad Fifth World Forestry CongressProceedings 704 Los ya realizados confirman Ia amplia compatibilidad production on fertile, irrigated land. The purpose of the intrasec- tional crossing of Leuce and the intersectional crossing of Leuce de las especies de las Secciones Leuce y Aigeiros, cuya and Aigeiros was to obtain poplars that require less water and extension a la Sección Tacamahaca la pusieron de mani- soil. We confirmed the fact that the species of the Leuce and fiesto los cruces de Schreiner entre negros y balsamIferos, Aigeiros sections are completely compatible. y antes, la presencia de hIbridos naturales en el Canada We also obtained natural hybrid seeds for planting, growing, and selection from maternal trees of Populus grandidentata on entre Pop ulus deltoides y P. tacamahaca, en los puntos April 27, P. deltoides on June 5, P. sargentii on June 6, and P. donde establecen contacto sus areas. wislizenii on July 2. Cultivamos en viveros de Madrid y Granada Populus euphratica Oliv., que esperamos nos suministre pronto Etude traitant de l'amélioration du peuplier material para cruzamientos, que perseguirán aumentar el Nous disposons, pour les croisements du Populus, de sept rendimiento leñoso y la escasa facultad de reproducción compartiments de serre, dans lesquels nous avons utilisé le pollen por estaquila de esta especie, sin perder su capacidad de desvariétéssuivantes:Populustremula,tremuloides,alba, adaptación a suelos salinos. bolleana, nigra, deltoides cv. "Carolin" et deltoides monilifera. También hemos recogidosemillasde hibridaciones Des rameaux femelles aux pousses dormantes sont réunis a un sujet au moyen d'une greffe latérale pratiquée de facon a laisser naturales para su siembra, cultivo y selección en árboles libre l'extrémité inférieure du greffon que l'on introduit dans un madres de los viveros del Instituto de Populus grandiden- verre dont l'eau est renouvelée tous les jours. Au moment de tata (27 de Abril), P. deltoides monilif era de Dakota del s'ouvrir, les fleurs sont pollinisées artificiellement; entre le verre Norte y Kansas (5 de Junio), P. sargentii (6 de Junio) y et Ic sujet, elles assurent le développement des fruits, même ceux des peupliers noirs, qui sont lents a mirir. P. wislizenii (2 de Julio ). Pour nos sujets, nous nous servons des Populus simoni fastigiata et P. przewalskii,qui, au printemps, reprennent leur activité RESUMES végétative avec une certaine avance sur les greffons. On obtient Research to Improve the Poplar de bonnes greffes aussi bien quand sujet et greffon appartiennent aIa même variétéquelorsqu'ilsreprésententdesvarlétés For crossing Populus, we have seven greenhouse sections, in différentes. which pollen from P. tremula, P. tremuloides, P. alba, P. bolleana, On applique le pollen au moyen d'une poudreuse et cette P. nigra, P. deltoides cv. "Carolin," and P. deltoides inonilif era operation Se renouvelle au fur et a mesure que les fleurs s'ouvrent has been used. sur les rameaux. Une fois les semences arrivées a maturitd on Female branches with dormant buds are joined by a lateral effectue des semis quotidiens dans des pots de fleurs. Les graines graft to a stock, leaving free the lower end of the scion which germent en l'espace de 24 a 48 heures, et plus rapidement encore is inserted in a glass of water, changed daily. When the flowers lorsque le temps est beau comme cela arrive très fréquemment a open, they are pollinatedartificially, and the glass and stock Madrid. On n'a constaté aucun cas de "damping-off." Quand les ensure the development of fruit even in poplars slow in matura- petits plants ont de 4 a 6 feuilles, ils sont repiqués en pépiniêre tion. avec un espacement de 40 centimetres dans tous les sens. We use stocks from Pop ulus simoni fastigiata and P. przewal- Nos croisementsd'Aigeirosont pourobjetd'obtenirun skii, which resume their vegetative activity in the Spring a little maximum de production sur des terrains fertiles et lrngués. Au before the grafted scions. Good grafts are obtained whether stock moyen de croisements opérés avec des variétés de Leuce entre and scion belong to the same section or to different sections. elles et les croisements entre les variétés Leuce et Aigeiros, nous The pollen is applied with a duster, the operation being repeated essayons d'obtenir des peupliers moms exigeants quant a l'eau et on the flowers as they open on each branch. au sol.Nous avons pu confirmer qu'il existe une grande com- Ripe seeds are sowed daily in pots and germinate in 24 to 48 patibilité entre variétés Leuce et Aigeiros. hours, or less on bright days, which are very frequent in Madrid. Nous avons également prdlevd, en vue d'ensemencement, de There was not a single case of damping-off. When the seedlings cultureet de selection, des semences, produits d'hybridation have 4 to 6 leaves, they are transplanted to the nursery, 40 naturelle, sur les arbres mères de P. grandidentata (le 27 avril), centimeters apart, in squares. P. deltoides (le 5 juin), P. sargentii (le 6 juin), et P. wislizenu The purpose of crossing Aigeiros was to attain maximum (le 2 juillet).

Approval of International Code of Nomenclature For Cultivated Plants

ELBERT L. LITTLE, JR. Forest Service, U. S. Department of Agriculture, Washington, D.C., U.S.A.

The purpose of this paper is to propose that the Inter- and as the forestry member on the Editorial Committee. national Code of Nomenclature for Cultivated Plants be Therefore,asforestryrepresentativefromthehost approved or endorsed by Section II (Forest Genetics) and country and on behalf of my forestry colleagues from other by the Fifth World Forestry Congress. This Code, pub- countries on this Commission who have participated in lished in 1958, was formulated and adopted by the Inter- the preparation, I wish to present this Code for your con- national Commission for the Nomenclature of Cultivated sideration and use. Plants, of the International Union of Biological Sciences. International Code of Nomenclature for Cultivated Since this Commission was reorganized in 1956,I have Plants, by the International Commission for the Nomen- served as forestry representative from the United States clatureof Cultivated Plants,isa 28-page pamphlet Genetics and Tree Improvement 705 published in English in 1958 by the International Bureau Dutch, 'razza' in Italian, etc. Anyone is free to use the forPlant Taxonomy and Nomenclature,106 Lange term cultivar or one of the equivalent terms." (Article Nieuwstraat, Utrecht, Netherlands, where copies can be 10.) purchased.Copies are for sale also by the following Formation and Use of Cultivar(Variety)Names. distributors:American Horticultural Council, Donald Beginning in 1959, names proposed for new cultivated Wyman, Arnold Arboretum, Jamaica Plain 30, Mass., varieties, such as clones, lines, and uniform hybrid groups, U.S.A., (price 50 cents); and the Royal Horticultural must be fancy names (that is, in modern languages) and Society,Vincent Square, London, S.W.1,England. not in Latin form, though older Latin names may be Authorized translations of this Code are being published retained (Article 15). These cultivar (variety) names of also in other languages. preferably one or two words are attached directly to a History of the Code. This Code follows the edition scientific name or common name and are capitalized and of 1953, prepared primarily by those interested in horti- distinguished by the abbreviation cv. or typographically, cultureand adopted by the Thirteenth International such as by single quotation marks (Articles 16, 20). Horticultural Congress at London in 1952. Agriculturists Certain cultivar (variety) names are inadmissible from and foresters welcomed that Code for naming their 1959 onwards, for exampleS names containing numerals crops. In order to make future editions equally applicable or symbols except as established custom requires,the to agriculture and forestry, the International Union of scientific or common name of a genus or common name Biological Sciences agreed in 1955 to undertake this work of a species, excessively long words or phrases, names through its International Commission for the Nomencla- exaggerating the merits, names vaguely descriptive, names ture of Cultivated Plants in its Division of Botany.In within the same genus likely to be confused, etc. (Article 1956 this Commission was enlarged to twenty-five mem- 21.) bers appointed by the Union representing the three Publication. From1959onwards,newcultivar groups, the foresters selected after consultation with the (variety) names must be published in printed or similarly International Union of Forest Research Organizations. duplicated matter and accompanied by a description or by Forestry is well represented on this Commission with six a reference to a previously published description.(Articles members from Australia, England, France, Germany, 23, 24, 26.) "Any language may be used for the descrip- Japan, and the United States of America. tion. .. It is strongly recommended that English, French, This Commission published the 1958 edition of the German, Russian, or Spanish be used, or that a transla- Code after meeting at Utrecht, Netherlands, November tion or summary in one of these languages be provided." 21-23,1956, and at London, December 4-6,1957. (Article 27.) Another meeting was scheduled for Cambridge, England, Priority. "The naming of cultivars (varieties) is based on June 3-6, 1960. onpriorityofpublicationexceptwhenexpressly This Code was approved for horticulture with minor limited..." (Article 28.) recommendations by the Fifteenth International Horti- Translations, Transliterations, and Commercial Syno- cultural Congress at Nice, France, in 1958. Endorsement nyms."When a cultivar(variety)is introduced into for agriculture is being sought from the Food and Agri- another country, its original name is normally retained. culture Organization of the United Nations. This Code is However, when there are linguistic and other difficulties, submitted here for endorsement for forestry and will be translation, transliteration, or change of name (commer- submitted also to the International Union of Forest cial synonym . ..)is allowed." (Article 36.) Research Organizations at its next meeting. Registration. The Code provides also rules and recom- The Code provides for naming the varieties of culti- mendations for registration of cultivar (variety) names, vated plants and for registration of names on an inter- that is, their acceptance by an official registration author- national level.It occupies 14 pages and consists of 56 ity and inclusion in a register. "An official registration Articles with additional Recommendations and many authority is any international or national organization or examples. The main rules can be quoted or summarized agency so designated either by appointment orby agree- here. ment with those concerned . ..The testing of cultivars General Considerations and Guiding Principles. "Cul- (varieties) is of the greatest importance and should, when tivated plants are essential to civilization.It is important, possible, be carried out before a name is submitted for is therefore,thataprecise,stable,andinternationally registration, butitisemphasized that registration accepted system should be available for their naming." independent of testing." (Article 51.) (Article 1.)"The aim of this Code is to promote uni- Modification. The Code may be modified by the Com- formity, accuracy, and fixity in the naming of agricultural, mission, to whom proposals for amendment may be sent. silvicultural and horticultural cultivars (varieties), (Article 56.)Terms of present forestry representatives which are normally given fancy names ... The common will expire at the next meeting of the International Union names of genera and species ... are notregulated by this of Forest Research Organizations, which will select the Code." (Article 3.)"Registration of cultivar (variety) future forestry members. names is of the greatest importance for nomenclatural Applications of This Code to Forestry.This Code stability ..." (Article 6.) serves as a guide for the naming andregistration of new "Cultivar is an international term for the category cultivated varieties of forest trees developed by forest known indifferent countries by different names, for geneticists and others in tree improvement programs. At example, 'variety' in English, 'variété' in French, 'vane- present, cultivated varieties of forest trees arerelatively dad' in Spanish, 'Sorte' in German, 'sort' in the Scandina- few in comparison with cultivated varieties of agricultural vian languages and in Russian,'ras'or'varieteit'in and horticultural crops.However, the Code is already

706 Fifth World Forestry Congress Proceedings available in advance for naming and registering these langue vivante) et doivent faire l'objet de publication avec une description dans une langue quelconque. L'appellation est fcndée improved trees on an international level. Much confusion sur la priorité de publication, sauf lorsqu'elle est expressément can be avoided by agreement to follow this Code. limitée.Une réglementation etdes recommandations ont été TheInternationalPoplarCommissionhasbeen prévues pour l'homologation des noms de cultivars (variétés), appointed by the Food and Agriculture Organization of c'est-à-dire que ceux-ci doivent être acceptés par un organisme officiel d'homologation et porte a un registre. the United NationsastheInternational Registration La Commission internationale du Peuplier observe ce Code, Authority for forestry cultivars (varieties) of the genus qui sert de guide pour l'appellation et l'homologation de nouvelles Populus. That Commission follows this Code to deter- variétés cultivées d'essences forestières mises au point par des mine thecorrect,uniform, and stable names of the généticiens forestiersetautresspécialistes dans le cadre des programmes d'amélioration desarbres.Pour cesraisons,je numerous clones of poplars. propose l'approbation du Code par les sylviculteurs au cours de Proposal.Therefore, I propose the approval of this la présente rencontre internationale, ce Code représentant le meil- Code by foresters at this international meeting as the best leur moyen de cooperation internationale en la matière. means of international cooperation in the naming and registrationof cultivatedvarieties.Adherence tothe Aprobación del Código International de Nomenclatura Code is voluntary and subordinate to any possible con- para Plantas Cultivadas flicting national laws and regulations. However, confusion El objeto de este artIculo es proponer que el Código Interna- can be avoided if all concerned try to follow the same cional de Nomenclatura para Plantas Cultivadas (International Code of Nomenclature for Cultivated Plants) sea aprobado a rules. The Code contains no controversial items affecting endosado por la Sección II (Genética Forestal) y por el Quinto foresters. Minor amendments have been suggested toward Congreso Mundial de Silvicultura. Este Código, publicado en clarification of certain details. The optional term cultivar Utrecht, Holanda, en 1958, fué formulado y adaptado por la has been opposed by many agronomists, who are author- Comisión Internacional para la Nomenclatura de Plantas Culti- vadas, de la Union Internacional de Ciencias BiolOgicas. Esta ized to use the national equivalent terms, such as variety. Comisión de veinticinco miembros designados por la Union, incluyeagrónomos,horticultoresyseis miembros ingenieros RESUMES forestales, quienes han participado en la preparacidn del COdigo. Homologation d'un code international pour une nomencla- Como miembro forestal del pals huésped y en nombre de mis ture des plantes cultivées colegas forestales en esta Comisión, deseo presentar este Código para Ia consideración y el uso de Uds. La présente communication se propose de soumettre a l'appro- Este Código fué aprobado para la horticultura con recomenda- bation ou a l'adoption par la Section II (Génétique forestière) ciones menores por el Décimoquinto Congreso Internacional et par le Cinquième Congrès Forestier Mondial un Code inter- Horticola en Nice, France, en 1958. No contiene ningun artIculo national pour une Nomenclature des Plantes cultivées. Ce Code, controversial que afecte a los ingenieros forestales. publié a Utrecht, aux Pays-Bas, en 1958, a été élaboré et adopté El Código provee por nombrar las variedades de plantas culti- par la Commission internationale de la Nomenclature des Plantes vadas (cultivares)y el registro de sus nombres en un nivel cultivées de l'Union internationale des Sciences biologiques. Cette internacional pero no regula los nombres vulgares de los géneros Commission de vingt-cinq membres désignés par l'Union, compte ni de las especies. Empezando en 1959, los nombres propuestos des agronomes, des horticulteurs, et six membres représentant la para las variedades cultivadas nuevas deben ser nombres dis- sylviculture, qui ont participé a l'élaboration du Code. En tant tintivos (es decir, en idiomas modernos, que deben publicarse que sylviculteur du pays invitant et au nom de mes collègues con una descripción en cualquier idioma.El nombrar se basa sylviculteurs de la commission, j'aimerais soumettre ce Code a en la prioridad de publicación excepto cuando es expresamente votre examen et vous en recommander l'usage. limitado. Se proveen reglas y recomendaciones para el registro L'utilisation de ce Code pour 1'Horticulture a été approuvée de nombres de cultivares (variedades), es decir, su aceptación por après quelques recommandations mineures parleQuinzième una autoridad oficial y so inclusiOn en un registro. Congrès international d'Horticulture, tenu a Nice, France, en La Comisión Internacional de Populus acepta este COdigo, que 1958. Il ne contient rien qui puisse prêter a controverse parmi sirve coma gula para nombrar y registrar las variedades nuevas les sylviculteurs. cultivadas de los árboles forestales desarrolados por los genéticos Le Code prévoit la designation des variétés de plantes culti- forestales y otros dentro de los programas de mejorIa de los vées(cultivars)et l'homologation des noms au niveau inter- árboles. Por tanto, yo propongo la aprobación de este Codigo national, mais ne réglemente pasles noms usuels des genres et en nombre de los ingenieros forestales en esta reuniOn interna- des espèces. Depuis 1959, les noms proposes pour les nouvelles cional corno el mejor método de cooperación internacional en esta variétéscultivées doivent être des noms inventés(dansiine materia.

Genetics and Tree Improvement 707 The Certification of Forest Tree Seed in Britain

R. T. F. LARSEN Forestry Commission of Great Britain, London, England

It is generally recognised that one of the most important Seed Sources and far-reaching factors in good forestry is the rearing of In accordance with the recommendations of the6th trees derived from seed of selected trees and suitable Session of the F.A.O. Conference in Rome in 1951, provenances: it is the foundation without which silvicul- Permanent Identity Numbers are given to the classified ture and management, however well planned and carried seed sources based on the Universal Decimal Classification out, can only be partly successful. The long-term nature System.For example, "(413)" refers to:4, Europe; of managed forestry makes this all the more important, 1, Scotland; 3, West Scotland. A fourth digit indicates for succeeding generations will reap the results of its the county, e.g., "(4131)" is Argyllshire in West Scotland, application. and a fifth digit, outside the brackets, denotes the perma- nent number ofa plus or almost plusstand,e.g., Research Work "(4131)2." Seed collected from plus and almost plus The Research Branch of the Forestry Commission has stands is kept separate, and the year in which the crop devoted much work to the study of the behaviour of dif- formed, i.e., "58" for 1958, is added on to the code num- ferent provenances of species, both exotic and indigenous, ber, e.g., "58 (4131)2."It is important to base such a in this country. Some of the experimental plots are over classification on climatic and edaphic criteria, but present thirty years old and provide a useful basis for the choice of knowledge has limited this and, although the third digit origins of seed to be imported or to be collected in this represents a group of counties within a broadclimatic country. In 1948 a Genetics Section was formed, and this region, the fourth, generally, represents a county, a purely section has undertaken an extensive survey of the wood- political unit. Seed from normal seed sources is not kept lands and plantations in Great Britain, in which potential separate but is mixed and distributed as generalcollections seeds were classified on the following basis: from specified regions or counties. Plus in which more than 75% of the Of the seed orchards, some 130 acres belong to the dominant treesare vigorous, well Forestry Commission and about 20 acres are privately formed, and substantially free from owned. There are nearly 3,000 acres of almost plus and disease. plus seed sources in Great Britain at present. Almost Plus in which 50-75% of the dominant trees are vigorous, well formed, and Legislation substantially free from disease. There are certain government controls (Seeds Acts of Normal in which 25-50% of the dominant 1920 and 1925 and subsequent amendments) whichapply trees are vigorous, well formed, and to most seeds and in which one of the mainprovisions is substantially free from disease. that seed for sale must have been tested for purity and Minus in wflicn lessthan 25% of the germination at one of the official Seed Testing Stations dominant trees are vigorous and well at Cambridge, Edinburgh or Belfast, and thatthe results of these tests must be shown on sale or exposure for sale. formed, or any stand suffering un- This provision safeguards the buyer to a certain extent duly from disease or insect attack. but, of course, is irrelevant to the origin of the seed; there During this survey, the best individual phenotypes were are no regulations at present to compel theorigin of the selected and recorded as "plus trees."These are being seed (beyond the country) to be shown, but, in practice, propagated vegetatively, by grafting or from cuttings, and most merchants will readily do so. planted out in seed orchards to provide commercial quanti- ties of seed of improved varieties (cultivars). Eventually Seed Associations the parent clones in each orchard will be crossed sys- The Scottish Forest Tree Seed Association was formed tematically by controlled pollination with the other parents in 1956, and the Forest Tree Seed Association of England in the same orchard, and the resulting progenies will be and Wales, in 1959. These bodies are non-profit-making tested on a range of forest sites. Parent "plus" trees which and have as their object the improvement of the quality produce superior progeny will be classed as "elite" trees. of all species of forest trees by encouraging the use of A second kind of seed orchard is that in which the seed seed and plants of the best known origins. Members are trees are selected seedlings planted at wide spacing for drawn from all persons interested in forestry, including seed production purposes. Notable examples of these are landowners, nurserymen and consultants, and the manage- to be found at Birkhill Estate in Scotland. ment committees have representatives from the appro-

708 Fifth World Forestry Congress Proceedings priate landowners' associations and forestry societies, the broad-leaved seed is imported. The large proportion of Horticultural Trades Association and the Forestry Com- imported conifer seed is due partly to the extensive use mission. The Associations furnish information on seed of exotic species (of which the plantations in this country sources and their treatment, on the assessment, timing are still young for bearing seed) and partly to the large- and methods of collection of seed crops, and the Scottish scale felling of mature trees in this country during the Association hires out seed collection equipment. Informa- war.There is, clearly, room for increasing the supply tion on extraction, storage and testing is also given, and of home-collected seed.In Scots pine, European and registers of selected seed sources (drawn up in conjunc- hybrid , Thuja plicata, Tsuga heterophylla, Lawson tion with the Research Branch of the Forestry Commis- cypress, the and beech, we either are or shall be self- sion), kept.Provision is made for the registration of supporting; in Corsican and lodgepole , Japanese nurseries, extractories and seed stores which are con- larch, Norway and Sitka spruces, Douglas and silver firs sidered suitable for handling and maintaining the identity we should be able greatly to increase home collections, but of certified seed and plants. The technical officers of the not so much as to preclude imports, at least for some con- Associations give supplementary advice and information. siderable time to come. Recent improvements in climbing techniques and equip- Seed Certification ment have made it easier and safer to collect from tall The most important function of the Tree Seed Associa- trees. It is desirable to collect cones only during good seed tions is, perhaps, the certification schemes which they years when collections are cheaper and the cones contain sponsor. A member wishing to collect seed can locate a higher proportion of viable seed. The recent installation from the register in his handbook all the seed sources of of large, refrigerated seed stores to hold reserves of seed the species which he is interested in.Having selected over the poor seed years makes such selective collecting a seed source, he may then apply for a collection schedule, possible. Most tree species will not normally bear cones which gives fuller details of the stand, including owner, abundantly until they are twenty to thirty years old, and precise location, special conditions attached to collection, the "coming of age" of the extensive plantings of exotic and describes the seed source physically, that is, the age, species such as Sitka spruce and lodgepole pine should, in average number of seed trees per acre and difficulty or time, provide a large source of seed from populations otherwise of collection.If he wishes to obtain seed he which have, to some extent, become selectively more suited makes the necessary arrangements with the owner. to the local environment. Provisional certificates of origin for untreated cones or With this development of home collection the certifica- broad-leaved seed, for cleaned seed, and for seedlings or tion schemes must evolve. At present we are familiar transplants are issued in the form of advice notes by the only with phenotypes which may or may not produce holder of the stock when it changes hands, both to the good progeny, and careful records of the sources and recipient and to the Secretary of the Tree Seed Associa- performance of seed from classified seed sources must be tion.In this way, a record of the movement of stock is maintained in both State and private forestry to further kept and its identity preserved. If the stock, in any of the this knowledge. three stages described, passes into the hands of a non- member, or when it is finally purchased or retained by a Costs of Seed member, a Final Certificate of Origin is issued by the The costs of collecting seed are, of course, very variable, Secretary. This gives descriptive details of the seed source, and depend on the crop, distance from the source of which it is intended should be preserved in the records labour, difficulties of climbing, and so on. The use of of the management plan of the plantations in which the improved equipment in climbing, in properly managed future trees will grow. seed sources and plantations where the seed trees are The certification schemes are based on mutual trust, and given plenty of growing space and the crowns are rela- the certificates guarantee origin only, but the importance tively large, will help to reduce these costs. of the idea has been recognised in an agreement made by the Forestry Commission, the Tree Seed Associations, and The two Forest Tree Seed Associations in this country the Nursery Trade and Woodland Owners' Association are supported by members' annual subscriptions of one in 1959, that a percentage increase on normal prices is guinea, plus assistance from the Forestry Commission for admissible for stock certified in this way. And such the first few years. This assistance takes the form of the practical recognition should stimulate the demand. provision of office accommodation and stationery and the These schemes are, at present, confined to seed sources feeservices of the secretaries and technicalofficers. in Great Britain, owing to the difficulties in implementing Whether the Associations can maintain themselves without any guarantees that might be made about provenances this assistance and without increased subscriptions remains from abroad, but the Associations are seeking to widen to be seen; the possibility of affiliation with the woodland their information about these sources and to make this owners' associations must also be considered. available to members. The Future Certification and the Supply of Seed Great Britain is not likely to be self-supporting in the Over the past six years the Forestry Commission, the provision of forest tree seed of all species, at least in the largest single planter, has sown an annual average of six- near future, but the position can be and is being greatly teen thousand pounds of conifer and one hundred and improved. The expected mast year, next year (1960- eighty-six thousand pounds of broad-leaved seed. Of these 196 1), for most species, the first in which both certifica- amounts, three-quarters of the conifer and one-fifth of the tion schemes and improved methods of collection and Genetics and Tree Improvement 709 storage will have been operative, should give great impetus Grace aux magasins réfrigérés, ilest maintenant possible de s'approvisionner en graines de meilleure qualité, obtenues au to this expansion and will certainly provide a challenge cours des années propices aux semences. to the Associations. Much has also to be done in the Les lois en vigueur stipulent que les caractéristiques des graines improvement of liaison with overseas tree seed organisa- offertes a la vente doivent faire l'objet d'une declaration. tions, and future global certification schemes, possibly Deux Associations de Graines d'Arbres Forestiers ont été créées, l'une pour l'Ecosse et l'autre pour l'Angleterre et le Pays involving F.A.O. participation, should be viewed with de Galle. Elles diffusent des informations parmi leurs membres et optimism. sont a l'origine de plans visant a la certification des graines provenant tie sources sélectionnées; elles tiennent également a jour References des registres des peuplements de semences, et dressent une liste des pépinières, des établissements d'extraction et des magasins de Anderson, M. L., and Fairbairn, W. A., 1955. The division of graines qui se conforment aux normes garantissant le maintien de Scotland into climatic sub-regions as an aid tosilviculture. l'identité des lots de graines. Edinburgh University Department of Forestry, Bulletin No. 1. L'approvisionnement en graines en Grande-Bretagne depend Holmes, G. D., and Buszewicz, G., 1958. The storage of seed of dans une grande mesure des importations, mais le développement temperate forest tree species, Forestry Abstracts, Vol. 19, 3 de sources indigènes de graines Se poursuit et devrait en fin de and 4. compte permettre au pays de suffire a ses propres besoins en ce Scottish Forest Tree Seed Association, Members' handbook. qui concerne hon nombre d'essences. Seal, D. T.,1958.The use of selected forest tree seeds and plants. Scottish Forestry, Vol. 12, No. 4. Certificación de Semillas de Arboles Forestales en la 1959.Collection of cones from standing trees, Forestry Commission Forest Record No. 39. H.M.S.O., London. Gran Bretaña Macdonald, J., Wood, R. F., Edwards, M. V., and Aldhous, J. R., El empleo de semillas de árboles forestales escogidas, tanto del 1957.Exotic trees in Great Britain.Forestry Commission pals como del exterior, desempeña un papel de creciente im- Bulletin No. 30. H.M.S.O., London. portancia en la silvicultura británica.El valor de la estirpe Matthews, J. D., 1958. The permanent seed identity code. Forestry seleccionada se reconoce cada vez más en la silvicultura estatal y Commission Journal No. 27. H.M.S.O., London. particular y en el comercio hortIcola conexo. 1959. The production and use of superior tree seed La investigación realizada en silviculturaestatal y en las in Britain. Quarterly . universidades ha acopiado muchos conocimientos: un estudio de la Gran Bretafia, ya casi terminado ahora, ha conducido a un registro RESUMES de las procedencias de semillas y de buenos árboles.Se ha La certification des graines d'arbres forestiers en Grande- asignado un ndmero a cada una, de acuerdo con la Clasificación del Sistema Decimal Universal. Bretagne A la vez, los estudios de genética forestal y demejoramiento L'utilisation de graines d'arbres forestiers provenant de sources de árboles han dado como resultado la formación de semilleros sélectionnées tant dans le pays qu'à l'étranger joue un role de para el suministro tanto para fines comerciales como parala plus en plus important dans la sylviculture britannique. La valeur producción de variedades mejoradas (cultivares). des essences sélectionnées est reconnue par un nombre croissant de Las mejoras técnicas de escalamiento de árboles han hecho que sylviculteurs officiels et privés, ainsi que parmi les horticulteurs. Ia recollección de semillas resulte más barata y seamás segura. Les travaux de recherche poursuivis par les organismes fores- Las bodegas refrigeradas han permitido contar con mejores semillas recogidas en los buenos años de producción. tiers nationaux et les universités ont permis de recueillir une masse Está en vigor una ley que establece la declaración de las de renseignements: une étude portant sur l'ensemble de la Grande- caracterIsticas de las semillas que se ofrecen a la yenta. Bretagne, et presque achevée a l'heure actuelle,a permis de Se han formado dos Asociaciones de Semillas de Arboles cataloguer les sources de graines et les "meilleurs arbres."Les Forestales, una de Escocia y la otra de Inglaterra y Gales, que sources de graines ont été numérotées conforniément a la Classi- diseminan informes a sus miembros y patrocinan medidas de fication Décimale Universelle. certificacióndesemillasdeprocedenciaescogida;también Simultanément, des etudes de génétique forestière et de sélec- mantienen registros de rodales de semillero y de almácigas, de empresas extractoras y tiendas de semillas quefuncionan bajo tion dendrologique ont eu pour résultat Ia creation de pépinières normas apropiadas para mantener la identidad delos lotes. de semences destinées a fournir les graines en quantités commer- El suministro de semillas en la Gran Bretafla depende en gran ciales suffisantes et a la culture d'essences améliorées (cultivars). medida de las importaciones, pero el establecimiento de fuentes Les perfectionnements apportés aux techniques employees pour nacionales de semillas está cobrando impulso y con el tiempo ha grimper aux arbres ont facilité la récolte des graines, tant sur le de hacer que el pals se baste a si mismo en lo que respecta a plan du prix de revient que sur celui de la sécurité. muchas especies.

710 Fifth World Forestry Congress Proceedings The Improvement of Forest Trees and Seeds in Portugal

DOMINGOs PEREIRA MACHADO Portugal

The total extent of Portuguese metropolitan forests is to produce cork of inferior quality. These few trees will about 5,500,000 acres, and our forest planting projects be eliminated in the thinnings of the future new stands. show that this total shall increase at least 3,850,000 acres Thus, for the cork oak tree in Portugal, we obtain by in the next several years. this method a slight improvement, which has the objec- A high percentage of the Portuguese soil is very poor, tive of obtaining mass production of superior trees, better and the rational utilization of immense zones of low than the average of our native populations, or, referring fertility,unsuitable for farming, should, in the future, to the characteristic more advantageous tous, good become one of the soundest supports to increase the we!- quality cork. fare and human dignity of our increasing population. The situation regarding pine (Pinus pinaster) is very For some years the program of forest planting has different. We collect yearly from our native stands some developed more and more, and larger areas of unproduc- tens of tons of seed without any selection. The seed is tive and barren soils should be changed into beautiful obtained from the usual regions of good stands of pine forests in the future. without any selection of the female parents, either by Under present conditions, our forests are more and rate of growth, stem form, wood quality, resistance to more influenced by the direct or indirect activity of man. frost, drought, diseases and insects, or by capacity for If we consider pure, natural, individual stands, they have yielding gum. Thus, the seed of pine gathered annually either disappeared or have been greatly altered for com- for the direct seeding to plant large areas, on account of mercial exploitation. the high heterozygosity of the individuals which constitute Our wild forests, in their conditions of heterogeneous our native stands, bear a very great percentage of undesir- biological but harmonious individuals, constitute the start able offspring of inferior quality. of all patterns of the technique of , and it is In order to prevent this, we have set up in Portugal a from those complex and highly heterozygotic stands that project of genetic improvement for the production of the improvement has to be brought into action. selected seed of pine with characteristics of most interest In order to develop those plans of reforestation of the to us: good quality of wood and high natural capacity for forest areas denuded by uncontrolled commercial exploita- yielding gum. These improvement projects, on account of tion, we need large quantities of seeds and seedlings. excessive complexity, are very slow and will require a However, we don't control the genetic quality and seed great number of years to be realized.Nevertheless, we origin, except in the planting of cork oak (Quercus suber have begun something in recent years in Portugal which L.).For this species the seed is usually collected in we believe in the future will contribute much to improve regions yielding good quality cork and only from native, our forest production. improved stands where earlier thinnings have been made In 1952, we started the development of high-yielding and where all undesirable trees have been eliminated. strains of Pinus pinaster. We selected 16 elite trees with This is, however, doubtful selection and is done only good form and wood of high quality, and very good pro- by the quality of the cork (phenotype); the inherent ducers of gum. This selection was made after a 4-year quality of the offspring can be determined only several period of turpentining, and we selected only those trees years after the sowing of the selected seed or the plant- which yielded at least two and a half or three times as ings.Cross-pollination in improved native stands with much gum as the average tree of the same diameter, trees of more or less uniform characteristics should yield growing in the same site. good seed. These 16 elite trees are spread over the country, some Nevertheless, it is estimated that a high percentage of in the seashore zone, others in the mountainous zones; the progeny should provide cork of good quality as the they are useful as parent stock to furnish us: parent trees do; since it has been proved (Mergen, 1953; uncontrolled pollination seed for the one-parent Machado, 1954; Wettstein, 1959; et al.) that on the one- progeny tests, in order to evaluate their inherent parent progeny tests of trees of high heterozygosity, with qualities; open pollination, some of the characteristics of the female seedsfromcontrolledinterpollinationbetween parent are dominant. them, each performing as male parent and as As the selected native stands don't contain any trees female parent, to obtain intraspecific hybrids; and producing bad quality cork, there is no interference by cuttingsfor vegetative propagation in order to undesirable pollen, and thus we get seed of known origin establish seed orchards. from good phenotypes. But we realize that good cork In the trials we have conducted of the one-parent seed trees might carry as well, as a recessive, certain progeny tests of some elite trees, a great percentage of hereditary factors that could cause some of their offspring seedlings of the open-pollinated seed exhibit the character-

Genetics and Tree Improvement 711 istic of high gum-yielding capacity of the female trees. they rooted, since being in the tops of very tall trees and This fact seems to prove that even though we do not know constantly beaten by the wind, a high percentage of them the characteristic of yielding capacity of the male parent broke off. which has contributed half the germ plasma of the This year, after girdling and placing lanolin paste with progeny, the genetic characteristic of production of gum growth hormones, we used a split tied above and below of the female parent is inherited. the ringing in order to prevent breakage. After this pro- We have obtained some intraspecific hybrids by con- cedure, the incision was covered with moist moss and a trolled pollination between some elite trees, and also one plastic bag. In this way we got the best results. obtained from a tree which is a very good producer and The establishment of seed orchards that will produce whose turpentine is normal levorotatory and another tree, seeds of proven quality is a method which leads to a also a good producer but whose turpentine is highly dex- small but progressive improvement of the timber quality trorotatory. This latter elite tree has been used in artificial and gum yield of our future stands, while we are awaiting hybridization as male and as female parent. the definite benefits of controlled breeding, hybridization, These intraspecific hybrids, after 6 years, have exhibited and induced mutation, which attempt to develop new a higher gum-yielding capacity, compared with seedlings types of trees. of the same age from wind-pollination seeds of the female parent, using the microtaping technique developed at the RESUMES Lake City Research Center in Florida.These crosses Amelioration des essences et semences forestières au show in the F1 a certain hybrid vigor or heterosis. Portugal The intraspecific hybrids from the two elite trees, one Les forêts du Portugal se sont remarquablement développées au producing gum with highly dextrorotatory and the other cours de ces dernières années et nos plans de boisement prévoient with normal levorotatory turpentine, are still too young la transformation d'immenses territoires déboisés et d'une faible productivité en magnifiques peuplements. to permit us to extract gum for tests of the rotatory power La demande en semences de pins dépasse l'offre, et il s'agit of their turpentines. habituellement de semences de qualité inférieure. We foresee that the progeny which had the tree with En raison du caractère hétérozygote prononcé de noire Pinus dextrorotatory turpentine as female parent will have the pinasterespèce essentiellement a fécondation croiséedes sujets appartenant au même peuplement peuvent manifester des varia- characteristics of a good producer and that its turpentine tions héréditaires marquees a leurs caractères: taux de croissance, will also be dextrorotatory. The development of such a forme de la tige, qualitC du bois, résistance a la maladie et aux strain will be very useful in order to obtain dextrorotatory insectes, capacite naturelle a produire de la gomme. C'est pour synthetic camphor like the natural one, thus avoiding the cette raison que les ramasseurs de graines doivent procéder avec le plus grand soin a la selection des sujets dont ils récoltent les inconvenience of the application of levorotatory synthetic graines. Ils doivent s'efforcer d'obtenir des peuplements de sujets camphor in medicine. satisfaisants, d'établir des jardins de porte-graines qui fournissent But thefaster, more efficient way to conduct the d'une manière continue des semences de haute qualité. improvement program, which has the objective of obtain- Iia évidemment été prouvé que même avec uncaractère ing mass quantities of seed of proven quality to help the hétérozygote prononcé et même s'ils sont anémophilescomme c'est le cas pour notre Pin us pinasterun pourcentage important increasing expansion in programs, is the des descendants de parent unique ont les mêmes caractéristiques establishment of seed orchards, either with intraspecific que le parent femelle. hybrids that show some hybrid vigor or with trees Nous nous efforcons, au Portugal, d'établir des jardins de obtained from the vegetative propagation of the elite trees. porte-graines qui pourront, dans quelques années, fournir les For this we are raising clones from the elite trees by semences nécessaires a la production en série deplants de qualité. the process of air layering developed at Lake City. The Cette mCthode amènera, plus rapidement, l'amélioration pro- rooting of branch cuttings of those pines assures us of gressive de la qualité de notre bois et de son rendement en trees with the same characteristics as the parents. gomme, et nous en attendons les avantages durables ducontrôle The clones obtained will be transplanted to a site de la reproduction et de l'hybridation. where there is no other pine tree within a radius of at Arboles SenüllasForestalesen least one mile, in order to avoid fertilization by foreign Mejoramientode y and undesirable pollen. The clones will be set in lines Portugal La zona forestal de Portugal ha aumentado notablemente en perpendicular to the predominant wind in order to avoid los ültimos años y nuestros planes de arborización prevén el self-fertilization between the trees of the same clone, cambio de inmensas zonas desnudas y de baja productividad en which leads to degenerate lines with loss of vigor. espléndidos bosques. Open pollination between the trees of the orchard, La demanda de semillas de pino excede a la producción que, all with good stem form, wood of high quality, high rate en general, es de calidad inferior. De acuerdo con la gran heterogeneidad embrionaria de nuestro of growth and being good gum producers, will yield seeds Pinus pinastercuya polinización se realiza predorninantemente for F1 intraspecific hybrids, which, having true hybrid con árboles diferentesárboles individualesdel mismo rodal vigor, will be better than the parent trees. pueden mostrar gran variedad de caracterIsticas hereditarias, a saber:grado de crecimiento, forma deltallo,calidad de la The method we use for rooting the cuttings has been madera, resistencia a enfermedades e insectos y capacidad natural constantly improved; the percentage of cuttings which de producir resina. Por esta razón los recolectores de semiflashan take root is not yet good, but, by degrees, we get some. de escoger con sumo cuidado los árboles de loscualeslas Their rate of growth is much higher than that of the obtienen. Tratarán de contar con sotos de árboles convenientes seedlings of open pollination of the same age and tree. para semilleros para disponer de unacontinua provision de semillas de buena calidad. Next year we shall set up the first orchard producing Hay certeza de haberse probado que hasta en la condiciOn de selected seed with the trees we have in fiowerpots. Up to gran heterogeneidad embrionaria y hasta enla polinización por this year we have lost a great number of cuttings before el vientocomo es la de nuestro Pinus pinastergran propor-

712 Fifth World Forestry Congress Proceedings ción de los descendientes de un solo progenitor tiene las mismas Este método conduce con más rapidez al mejoramiento pro- caracterIsticas del árbol hembra. En Portugal tratamos de establecer semilleros que dentro de gresivo de la calidad de nuestra madera y de la producción de pocos años puedan suministrar la base para una vasta producción resina, mientras esperamos los beneficios concretos de la reproduc- de arbolillos de calidad superior. ción e hibridación reguladas.

Premieres observations sur l'amélioration du saule effectuées auprès de 1'Institut de Casale Monferrato

S. MAY Ente Nazionale per la Cellulosa e per Ia Carta, Istituto di Sperimentazione per la Pioppicoltura, Casale Mon ferrato, Italie

Depuisquelquesannées,l'utilitéd'effectuerdes formes dans l'espèce Salix alba.Ccci peut être dü aussi recherches tendant a l'amélioration du saule, recherches au fait que le Danube, riche véhicule de semences, doit basées sur des méthodes déjà appliquées avec succès au avoir transporté et réuni là au cours des ans les "écotypes" peuplier, s'est manifestée avec une intensité accrue, corn- et les "biotypes" différenciés selon les diverses latitudes me en témoignela demande croissante de materiel et altitudes de son immense bassin. Mais même là oü II sélectionné de cette essence ligneuse, pour faire face aux estpossible d'exclure a coupsflrl'effetde l'action problèmes poses par les milieux particuliers, oü les con- véhiculaire des eaux fiuviales, les différenciations obser- ditionsécologiques,pédologiques ou hydrauliques ne vables selon les divers rnilieux climato-pédologiques sont permettent pas de pratiquer d'autres cultures agraires ou innombrables. forestières. Dans un de ces milieux, et précisément a Valenza Po La Direction de l'Institut d'Expérimentation pour la (province d'Alessandria) oü existe encorerare excep- populiculture de Casale Monferrato, comprenant le bien- tion pour notre paysune saulaie adulte sur une vaste fondé de ces exigences et entrevoyant sur le plan pratique superficie de terrain, nous avons pu reconnaItre de multi- les possibilités du développement de la culture du saule ples variations de l'espèce Salix alba, parmi lesquelles associée a celle du peuplier dans les stations appropriées, nous avons choisi le materiel qui figure aujourd'hui parmi entrepris en 1957 l'expérimentation qui est aujourd'hui les plus prometteurs en phase d'experimentation auprès menée selon les mêmes critères rigoureux qui guident Ia de l'Institut de Casale.11 est possible en effet que, au selection du peuplier. scm d'une considerable quantité de types, distingués par Après quelques années seulement, les résultats obtenus leurs variations, surgisse parfois quelques sujets de valeur grace a ces travaux permettent déjà d'envisager des qui réunissent en eux d'excellentes caractéristiques de dé- succès encourageants. veloppement, de qualite du bois, de forme et de port du Les méthodes d'amélioration adoptées sont celles qui, tronc, de robustesse et résistance aux risques, etc. ayant des buts pratiques immédiats, permettent d'obtenir, Ii est evident que les chances de trouver réuni dans un avec le maximum de rapidité, du bon materiel sélectionné seul individu l'ensemble des facteurs positifs que la cul- répondantauxexigencesd'uneproductiondebois supérieure en qualite et en quantité, ainsi qu'aux exigences tureet les utilisations industrielles ultérieures exigent, de robustesse et de résistance aux risques les plus a demandent un examen étendu a un grand nombre de craindre que peut encourir la culture au cours de son sujets. développement. Le type convenable une fois isolé, ii ne reste qu'à le Le travail, en cc qui concerne le saule, est grandement multiplier au moyen de boutures, constituant ainsi un facilité par la propriété dioIque de cette espèce, corn- clone qui sera prêt pour la culture des qu'il aura satisfait binée a une faculté de multiplication agame très poussée. aux nombreux et sévères examens de la phase expéri- Le saule, comme le peuplier, porte des fleurs unisexuées mentale. La propagation végétative de sujets déjà cxi- sur des individus différents et la fécondation est de ce fait stants, et choisis dans la masse pour leurs qualitds, est allogame: par anémophilie ou par entomophilie.Cette étendue aussi au materiel de provenance étrangère. condition, qui rend possible toutes sortes de croisements Les méthodes d'amélioration ne sont toutefois pas naturels,aussi bien intraspécifiques qu'interspécifiques, basées uniquement surla propagation végétative:on favorise un état d'extrême heterozygosis, de sorte que, attache aussi beaucoup d'importance a la selection établie dans les formations spontanées, on peut rencontrer une parmi un grand nombre de plantes provenant de semences gamme a peu près illimitée de formes et de types qui de fécondation spontanée, recueillies sur des sujets qui different entre eux dans leurs divers caractères. répondent aux qualités requises. Au cours d'un recent voyage en Yougoslavie, nous Les populations de saules existant, et les innombrables avons Pu observer dans les vastes forêts de saules spon- individus qu'on obtient des semences provenant de la tanés qui recouvrent les plages periodiquement inondées libre fécondation naturelle, offrent une grande disponibilité du Bas-Danube, une impressionnante différenciation de de materiel, facile a obtenir et ayant un hon degré

Genetics and Tree Improvement 713 d'acclimatation; et c'est pour cette raison que l'on trouve Nous ne possédons malheureusement pas les résultats les deux méthodes a la base de notre recherche. relatifs a la deuxième année de vivier, étant donnC que le L'hybridation artificielle appliquée aussi au saule pour- premier vivier constitué en 1958 a dâ Ctre extirpé a la rait sembler intéressante, mais jusqu'ici nous ne l'avons fin de la phase végétative, le terrain sur lequel s'étendait pas mise en pratique. Le caractère des croisements artifi- ce vivier ayant etC utilisé comme surface a bâtir. ciels est en effet tout aussi aiéatoire que celui des croise- Les plants de saule d'un an arrachCs a ce moment là ont ments naturels; ces derniers pourtant fournissent une servi a constituer deux plantations expérimentales, l'une quantité de semences incomparablement supérieurea dans le domaine de l'Institut de Casale et l'autre dans la celle qu'on peut obtenir par croisement artificiel, et par propriété de la Société Agricole "Valenza Po" (commune consequent, les chances de succès s'en trouvent con- de Valenza), sur les terrains mêmes oü se trouve la sidérablement augmentées.Illimporte de considérer saulaie spontanCe qui a joué un si grand role dans la aussi, comme l'enseigne le Prof. Piccarolo, que l'utilisa- formation des meilleursclones, comme nous l'avons tion rationnelle de ce que la nature nous offre spontané- signalC. ment ne diminue en rien le caractère scientifique du Les recherchesse poursuivront done au cours des travail d'amélioration, pourvu qu'il ne soit pas aban- années a venir, a la fois sur les viviers et sur les deux donné a l'empirisme on a l'improvisation. premieres saulaies expCrimentales. Le travail accompli Ceci pose, les travaux d'amélioration du saule auxquels jusqu'ici permet des previsions encourageantes en ce qui procède l'Institut de Casale ont jusqu'ici été fondés sur les concerne les rCsultats futurs. deux méthodes indiquées ci-dessus. En 1957, la premiere plantation expérimentale de boutures de saule a etC con- RESUMES stituCe au moyen de boutures de provenance nationale et Preliminary Observations at the Institute of Casale Mon- étrangère.Ii y avait 18 clones, avec un total de 1838 ferrato on the Improvement of the Willow pieds.Par la suite, les observations ont porte sur un Work carried out by the Casale Monferrato Research Institute nombre supérieur de clones et de sujets. Exactement: to improve the willow included the examination of at least 26,608 en 1958 sur: - environ 6.000sujets de 12 pro- plants belonging to 157 different clones in the stage of develop- ment in nurseries. venances diverses en pépinière, The best results were obtained from clones formed from stocks - 44 clones en plantations de boutures of the Salix alba species selected from the Valenza Po willow pour un total de 6.505 pieds, plantation.By the time they had completed one year in the - 18 clones envivier* d'un an pour nursery, some of them had attained an average diameter of about un total de 1.297 plants de saule. 3 cms. and an average height of about four meters, and under en 1959 sur: - 142 clones en plantations de boutu- equal conditions, they can keep up with, or even surpass, the best res pour un total de 13.119 pieds, poplar clones. - 121 clones en vivier d'un an pour Observaciones Preliminares en el Instituto de Casale Mon- un total de 3.849 plants. ferrato sobre la Mejora del Sauce Par consequent, sans tenir compte des pépinières, les El trabajo realizado en el Instituto Casale Monferrato de In- examens en vivier ont porte jusqu'ici sur 26.608 pieds vestigaciones para mejorar el sauce incluye el examen de por lo appartenant a157 clonesdifférents.Le materiel de menos 26.608 plantas pertenecientes a 157 clones en diferentes estados de desarrollo en los criaderos. provenance étrangère nous a été envoyé par les pays Los mejores resultados se obtuvieron de los clones formados de suivants:France, Pays-Bas, Allemagne, Turquie, Argen- material de la especie Salix alba, seleccionado en la plantación de tine et Japon. sauces de Valenza Po. Después de haber completado un aflo en el vivero, algunas plantas habIan alcanzado un diámetro de 3 Les meilleurs résultats en vivier atteints jusqu'ici ont centImetros y una altura promedia de cuatro metros, y en condi- été obtenus dans les clones formés par des sujets choisis ciones análogas pueden guardar proporción y aun sobrepasar en dans la saulaie de Valenza Po et appartenant tous a crecimiento a los mejores clones de alamo. l'espèce Salix alba.Parmi eux, on en trouve dont le développement, a la fin de la premiere annCe de vivier, égale ou même dépasse les meilleurs clones de peupliers Comments places dans les mêmes conditions, atteignant un diamètre William D. Hagenstein (U.S.A.): de 3 cm. environ et une hauteur moyenne de près de 4 m. Lest the implication be left that my friend, Leo Isaac's Dans bien des cas, ces sujets offrent un remarquable suggestion for a system of seed certification is a new one degré de perfectionmanifesté dans la forme et le port du for the Pacific Northwest, I would like to tell you of the tronc, qui se présente alors droit, et non fourchu, jusqu'à efforts of my employer, Industrial Forestry Association, la cime, avec des ramifications minces et bien rCparties, to get the right tree in the right place. On comme IIest rare d'en rencontrer dans le saule. We began a seed certification program in conjunction remarque en outre une forte tendance a l'autotomie des with our forest nursery at Nisqually, Washington, in 1949 branches, qui tombent peu a peu spontanCment, en corn- when our contractors for planting stock began to collect mençant par lesplusbasses,des que leur fonction assimilatrice se ralentit, au fur et a mesure que diminue and furnish their own seed. The Association acted as la quantité de lumière filtrCe a travers la couronne. Cette certifying agency for seed furnished to it for growing trèsutileetappreciable pour les trees for the contractors. It furnished certificates on each caractCristiqueest seed lot on request of the contractor and kept a permanent plantations définitives, oü le contrôle par l'élagage se file of the certificates. This provided a permanent record trouve ainsi reduit au minimum to check performance of seed lots as plantations of the *pépjnjère pour la production de plants. trees grown from them developed into forests. The seed

714 Fifth World Forestry Congress Proceedings certification program was not designed for commercial It was the adoption of these minimum standards that use because, normally, the Association's nursery contrac- precipitatedthepreparationandcirculatingofthe tors do not sell seed. questionnaire by the Society of American Foresters. Many The only failure of our seed certification program is American foresters, including the Society's Subcommittee, that not enough of our own people have taken advantage did not fully agree with the standards. A major point of of it as a means of providing a permanent record of the disagreement was that the standards did not provide for results of the seed furnished us for growing trees for their the inclusion of "wild" seed. tree farms. The ICIA has provisions for annual review and amend- I would also like to comment, in view of the general ment, where necessary, of the minimum standards. They genetics theme of this Session, that the Industrial Forestry have indicated a willingness to consider new suggestions Association started a forest tree improvement program in for the forest tree seed standards, and we have reason to the Douglas-fir region in 1954. As part of it, we have believe that they might be willing to make provisions for established a plus tree register and have more than 100 including "wild" seed. We expect to present a report to foresters of our member companies cooperating in the the ICIA annual meeting this fall.It will include recom- location and registration of plus trees.The plus trees mendations based on this sampling of the opinion of recorded in our register are freely available as sources of foresters and forestry organizations interested in seed scion material for others interested in genetic improvement certification. of trees in our region. Now, permit me to express a personal opinion: "The important thing is not who does the certifying, but how In conclusion, I would like to say, in behalf of the it is done." In closing, let me echo the suggestion made industrial foresters of this region, that we are glad to have by Bob Callahan. Let us strive to develop and adopt uni- Dr. Syrach-Larsen visit us again.Our geneticists and form certification standards worldwide. foresters hope to take advantage of his long experience to help them chart the course of our own infant program of Scott S. Pauley (U.S.A.): tree improvement. Dr. Larsen, we welcome you to the As the papers presented for Topics 2, 3, and 4 indicate, region and hope that your visit will be mutually profitable. the problems associated with the international exchange Elbert L. Liffle, Jr. (U.S.A.): of seed and other ligneous plant materials are numerous and vexing. The International Commission for the Nomenclature Dr. Piccarolo has made an important basic distinction of Cultivated Plants is preparing a list of widely used between the two classes of such materials; namely, (1) scientific names of important economic plants for which those that are exchanged usually in rather restricted stabilization seems important, whether or not these names amounts by individuals or institutions for research pur- are now threatened.This request by the International poses; and (2) those that are better classified as com- Bureau for Plant Taxonomy followed a resolution by the mercial transactions, involving large quantities of seed of Ninth International Botanical Congress at Montreal in a previously tested variety or seed source known to be 1959. This list of important economic plants of the world well adapted to the proposed planting site. includes forestry, agriculture, and horticulture. Next, the With reference to the exchange of experimental mate- correct scientific names will be submitted to the Tenth rials, Dr. Piccarolo has recommended that such materials International Botanical Congress in 1964. It is hoped that continue to be exchanged directly between individuals or the Congress will act to stabilize some of these threatened institutions rather than through some sort of international or controversial names. If not, the publication of this list clearing house or agency.Since most of such material of scientific names of important economic plants will exchanged in genetic or breeding studies consists of pollen, serve to stabilize these names against possible changes cuttings, scions, etc., the time factor in transit and the for a period of years. The Commission agreed to submit manner of their treatment is often the determining factor the name Pseudotsuga taxifolia for Douglas-fir. in their survival. Any bureaucratic sidetracking through an international "authority" would clearly slow down Paul 0. Rudolf (U.S.A.): transit time and thus impair chances for survival of the All the papers presented this morning have been very material. interesting, but I had special interest in that given by On the other hand, Dr. Piccarolo's suggestion that Leo Isaac. institutionsinterestedintheexchangeofbreeding Just last month I was drafted as Chairman of the Society materials might be organized under the FAO Forestry and of American Foresters' Subcommittee on Forest Tree Forest Products Division has, I think, much to commend Seed Certification.I am responsible, therefore, for pre- it.Such an organization could be of most usefulness in paring a report which will embody the results of the preparing lists of participating institutions and the ma- questionnaire that was quoted by Mr. Isaac. terials each has available, as well as the material each TheInternationalCrop Improvement Association, desires. which represents 45 States and most of the Canadian Problems associated with the certification of seed that is Provinces, already has(in 1959)adopted asetof exported in commercial quantities obviously pose com- minimum standards for certifying forest tree seeds.As a plications of much greater complexity than do those in- result, any crop improvement association in a State or volving the direct exchange of experimental materials Province that has laws covering forest tree seed certifica- between individuals or institutions. tion must adopt standards that will equal or exceed these I have been pleased to note that with respect to such minima. tree seed exports Prof. Rohmeder and Mr. Isaac ap-

Genetics and Tree Improvement 715 parently share with Dr. Piccarolo an antibureaucratic chinery within the participating countries that do not now frame of mind They do not favor the idea of establishing have tree seed certification systems. somesortofinternationalcertificationauthorityor Some idea of the enormity of these problems in Rather, as Prof. Rohmeder suggests, mutual countries with a highly diverse tree flora has been dis- agency. cussed by Mr. Isaac. His suggestion that certification be international agreement on details of a standard certifica- made by a professional nonprofit tree seed certification tion form might be obtained from participating countries. authority or organization, such as that which now functions Any necessary coordination of such an agreement might in Scotland and some Of the Scandinavian countries, be undertaken by the FAO Forestry and Forest Products has, in my estimation, real merit. In the United States, Division. at least three such organizations would likely be desirable: International agreement on details of the certification one for the West and two for the Eastern States (North form to be used will certainly require some negotiation and South). The development of such internal certifica- and revision from time to time but will likely be less diffi- tion machinery is, of course, primarily a domestic matter, cult to implement than the necessary certification ma- and final decision must be made locally.

Session B

S Delineation of Improvement Objectives and Their Possible AttainmentGrowth and Stem From

HELGE JOHNSSON Swedish Forest Tree Breeding Association, Ekebo, Svalöv, Sweden

The general objective of forest tree improvement is to than other trees in the population of the same age growing breed materials giving an increased production on comparable sites; and, in addition to this,they must be of valuable timber per unit area and time unit in com- perfectly healthy and free from parasites. parison with a given standard. Such an increase in pro- The requirements in regard to growth rate and resistance duction of valuable timber can be attained through an will certainly be absolutely valid for the future. Only if increase of growth rate unless the rise in growth rate is timber were to lose its importance as raw material for the counterbalanced by a decline in quality, or through an chemical industry and, as once before, be used only for its increase of one or more quality factors unless the improve- mechanical properties, would growth rate become of little ment is counterbalanced by a decrease in growth rate, importance. A development along such lines appears, or through increase in resistance to adverse environmental however, improbable, every forecast pointing in the op- influences, pathogenes, insects, climatic factors, etc.At posite direction, namely, that timber consumption will present, when forest tree breeding is still in its infancy, increase very considerably in the years to come. Hence, all these three main factors are generally pursued at the breeding of forestation material with increased growth rate same time in efforts to reach combined effects.An must be set down as one of the fundamental objectives of instructive example, showing results obtainable in this way, forest tree improvement. is seen in the F1 hybrid Larix leptolepis x decidua. When On the other hand, seeing that an ever-increasing the individual parents of the two species have been suc- amount of the timber production is absorbed by the cessfully chosen, this hybridat least when cultivated in industry, it can be argued that stem form, branchiness, a climate of maritime typepossesses a higher growth self-pruningability, and similar properties, which ap- rate than both parent species, better stem form than the parently are of the greatest importance for high-grade Japanese parent, and a highly improved resistance to sawtimber, might well attract less attention in an improve- Dasyscypha wilikommi, as compared with the European ment project, working for the future. Certainly not! These one. In conformity with this it is also generally required quality properties are also of the greatest importance for that plus trees, selected for seed orchards, must be superior the quantitative production. It is still a matter of dispute in regard to growth rate and stem form as well as whether and to what degree the total production per unit resistance. For instance, the instruction for the selection area can be increased under extensive forest conditions of plus trees adopted in Sweden lays down that such trees by cultivating varieties, which, per Se, have a higher must have straight stems, thin branches, good self- growth rate than the original population. For many years ability, and considerably greater height and stem diameter a great number of authors haveargued that the increased

716 Fifth World Forestry Congress Proceedings production per unit area, which has been attained in been taken up at a far later date and we still have to agricultural crops, is to be considered as the combined rely on but small, well-established evidence, proved by resultof improved methods ofcultivation,including experiment. In any case, the most superficial observation manuring, and of selective adaptation of varieties.In makes it clear that forest trees are highly modifiable, the forest, however, it is not realistic to calculate to any and that environmental conditions arealso changing considerable degree onartificial improvement of the within limitedareas; hence the phenotypic variation, environment nor, consequently, to count on a noteworthy particularly in individual growth, must be modificatory to rise in total production through varieties possessing an a considerable degree and thus of non-hereditary nature. inherent, improved growing capacity. This very important Also in an even-aged, one-clonal poplar stand, planted and complex problem has hitherto remained unsolved. in regular spacings, an obvious variation, greatest in regard It is fairly probable, however, that diverse environmental to diameter and volume growth, appears. However, even factors such as nutritional supply, water balance, and so if unknown, a certain portion of the phenotypic variation forth, will often limit the possible increase in total wood in a population must, a priori, be assumed to be caused production to rather small amounts. For this reason, it is by genotypical differences, on account of which selection so much more important for the future to breed varieties must give some effect. By comparing the variance in a which convert the largest possible portion of the total clonal stand of Cryptomeria japonica with the variance in production into usable timber,i.e.,varieties with thin a population, raised from seed, of the same species, Toda branches and little tapering. Fairly straight, isodiametric (1958) arrived at the conclusion that a selection of the stems without knots and spiral grain, giving a higher best 5% of the trees of the population and their vegetative output to industrial processes and facilitating transport propagation should result in a stand, established by this and mechanical treatment, must be desirable also in the clone mixture, showing the following superiority in com- years to come. parison with the original population: Also, silvicultural tendencies emphasize the urgency of height growth 8% paying the greatest attention to stem form, type of branch- diameter growth 15% ing, and similar growth form characteristics.It has often volume growth (individual) 43% been held forth as an essential difference in requirements To what degree the per unit area in- on varieties, used in agriculture and forestry, that in most creases by cultivation of this clone mixture will probably agricultural crops every seed must give rise to a perfect partly depend upon soil factors. However, it may be that individual, whereas only a small fraction of a seedling the selected and vegetatively propagated material will stand in the forest must fulfil this requirement. This is, of make it possible to produce trees of a certain uniform course, true but only in regard to fully stocked, natural dimension in a shortened period of rotation. Selection of regenerations and to artificial ones in dense spacing of the single trees and their vegetative propagation must be con- plants. It was not so very long ago that a Swedish forester sidered as the most efficient mode of improvement. The was grateful if the natural seedling stands were dense. application of this method is, however, limited to the few Today, the natural seedling stands are thinned to a spacing forest tree species which can be propagated vegetatively of 2 x 2 meters or more when, in northern and central at sufficiently low costs, i.e., firstly, to the poplar species Sweden, the young trees are about one meter tall. Earlier, and to Cryptomeria.In this way a number of rapid- spruce plantations could be made in spacings as close as growing poplar clones have been raised. How much 0.6 x 0.6 meters, or with 27,700 plants per hectare, in progress these poplar clones represent is hardly possible southern Sweden.Today, the spacing usually recom- to assess, as the selection has been performed in hy- mended is 1.7 x 1.7 meters, corresponding to 3,500 plants bridous populations of undefined origin,so adequate per hectare.This indicates that it is now necessary to standards of comparison are lacking. establish the stands with such wide spacing that the first Even if efficient methods for vegetative propagation of will be profitable, because of the yield of pulp- other forest trees can be developed in the future, the wood; and in all probability this tendency will be still improvement work in most tree species must be based on more pronounced in the future. Consequently each plant sexual reproduction; and here it must be noted that forest in a seedling stand must possess the ability to develop trees generally are strongly heterozygous allogames. For into an acceptable pulp tree and, in spite of the light this reason, the immediate effect of a strong selection must original stocking, every tree must be able to lay down a be expected to be comparatively small. With studies of high portion of its growth as stem wood. The inevitable variation as a starting point, Toda and co-workers (1958) conclusion must be that the forestry of tomorrow will estimate that selection of the best 5% of the trees in a urgently need varieties with the best form of growth. population of Cryptomeria, together with panmictic sexual Therefore,foresttree improvement, working forthe reproduction of the selected trees should give one-third or future, must aim at an increased growth rate as well as a possibly one-half of the effect attained through vegetative better form of growth. propagation, i.e., for height growth 3-4% Prospects of Attaining Increase in Growth Rate diameter growth 5-8% Through Selection volume growth (individual)15-20% Research in forest tree genetics was initiated half a The effect of this selection on the total production per unit century ago with studies on intraspecific geographical area during a certain period of rotation with repeated variation,andconsiderableinformationelucidating thinnings will be about the same or somewhat lower than thiskindofvariationhassincethenbeencol- the increase in individual volume growth, provided that lected.Studies on hereditary individual variation have limiting soil factors do not occur.

Genetics and Tree improvement 717 As pointed out, these calculations are valid for pan- the selection has been without effect. The best success mixia among the selectedtrees.Nilsson (1958) has may involve a very considerable improvement.Certainly, studied the correlations between mother trees of Picea the results will vary considerably from case to case. abies and Pinus sylvestris and their 10- to 20-year-old, This plus-tree seed orchard method is, of course, uni- one-parent progenies from natural germination in the versally applicable for every tree species under all condi- original populations.In thismaterial no correlations tions and must be regarded as the main line to be fol- could be traced between the volume of the mother trees lowed. Apart from the attainable genetical improvement, and the height growth of their progenies. On the other production of forest tree seed in orchards also involves an hand, a clear connection could be established between the important organizatory rationalization of the seed harvest height/diameter quotient for the mother trees and the and permits an efficient variety control. height growth of their progenies, the coefficient of this Establishmentof"phenotypical"seed orchardsis, correlation being fully significant and equal to + 0.28. however, to be considered merely as an introductory step Nilsson draws the conclusion that the diameter growth is to a long-term improvement project.The progenies of too strongly influenced by the environment to be independ- the selected orchard trees ought to be tested as soon as ently used in selection, but that a successful selection possible in order to enable replacement of the present can be based on the relation between height and diameter seed orchards, based on mass selection, in a not too growth for the dominant trees in a population.In the remote future, with new ones, composed of selected trees material studied by Nilsson, the h/d quotient exceeded having the best combining ability. Only this "second the standard value by 14%, and the height growth of generation" of seed orchards will give really important the progenies was 5% superior. The effect of selection progress. The progeny tests ought to be planned so that was, in this case, well in line with the calculations of not only the general combining ability of the plus trees Toda, but it is self-evident that the same selection pressure will be revealed but also so that their specific combining will not give the same response under all conditions. The ability can be studied at least in some degree.This greater the influences of environmental factors in the requirement can be met by crossing the n-clones in an single cases, the smaller will be the effects of selection. orchard with three or four fathers, chosen among the The effect of selection estimated by Toda has been orchard clones, and by testing the 3n-4n separate prog- obtained by a relatively weak selection, as the best tree enies.Further, the tests ought to show the production of only 20 has been chosen. However, it is to be observed per unit area and, as we still lack decisive information on that the result refers to panmixia among the selected trees. the correlation between the juvenile growth and the later Seed harvest from the best one of twenty trees after open productivity, the trials should give reliable evidence dur- pollination in the original stand should have decreased ing at least the first half of the rotation period. the effect of selection considerably, or to about one third, In this connection development of reliable methods i.e., given an increase in volume growth of about 5%. for juvenile progeny testing in the laboratory as well as Thus, seed harvest from selected trees in a stand con- in the field constitutes a most important task. taining the whole of the original population cannot be expected to give anything but a rather limited improve- Prospects of Attaining Improvement in Growth Rate ment.On theother hand,systematically performed Through Hybridization and Polyploidy selective thinnings during the entire rotation period, until The possibilities of attaining an appreciable increase in there remain only the seed trees for natural regeneration, growth rate through specieshybridization have been should result in panmixia among the selected trees and be amply shown in the genera Populus and Larix. Within accompanied by an improvement corresponding to Toda's each of these genera a number of highly interfertile species estimates. occur, which give rapid-growing F1 hybrids inseveral Of course, it is possible to sharpen the selection con- combinations. The poplar hybrids can easily be employed siderably, perhaps to the best tree in 20,000 or more, in in silviculture by means of vegetative propagation after order to obtain a better response. The plus-tree concept, previous selection in the hybrid populations (black and generally adopted, presupposes a very strong selection, if balsam poplars) or through mass production of the F1 possible, extended to trees that fall outside the continuous populations by seed (aspen hybrids). The larch F1 hybrid range of variation in the population. A selection of such can be produced in large quantities in seed orchards, strength could possibly lead to trees carrying "major suitably arranged, and also by large-scale, artificial polli- genes" for growth rate.The likelihood of such cases nation. As combinations between specific parent individ- must, however, be considered to be small. Certainly, we uals often show heterosis to a different degree, and as almost always have to be satisfied if we can find rare the area of cultivation of a hybrid is dependent upon the polygenic genotypes with high general or specific com- geographical origin of the parents, the importance of try- bining ability. ing to find the best individual parent combinations for Most improvement projects at present in progress are different areas of cultivation is obvious.It is also to be based on plus-tree selection and panmictic sexual repro- considered that individual differences in degree of com- duction among a number of plus-trees, as a rule 20-50, patibility may occur.For mass production of F1 seed multiplied by grafting and cultivated in seed orchards. The itis also urgently needed to look out for highly self- improvement in growth capacity, which can be attained sterileor male sterile mother clones,or to develop in this way, cannot be predicted at present, as the experi- methods for artificial induction of male sterility,for mental evidence is still inconclusive. The most unsuccess- instance, through spraying with chemicals. Also, in other ful result to be expected is that the orchard seed is just important forest tree genera, such as Pinus, Picea, Abies, the same as the seed from the original population, i.e., Eucalyptus, Alnus and Betula, cases of rapid-growing

718 Fifth World Forestry Congress Proceedings species hybrids are known, especially in Pinus, owing to scabra, Alnus glutinosa). As yet the growth capacity of the investigations that have for many years been under triploid conifers is almost unknown. way at the Placerville Institute and elsewhere in Cali- fornia. Prospects of Attaining Improvement in Stem Form A priori, it must be presumed that F1 hybrids possess Strong, more or less monstrous deviations in stem and a more pronounced hybrid vigor than later generations crown form, falling outside the continuous variation, as and backcrosses.However, cases will occur and are Opperman's freak beech (Fagus silvestris), stem fascia- known (i.e., Pinus jeffreyi x coulteri)(Libby, 1958) tion in pine (Pinus sylvestris), snake spruce (Picea abies), when the interfertility between the parent species of a fastigiate forms (Populus nigra, P. tremula) and so on, promising hybrid is too low to permit mass production have experimentally been shown to be caused by major of the F1 on an economic base. In such cases, if studies genes, apparently often dominant or semi-dominant, and of a large amount of material have confirmed that are thus transmitted to the progenies in simple ways. specific individual parent combinations with exceptionally Such genes may also have pleiotropic effects. This is the good compatibility do not occur, that vegetative propaga- case with the curly genes in Betula verrucosa which tion is excluded, and that the fertility of the F1 hybrid is cause spiral grains, intrusion of bark tissue into the wood, reasonably good, it is pertinent, of course, to study the F2 swellings on stems and branches, bent stems, rapid taper- generations and backcrosses. Good growth capacity has ing and slow growth. Trees with less drastic deviations been reported, for instance, in backcross populations in from the continuous variation such as repeated forkiness, larch (L. (leptolepis x decidua) and leptolepis) (Larsen, a certain type of stem curvedness, spiral grains, etc., not 1956) and in pine (P. jef/reyi x (jeffreyi x coulteri), infrequently occur in groups in the stands revealing their Libby, 1958). origin from a common mother or father tree, carrier of In fact, it is important to investigate the growth capac- major genes for the deviation. ity of F2 and of backcrosses also, when F1 can be obtained However, such abnormal deviations, caused by major on an economic scale.If the F1 is fertile and its F2 or genes, are of little interest to the tree breeder, who has backcrosses have inferior growth, the cultivation of the to concentrate on the continuous variation in the stands. F1 hybrid must be controlled so that self-regeneration be Thus, it is to be presumed that stem form as well as other avoided and plantations of the F1 be excluded as pollen morphologicalcharacteristicsoftechnicalsignificance sources for neighbouring stands, which are self-regen- such as branchiness, thickness of the bark, and self- erated or used for seed harvest. pruning abilityare polygenic in nature and strongly There must not, in principle, be any difference between influenced by the environment.It seems, however, as strongly interfertile species of the same genus, geographi- though some stem characters such as straightness and cally isolated, and geographical races of the same species; tapering are less dependent on the environment and are and hybrid vigor can also be released through hybridiza- possibly controlled by a simpler gene complex than tion between such races. As most forest tree species have growth rate; on account of this, stronger response to a vast area of distribution with a rich strain differentia- selection on these properties than on growth is to be tion,racehybridizationoffers,practicallyspeaking, postulated. A considerable number of the plus trees of unlimited possibilities which ought to be utilized. Several Pinus sylvestris selected in Sweden, particularly the ones cases of promising race hybrids can also be quoted, for belonging to the northern subspecies lapponica, differ instance, hybrids between North European and Central conspicuously from theirsurroundingsjust by their European Picea abies(Nilsson,1958), and between favorable tapering, a peculiarity which makes a strong North Swedish and South Swedish Populus tremula. Test- impression of significance. Nilsson, as quoted earlier, has ing of race hybrids also involves ascertaining the environ- also found a significant positive correlation between the ment in which they do best.It may be in the area of height/diameter quotient of the mother trees and the origin of one or other of the parent races, or in quite height growth of the one-parent progenies in Pinus sylves- another area. Mass production of seed of a good race tris and Picea abies. Thus, due attention should be paid hybrid, pure or in mixture with the parent races, can to tapering in the selection of parent trees. easily be performed in a clonal seed orchard. Several of The tendencies of the stem to growing straight is, to a the plus-tree orchards in progress in Sweden have a certain high degree, connected with the geographical origin, as character of race-hybridizing orchards containing plus northern races and strains from high altitudes possess trees from a larger area than the orchards will cover. much more pronounced tendencies of this kind than At least in some trees, undoubted possibilities exist of southern races and strains from low altitudes. At the attaining improvement in growth rate through polyploidy. same time, a variation within the population does occur, For instance, positive results of autopolyploidy as well as especially in the southern strains.Thus, introduction of of allopolyploidy have been obtained in Populus tremula. "northern genes" in forestation materials, intended for Particularly would it seem worth while to test triploid southern parts of the distribution area of a forest tree, strains. Up to now, experiments with ligneous plants may be advantageous. The hereditarycontrol of stem have generallyresulted inautotetraploids being con- straightness has been convincingly shown by Swiss studies siderably inferior in growth rate to their diploids (Populus on the transmission of stem form in larch,the results of tremula, A inus glutinosa, Betula verrucosa, Ulmus scabra, which have been summarized by Fischer (1953) in the Larix decidua, Pinus sylvestris, Picea abies), whereas the following way: "Krummwuchsigkeit wird also phaenoty- corresponding autotriploids are as good or better than the pisch nur realisiert, wenn die entsprechende Veranlagung diploids(Populustremula,Betulaverrucosa,Ulmus dazu vorhanden ist." Genetics and Tree Improvement 719 Crown and branch characteristics are also significant susceptiblesd'êtreconverties dans des proportionsaussi im- portantes que possible en bois d'oeuvre, c'est-à-dire des espèces for geographical strains. As a rule, northern races possess dotées de branches minces et chez lesquelles la partie décroissante shorter and thinner branches than southern ones, the du füt est aussi réduite que possible. La sylviculture de demain crowns of which are typically more robust (for instance, exigera également des espéces dotées de la meilleure forme de Pinus sylvestrissubsp.lap ponica contra P.sylvestris croissance,étant donné que dans un système forestier avan- cd chacun des sujets d'une pépinière doit pouvoir devenir tin subsp. septentrionalis).Undoubtedly, a strong, negative arbre a pâte acceptable et chaque arbre doit donner en bois de correlation prevails between branchiness and diameter füt une partie importante de sa croissance. growth, on account of which a one-sided selection on thin La selection de sujets isolés et leur propagation végétative par branches will result in decreased diameter growth and utilisation des clones pour l'implantation représentent Ia méthode reduced production per unit area. However, this negative la plus efficace d'amélioration, mais elle n'est applicable qu'à un nombre limité d'essences forestières, a savoir le peuplier et le effect will be counterbalanced to some degree by the fact Cryptomeria. Les travaux d'amélioration de la plupart des essences that weak branch development is accompanied by slow doivent Se fonder sur la reproduction sexuée et les consequences tapering.In selecting parent trees, those with as thin immédiates d'une selection poussée sont relativement réduites; ii branches as possible ought to be chosen, but without en est de même ii l'on applique Ia panmixie entre sujets sé- lectionnés. La récoltede semences prélevéessurdessujets neglecting the claim tosatisfactory diameter growth. sélectionnés d'un peuplement qui représente la totalité du peuple- Already, in the introduction, it has been pointed out that ment primitif ne saurait fournir au plus qu'une amelioration perhaps more is to be gained by increasing the production limitée. of usable timber per unit area indirectly through strains La plupart des programmes d'amélioration actuellement en which convert a high percentage of the total production cours se fondent sur la selection de sujets de signe plus et sur la reproduction sexuée par voie de panmixie pratiquée stir tin in stem wood, than through strains with a specific rapid certain nombre de sujets de signe plus, multipliée par greffe et growth; and there is good reason to repeat this thesis here. cultivée en pépinières. L'amélioration de Ia capacité de croissance Inevitably, the main impression to be gathered from susceptible d'être réalisde de cette manière est imprévisible a this report will probably be that conclusive evidence of I'heure actuelle, du fait que les données expdrimentales ne sont pas encoreconcluantes.Indépendamment d'unprogrès génétique what is attainable through breeding measures in forest éventuel, la production de semences forestières en pépinières exige trees is still lacking. The general objective of forest tree également untravailimportantderationalisationquanta improvement, applicable toall forest trees under all l'organisation de Ia récolte de ces semences et permet de mainte- conditions, remains, however, perfectlyclear, namely, fir Ufi contrOle efficace des variétés. L'établissement de pépinières "phenotypes" de semences ne mass-production of plants for forestation purposes, giving représente toutefois que la premiere étape d'un long programme better trees in shorter time and an increased yield of qui ne sauraitêtre mené a bien ques'ilse fonde sur des merchantable timber per unit area. In this report, some essais de lignée sOrs qui permettent de découvrir les sujets offrant problems in relation to this objective and its attainment les meilleures possibilités de combinaison pour la génération de have been superficially discussed. In a following session, semences suivante. L'amélioration du taux de croissance des espèces interfertiles papers will be presented giving opportunities to penetrate peut en généralêtre obtenue par voie d'hybridationetles these problems more thoroughly. hybridesF1peuventêtreproduitsengrandesquantitésen pépinières. Les générations ultérieures et les sujets produits par References rétro-croisementpeuvent égalementposséderlavigueur des hybrides. En outre, pour bon nombre d'essences, l'hybridation Fischer, F., 1953. Ergebnisse eines Versuches über die Vererbbar- d'espèces géographiques offrent certaines possibilités. keit der Wuchsform bei Lärche (Larix decidua Miller) mit Chez les plantes ligneuses, les autotétraploIdes sont inférieurs a einem Beitrag zur Methodik der Erfassung von Formmerk- leursdiploides quant au taux de croissance,tandis que les malen. J.U.F.R.O. Congress, Rome. triploIdes correspondants de certaines espèces feuillues sont égaux Larsen, C. Syrach,1956.Genetics in silviculture. Edinburgh. ousupérieurs aux diploides. La capacité de croissance des Libby, W. J., 1958. The backcross hybrid Jeffreyx (Jeffrey x conifères triploides est a peu près incoimue. Coulter) pine. Jour. Forestry 56. Certaines caractéristiques des troncs telles que la rectitude et Nilsson,B.,1958a. Om sambandet mellan modertrbd och l'effilement dependent moms du milieu et peuvent être modifiées avkomma hos tall och gran. Svenska Skogsvârdsf. Tidskrift 56. par un complexe gérlétique plus simple que celui qui régit le 1958 b. Studier av 3-âriga avkommor efter korsning taux de croissance; on peut done prévoir une reaction plus nette svensk gran och kontinentgran. Ibid. a Ia selection en ce qui concerne ces caractéristiques qu'en cc Toda, R., 1958. Variation and heritability of some quantitative qui concerne la croissance. Ii convient done de prêter l'attention characters in cryptomeria. Silvae Genetica 7. voulue a la rectitude et a l'effilement ainsi qu'aux caractéristiques Nakamura, K. and Satoo, T. 1959. The heritability de la cime et des branches lorsqu'on sélectionne des sujets repro- of tree height and stem girth in cryptomeria through sexual ducteurs. reproduction. Ibid 8. Bosquejo de Objetivos de Mejoramiento y su Posible RESUMES RealizaciónCrecimiento y Forma de Tallo Plan d'ensemble des progrès a réaliser et de lear réalisa- El objetivo principal que se persigue con el mejoramiento de tion éventuelleCroissance et forme de la tige árboles forestales es producir materiales forestales que aumenten Les programmes d'amélioration des essences forestières visent la producción de maderas valiosas por unidad-área y por unidad- essentiellementasélectionnerdesespècesquipermettent tiempo.Este objetivo puede lograrse ya sea aumentando el d'augmenter la production de boisrentable par unite de super- Indicede crecimiento, mejorando losfactorescualitativos o ficieet de temps. Une augmentation du taux d'accroissement, aumentando la resistencia de las especies que se cultivan. des facteurs de qualité ou de la résistance permettent de réaliser No solo el crecimiento rápido y la resistencia adecuada, sino ce but. también la obtenciOn de árboles cuyos troncos presenten carac- Non seulement la rapidité de l'accroissement et Ia résistance, terIsticas favorables para su explotaciOn tienen tanta importancia mais aussi les propriétés positives des tiges demeureront dans enlaactualidad, como la que revestirán enelfuturo.Es l'avenir aussi essentiels qu'ils le sont aujourd'hui.Ii est probable posible que factoresrelativosal medio ambiente a menudo que les facteurs düs au milieu limiteront les possibilités d'accrois- limitenelprobableaumentoenlaproducciOntotalde sement de la production totale de bois par unite de superficie. madera por unidad-área. Por tal motjVo, es de suma importancia C'est pour cela qu'il est important de sélectionner des espèces desarrollar variedades que produzcan la mayor proporciOn posible

720 Fifth World Forestry Congress Proceedings de madera utilizable o sea, en otras palabras, especies de ramas también involucra una importante racionalización de la recolección delgadas y poca conicidad. La silvicultura del futuro requerirá de las semillas y posibilita la regulaciOn eficaz de las variedades. especies que presenten las formas más favorables de crecimiento Sin embargo, elestablecimiento de huertos para semilleros en virtud de que dentro de un sistema progresivo de silvicultura fenotipicos solo constituye un paso preliminar en un plan de cada una de las estacas recién plantadas debe tener caracterIsticas mejoramiento a largo plazo, que tmnicamente puede lievarse a cabo que le permitan convertirse en un árbol que rinda una cantidad por medio de pruebas seguras de progenie, con el propOsito de razonable de pulpa y, asimismo, que cada árbol produzca una determinar cuáles son los árboles que tienen mejores aptitudes de gran porción de su erecimiento en forma de madera de tronco. combinaciOnparalapróximageneracitmndehuertospara El método más eficaz para mejorar la selección de árboles semilleros. individuales y su propagación vegetativa, consiste en la plantación En géneros, con especiesinterfértilespuede obtenerse un de clones, pero este sistema puede aplicarse a solo unas pocas aumento del indice de crecimiento, mediante la hibridacitmn de especies de árboles forestales, como ser álamos y Cryptomeria. En lasespecies; y los hIbridos F1 pueden producirse en grandes casi todas las especies de árboles la tarea de mejoramiento de los cantidades en los huertos para semilleros. Asimismo, generaciones mismos debe basarse en Ia reproducción sexual yelefecto posteriores y cruzamientos pueden poseer vigor hIbrido.Del inmediato de una selección acentuada debe ser comparativamente mismo modo, en muchas variedades de árboles la hibridación de pequeño, asimismo, por medio de la "panmixia" entre árboles especies geográficas ofrece buenas posibilidades. seleccionados.Solo puede esperarse un limitado mejoramiento En el caso de plantas leuiosas,el crecimiento de los auto- cuando se procede a la recolecciOn de semillas de árboles de un tetraploides es menor que el de sus diploides, en tanto que los bosque seleccionado, que atmcontenga la totalidad de su pobla- triploides correspondientes de algunos árboles de hojas anchas son ción original. tanbuenosomejores que losdiploides.Prácticamentese La mayor parte de los planes de mejoramiento que se están desconoce la capacidad de erecimiento de las conIferas triploides. ilevando a cabo en la actualidad, se basan en la selección de Es probable que algunas caracterIsticas del tronco, como ser árboles positivos y en la reproducciOn sexual panmIctica entre un su rectitud y conicidad dependan menos del medio ambiente y nOmero de árboles positivos, multiplicados por injertos y cultivados posiblemente estén reguladas por un complejo genético más simple en semilleros. Todavia es prematuro predecir hasta qué punto se que el Indice de crecimiento; por este motivo es de esperarse una puede aumentar por este método la capacidad del crecimiento, mayor reacción a la selecciOn de estas propiedades que al Indice pues los resultados experimentales no permiten liegar a conclu- de crecimiento. A estos efectos, en la selección de árboles "padres" siones definitivas. Además del posible mejoramiento genético, Ia debe tenerse muy en cuenta tanto la rectitud y comcidad del producción de seinillasde árboles forestales en plantaciones, tronco como las caracterIsticas de Ia copa y de las ramas.

Objectives of Pest-Resistance Improvement in Forest Trees And Their Possible Attainment

ERNST J. SCHREINER In Charge, Forest Genetics Research, Northeastern Forest Experiment Station, Forest Service, U. S. Department of Agriculture, Upper Darby, Pennsylvania, U.S.A.

There is sound evidence for optimism on the practical tionship.For biologicand economic reasonsthese possibilities of "pest-resistance control," the control of standards must be flexible in time and place. pest damage by the use of inherently resistant forest trees. I freely admit that pest-resistance control has limitations. Basic Aspects of Pest-Resistance Improvement It will not solve all forest pest problems; it will not elim- The following delineation of information needed for inate all need for other methods of control (49)1 But scientific rather than empirical pest-resistance improve- the possibilities far outweigh the limitations. ment is presented as a basis for the discussion of pos- These possibilities have already been demonstrated in sibilities and methods. poplar culture.If the last decade's tremendous upsurge of forest genetics research can be combined with effective Variation in Pest Resistance of Forest Trees international cooperation during the next ten years, pest- The basis for pest-resistance improvement is the species, resistance control may be expected to have a major role varietal, racial, and individual variation in the inherent in the forest practices of the 1970's. resistance of forest trees. Pest-Resistance Improvement Objective Diseases. Populus clones resistant to leaf rust (Mel- ampsora sp.) are now widely cultivated (50). The occur- Simply stated, the objective is to select or breed trees rence of individual variation and inheritance of resistance that are immune to attack or have sufficient resistance to to blister rust (Cronartium ribicola) in Pinus strobus2 provide a profitable harvestImmunity isusually an has been studied since 1938(39). Individual variation in unrealistic objective.Since resistance to pests is seldom blister rust resistance of Pinus monticola and preliminary absolute, it is necessary to set up minimum standards of evaluation of rust resistance among eight juvenile hybrid resistance acceptable in practice for each host-pest rela- 2Authorities forscientific names of American treespecies 1Numbers in parentheses denote the references listed at the follow Little, Elbert L., Jr., 1953. Check list of native and natural- end of this paper. ized trees of the United States. U.S. Dept. Agr. Handb. 41.

Genetics and Tree Improvement 721 progenies of P. monticola and P. strobus have also been Inheritance of Pest Resistance reported (9). Scientific breeding requires basic knowledge of the Clonal variation in resistance to Septoria canker (64), mode of inheritance of the characters to be improved, Dothichiza canker (65), bacterial canker (Pseudomonas), for selection and rejection of progeny, and for application and spring dieback (Venturia) (50) of Populus, and of of the best breeding methods. The following examples Ulmus to Dutch elm disease(66) has already been from crop plants are cited to indicate the type of in- utilized. heritance that may be expected in forest trees. There is also variation in resistance to omnivorous root Host-parasite interaction in flax rust (Melampsora lini) fungi.Clonal variation inresistance to mimosa wilt has been explained by assuming a gene-for-gene relation- (Fusarium oxysporum f. perniciosum) has made it pos- ship between rust reaction in the host and pathogenicity sible to select resistant clones for commercial use (56). A in the parasite.In flax and the flax rust fungus, at least preliminary one-parent progeny test with Pinus echinata 25 such pairs of genes have been identified in the United has indicated definite inheritance of resistance to the little- States (20), and the gene-for-gene relationship has been leaf disease (Phytophthora cinnamomi) (72). confirmed by research in the Netherlands (27). Resistance Robinia pseudoacacia offers an outstanding example of to apple mildew (Podosphaera leucotricha) is inherited variation in resistance to wood decays: the wood of quantitatively, and the influence of the parents on the certain clones such as the shipmast locust is much more performance of the progeny is very marked; the direct durable than that of other clones of this species (46). assessment of varietal resistance can provide a sufficiently Pinus strobus, P. taeda, P. ponderosa, and P. palustris reliable guide to breeding behavior (11). have shown sufficient intraspecific variability in heartwood Resistance breeding generally depends upon the use of decay resistance for significant genetic improvement (15). a resistant parent. But there is at least one noteworthy Variation in durability of the wood from individual trees exception. A cross between potatoessusceptibleto of Quercus alba has also been noted (70). virus-X has produced some immune plants, presumably More than 2,000 selections of Ulmus americana and due to the effect of two complementary factors (3). 1,000 hybrids of U. pumila have been found resistant Hessian fly resistance in different strains of wheat may or immune to the phioem necrosis virus (57). The Stewart involve four dominants and a recessive, either as individual clone of Carya illinoensis is reported to be resistant to or duplex factors or in combination (25, p. 157); resistance asymptonilesscarrierof theviruscausing witch's of maize to the corn borer (Pyrausta nubilalis) apparently broom (56). depends on the cumulative effect of an undetermined num- Insects.There is sound evidence on clonal variation ber of multiple factors (25, p. 159). in the resistance of hybrid poplars to the Japanese beetle Resistance to the potato root nematode has been found (Popillia japonica) (48), clonal variation in Pseudotsuga to be due in some cases to a single dominant factor (18, menziesii to attack by Cherines cooleyi (40), and resis- 60).Segregation ratios in other progenies indicate the tance of the backcross hybrids, Pinus jeffreyi x (P. existence of two additional genes causing resistance only jefJreyi x P. coulteri)to the pine reproduction weevil when both are present (60). (Cylindrocopturus eatoni) (23, 35). Clonal variation in There islittle basic information on the mode of in- locust borer (Megacyllene robiniae) resistance has been heritance of pest resistance in forest trees. The difference reported in Robinia pseudoacacia (22, 69). Correlations between reciprocal crosses of Larix europaea DC. and between infestation of Pinus ponderosa by the resin midge L. leptolepis Gord. with respect to susceptibility of the (Retinodiplosis sp.) and the glacous or glabrous character progeny to a needle blight is of particular interest because of the young shoots as against viscid shoots (presumably it apparently involves cytoplasmic inheritance (30). inherited characteristics) indicate that viscid individuals are more susceptible to attack (4). Variation and Inheritance of Virulence in Pests Nematodes. It has long been known that nematodes can Knowledge of pest variability is needed for selection, be found in trees even to their very tops (14, 17, 55, 61), breeding procedure, and the choice of pest biotypes against but their importance as forest pests and the extent of which progenies should be tested. variation in host resistance has not been determined. It is Diseases.The literature on the genetic variation of to be expected that some nematodes eventually will be pathogens attacking agricultural and horticultural crops is recognized as serious primary or pests. extensive. The variability in fungi has raised many prob- Since there is inherent variation in the resistance of crop lems (54); most plant viruses are complexes of strains plants (18, 25, p. 163) such variation will undoubtedly that vary in virulence, kind of disease produced, host be found in forest trees. range, or other characteristics (6); and thereis also a wide plant Mammals and birds.Occasional references in the range in the inherent virulence of bacteria causing literature suggest that there is intraspecific variation in diseases. Biotypes of Melampsora larici-populina varyingin resistance of trees to damage by mammals and birds. pathogenicity have been isolated, and crossing experiments But thisarea of pest-resistance improvement will be have shown that new types can arise by hybridization omitted because the evidence does not provide a sound (62). Variation has been reported in rate of growth and basis for discussion. In my opinion, the possibilities for virulence between individual cultures of Fomes annosus improvement of mammal- and bird-resistance in forest from different localities and different species of trees in trees will be much more limited than for other pest-resis- Norway (44).Research on European larch canker tance improvement. (Dasyscypha willkommii) has indicated that there is a

722 Fifth World Forestry Congress Proceedings parasitic form of the fungus on cankered tissue and a vious heavy Melampsora rust infection (34).Another saprophytic form that is found on dead branches (32, 43). example is the beech bark disease of Fagus grandifolia Insects. Taxonomic races of forest tree insects have which is epidemic in many stands in New England and been described, but there is apparently no basic informa- New York.Trees are first infested by the bark scale tion on inherent variation in the adaptability of such insect, Cryptococcus fagi; subsequent attack by the fun- biotypes to the host species. From research with agricul- gus, Nectria coccinea faginata, usually leads to the death tural crops it is common knowledge that there is sufficient of trees in all stages of vigor (21). natural variation in insect populations to develop biotypes that become adapted to originally resistant varieties of Type of Pest and Establishment of Parasitism or agricultural crops (38), and to become resistant to in- Infestation secticides (5, 41). We need to know whether a pathogen is an obligate Nematodes.The evidence for genetic variationin parasite, one that must complete its life cycle in a parasitic nematodes comes from agriculture and horticulture. A relation to its respective host or hosts (rust fungi); a large number of biologic races are known to exist (25, p. facultative saprophyte which may subsist as a saprophyte 163).Populations of potato root eelworm which are for part of its life cycle, but does not complete its life aggressive toward resistant potato varieties have been cycle away from the host (some smut fungi); or a facul- shown to exist in advance of any selective influence by tative parasite, a saprophyte that becomes parasitic only these varieties(19, 28).Preliminary research has in- when the environment predisposes the host and permits dicated that the occurrence of root-knot in Shah! peach in the expression of its weak, pathogenic properties (many some orchardsis more likely the result of races of damping-off fungi). As defined, the facultative saprophyte nematodes than of variations in the host (16). has a much higher potentiality as a pathogen than does the facultative parasite (63, p. 9). Effect of Environment on the Host-Pest Relationship Information on whether an insect pest is monophagous, Pest-resistance improvement requires consideration of oligophagous or polyphagous (12), and on the host range the effect of environment on the resistance or susceptibility of insects in the last two categories, should be available to of the host, on the biology and pathogenicity of the pest, the tree breeder. and on the host-pest relationship. For diseases, the establishment of parasitism involves The rust reaction of 8 inbred lines of corn to one or study of the prepenetration phase, the act of penetration, more uredinial clonal lines of Puccinia sorghi at 4 different and the post-penetration phase (1). For insect infesta- constant temperatures and at 2 different alternating day/ tion, this will require investigation of the three proposed night temperatures is an example of the influence of the mechanisms for resistance(38): preference or non- environment on an obligate parasite. Some of the inbred preference of the insect for the host plant; antibiosis, the lines showed strikingly different rust reactions under these detrimental effects of the plant of the biology of the differentconditions,demonstrating the importance of insect; and tolerance, the ability of the plant to withstand determining the range of stable phenotypic reaction of an insect population that might damage a more suscep- lines used as host differentials (58). tible host. The variation in resistance of some poplar clones to Melampsora rust under different environmental condi- Nature of Pest Resistance tions may indicate variation in the rust biotype, the effect Information on the nature (or mechanism) of resist- of environment on the host, on the pathogen, or on the ancewillbeextremelyvaluableforpest-resistance interaction between host and pathogen. improvement (38, 67). Selection and breeding for resist- There is considerable evidence on the effect of environ- ance will be greatly simplified where the host characters mental conditions that reduce the vigor of the tree and responsible for pest resistance are easily recognized or thus permit saprophytes to invade and even kill the host, for example, Tympanis canker on Pinus resinosa (24) and measured. Valsa canker on Populus (36, 47). The earlier reports There have been occasional references to acquired that the spread of Valsa sordida in living twigs is related resistanceinplantssimulatingconditionsinanimal co the water content of the tissue (which can be drastically diseases.Virusdiseasesprovidetheonlyauthentic affected by environment) has been supported by recent example of two types of acquired resistance in plant research not only on this fungus (13, 36) but also on pathology; these are not the result of antibody formation Cryptodiaporthe canker of Salix (7). (1, 67), and the resistance is not heritable. The effect of environmental conditions on insect out- In astand ofCastanea sativaMill.,soseverely breaks is universally recognized. Adverse conditions af- damaged by Endothia parasiticathat there were no fectingthe growth of individualtreesincreasetheir sprouts older than 4 or 5 years, about 85 % of the sprouts susceptibility to many insects, and stand- or region-wide were infected, but most of the infections were apparently adverse climatic conditions and catastrophe, such as fire limited by callus or cork barriers (10). It will be interest- and snow breakage, can be responsible for epidemic out- ing to learn whether thisis a case of acquired host breaks of normally secondary pests. resistance, loss of pest virulence, or environmental modi- The interaction of two diseases, or of insects and fication of the host-pest relationship. diseases, to produce serious detrimental effects in the host isalso becoming well known in forest trees.Recent Pest-Resistance Improvement Possibilities and Methods investigationshaveindicatedthatsevereattackby The prospects are better for rapid, significant improve- Dothichiza canker on Populus can be correlated with pre- ment of pest resistance in forest trees than in cultivated

Genetics and Tree Improvement 723 crops because forest "crops" are essentially natural popu- the mode of inheritance; it has been particularly useful in lations that provide a wide range of genotypes. Further- breeding for pest resistance. Potato breeding has demon- more, the following observation has particular significance stratedthepossibilityofobtainingduplexparental for present-day forest tree breeding: "As with all breed- material for disease resistance by one generation of ing, in the beginning results can be gained with relative inbreeding (59). ease; but making better varieties than the existing ones It has been too generally assumed by forest geneticists grows more troublesome with the years."(59). In this thatinbreeding wasimpracticablewithforesttrees early period of tree breeding, improved pest resistance because of their presumed self-incompatibility. There is per se will be a significant advance. It will not be neces- evidence of some degree of self-compatibility in most sary or possible, in the early stages, to combine pest of the species in which considerable breeding has been resistance in forest trees with highly improved and often carried on up to the present time. The possibilities for inherently complex "market" qualities. And it should be inbreeding in Pseudotsuga menziesii are promising (37), noted that breeding for increased vigor and greater and twenty-eight trees of Pinus monticola tested for self- environmental adaptability will produce trees that are less compatibility averaged about50%in self-ability in com- susceptible to facultative parasites and secondary pests. parison to cross-pollination (8). I am confident that more Pest-resistance breeding with forest trees must and intensive work on self-pollinationwillindicate many should continue on an empirical basis.At this early excellent possibilities for this method. stage, basic knowledge of the inheritance of resistance is Backcross breeding is highly effective for determining not essential for practical improvement, and waiting for the mode of inheritance, and to transfer one or two simply such information would unnecessarily delay practical inherited characters to an otherwise desirable type. The progress. As examples of such progress, the U.S. Forest resistance of Pinus jeffreyi x (P. jeff reyi x P. coulteri) Service has started a large-scale program to produce progenies to the pine reproduction weevil is evidence that Pinus Jeffreyi x (P. jeff reyi x P. coulteri) stock for use this method can be used successfully with forest trees on high-weevil-risk planting sites in California (33); and withoutrepeatedbackcrossesorintermediateselfed the successful selection and breeding of disease-resistant progenies. Populus clones has been achieved by empirical methods. Seed orchards of selected 'Ledger' clones were the With Populus, rapid and impressive progress has been It possible in the first easy stage of improvement because of basis of the quinine culture of the Dutch East Indies. the variation in disease resistance between and within is at present the most promising method for the early mass the natural species, the wide variety of genotypes result- production of improved forest tree seed. The polycross ing from natural and controlled hybridization between test will provide the most practical method for evaluation species and their fertile hybrids, and the ease of vegetative of the general combining ability of selected phenotypes in propagation by cuttings. But for the most effective future seed orchards. Proper field layout is essential for maxi- progress, we must recognize the need for, and begin to mum seed production(31, 53)and for efficient polycross obtain, the basic information outlined in the previous tests(45,68). sections. Testing for Resistance The search for resistance must not be limited to popu- lations that have been exposed to the pest; the existence Parents and progenies should be tested againstall of resistance genes in nonexposed populations isnot known biotypes of the pest, and inoculation and pest- uncommon Where such preadaptation involves "major" exposure methods should be as similar aspossible to gene control of resistance, demonstrated for at least 84 natural infection or infestation. Massive spore or mycelial pests of33crop plants (29), it will facilitate rapid pest- inoculations, or cage tests with insects, can be so severe resistance improvement. that they assess only immunity, not relative resistance. It may be expected that the genetic basis of pest Fortunatelyitisnotabsolutely necessary totest resistance in trees will vary from single factor to quantita- improved forest trees with finality before they are used tive and cytoplasmic inheritance, and inheritance of pest in practice, because the genetic uniformity essential for virulence may range from gene-specifictopolygenic agricultural plants is not required in silviculture (42). pathogenicity. The appearance of aggressive strains of Improved seedling progenies or clonal mixtures may be pest biotypes against which a particular kind of resistance used for the entire plantation, or the improved types may in the host is no longer effective must be accepted as a be interplanted with common (native) planting stock. calculated risk. Pest-resistance control, like insecticidal Even where the entire area is planted with the improved control, will be a continuing commitment in forest prac- stock (seedlings or a clonal mixture), there should be tice but in my opinion it will be more effective and less sufficient genetic variation to prevent excessive loss; those costly in the long run. individuals that are not sufficiently pest resistant can be salvaged in intermediate cuttings. This provides an excel- Breeding Methods lent method for testing under many environmental con- Pedigree breeding will probably be the method most ditions. generally used with forest trees. Both this method and It is important to recognize the difference between multiple-cross breeding should be applied to pest-resist- pests for which tests can be made on young treesand ance improvement, but inbreeding and backcross breeding those that are important and should be tested in older will have particular value. trees. There is evidence, in both agriculture and forestry, Inbreeding usually provides the most rapid method to that the change in host resistance or susceptibility may be intensify and fix inherent characteristics and to determine in either direction. Juvenile resistance in Ulmus to the

724 Fifth World Forestry Congress Proceedings Dutch elm disease is an unavoidable hindrance to early International Cooperation selection (26). International cooperation will be essential for the most Uniform and,ifpossible,international systems for rapidprogress. Theproposed"InternationalTree rating pest resistance will be needed eventually.It was Disease Study" is a step in this direction, but the prelim- necessary to develop a uniform rating system for Melamp- inary objectives do not go far enough to include effective sora leaf rust infection on Populus(51)to obtain com- pest-resistance improvement (2). parable evaluations by foresters responsible for the rating International "gene-banks" or "gene-reserves" should of test plantations in the northeastern region of the United be established, with genotypes that have been adequately States.Rating systems should be based on "practical tested for pest resistance in at least one locality, for resistance," sufficient tolerance of, or recovery from, the additional artificial and natural exposure to native pests, attack of a pest to provide a profitable harvest. They and for use in breeding. Effective international coopera- should assess,as closely as possible, the effect of the tion could be started with Populus under the aegis of the pest on the growth and vigor of the tree and on the quality International Poplar Commission. There is world-wide of the timber. interest and research on this genus; and tested clones, Clonal Propagation resistant to pests under specific conditions in various countries, are already available. Clonal propagation to multiply trees on their own roots (as from cuttings) will greatly reduce the time and cost We also need international cooperation for the ex- required to test for resistance and to produce resistant change of information, particularly translation facilities stock for commercial use.This is exemplified by the to make available more than brief abstracts. improvement of Populus.Although pest resistance in In closing,I wish to ask your indulgence for the many cases can be tested on grafted stock, there is no staccato tempo of this dissertation; it stems from the assurance that the rootstock may not have an effect attempt to compress this broad topic into 4,000 words. (direct or indirect) on the susceptibility of the scion. Resistance to root diseases obviously cannot be tested References with grafted trees. Anon., 1948. Physiology of disease resistance in plants. Nature 161: 422-424. I believeit will be possible to develop economical , 1959.International tree disease study launched. methods for clonal propagation of most forest trees on Jour. Forestry 57: 850-851. their own roots, but I doubt that the answer will come .1960. New sources of immunity to virus X. U. S. Dept. Agr. Agr. Res. 8 (7): 3-4. from continuance of the past and present empirical Austin, Lloyd, 1945. Use of shoot characters in selecting approach.The time has come to recognize that this ponderosa pines resistant to resin midge. 26: 288-296. problem requires fundamental research. A recent break- Beard, Raimon L., 1957. Selection of physiologic strains of through on a basic aspect of cuttage is the report of a Oncopeltus and itsrelation to insecticide resistance.Conn. definite relation between growth inhibitor content and Agr. Expt. Sta. Bul. 611. Bennett, C. W..1953. Viruses, a scourge of mankind In rooting response of Vitis cuttings (52). Plant diseases. U.S. Dept. Agr. Yearbook: 15-22. Bier, John E., 1959. The relation of bark moisture to the Heterogeneous vs. Homogeneous Plantations of development of canker diseases caused by native, facultative Improved Trees parasites.I. Cryptodiaporthe canker on willow. Canad. Jour. Bot. 37: 229-238. Clonal selections will provide material for early use in Bingham, R. T., and A. E. Squillace, 1955. Self-compati- practice, but the planting of pure clones (single geno- bility and effects of self-fertility in western white pine. Forest types) is extremely hazardous. Quinine culture in Java Sci. 1: 121-127. , A. E.Squillace and R. F. Patton,1956. was not based on monoclonal plantations. The possibili- Vigor, disease resistance, and field performance in juvenile ties of greater heterozygosity in agricultural crops is also progenies of the hybrid Pinus monticola Dougi. x Pinus strobus receiving attention and is being tested in wheat (71), L. Ztschr. Forstgenetik 5: 104-112. Biraghi, A., 1954. Possible active resistance to Endothia where it appears that there is no inherent disadvantage in parasitica in Castanea sativa. IUFRO, 11th Congress Proc.: the use of multiline varieties and that, properly con- 643-645. trolled, such mixtures might offer considerable assurance Brown, A. G., 1959. The inheritance of mildew resistance in against disease(25, p. 119). progenies of the cultivated apple. Euphytica 8: 8 1-88. Brues, Charles T.,1952. How insects choose their food At the Northeastern Forest Experiment Station, U. S. plants. in Insects. U.S. Dept. Agr. Yearbook: 37-42. Forest Service, we propose to recommend clonal mixtures Butin, H., 1955. Uber den Einfiuss des Wassergehaltes der of as many parental cross-combinations as possible of Pappel auf ihre resistenz gegenuber Cytospora chrysosperma hybrid poplars of approximately similar growth-vigor. A (Pers.) Fr. Phytopath. Ztschr. 24: 245-264. Christie,Jesse R., 1959. Plant nematodes, their bionomics mixture of clones derived from20or more parental and control. Univ. Fla. Agr. Expt. Sta. combinations should provide greater variation in resist- Clark, Joe W., 1957. Comparative decay resistance of some ance than even a natural forest stand. The use of clonal common pines, hemlock, spruce, and true fir. Forest Sci. 3: mixtures or of seed derived from crosses between a num- 3 14-3 20. Clayton, C. N., 1947. Roots of Shalil peach seedlings are ber of parents with satisfactory combining ability for not resistant to all races of root-knot nematode. U. S. Dept. pest resistance should provide sufficent heterogeneity for Agr. Plant Disease Rptr. 31:153-154. assurance not only against heavy losses in the plantation Cobb, N. A.,1914. Nematodes and theirrelationships. itself, but presumably also against the buildup of new U.S. Dept. Agr. Yearbook: 457-490. Cole, C.S., and H. W. Howard, 1957. The genetics of pest biotypes with high pathogenicity against a single host resistance to potato root eelworm of Solanum tub erosum Subsp. genotype. andigenu.'n, clone C.P.C. 1690. Euphytica 6: 242-246.

Genetics and Tree Improvement 725 Dunnett, J. M., 1957. Variation in pathogenicity of potato (50) ,1959. Production of poplar timber in Europe root eelworm (Heterodera rostochiensis Woll.) and its signifi- and its significance and application in the United States. U.S. cance in potato breeding. Euphytica 6: 77-89. Dept. Agr. Handbook 150. Flor, H. H., 1955. Host-parasite interaction in flax rust- (51) , 1959. Rating poplars for Melampsora leaf its genetics and other implications. Phytopathology 45: 680- rust infection. U.S. Forest Serv. Northeast. Forest Expt. Sta. 685. Forest Res. Note 90. Fowler, Marvin E., 1960. Beech bark disease. 's (52) Spiegel, P., 1954. Auxin andinhibitors in canes of Vitis. News 25 (1): 1-3. Res Coun. Israel Bul. 4:176-183. (Seen in Hort. Abs. 25: Hall, Ralph C., 1937. Growth and yield in shipmast locust Item 1396). on Long Island and its relative resistance to locust borer injury. (53) Squillace, A. E., and R. T. Bingham, 1958. Selective fertil- Jour. Forestry 35: 721-727. ization in Pinus monticola Dougl. Silvae Genetica 7: 188-196. , 1959. Field tests on the resistance of hybrid (54) Stakman, E. C., and F. F. Christensen, 1953. Problems of pines to the pine reproduction weevil. U.S. Forest Serv. Pacific variability in fungi. In Plant diseases. U. S. Dept. Agr. Year- Southwest Forest & Range Expt. Sta. Tech. Paper 33. book: 35-62. Hansbrough, John Raymond, 1936. The Tympanis canker (55) Steiner, G., 1930. The nemic fauna of the slime flux of the of red pine. Yale Univ. School Forestry Bul. 43. Carolina poplar. Jour. Agr. Res. 41: 427-434. Hayes, H. K., F. R. mimer, and D. C. Smith, 1955. Methods (56) Stevenson, Frederick J., and Henry A. Jones, 1953. Some of plant breeding. 2nd Ed., McGraw-Hill Book Co., New York. sources of resistance in crop plants. In Plant diseases. U.S. Heybroek, H. M., 1957. Elm-breeding in the Netherlands. Dept. Agr. Yearbook: 192-216. Silvae Genetica 6: 112-118. (57) Swingle, R. V.,1954. Elm phloein necrosis. N. J. Dept. s'Jacob, J. C., 1955. Research on the susceptibility of flax Agr. and Cornell Univ. Ent. Dept. Conf. on Dutch Elm to flax rust (Melampsora lini). Euphytica 4: 107-115. Disease, Elm Phloem Necrosis and Oak wilt: 50-51 (mimeo) Jones, F. G. W., 1957. Resistance-breaking biotypes of the (58) Syamananda, Riksh, and J. G. Dickson, 1959. The influence potato root eelworm (Heterodera rostochiensis Woll.). Nema- of temperature and light on rust reaction of inbred lines of tologica 2: 185-192. corn inoculated with specific lines of Puccinia sorghi. Phyto- Knight, R. L., 1948. The role of major genes in the evo- path. 49: 102-106. lution of economic characters. Jour. Genet. 48: 370-376. (59) Toxopeus, H. J.,1953. On the significance of multiplex Langner, Wolfgang, 1952. Reziprok unterschiedliches Ver- parental material in breeding for resistance to some diseases halten von Lärchenbastarden gegen eine Nadelerkrankung. in the potato. Euphytica 2: 139-146. Ztschr. Forstgenetik 1: 78-8 1. (60) , and C. A. Huijsman,1953.Breeding for ,1953. Die Klonanordnung in Samenplantagen. resistance to potato root eelworm. I. Preliminary data con- Ztschr. Forstgenetik 2: 119-121. cerning the inheritance and the nature of resistance. Euphytica Latour, J. M., 1949. Intervention de la gelée dans la forma- 2: 180-186. tion du chancre du mélèze d'Europe.Sta.de Rech. de (61) Viggars, R. M., and A. C. Tarjan, 1949. A new root disease Groenendaal, Ser. C. No. 15. of pin oaks possibly caused by the nematode, Hoplolaimus Libby, W.J.,1958. The backcrosshybridJeffreyx coronatus Cobb. U. S. Dept. Agr. Plant Disease Rptr. 33: (Jeffrey x Coulter) pine. Jour. Forestry 56: 840-842. 132-134. Meiden, H. A. van der, and H. van Vloten, 1958. Roest (62) Vloten, H. van,1949.Kruisinsproeven met rassen van enschorsbrandalsbedreiging van de teelt van populier. Melampsora Larici-populina Klebahn. Tijdschr. P1. ziekten 55: Bosbouwproef stationWageningen KorteMeded.37:261- 196-209. 273. (63) Walker, John Charles, 1950. Plant pathology. McGraw-Hill Miller, John M., 1950. Resistance of pine hybrids to the Book Co., Inc., New York. pine reproduction weevil. U.S. Forest Serv. Calif. Forest & (64) Waterman, Alma M., 1954. Septoria canker of poplars in Range Expt. Sta. Forest Res. Note 68. the United States. U.S. Dept. Agr. Cir. 947. Müller-Stoll, W. R., and Ursula Hartman, 1949-1950. Uber (65) ,1957. Canker and dieback of poplars caused den Cytospora Krebs der Pappel (Valsa sordida Mitschke) und by Dothichiza populea. Forest Sci. 3: 175-183. die Bedingungen für eine parasitäre Ausbreitung. Phytopath. (66) Went, Johanna C., 1954. The Dutch elm disease. Sum- Ztschr. 16: 443-478. mary of fifteen years hybridization and selection work (1937- Orr-Ewing, A. L.,1957. Further inbreeding studies with 1952). Tijdschr. P1. ziekten 60: 109-127. Douglas-fir. Forestry Chron. 33: 318-332. (67) Wingard, S. A., 1953. The nature of resistance to disease. Painter, Reginald H., 1951. Insect resistance in crop plants. In Plant diseases. U. S. Dept. Agr. Yearbook: 165-173. Macmillan Co., Inc., New York. (68) Wit, F., 1952. The pollination of perennial ryegrass (Lo- Patton, R. F., and A. J. Riker, 1958. Blister rust resistance hum perenne L.) in clonal plantations and polycross fields. in eastern white pine. Northeast. Forest Tree Improve. Conf. Euphytica 1: 95-105. Proc. 5: 46-52. (69) Wollerman, Edward H.,1956.Strains of blacklocust Petersen, B., and B. SØegaard, 1958. Studies on resistance to resistant to borer. Northeast. Forest Tree Improve. Conf. Proc. attacks of Chermes cooleyi (Gill.) on Pseudotsuga taxifolia 3: 35-42. (Poir.) Britt. Forstl. Forsogsv. 25: 37-45. (70) Zabel, Robert A., 1956. Decay resistance variations within Porter, B. A., 1952. Resistance to insecticides. In Insects. U.S. Northeastern forest tree species. Northeast. Forest Tree Im- Dept. Agr. Yearbook: 317-319. prove. Conf. Proc. 3: 13-17. Righter, F. I., 1946. New perspectives in forest tree breed- (71) Zadoks, J. C., 1959. On the formation of physiologic races ing. Science 104 (2688): 1-3. in plant parasites. Euphytica 8: 104-116. Robak, Hâkon, 1953. tlber saprophytische und parasitische (72) Zak, Bratislav, 1955. Inheritance of resistance to littleleaf Rassen des Lärchenkrebspilzes Dasyscypha willkommii (Hart.) in shortleaf pine. U. S. Forest Serv. Southeast. Forest Expt. Rehm. Ztschr. Forstgenetik 2: 104-106. Sta. Note 88. Roll-Hansen, Finn,1940.UndersØkelser over Polyporus annosus Fr., saerlig med henblikk pa dens forekomst i det RESUMES sØnnafjelske Norge. Norske SkogforsØksv. Meddel. 24. Schaepman, H., 1952. Application of the polycross test to Accroissement de la résistance aux parasites des arbres grass breeding. Euphytica 1: 105-111. forestiers: objectifs et réalisations Scheffer, Theodore C.,1949. Decay resistance of black locust heartwood. U.S. Dept. Agr. Tech. Bul. 984. Les programmes d'amélioration de la résistance aux parasites Schreiner, Ernst J.,1931. Two species of Valsa causing ont pour objet de sélectionner ou de produire des essences disease in Populus. Amer. Jour. Bot. 18: 1-29. présentant une résistance suffisante pour assurer une production ,1949. Poplars can be bred to order. In Trees. rentable. L'immunité étant un objectif généralement inacessible, U.S. Dept. Agr. Yearbook: 153-157. il s'avérera nécessaire d'établir des normes minimales de résistance ,1957. The possibilities and limitations of selec- pour chacun des rapports hôte-parasite. tion and breeding for pest resistance in forest trees.Soc. Les possibilités d'améliorer de manière significative la résistance Amer. Foresters Proc.: 50-52. aux maladies, insectes et nématodes sont particulièrementfavo-

726 Fifth World Forestry Congress Proceedings rabies pendant la phase que nous traversons, a savoir le debut de Objetos de Mejoramiento de la Resistencia de Arboles a la propagation selective des essences forestières. On a tout lieu de prédire que le contrôie de la résistance aux parasites, c'est-à-dire las Plagas y Posibilidades de Lograrla le contrôle des dommages düs aux parasites grace a i'utilisation El objeto del mejoramiento de la resistencia de árboles a las d'espècesforestières natureilement résistantes,jouera un role plagas es el de seleccionar o criar árboles que tengan resistencia essentiel dans les pratiques sylvicoles a partir de 1970. Le contrôie suficienteparaproporcionar una provechosarecolecciónde de la résistance aux parasites, de méme que ceiui de la résistance madera. Dado que la inmunidad casi no es posible de lograr, se aux insectes, constituera l'une des tâches continues que Ia syivicul- hace necesario fijar normas mInimas de resistencia para cada ture s'engage a accomplir; elle deviendra toutefois plus efficace et relaciOn entre el huésped y la plaga. moms onéreuse avec le temps. Las posibilidades de verdadero mejoramiento de la resistencia La selection génétique en vue de la résistance aux parasites contra enfermedades, insectos y nematodos son particularmente devra se poursuivre de manière empirique: attendre de disposer de favorables en esta primitiva etapa de cria de árboles para bosques. données de base sur les règles de transmission de la résistance Hay razones para pronosticar que la resistencia,asI como la serait retarder sans nécessité les progrès pratiques. Toutefois, si disminución de daflos con el empleo de árboles inherentemente nous voulons a l'avenir réaliser des progrès efficaces, ii nous faudra resistentes,se puede esperar que desempeñen muy importante disposer de renseignements de base sur les modes de transmission función en la silvicultura en el decenio de 1970. La resistencia de la résistance chez les essences forestières, sur la variation et a las pestes, asI como a los insectos, continuará siendo objeto la transmission de la virulence chez les parasites forestiers, sur importante de la silvicultura, pero a la larga será más efectiva y les effets du milieu sur le rapport hôte-parasite, sur le type et menos costosa. l'établissement du parasitisme et la nature de la résistance aux La crIa para resistencia a las plagas tiene y debe seguir a base parasites. empIrica, pues la espera de conocimientos fundamentales sobre La résistance des arbres forestiers aux parasites vane suffisament la herencia necesariamente retardaria el progreso práctico.Sin suivant les essences, les variétés et les arbres particuliers pour embargo, para verdadero progreso se necesitarán conocimientos pouvoir être améliorée avec succès. La recherche de la résistance fundamentales sobre la resistencia por herencia en los árboles de ne doit pas se limiter aux peuplements qui ont déjà été exposés los bosques, sobre la variación y herencia de la virulencia de las aux parasites; l'existence de genes résistantes dans des peuplements plagas forestales, sobre el efecto del ambiente en la relación entre non exposés n'est pas rare. ci árbol y la plaga, sobre la clase y establecimiento del parasitismo La selection par pedigree et par croisement multiple seront y sobre la naturaleza de la resistencia de la plaga. probablement les méthodes les plus couramment utilisées pour Hay en los árboles de los bosques suficiente resistencia especIfica, les arbres forestiers, mais la selection par in-breeding et par back- caracteristica e individual en grado variable y capaz de mejora- cross sera particulièrement efficace pour determiner les modes de miento y su büsqueda no se debe limitar a poblaciones que hayan transmission de la résistance et pour développer rapidement la estado expuestas a plagas, pues la existencia de factores de resisten- résistance aux parasites. On a trop généralement accepté l'hypo- cia en poblaciones no expuestas es bastante comtin. these que i'm-breeding serait impossible dans la pratique en raison La crIa por genealogIas y el cruce multiple serán probablemente d'auto-incompatibilités présumées; ii semble que des recherches los métodos que más se emplearán con árboles forestales, pero el plus poussées dansledomaine de l'in-breeding puissefaire cruce en una misma especie y el recruce serán muy eficaces, en apparaltre d'exceilentes possibilités d'application de cette méthode. particular, para determinar la herencia y para el progreso rápido en ci mejoramiento de la resistencia a las plagas. Muy en general Les parents et leurs descendants devraient être soumis a des se supone que el cruce en una misma especie resulta impracticable essais en fonction de tous les biotype connus d'un parasite donné; porque se cree que hay mucha incompatibilidad propia; pero hay les méthodes d'inoculation et d'exposition aux parasites devraient pruebas de que estudios más profundos en ci cruce de una misma ressembler autant que possible aux conditions d'infection ou especie indiquen excelentes posibilidades para este método. d'infestation de manière qu'on puisse obtenir des renseignements Padres y progenies se deben someter a prueba contra todo tipo sur la résistance relative. Des systèmes uniformes de mesure de conocido de plaga y la inoculaciOn, lo mismo que los métodos de la résistance aux parasites permettraient d'évaluer, avec suffisament exposición a la plaga, deben ser tan semejantes como sea posible de precision, l'effet du parasite sur la croissance et la vigueur de a la infección o infestación natural a fin de bograr conocimientos I'arbre et la qualité du bois. de Ia resistencia relativa.Sistemas uniformes para avaluar ci Du fait que la résistance aux parasites est rarement totale, des grado de resistencia deben indicar, con precision razonable, el normes minima de résistance acceptable dans la pratique seront efecto de la plaga en el crecimiento y vigor del árbol y en la nécessaires pour chacun des rapports hôte-parasite existants. Elles calidad de su madera. devront se fonder sur la "résistance pratique", la tolerance suffi- Dado que la resistencia a la plaga rara vez es absoluta, se sante a un assaut de parasites, ou la guérison après cet assaut, necesitan normas mInimas de resistencia en la práctica para cada pour qu'on puisse s'attendre a une production rentable. relaciOn entre el árbol y la plaga. Estas normas se deben basar Les méthodes pratiques de propagation clonale des arbres sur en "resistencia práctica," tolerancia suficiente o restablecimiento les propres racines simplifieront la marche a suivre et réduiront deataque de una plaga para proporcionar una recolecciOn considérablement le temps et les fonds nécessaires a la production provechosa. et a la mesure de genotypes résistants et a leur multiplication a Métodos prácticos de propagación cbonal de Orboles en SOS des fins commerciales.Ceci exigera des travaux de recherches propias raices simplificarán ci procedimiento y reducirán conside- fondamentales sur la propagation végétative chez de nombreuses rablemente ci tiempo y ci costo necesarios para producir y avaluar espèces forestières. genotipos resistentes y para multiplicarlos en escala coinercial. Le contrOle de la résistance aux parasites réussira surtout dans Esto requerirá investigaciones básicas de la propagación vegetativa des peuplements forestiers présentant une hétérogénéité suffisante de muchas especies de árboles forestales. pour éviter des dommages importants dOs a des parasites en La resistencia a las plagas tendrá más éxito en masas de sufi- fonction desquelslesarbresaméliorés n'ont pas encore été ciente heterogeneidad genética para evitar daños graves de plagas soumis a des essais, et pour empêcher l'amorcage de biotypes contra las cuales no Se hayan probado los árboles mejorados y parasitiques nouveaux. Pour cette raison, les travaux devraient para impedir el acrecentamiento de nuevos tipos de plagas. Por porter sur le développement d'un nombre aussi grand que possible tanto, el mejoramiento Se debe encaminar a la creaci5n de tantos de genotypes resistant a un parasite déterminé. genotipos distintos como sea posible y que sean resistentes a IIconviendrait d'établir des "banques" ou des "reserves" alguna plaga en particular. internationales de genes disposant de genotypes ayant été soumis a Se deben establecer "bancos de genes" o "reservas de genes" des essais suffisants du point de vue de la résistance aux parasites internacionales con genotipos debidamente probados parare- dans une localité au moms, et destinés a être a nouveau exposés sistencia a las piagas por bo menos en una localidad, con el dans des conditions artificielles et naturelles aux parasites beaux objeto de someterbos a nueva exposición, artificial o natural, a las et a être utilisés a des fins de selection. plagas locales, asI como para su uso en Ia reproducción.

Genetics and Tree Improvement 727 Cytology and Breeding of Conifers

P. N. MEHRA Head, Department of Botany, Pun jab University, Chandigarh, India

Conifers form important forest belts all over the world. importance.The groupisdivided intosixfamilies, Some of them yield valuable timber which is utilised for although lately there has been a tendency to further a variety of purposes. Special mention in this connection segregation. may be made of various species of pines which are ex- The Pinaceae include some of the important forest ploited throughout the world, the larches in Europe, species like the pines,firs,spruces, and deodars.All Douglas-firofwestern North America,Kauripine the nine genera in the family have been investigated and (Agathis australis) of the New Zealand forests, Cedrus they uniformly show the haploid chromosome number deodara of the Himalayas, Cunninghamia lanceolata or n = 12, with the exception of Pseudotsuga, which has theChinesefir,and Sciadopitysverticillata,or the n = 13, and the monotypic Pseudolarix amabilis (native Japanese umbrella pine.There are many other species of Eastern China), which possesses n = 22. The latter of conifers which grow extensively and which could is, however, so scarce that it has hardly any forestry equally well be exploited if proper attention is paid to importance worthy of the name The genera that show them, particularly the ones that grow abundantly in n = 12 chromosomes exhibit considerable difference many of the underdeveloped countries of the world. among themselves as regards the morphology of the To effect systematic improvement in any plant species, karyotype, indicating that numerous chromosomal muta- whether it is of forestry importance or agricultural or tions have occurred in the evolution of different genera horticultural interest, itis prerequisite that one should within the family. However, confining our observations know all about its chromosome number and morphology, to the individual genus it is striking to note that all the chromosomal races,if any, and their interrelationships, species in a genus conform to the same basic pattern of the climatic races, gene ecology, the biology of flowering, karyotype, although there may be minor differences with embryology, and other methods of reproduction,just regard to the number and position of the secondary as a workman must have a thorough knowledge of his constrictions.It suggests, therefore, that gene mutations tools and materials before he can be expected to carve are chiefly responsible for the differentiation of species out objects according to his requirements.It is to the within a genus.It may be added here that the same chromosomal knowledge of the conifers in relation to their holds true in respect of the genera belonging to the other breeding behaviour that the present attempt is directed. families of conifers in the matter of species differentiation. A striking feature in the family is the complete lack of Survey of the Chromosomal Data polyploidy in the generic, species or varietal evolution in Fortunately, the cytology of many coniferous genera nature. is now known chiefly through the works of Dark (1932), The Taxodiaceae include some of the giant trees of Sax and Sax (1933), Flory (1936), Stebbins (1948), the world like the redwoods (Sequoia sempervirens), Mehra and Khoshoo (1956 a, b), Hunziker (1958), and Sequoiadendron giganteum and Taxodium mucronatum. Hair and Beuzenberg (1958). These investigations have There are, in all, 10 genera of which Glyptostrobus and been based on the squashes of young roots, leaves, or stem A throtaxis have not been cytologically investigated. The apices with or without a pretreatment with chemicals former, however, has no forestry importance either.All like colchicine, 8 oxyquinoline or L-bromonaphthalene the others have uniformly n = 11, with the exception which have been employed for critical analysis of the of monotypic Sciadopitys verticillata, which has n = 10, karyotypes. Sax and Sax (1933) have preferred endo- and Sequoia sempervirens, which is a polyploid with sperm for the purpose because of the haploid nature of n = 33.Incidentally, this is the only polyploid genus the tissue and the frequency of cell divisions. In many known among the conifers, and Stebbins (1948), on the cases the cytology is based on meiotic studies. basis of meiotic studies and comparative morphology, Conifers comprise in all 48 genera and approximately rightly considers it to be an autoallohexaploid with pos- 480 species, according to the estimate given by Dallimore sible relationship to Metasequoia. It does not seem to have and Jackson (1948). This includes, however, the newly stabilised itself sexually yet, as it exhibits considerable discovered monotypic genus Metasequoia glyptostroboides. pollen and seed sterility. No other polyploid species is For the present enumeration, the two species of Sequoia known. have also been treated as belonging to two different Cupressaceae includes as many as 15 genera of which genera, and Thuja orientalis has been raised to the rank of two, namely, Callitropsis and Diselma, have no forestry a separate genus, designated as Biota orientalis.All the importance.Three others, namely, Fitzroya, Fokienia, genera, with the exception of a few which will be in- and Thu jopsis have not been cytologically worked. All dicated under their respective families, are of forestry the others, including the valuable cypresses, have n = 11

728 Fifth World Forestry Congress Proceedings chromosomes.There are only two natural polyploid Polyploidy in Relation to Breeding species known in the entire family, both belonging to the genus Juniperus. It will be noticed from the data given above that J. chinesis pfitzeriana is considered to polyploidy is exceedingly rare in conifers in nature. The be an allotetraploid with n 22, as it exhibits perfect only cases so far known are the giant redwood tree which pairing at meiosis. The other (J. squamata meyeri) is isanautoallohexaploid,theallotetraploidJuniperus also a tetraploid, but its cytological analysis has not yet chinesis been made to reveal the nature of polyploidy. pfitzeriana,and thetetraploidJ.squamata The Kauri pines (Agathis spp.) of New Zealand and meyeri, the real nature of which is undetermined but monkey puzzles (Araucaria spp.), the two genera belong- may also probably be an allotetraploid. ing to the Araucariaceae, both have n = 13 chromosomes. Within a species, the occurrence of polyploid races is There are no polyploid species so far known in this unknown. There are, however, records of stray poly- family ploid individuals in some species which may be men- Podocarps form forests of significance in the southern tioned. A single tree of European larch, Larix decidua, of hemisphere. The two genera Microcachrys and Pheros- tetraploid constitution and approximately 56-5 8 years of phaera are bushes and, therefore, of not much forestry age, has been found on a private estate in Denmark. This interest, but the others, namely, Acmopyle, Saxegothaea, is generally inferior in growth compared to the normal diploid of the same age.Cytologicallyit shows con- Phyllocladus, Dacrydium and Podocarpus, include trees, siderable irregularity in pairing at meiosis resulting in a some of which, particularly those belonging to the last high degree of pollen sterility. There is the formation of genus, are stately in height. All the seven genera have monads, diads, tetrads and polyads (Christiansen, 1950). been investigated by Hair and Beuzenberg (1958). The A single tetraploid individual of Picea abies has also position with regard to chromosome number inthis been discovered in Sweden. The third instance is of an family ishighly interesting and different from all the apparently autotriploid Juniperus virginiana reported by other families of conifers.The chromosome numbers Stiff (1951), growing in the Orland E. Wight Arboretum not only differ in the different genera, but this is so even of the Blandy Experimental Farm in the U.S.A. among the different species of the two genera, Podocarpus Not that the autopolyploids do not arise in nature, but and Dacrydium. For example, in the former, the num- it has been observed that their growth in general is so bers 10, 11, 12, 13, 17, 18, and 19 are present, and in poor compared to the diploids that they cannot stand in the latter, the numbers hitherto reported are 9, 10, 11, competition with the latter.Kiellander (1950) found in 12, and 15.The numbers in the other genera of the Picea abies a very small percentage (0.00216%) of family are: Acmopyle, n = 10; Saxegothaea, n = 12; seedlings in nursery beds, the majority of which were Phyllocladus, n = 9; Pherosphaera, n = 13; and Micro- tetraploids and some tripioids or mixoploids. An occa- cachrys, n = 15. But since many species in these genera sional aneuploid was also observed. Sporadic occurrence have not been worked it is likely that variation in num- of such individuals in this species was later confirmed by ber in these may also be found. A point of some interest Illies(1953) who found them to be associated with brought out by Hair and Beuzenberg on the basis of polyembryonic seedlings.Kanezawa (1949) found the karyotypic studies is that a precise numerical relation- same phenomenon in A bies firma and discovered tetra- ship exists between the numbers of V chromosomes and ploid and aneuploid seedlings. Zinnai (1952) and Rodger I chromosomes, so that the total number of arms in a (1953-54) reported tetraploid seedlings in Pinus densi- set remains twenty.According to these authors, "With flora and P. radiata, respectively, but, as in the previous each successive change in basic number a V replaces or instances, the percentage of such seedlings was very low. is replaced by two I's." Basically, therefore, the chromo- Recently, Mergen (1958) discovered a very small pro- some number isthe "same" in different genera,the portion (0.0002%) of natural mixoploids in slash pine variations in actual number being accounted for on the (Pinus elliottii).The composition of the seedlings was basis of fragmentation of V's or unions of I's during the predominantly tetraploid, but there was an admixture of course of evolution. As appears from the data given by diploid and triploid tissue as well. Such seedlings were these authors, exceptions to this numerical relationship abnormal looking and poor in growth, possessed defec- between V's and I's are to be found in the three species of tive root systems and thicker and smaller leaves, and the genus Dacrydium, namely, D. biforme, D. kirki, and appeared incapable of surviving in competition with the D. bidwilli, and also in the genus Phyllocladus. There is normaldiploidseedlings.Tetraploidandmixoploid no real polyploidy within the entire family. seedlings have also been discovered in Japanese larch The last family, Taxaceae, includes five genera in all. (Larix leptolepis) by Chiba and Watanabe (1952). By The yews (Taxus spp.) have n = 12 chromosomes, and and large, the polyploid seedlings are sickly and incapable so has the genus Cephalotaxus. The other genera, namely of survival in nature, but there is only a single instance of Austrotaxus and Torreya, have not been worked, and tetraploidseedling with gigas characters reported by the last one, Amentotaxusa bush of no forestry value Chiba (1950) and Zinnai and Chiba (1951) in Crypto- is also unworked. meria japonica. The above data briefly records the position with regard Conifers easily respond to the action of a polyploidising to chromosome numbers in the conifers.It may be stated agentlikecolchicine.Such experimentally produced that among the genera whose chromosome numbersare polyploids, like the natural ones, are also found to lack known, only some of the more important species have been in vigour compared to the diploids.The first artificial worked, and many more which grow in virgin forests induction of polyploidy in conifers with the help of in many parts of the world still remain uninvestigated. colchicine was done by Mirov and Stockwell (1939) in

Genetics and Tree Improvement 729 the case of pine seeds.In 1941, Jensen and Levan Surveying, therefore, the data as a whole, natural as effectedtetraploidyinSequoiadendron giganteum by well as experimental, it seems doubtful if induction of treating the seeds with 0.2 % coichicine. The 1½ -year- polyploidy will be of much use in the breeding of coni- old plants were darker green in colour with coarser fers.In the first place, polyploids are generally weaker branches and broader and thicker leaves than the normal compared to the dipboids, and, secondly, they will suffer but did not show any significant difference in size com- from the disability of reduced fertility, which is a serious pared to the normal. Hyun (1954) induced polyploidy handicap in their propagation. in several pine species (Pinus ponderosa, P. jeff reyi, P. x attenuradiata)with 0.2% and 0.4% coichicine and Hybrdisation produced tetraploids and mixoploids with 2n, 3n and 4n There are frequent reports of occurrence of natural tissues in various combinations. The 18-month-old seed- hybrids in conifers.Larix sibirica and L. gmelini are lings of P. ponderosa depicted in the photographs by the reported to form intermediate population around Lake author were of the same height as the diploid controls, Baikal. Pinus nigra crosses with P. sylvestris, and Pinus but the size of the needles was much reduced.The sylvestris with P. muga to form hybrids in Central Europe. present writer had an opportunity toobserve these Duffield and Righter (1953) report the occurrence of individualsatPlacervillein1957, when they were spontaneous hybrids between Pinus attenuata and P. approximately six years old.They showed very poor radiata in Santa Cruz County, California, and between growth, none exceeding a height of 2 ft., and were sickly P. contorta var. latifolia and P. banksiana in Alberta. in appearance, whereas the controls of the same age were Both of these hybrids were successfully produced experi- nearly 20 ft. tall. mentally at the Institute of Forest Genetics, Placerville, It appears, therefore, that autopolyploidy in general is and were designated as X attenuradiata and X murray- not of much use in producing superior types in conifers. banksiana respectively (Righter and Duffield, 195la, b; The case is not comparable to aspen (Populus tremula) Righter and Stockwell, 1949). The latter was found to where the autotriploid is known to be very much more show greater vigour compared to the seed parent, P. vigorous than the diploid and has 36% increase in the contortavar.latifolia.Hall(1952)noticedhybrid volume of wood, or the triploid and tetraploid swarms between Juniperus virginiana and J.ashei in which are markedly fast growing compared to the dip- Southeastern United States. The former species was also bids. It appears that in conifers in general, chromosomal found to hybridise with three other species of the genus, saturation in relation to cytoplasm has already reached namely, J. horizontalis, J. scopulorum and J. barbadensis its maximum at the diploid level and that any further in areas where they overlapped. Juniperus ashei was also addition of chromosomes or whole chromosomal set found to produce hybrid populations with J. monosperma creates a condition of imbalance which is not conducive and J. pinchotii. Cytological evidence of hybridisation of to optimal functional relationship of the two, as a result the species between J. virginiana and J. horizontalis was of which there is a decrease in vitality. presented by Ross and Duncan (1949). A natural hybrid There is an instance of a triploid hybrid larch that between black and white spruce (Picea mariana X P. deservesspecial mention.This arose as a resultof glauca) has recently been described by Little and Pauley experimental pollination made by Syrach-Larsen between (1958). There is no doubt that many reports of similar Larix decidua used as the female parent and L. occidenta- nature will be brought to light in the other generaof us as the male parent. From the 534 seeds produced in conifers in future. this cross, only a single plant grew which was triploid in A number of instances are known of hybrids which constitution and is interpreted to have arisen through have either originated spontaneously under cultivation in the fertilisation of an abnormal diploid pollen of L. botanic gardens, private estates or arboreta or have been occidentalis with the haploid sex cell of the other parent artificially produced by nurserymen through experimental (Syrach-Larsen and Westergaard, 1938).The treeis pollination.These belong to almost all the coniferous fairly vigorous in growth, which may probably be due to genera of forestry importance such as Pinus, Larix,Abies, hybridity rather than the effect of triploidy.It has been Picea, Tsuga, and Taxus.It will be cumbersome to cytologically investigated by Knaben (1953), who finds mention them individually, but reference could be made a number of trivalent associations in addition to the to Dallimore and Jackson (1948), Righter and Duffield bivalents and univalents which means that close homology (1951a), Syrach-Larsen (1934; 1937) and plant breed- existsbetweenthetwoparentalchromosomesets. ing abstracts for further information. Some of these have Obviously, this results in considerable pollen sterility and been cytologically investigated and show that pairing at thus reduced seed formationfeatures which are unde- meiosis is normal to a fairly great extent, and the seeds sirableinaforesttree which otherwiselacksany produced are fertile. Some are reported to be unusually natural method of vegetative multiplication. vigorous in growth such as X Pinus holfordiana A. B. It has been concluded that much of the speciation Jackson, which is a natural cross between P. ayacahuite in conifers has been at the ecospecific level as shown by X P. wallichiana (Dallimore and Jackson, bc. cit.). the fact that pairing is normal to a fairly great degree in Oftheseinterspecifichybrids,particularinterest the hybrids(Duffield,1952; Khoshoo, 1959).This attaches to the classic example of hybrid larch, Larix means that there is close homology of the chromosomes eurolepis that arose naturally in Scotland as a cross of the parents that are capable of hybridising. Polyploid- between the Japanese larch, L. leptolepis, acting as the isation of such hybrids to form tetraploids is expected to seed parent, and the European larch, L. decidua, acting result in serious disorder at the time of meiosis which as the pollen parent.Not only does it evince hybrid would impair the seed-producing ability. vigour but also combines the superior qualities of both

730 Fifth World Forestry Congress Proceedings the parents, the straight form of European larch and the Hybridisation experiments at intraspecific as well as disease resistant quality of the Japanese larch against interspecific level are pregnant with potentialities for the the larch canker disease caused by the fungus Dasyscypha future. There is the combining of the desirable qualities wilikommi, to which the European larch is highly suscepti-. of the parents as well as the introduction of hybrid vigour ble. The pairing in the F1 hybrid is almost normal, the in many cases. Considerable heterosis has been found in chiasma frequency is nearly as high as in the parents, interspecific hybrids between Pinus ponderosa X P. lati- and the fertility of the pollen is 90% (Sax, 1932). The folia and P. monticola X P. strobus at Placerville (Righter percentage of seed setting is also high. and Duffield, 1951a, b).Fortunately, conifers are a Righter (1946) early realised the importance of experi- particularly suitable material in this respect, as much of mental hybridisation as a tool in effecting improvement the speciation in nature in this group has been at ecospeci- in pines, in view of the consistency in the number and fic level with changes confined to gene mutations thus morphology of chromosomes in the different genera of affording a large gene pool from which to make suitable conifersand the common occurrence of hybridsin combinations.Thisisperhaps thebest method of nature. An extensive program of interpollination experi- improvingforesttreespecies among conifers where ments was built up at the Institute of Forest Genetics, polyploidy is almost a failure. Placerville.Till 1951, as many as 230 crosses had been Experiments so far conducted and programs outlined attempted between the different species and varieties, are chiefly in the direction of selection of elite parent trees including backcrossings with the parents (Righter and from natural stands for the production of seeds for Duffield,1951a).Of these, 46 crossings have been future forests. Conifers are known to be cross-pollinated, successful and some have yielded rather promising results. and hence in any elite individual, howsoever good it may Some of the hybrids evince considerable growth vigour appear phenotypically, there is a possibility of the presence and are being tried in different parts of the U.S.A. and at of recessive deleterious genes which may segregate out at other places in the world. the time of sex cell formation.Application of genetic An interesting feature of these crosses and one of principles as applied to crop plants is highly desirable, practical utility is that the fertility in these is fairly high. although itcertainly is a time-consuming process, but Duffield (1952) states that of the 22 species hybrids worth giving a trial. Conifers are not self sterile as shown produced at Placerville, 10 F1 generations have come to by On-Ewing (1954; 1957 a, b) in the case of Pseudot- flower and none shows more than 40-50% sterility. The suga. Elites should at first be inbred for one or two gen- seed fertility is higher still and is at least 80% compared erations to weed out the deleterious genes as far as pos- to that of the parents. He has, therefore, concluded that sible.The selected individuals which show desirable strong homologies exist between the chromosomal makeup characteristics should then be employed for raising stock of different compatible species of the genus. On the basis of seeds through hybridisation. of results on the crossability behaviour, supplemented There appear to be bright chances of producing better with data on anatomy and chemical composition of pines and vigorous types by using methods similar to those of the species tried at Placerville, Duffield has drawn a employed in the production of hybrid corn by double tentative scheme of classification of the diploxylon pines crossing of the superior pure genotypes within a species which will be helpful to breeders in their future attempts and even between two different compatible ones. at pine breeding.Khoshoo (1959) has similarly con- The case of podocarps, however, seems to be different. cluded, on the basis of pairing phenomenon in respect of As already stated, in this group of plants there are the natural and artificial hybrids, that in conifers, in structural changes in the chromosomes in the evolution general, the speciation has been at ecospecific level and of species and genera.Therefore, while intraspecific there is considerable amount of gene exchange. hybridisation for tree improvement may be feasible here, Similar experiments have been tried on larches in Den- it may not work at the interspecific level. mark by Syrach-Larsen (1934; 1937).Hybrids have been produced between Larix decidua and L. leptolepis, Aberrant Genotypes L. occidentalis, L. laricina, L. gmelini and L. leptolepis, It is not my intention to dwell upon the characters and between L. leptolepis and L. gmelini var. olgensis. utilised for the selection of superior genotypes in individ- The interesting triploid hybrid that arose in a cross ual species.This is well known to tree breeders. But between L. decidua as female parent and L. occidentalis in the selection of plus types, particularly for seed produc- as pollen parent has already been referred to.It is fairly tion, one has to be careful to avoid the aberrant genotypes vigorous, and that probably is due to hybrid vigour and which may be responsible for defective sex cell formation. not the result of triploidy.Unfortunately, no diploid Some of these known in conifers may be illustrated. hybrid between the two parents was produced which Asyndetic individuals:Enar Andersson (1947 a, b) could have given an opportunity. to make a comparison found among the elites of Picea abies an individual with between the vigour of the two and to detect the role of an abnormal genotype. In open pollination it produced only additional chromosome set. As stated earlier, the pairing 1.99% of the normally developed seeds, while the majority in the triploidis disturbed and thereis considerable of these were small and empty. Even among the large sterility. seeds the germinability was only 17%. Meiotic analysis Recently, Wright (1959) reported 16 species hybrids revealed that the zygotene and pachytene stages were from 38 species crossed between white pines. Amongst normal, but the homologous chromosomes fell apart at hard pines as many as 23 hybrids and one probable the subsequent stage.The mother cellsexhibited at hybrid were obtained in 55 attempted crosses by Wright M1 either all univalents or a few bivalents as well. Con- and Gabriel (1957). sequently, the chromosomal distribution at A1 and A2 was

Genetics and Tree Improvement 731 highly irregular, resulting in a high percentage of pollen Christiansen, H., 1950. A. tetraploid Larix decidua Miller. Det. Kg!. Danske Vidensk. Seisk., 19:1-9. sterility.The aberration was thus gene determined and Dallimore, W. and Jackson, A. B., 1948. A handbook of Coni- not structural. Progeny tests of the germinable seeds of ferae. London: Edward Arnold and Co. this tree showed very heterogenous population in the Dark,S.O.S.,1932. Chromosomes of Taxus,Sequoia Cryp- nursery, with wide differences in the growth height and tomeria and Thuja. Ann. Bat., 46:965-977. Duffield, J. W., 1952. Relationships and species hybridization in generalhabit.Chromosomal determinationsof these the genus Pinus. Z. Forstgenetik, 1, Band, Heft. 4: 93-97. individuals revealed unbalanced numbers. and Righter, F.I.,1953. Annotated list of pine Sticky types: Another aberration reported by the same hybrids made at the Institute of Forest Genetics. Forest Res. author in the same species was of some elites having Notes. U.S. Dept. of Agri. No. 86: 1-9. Flory, W. 5.,1936. Chromosome numbers and phylogeny in sticky chromosomes. This abnormality was also probably Gymnosperms. J. Arnold Arbor., 17: 83-89. gene determinedIn these individuals the chromosomes Hair, J. B. and Beuzenberg, E. J.,1958. Chromosomal evolu- formed fused masses at meiosis thus losing their indi- tion in the Podocarpaceae. Nature, 181:1584-1586. viduality. The abortion of pollen was very high. Hall, M. T.,1952. Variation and hybridisation in Juniperus. Ann. Missouri Bat. Gard., 39:1-64. Structural heterozygosity: This is not uncommon in Hunziker, J.H.,1958. Karyotypic analysis in Cupressus and certainspecies.In Cephalotaxus drupacea,Sugihara Libocedrus(abstract). Proc. X mt. Cong. Gen., 2: 128-129. (1940)found that25out of34individuals displayed Hyun, S. K., 1954. Induction of polyploidy in pines by means multipartite ringsof4-6chromosomes, the remaining of colchicine treatment. Zeitschrift für Forstgenetik und Forst- pfianzenzuchtung Band 3, Heft 2: 25-33. being bivalents. Only9individuals were normal. Such lilies, Z. M., 1953. (Selection of multiple seedlings in single plant heterozygous genotypes arising as a result of segmental progenies of Picea abies.) Zeit Forstgen. Forstpfianz, 2:21. interchanges are expected to give poor formation of Vide P1. Breed. Abstr. 1953, 23: No. 1486. fertile pollen and should be avoided as parents for seed Jensen, H. and Levan, A., 1941. Coichicine induced tetraploidy in Sequoia gigantea. Hereditas, 27: 220-224. multiplication in any species. Kanezawa, R.,1949. Polyploids appeared in twin seedlings of Partial failure of spindle: This observation was made forest trees. (Japanese with English summary). J. Jap. Forestry by Khoshoo(1957)on an aberrant individual of Cephalo- Soc., 31:22-24. Khoshoo, T. N., 1957. Cytology of conifers III. Partial failure of taxus drupacea var. cuspidata. In this plant the chromo- meiotic spindle in Cephalotaxus drupacea var. pedunculata. some pairing was normal up to M1, but due to defective Cytologia, 22: 80-89. spindle organisation at anaphases, the distribution of the 1959. Polyploidy in Gymnosperms. Evolution, 13: chromosomes in many mother cells was extremely irregu- 24-39. lar.Besides the production of normal pollen there was Kiellander, C. L., 1950. Polyploidy in Picea abies. Hereditas, 36: 5 13-5 16. also present abnormal pollen in the same anther. Hence, Knaben, G., 1953. En cytologisk analyse av diploid og triploid the author concluded that the aberration is due to lack Larix. Biyttia, 11: 105-115. of a rigid gene control on the functioning of the spindle Little E. L. and Pauley, S. 5., 1958. A natural hybrid between mechanism. black and white spruce in Minnesota. Am. Midi. Nat., 60: 202-211. Abnormalities of similar or different nature are likely Mehra, P. N.and Khoshoo, T. N., 1956a. Cytology of conifers. to be met in nature.It is therefore imperative to weed I. J. Genetics, 54: 165-180. out the defective genotypes, and the easiest way to do and , 1956b. Cytology ofconifers. II. J. Genetics, 54: 181-185. that is to look at the mature pollen. Mergen, F., 1958. Natural polyploidy in slash pine. Forest Science, 4: 283-295. Irradiation and Use of Chemical Mutagens Mirov, N. and Stockwell, P., 1939. Colchicine treatment of pine seeds. J. Hered., 30: 389-390. Another approach worth giving a trial is exposure of Orr-Ewing, A. L., 1954. Inbreeding experiments with the Douglas- seeds of genotypically best parents to high energy radia- fir. Forestry Chronicle, 30: 7-16. tions and chemical mutagens for further improvement. l957a. Further inbreeding studies with Douglas-fir. Forestry Chronicle, 33:318-332. This method has already yielded some very significant 1957b. A cytological study of the effects of self- results in the case of crop plants. Production of mutant pollination on Pseudotsuga menziesii (Mirb.) Franco. Siivae barley with stiff straw, groundnuts with better and thicker Genetica, 6:169-200. pods and greater yield, white mustard with higher oil Righter, F. I.,1946. New perspectives in forest tree breeding. content, and flax with superior quality of fibre are some Science, 104: 1-3. and Duffield, J. W. 195la. Interspecies hybrids in of the well known improvements effected through the use pines, J. Heredity, 42: 75-80. of ionising radiations.Itis not unlikely that better and ,195lb. Hybrids between ponderosa mutants in forest trees may be produced with this new and Apache Pine. J. Forestry, 49: 345-349. technique. and Stockwell, P., 1949. The fertile species hybrid, Pinus murraybanksiana. Madrono, 10: 65-69. Rodger, G. J.,1954.Ann. Rep. Forestry and Timber Bureau, References Commonwealth of Australia vide P1. Breed. Abst. 1956, 26: Andersson, E., 1947a. A case of asyndesis in Picea abies. Here- No. 2861. ditas, 33: 301-347. Ross, J. R. and Duncan, R. E., 1949. Cytological evidences of 1947b. Pollen and seed setting studies of an asyn- hybridization between Juniperus virginiana and J. horizontalis. detic spruce and some normal spruces; and a progeny test of Bull. Torr. Bot. Club, 76: 414-429. spruces. Meddelanden Fran Foreningen for vaxtforadling av Sax, H. J., 1932. Chromosome pairing in Larix species. J. Arnold skogstrad 45:1-22. Arbor., 13: 368-373. Chiba, S.,1950. Triploids and tetraploids of Sugi (Cryptomeria Sax, K. and Sax, H. J., 1933. Chromosome number and mor- japonica D. Don) selected in the forest nursery. Bull. Govt. phology in conifers. J. Arnold Arbor., 14: 356-375. For. Expt. Sta. No. 49:99-108. Stebbins, G. L.,1948. The chromosomes and relationships of and Watanabe, 1952. Tetraploids of Larix kaemp- Metasequoia and Sequoia. Science, 108: 95-98. feri (=L. leptolepis) appeared in nurseries. J. Jap. Forest Stiff, M. L., 1951. A naturally occurring triploid juniper. Va. J. Soc., 34: 276-279. Sci. 2: 317. Vide P1. Breed. Abstr. 1952, 22: No. 1474.

732 Fifth World Forestry Congress Proceedings Sugihara, Y.,1940. On the multipartite chromosome-ring in les espéces et au sein des espèces donnera probablement d'aussi Cephalotaxus drupaceaSieb.etZucc.Sci.Rep. Tohoku bons résultats que pour le mais hybride qui, tout comme le Univ., Fourth Series, Biol., 15: 13-18. conifére est pollinisé par le vent. Le document indique qu'il est Syrach-Larsen, C., 1934. Forest tree breeding. Yearb. Roy. Vet. souhaitable de procéder a des experiences d'irradiation pour Agric. Coll. Copenhagen, 96-1 13. obtenir des mutants génétiques appropriés. II faut declarer en con- 1937. The employment of species, types and indi- clusion que l'introduction de nouvelles variétés sur une grande viduals in forestry. Yearb. Roy. Vet. Agric. Coil. Copenhagen, échelle dolt être préparée avec soin car elle risque de rompre 69-222. Reprint: Reitzel, Copenhagen. l'équilibrenaturelsurtoutdanslecasd'essencesforestières and Westergaard, M., 1938. A triploid hybrid between cultivées sur de grandes étendues, et ii faudrait insister davantage, Larix decidua Mill. and L. occidentalis Nutt.J. Genetics, 36: dansla mesure du possible,sur l'amélioration des essences 523-53 0. indigènes. Wright, J. W., 1959. Species hybridisation in the white pines. Forest Science, 5: 210-221. La Citologla y el Cultivo de Conif eras Wright, J. W. and Gabriel, W. J.,1957. Effects of continuous bagging of white pine cones. U.S. Forest Service. Northeast. En este trabajo se presenta un breve estudio general sobre ci Forest Expt. Sta., Sta. Paper 99. nümero de cromosomas en diferentes géneros de conIferas.Se Zinnai, I.,1952. Tetraploid plants of Japanese red pinePinus destaca que la poliplodia no es frecuente en la naturaleza debido densiflora S. et. Z.discovered in transplant beds. J. Jap. For. a la debilidad inherente de los poliploides sobre los diploides Soc., 34: 185-187. Vide Forestry Abstracts 1953, 14: 402. sexuales.Las conIferas parecen haber alcanzado el punto de and Chiba, S., 1951. Naturally occurring tetraploids saturación en lo que respecta a la relación que existe entre los of Cryptomeria japonica. Ikushugaku Zasshi Jap. J. Breed., 1: cromosomas y el citoplasma en ci nivel diploide.Además, la 43-46. Vide P1. Breed. Abstr. 1952, 22: No. 1473. diferenciacibn citogenética entre las especies compatibles parece haber sido en la mayorIa de los casos en el nivel ecoespeclfico y cualquier poliploide surgido por generación natural o producido RESUMES artificialmente tendrá más de dos grupos de cromosomas más o Cytologie et selection des conijères menos homólogos, lo que darIa por resultado acoplamientos irregulares y, por lo tanto, esterilidad.La mejor forma para Cette communication passe brièvement en revue les nombres de mejorar las conIferas es por medio de la hibridización.Los chromosomes dans les différentes espèces de conifères.Elle fait cruzamientos dobles entre e intra especies probablemente resuitan ressortir la rareté des polyploldes dans la nature en raison de la beneficiosos, al igual que en el caso del maIz hIbrido que, a faiblesseinhérente des polyploides par rapport aux diploides semejanza de las conIferas, logra la polinización por ci viento. Se sexuels. Les conifères semblent avoir atteint un degré de satura- destaca la conveniencia de realizar experimentos de irradiación tion quant au rapport entre les chromosomes et le cytoplasme au para obtener mutantes genéticos adecuados. Por dltimo, puede niveau diploide. En outre la différenciation cytogénétique semble seflalarse que las nuevas introducciones en gran escala deben ser avoir eu lieu surtout au niveau écospécifique et tout polyploide estudiadas con precaución dado que existe la posibilidad de que nature! ou artificiel aura plus de deux series de chromosomes plus ocasionen un desequilibrio de la naturaleza, particularmente en ou moms homologues ce qui se traduirait par une pollinisation ci caso de especies forestales que se cultivan en superficies exten- irrégulière donc infertilité. La meilleure méthode pour améliorer sas y, en la medida de lo posible, debe dedicarse mayor atención les conifères consiste a les hybridiser. Le croisement double entre al mejoramiento de las especies nativas.

The Role of Physiology in Forest Tree Improvement

S. DENNIS RICHARDSON Professor, Department of Forestry, University of Aberdeen Old Aberdeen, Scotland

Introduction purposes or with the selection of outstanding trees for general use, their attainment is mediated by control of In a recent address, Thimann (148) * suggested that a physiologist is a person who spends his time trying to the tree's internal physiology. The objective of the physiol- measure the rates at which biological processes go on; the ogist in this context, therefore, must be to recognise and prime concern of the applied geneticist, on the other hand, elucidate the processes which the tree-improver wishes to is to alter these rates.This analogy should not be ex- modify. amined too closely, but it can serve to introduce the One consequence of this viewpoint is that almost every affinities of the two pursuits with which this paper is con- publication concerned with forest tree improvement has cerned. The important resemblance lies in the fact that some relevance to the title of this paper. When it is the processes which the physiologist tries to measure (and realised, however, that, in North America alone, well over to understand)are those which the applied geneticist 200 individuals are actively engaged in research in this tries to change, whether by individual plant selection or field (168) (and actively publishing in it), it is clear that by breeding. The only way in which heredity can affect a comprehensive literature survey would be beyond both plant growth and development is by influencing the con- the ability of the present writer and the endurance of his trolling physiological processes; and it follows that what- audience.This discussion will be limited, therefore, to ever the objectives of forest tree improvement, whether consideration of some of the more important and cosmo- concerned with the creation of new genotypes for specific politan objectives in forest tree improvement programmes, *Numbers in parentheses denote the references listed at the and to illustrations of the ways in which the physiologist end of this paper. can contribute to the problems they raise. Genetics and Tree Improvement 733 Improvement in Growth and Form comparative photosynthesis measurements will not also In most countries, the primary objective of a forest be overcome. tree improvement programme is to select or breed trees Photosynthesis, of course, is only one of the many with increased growth rates and desirable stem form. processes which may limit tree growth.Moisture and Physiologically, growth is a most complex phenomenon, nutrient uptake, translocation, carbohydrate, nitrogen and comprising many involved and imperfectly understood fat metabolism, respiration and transpiration are others processes. To the forester, however, who, in the ultimate whichareimportant and which may be controlled analysis, is a carbohydrate farmer, the most important of genetically. In the selection or breeding of genotypes for particular "difficult"sites, an understanding of one or these processes is photosynthesis, since, once his trees are other of these processes may be of value. The problem established, it is the only one over which he can exercise for the physiologist here is to recognise and elucidate the much control. limiting process, and then devise practical means of assess- Over the years, a considerable body of data on photo- ing it.Some progress has been made. With regard to synthesis rates in trees has accumulated (for selective growth on moisture-deficient sites, for example, genetic reviews, see 107, 66) and it is known that there are (often ecotypic) variation is well established (128, 80, marked specific differences in both the efficiency and the 81, 177, 34, 3, 24, 74, 20). In some instances, drought maximum rate of photosynthesis (67, 64, 107, 9, 108, resistance is related to root development (42) and some- 116, 83). Moreover, it seems that, in general, trees may times it is simply an effect of early flushing (103) and be more efficient in their utilisation of solar energy than avoidance of the dry season. It can, however, have a more most agricultural crops. fundamental basis.Thus, Gilmore (44) reports an as- Variations in photosynthetic efficiency within a species sociation between drought resistance in Pinus taeda and have also been reported. Huber and Polster studied 16 low transpiration rate, particularly under conditions of clones of, mainly, Aigieros and tacamahac poplars and deficient soil moisture. Certain chemical properties were demonstrated marked differences(up to two-fold)in similarly associated. Polster (109) measured the transpi- photosynthesis per unit area of foliage which were related ration rates of 58 clones of poplar and concluded that to clonal differences in timber production (50). That such measurements could be used as an index of moisture such variations are genetic, and not due to possible dif- requirements. He also (111) established a correlation ferences in pre-conditioning, is indicated by the work of between transpiration and the reaction of stomata to Bourdeau (14), who foind significantly lower rates of intermittent light and suggests that, in poplars at any rate, photosynthesis in colchicine-induced polyploids of Pinus this stomatal reaction can be used as the index; while elliottii than in normal diploids under the same environ- Kaloyereas (57) advocates an empirical method based mental conditions. Again, these differences could be re- on the heat stability of chlorophyll. Themechanism of lated to growth rate.Genotypic variation in photo- drought injury is not understood (72, 51), though recent syntheticefficiency has also been reported in Tsuga work (60, 141) suggests the involvement of protoplasmic canadensis (33). reactions.Whatever the mechanism, however, it would These results have considerable significance for the seem that, as with photosynthesis, it should not bebeyond tree improver; if the genetic basis of intra-specific varia- the ability of the physiologist to devise relatively simple tion in photosynthesis rate is widespread, such measure- measurements which might be used to select drought- ments might be used as a basis for the selection of parent resistant parent trees for breeding work, and in the early trees for vegetative propagation or controlled breeding, assessment of progeny (see also 58). and for the early detection of potentially fast-growing Similar arguments can be applied in the field of low stock. Further, the silvicultural value of progeny bred for temperature restrictions to growth. Ecotypic variation in purposes other than improved growth rate, (e.g., disease frost hardiness is widely known (see, e.g., 70, 147, 118, resistance, timber quality,etc.) might also be rapidly 61, 65, 88, 113, etc.) and, again, such variation is some- assessed in this way. times associated with phenology (137, 62, etc.). There is, in fact, a close resemblance between drought resistance There are, of course, obstacles. Although the major and frost hardiness, as has been shown by Pisek and problems of instrumentation have been solved by the Larcher (105).Since, however, crosses between geno- adaptation, for photosynthesis work, of the Noyons dia- types differing in frost hardiness can result in progeny ferometer (5, 116) and the infra-red gas analyser (see which may be more or less hardy than either parent (see 32), there remain numerous difficulties associated with the 72), there would appear to be more than one hardiness interpretation of measurements (see 40) and with the factor involved.Attempts have been made to relate nature of plant material. For example, the rate of photo- hardiness to cell constituents such as sugars (155, 104, synthesis varies with age (167, 38, 116), development 97) and proteins (142), but the precise physiological stage (10, 11), season of the year (37, 172, 96, 106, 110, basis of protection remains obscure. The classic researches 12, 76) and growing conditions(see 66).Different of Siminovitch and collaborators (72, 142) have added photosynthetic efficiencies between "sun" and "shade" much to our knowledge of the physical and biochemical leaves (53, 15, 151, 152), adaptation phenomena (8, 165, changes which accompany frost-hardening in bark tissues 13) and variation within the crowns of individual trees but, as yet, no simple test of hardiness has emerged. further complicate measurements. However, the situation This is also true of genetic variation in relation to cer- here is essentially similar to that which confronted the tain other features of marginal sites.Considerable work early proponents of Neubauer tests for nutrition analy- appears to have been done in Russia on the development ses; and there is no reason to suppose that the problems of of Pinus and Fraxinus strains capable of growing on saline

734 Fifth World Forestry Congress Proceedings soils (112, 1) and, in America, McMillan (77) has re- hotly contested by Götz (45), among others, in the ported on intra-specific variation with respect to adaptabil- course of a lively controversy in the German forestry ity to serpentine.Similar racial differences have become journals as to the criteria necessary for distinguishing apparent in Europe and elsewhere during the afforestation races.Recently Schmidt's suggestion has been revived; of base-deficient soils, but it is not always clear whether Schrock (136) has described a method of making short- such differences are direct responses to soil type or to some term measurements of the phototropic response of pine other environmental factors.Certainly, the physiological seedlings and has used it to detect, in the seedling stage, basis of these effects is completely unknown; and it is to trees of outstanding form. If these results are confirmed, be hoped that the current interest in forest fertilisation the method promises to be a valuable tool for the tree- will encourage investigations into these fundamental prob- improver. Phototropic responses are extremely variable, lems. however, and much more work will be required before it Any discussion of growth as a factor in tree improve- could be used with confidence. ment would be incomplete without mention of the phenomenon of photoperiodism. A literature survey of Selection and Breeding for Disease Resistance this topic will not be attempted here, because several good The past decade has seen a spectacular increase in the reviews are available (43, 158, 160, 2), including one on attention paid to pest and disease resistance in tree im- "Photoperiodism in relation to tree improvement" (99). provementprogrammesand,followingthesuccess Among the vegetative processes which are known to be achieved in agriculture and horticulture (see 94), geno- influenced by daylength, the duration of height growth, typic resistance has been recognised in a large number of internode extension, leaf growth in some conifers, leaf tree species and to a wide variety of fungal, insect and abscission, duration of cambial activity and the breaking bacterialpests.In North America,thebest-known of dormancy are relevant to the present discussion, since examples of intra-specific variation in resistance are, per- they all affect the gross increment of the tree. Of these haps, Castanea dentata with respect to Endothia para- processes, most attention has been paid to the first and the sitica (see 27), Pinus monticola to Cronartium ribicola last,i.e.,the onset and termination of dormancy; and (98, 7) and Pseudotsuga menziesii to Adelges cooleyi, several widely distributed species have been shown to though there are many others (see, e.g., 46, 47).In exhibit ecotypic variation in these respects. Thus, Sylven Europe, Pseudomonas syringae, Melampsora and Dothi- (146) found that northern races of Populus tremula, chiza on poplars are important examples (4, 133, 123), when planted in the south of Sweden, grew less than the but genotypic variation is also known in Pseudotsuga indigenous types; while southern races moved to the north menziesii with respect to Rhabdocline pseudotsugae and showed delayed dormancy and were damaged by autumn Phaeocryptopus gaeumannii (see 39), Ulmus with respect frosts.Similar ecotypic variation has been demonstrated to Ophiostoma ulmi(49) and Larix to Dasyscypha in other Populus species (100), in Pinus sylvestris and wilkommii (131). Other examples could be cited, includ- Alnus incana (156) and in Pseudotsuga menziesii (52). ing some of the rot fungi (127, 68, 169, 23). In spite Schultz (138) found that, while species of Salix and ofthesedevelopments, however, remarkablylittleis Betula from lower latitudes are unable to form resting known about the nature of host resistance and itis an buds under continuous illumination, subarctic species of obvious subject for physiological investigation. A few these genera are able to do so. empirical studies have been made, and with promising From studies of this kind, it has become clear that the results, but there is considerable scope for further work. photoperiodic response is a matter of primary concern Neugebauer (87) has shown that in Pinus sylvestris, to the tree improver. Pauley points out that "as a means susceptibility to the pine shoot , Rhyacionia buo- of increasing the net yields of wood or fibre, gene com- liana, is related to resin production; and that in genotypes binations nicely adapted for full utilization of the frost-free with a high resin flow, the larvae and the moth may be season in a particular habitat may well prove to be quite drowned during feeding.It has been suggested, too, that as promising as a search for heterotic hybrids." The role the same mechanism may operate against sistentes of of the physiologist, however, is less obvious. Although Adelges piceae on Abies grandis (36), and it is reported he can claim credit for the discovery of photoperiodic by Brown (17) that resin exudation from Pinus ponde- phenomena, his understanding of them is far from com- rosa is toxic to bark beetles. It is thought that qualitative plete(see 160).Perhaps he can best assist the tree differences in oleoresin composition determine resistance. improver by continuing to accumulate data on ecotypic More recently, Nienstaedt (89), working with Castanea, variation and by assessing the photoperiodic behaviour of has shown that the high concentration of pyrogallic tan- progeny. At the same time, basic studies of the relations nin in the bark of genotypes resistant to Endothia para- between photoperiodism, dormancy and general metabol- silica may be responsible for retarding the growth of the ism are desirable; in the long run, they will be of greater value than any amount of empirical investigation. fungus, and Varty (157) has suggested a possible relation between tannin and resistanceof Abies grandisto Turning now to the improvement of tree form, it must be confessed that the physiologist has, so far, made little Adelges. Varty also found evidence of a relation between contribution to an understanding of the factors involved. resistance and the pH of the needle tissue, while a report On a priori grounds, one might expect straightness of stem from Russia (69) relates enzyme activity to resistance of to be inversely related to the phototropic response, as was oak to Microsphaera aiphitoides.Apparently successful pointed out by Schmidt (129, 130) before the war. His attempts to use bark moisture content as an index of claim that the phototropic response of seedlings could be canker susceptibility have also been reported (19, 6, 95), used as an index of stem form in adults, however, was though the physiological basis is far from clear.

Genetics and Tree Improvement 735 One of the major difficulties in breeding disease-resist- processes. In this connection, studies ofthe physiology of ant genotypes is caused by the fact that resistance may cambial activity have demonstrated the importance of hor- change with age (143, 49) and, in consequence, progeny mones in initiating xylem development (see162, 163) trials must be continued over a long period of years. while several investigators have related the formation of There can be little doubt that if the biochemical or bio- reaction wood to hormones (166, 93, 85). In a paper physical basis of resistance and immunity were under- presented elsewhere in this Congress, experimental studies stood, selection and breeding could proceed much more of tracheid size and cell wall thickness in conifer seedlings rapidly and confidently.Significant advances in physio- are described, from which it appears thatwall thickness logical techniques have been made in recent years as, for is a function of the balance between photosynthesisand example, the development of chromatography in chemical respiration; tracheid size, on the other hand, seems to be analysis, the availability of isotopes for chemical track- linked, directly or indirectly, to the activity of the termi- ing and, of particular interest in the present context, the nal meristem. use of aphid stylets for vascular sampling(59). When it The physiology of heartwood formation (86) and is realised that genotypic variation applies to the pests as tylosis development (56) have also been studied. With well as to the trees, the urgency of the need for funda- a few exceptions, however, there is aregrettable lack of mental investigations becomes apparent. interest in "physiological wood anatomy" among foresters and, since any genetic control of anatomical variation Selection and Breeding for Timber Quality and must be mediated by physiological processeswithin the Extra ctives tree, it is to be hoped that this deficiency will berectified. of The literature relating to genetic improvement of timber Progress in this field will require the combined efforts quality has recently been discussed by Schreiner (135). the geneticist, the anatomist and the physiologist. Apart from heritability in knottiness (see, e.g., 159, 135, Closely linked to the genetic improvement of wood 145), several physical, chemical and anatomical features quality are the problems of selection and breeding for which affect the properties of wood from the utilisation increased cellulose yield (see 132, 139) and chemical viewpoint have been reported as subject to genetic con- extractives (see 79, 114). Restrictions of space prevent trol. These include wood density (16, 140, 154, 35, 115, these topics being treated here, and it must suffice to 41, 173, 174, 176, 31, 101), tracheid length in conifers point out that while significant progress has been madein (73, 120, 30, 31, 54, 26), vessel and fibre dimensionsin the field of wood chemistry (see, e.g., 153), ourunder- hardwoods (41, 82), cell wall thickness (22), orienta- standing of the tree as a chemical factory has not kept tion of tracheid fibrils (30, 25), the proportion of early pace. to latewood (63) and unusual grain orfigure (21, 35, 124, 55, 84, 92). In the opinion of the present writer, Techniques of Forest Tree Improvement however, with the exception of wood grain, heritable The problems of forest tree improvement which are variation in these properties within a species has not been currently attracting most attention among physiologists demonstrated unequivocally; and it will not be so demon- are, undoubtedly, the technical onesof vegetative pro- strated until systematic studies of the biology of xylem pagation, flowering and seed production; and, with equal development have been made. certainty, they are among the most difficult. This lack of certainty results from the failure of many Vegetativepropagationisimportanttothetree investigatorstodistinguishbetweensystematicand improver for purposes of clonal multiplication of, for apparently random variation in anatomical characteristics example,disease-resistantstock,orforinheritance within the individual tree, and to design stratified samp- analyses (see 71).It is probably true to say that, at the ling methods in accordance with this variation.Recent present time, most forest trees can be propagated vegeta- (unpublished)studiesof wood density and tracheid tively, either by using techniques developed over2000 length in conifers have shown that to compareindividual years ago and improved by theapplication of growth regu- trees objectively, samples must be taken atthe centre of lators (see, e.g., 149, 91) or with the aid of modern an internode and that, in any oneannual ring, the inter- developments such as air-layering (78, 170) andneedle nodes should be so chosen that they represent afixed fasicle rooting (171).It is also true, however, that very percentage of the total internode number.The common few forest trees can be propagated easily andcheaply. practice of comparing trees at one or more fixedheights Nienstaedt et al. (91) have surveyed some of the litera- above the ground must be deprecated, since,unless the ture relating to vegetative propagationand they discuss trees have identical internode lengths, systematicvariation the importance of water relations, food balance, ageof within the annual ring may distort the comparison. material and endogenous hormones in affectingrootabil- The basis of the sampling method suggested aboveis ity.The paucity of our understanding of these factors an important study by Duff andNolan (28, 29) of growth isunderlined by Nienstaedt'sconclusionthat,with patterns within trees, in which they attempt to separate "difficult" species, the prime requirement for successis the extrinsic and inherent determinants of growth. They increased knowledge of tree physiology.Schreiner, too, relate xylem development not only to the activityof the has written about vegetative propagation-"I ventureto cambium, but also to that of the apical meristemand to predict that this essentially physiological problemwill be competition within the tree for assimilates. Further studies solved eventually, but I doubt that the answer will come of this kind are highly desirable. from continuance of the past and presentempirical The physiologist can, thus, contribute to problems of research on rooting.The time has come to recognise anatomical variation by trying to elucidate the controlling that this problem requires fundamentalbiochemical and Fifth World Forestry Congress Proceedings 736 bio-physical research" (134). When the complexities of with the number of growth cycles. Biochemical investiga- normal root growth are appreciated (see, e.g., 18,150, tions of flower induction of the type envisaged by Stanley 117),however, those of root development on morpho- (144) would also be rewarding. logical shoots (as from cuttings) appear gargantuan. Per- As a final illustration of the role of physiology in forest haps this is the best possible reason for tackling them. tree improvement, reference can be made to certain prob- Of even greater current interest is the question of lems which will undoubtedly become increasingly import- flowering in forest trees, since the ability to accelerate ant in the future. These relate to the establishment and and control this process offers obvious and valuable management of seed orchards. Of major importance here, advantages in terms of an increase in pure line breeding is an understanding of stock-scion relationships in grafting and a reduction in the time required for seed production. since, if horticultural experience is a guide (see 119,121), Probably most tree breeders have at some time contem- increased evidence of graft incompatability can certainly plated or performed experiments designed to induce early be expected in forest trees.Such an understanding is flowering. Many of these are of the "pepper-pot" variety, important, too, for the recognition and elucidation of in which empirical treatments are applied, hopefully but rootstock effects and in the event of complications due to indiscriminately, "to see what happens," rather than with virus infection, for which there is now strong evidence in any background of knowledge. Some of them sometimes certain fruit tree combinations (see 48).Present tech- succeed; but the most consistent results are still being niques of flower stimulation (see175)need to be less obtained with the methods devised many years ago by empirically based and the effects of hitherto unimportant horticulturalists (see125)and, even here, the reasons for pathogens, such as cone and seed insectsand possibly success are not understood. insecticidesmay require attention. In all these matters, The problem of flowering in trees is closely related to the need for physiological investigations is obvious and juvenility.Nienstaedt (90) has recently emphasised the important. importance of distinguishing flower stimulation in trees which have reached the stage of readiness to flower, and Conclusion flower induction in juvenile material. The attainment of In a paper of this kind, comprehensive treatment of the "ripeness to flower" condition is, apparently, a result what is a very big subject is impossible; and it must be of the action of both endogenous and environmental confessed that these illustrations of the role of physiology factors, which may be mediated by the balance of certain in forest tree improvement have been chosen subjec- metabolites within the tree (164). tively and mainly according to the interests of the writer. In a most useful discussion of these and other problems No mention has been made of a number of important of ontogeny, Wareing (164) distinguishes between the aspects as, for instance, the part which the biochemist can transition from the juvenile to the adult state (which he play in genetic analyses; or that of the cell physiologist in calls "maturation"), and the loss of vigour which occurs studies of mutation; mutagenic techniques have been in the shoot system of the adult tree (which he terms ignored and no reference made to pollen physiology in "ageing"). Experiments with Betula verrucosa in a con- relation to seed production. Nevertheless, even if these trolled environment(75)and observations on the pat- topics had been discussed,itis doubtful whether this ternof reproductive development in Pinus sylvestris would affect the principal conclusion, which must be that (161) lead him to postulate that, in some species, flower- physiology has not yet been sufficiently exploited in forest ing depends on the attainment of a minimum size during tree improvement or, for that matter, inthe wider fields maturation while, in others, it is associated with ageing. of forestry. InPinussylvestris,both phenomena appearto be Quite apart from the obvious difficulties associatedwith involved, since the initiation of female cones is related to treesas experimental material, thereis a number of size, whereas male cones first appear on those parts of the reasons for this neglect. In the firstplace, the belief that branch which show the most advanced ageing. From these forestry research can be practised only in the forest dies and other considerations, he speculates that the transition hard, in both national fOrest services and some of the from the juvenile to the adult condition involves funda- universities. The writer has heard one research director mental changes in the state of the cytoplasm, which are complain that it is easier to indent for a bulldozer than transmitted from one cell generation to another, and for a test tube. This is, doubtless, an exaggeration,but which may control metabolism at the cellular level. it reveals an attitude of suspicion towards laboratory re- Other interesting work on juvenility has been carried search that is not yet entirely absent, even where lip- out in Russia in relation to the theory of phasic develop- service is paid to the value of it. ment (see 126), and certain implications for tree breeders Another reason can be traced to those of us who are have recently been discussed (122).This evidence of university teachers.It is a common complaint of forestry renewed interest in an old problem is encouraging. As students that informing their acquaintances of their voca- Wareing has said "it seems likely that in the future we shall tion evokes the response "so you want to cut down trees?". see rapid advances in our knowledge of a phenomenon This is,in part, a reflection upon a lack of awareness which is of great importance both to the tree-breeder among the general public that inorder to cut timber the and tothe student of developmental physiology and forester must also grow it; but it may also reflect, in part, morphogenesis."In the view ofthe present writer, the balance in the curricula of our forestry schools. Tree further studies using controlled environments to accelerate physiology seldom has the status of an independent sub- seasonal growth cycles are needed, to confirm that the ject; it is usually the poor relation of silviculture or forest achievement of "ripeness to flowering" depends on the botany. We should not be surprised, therefore, that, as attainment of a certain size and is not, in fact, associated Paul Kramer complains, foresters do not see the trees

Genetics and Tree Improvement 737 for the wood; all too often, their training does not fit common pines, hemlock, spruce and true fir. For. Sci. 3 (4), them to do so. 314-320. Contardi, H. G., 1957. Variabilidad en Eucaliptus rostrata. Nevertheless, there isevidence that the situation is Rev. Fac. Cienc. agrar., Mendoza 4 (1), 47. changing. In the past three years, at least three inter- Dadswell, H. E., 1958. Wood structure variations occurring national symposia on tree physiology have been held, during tree growth and their influence on properties. J. Inst. and with conspicuous success. Perhaps of even greater Wood Sci. 1, 11-33. and A.B. Wardrop,1959. Growing trees significance is the fact that, for the first time, a World with properties desirable for paper manufacture. Appita 12 Forestry Congress has included this subject in its deliber- (4), 129-136. ations;it provides welcome evidence of an awakening Diller,J.D.,1957. Natural selection of blight-resistant interest in the physiological problems of tree growth which American . Proc. 5th N. E. Forest Tree Improvement Conf., 69. can do much to mitigate the effects of past neglect. Duff, G. H. and N. J. Nolan, 1953. Growth and morpho- genesis in the Canadian forestspecies.I. The controls of References cambial and apical activity in Pinus resinosa Ait. Can. J. Bot. Aljbenskii, A. V., 1954, Methods of improving tree species. 31, 471-513. Goslesbumizdat, Moscow. (Russian-seen in Plant Breeding and ,1957. Growth and morpho- Abstracts 27, 4492, 1957.) genesis in the Canadian forest species. II. Specific increments Alleweldt, G., 1958. Die Bedeutung der Tageslänge für das and their relation to the quantity and activity of growth in Wachstum der Holzpflanzen. Aug. Forstzeits. 13, 778-780. Pinus resinosa Ait. Can. J. Bot. 35, 527-572. Anon., 1954. Second Progress Report, Forest Tree Improve- Echols, R. M., 1955. Linear relation of fibrillar angle to ment Program, Texas Forest Service. tracheidlength, and genetic control of tracheid lengthin ,1955.Versiag van het onderzoek naar de slash pine. Trop. 102, 11-22. populieren-kanker in 1952 en 1953, veroorzaakt door Pseu- ,1958. Variation in traceheid length and wood domonas syringae v. Hall I.sp. populae Sabet. Meded. Ned. density in geographic races of Scotch pine. Yale Univ. For. Heide mu. 21, 1-19. Bull. 64, 1-52. Aufdemgarten, H.,1949. Zur Kenntnis der sogenannten Egle, K. and A. Ernst, 1949. Die Verwendung des Ultra- Induktionsvorgänge bei der kohlensäureassimilation. Planta 29, rotabsorptions-schreibers für die vollautomatische und fortlauf- 643-678. ende CO,-Analyse bei Assimilations-und Atmungsmessungen Bier, J. E., 1958. Moisture relations in disease development. an Pflanzen. Zeit. f. Naturfors. 46, 351-360. Proc. IXth Tnt. Bot. Cong. Montreal, Vol. II,32. Ferchau, H. A., 1959. Ecotypic variability of Tsuga cana- Bingham, R. 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Freeland, R. 0.,1945.Apparent photosynthesis in some ,1956. Ecological implications of changes in conifers during winter. P1. Physiol. 19, 179-185. the photosynthetic response of Finns taeda seedlings during , 1952. Effect of age of leaves on the rate of ontogeny. Ecology, 37, 70-75. photosynthesis in some conifers.P1. Physiol. 27, 685-690. , 1958. The relationships of ontogenetic develop- Fuchs, M., 1958. Les parasites mycologiques du sapin de ment and environmental modification to photosynthesis in Pinus Douglas Pseudotsuga taxifolia (Lam) Britt. Ann. Gembl. 64, taeda seedlings. The Physiology of Forest Trees, ed. Thimann, 245-262. Ronald Press, U.S.A., pp. 197-215. Gaastra, P., 1959. Photosynthesis of crop plants as influ- Bourdeau, P. F.,1959. Seasonal variations of the photo- enced by light, carbon dioxide, temperature, and stomatal diffu- synthetic efficiency of evergreen conifers. Ecology 40, 6 3-67. sion resistance. Meded. v. d. Landbouwhogeschool, Wageningen, and M. 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Brown, R. C.,1953. Genetic variation in resistance of Proc. 4th Southern Conf. Forest Tree Improvement, 34-39 trees to insect attack. Proc.1st N. E. Forest Tree Improve- (Mineographed). ment Conf., 30-32. Gotz, H.,1939. Zum Aufsatz im Deutschen Forstwirt: Burstrom, H., 1953. The physiology of root growth. Ann. "SchlechtformigkeitundSchlechtrassigkeit"vonProfessor Rev. P1. Phys., 4, 237-252. Schmidt. Allg. Forst.-u. Jagdztg. 115, 8-20. Butin, H., 1955. Uber den Einfluss des Wassergehaltes der Hansbrough, J. R., 1953.Genetic variation in disease re- Pappel auf ihre Resistenz gegenüber Cytospora chrysosperma. sistance of native forest-tree species.Proc. 1st N. E. Forest Phytopath. Zeits., 24, 245-264. Tree Improvement Conf., 26-30. Cech, F. C. and R. E. Goddard, 1957. Selecting drouth Heimburger, C., 1958. Forest tree breeding and genetics in resistant loblolly pine in Texas. Proc. 4th Southern Conf. Canada. Proc. Genetics Soc. Canada, 3, 4 1-49. Forest Tree Improvement, 30-3 3 (Mimeographed). Herrero, J., 1951. Studies of compatible and incompatible Champion, H. G.,1933. The importance of the origin graft combinations with special reference to hardy fruit trees. of seed used in forestry. md. For. Rec. 17 (5), 1-76. J. Hort. Sci. XXVI (3), 186-237. Chowdhury, K. A., 1931. Anatomical studies of the wood of Heybroek, H. M., 1957. Elm-breeding in the Netherlands. a hybrid larch. J. For. 29, 797-805. Silv. genet., 6, 112-118. Clark, J. W., 1957. Comparative decay resistance of some Huber, B. and H. Poister, 1955. Zur Frage der Physiologi-

738 Fifth World Forestry Congress Proceedings schen Ursachen der unterschiedlichen Stofferzeugung von Pap- Meuli, L.J.,1936.Drought resistance of green ash as pelkionen. Biol. Centr. 74, 370-420. affected by geographic origin. Proc. Minn. Acad. Sci. 4, 38-42. lijin, W. S., 1957. Drought resistance in plants and physio- and H. L. Shirley, 1937. Effect of seed origin logical processes. Ann. Rev. P1. Phys. 8, 257-274. on drought resistance of green ash in the prairie-plains states. Irgens-Moller, H., 1958. Genotypic variation in the time of J. For. 35, 1060-1062. cessation of height growth in Douglas-fir. For. Sci. 4, 325-330. Meyer-Uhlenried, K. H., 1958.Untersuchungen fiber die Iwanoff, L. A. and N. L. Kossowitsch, 1929. Ueber die Vererbung eines anatomischen Merkmals bei Kreuzungen von ArbeitdesAssimilationsapparates verschiedener Baumarten. Pappeln verschiedener Sektionen. Züchter, 28, 209-216. I. Die Kiefer (Pinus sylvestris). Planta. 8, 427-464. 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The present position of forest tree processes in the living bark of the black locust tree in rela- breeding and seedsowing and methods of improvingit. tion to frost hardiness and the seasonal cycle. The Physiology Trud. Inst. Lesa, 8, 5-35. (Russian-seen in Plant Breeding Ab- of Forest Trees, ed. Thimann, Ronald Press, U.S.A., pp. 219- stracts 25, 551, 1955). 250. Pryor, L. D., 1957. Selecting and breeding for cold re- SØegaard,B.,1956. LeafblightresistanceinThuja. sistance in Eucalyptus. Silv. genet. 6, 98-109. Experiments on resistance to attack by Didymascella thujina and L. H. Bryant, 1958. Inheritance of oil (Dur.) Maire (Keithia thujina) on Thuja. Arsskr. K. Vet.-o characters in Eucalyptus. Aust. J. Sci. 21, 16. Landb-HØjsk., 30-48. Rees, L. W. and R. M. Brown, 1954. Wood density and Stanley, R. G., 1958. Methods and concepts applied to a seed source in young plantation red pine. J. For. 52, 662-665. study of flowering in pine. The Physiology of Forest Trees, ed. Richardson, S. D., 1957. The effect of leaf age on the Thimann, Ronald Press, N. Y., pp. 583-599. rate of photosynthesis in detached leaves of tree seedlings. Steven, H. M. and A. Carlisle, 1959. The Native Pinewoods Acta bot. Nderlandica 6, 445-457. of Scotland. Oliver and Boyd, Edinburgh. , 1958. Bud dormancy and root development Sylvén, N., 1940. Long-och Kortdagstyper av de svenska in Acer saccharinum. The Physiology of Forest Trees, ed. Thi- skogstraden. Svensk. Papp. Tidn. 43,3 17-324; 332-342; 350- mann, Ronald Press, N. Y., pp. 409-425. 354. Richens, R. H., 1945. Forest tree breeding and genetics. , 1940. Insänd uppgifter om det senaste vinter- I. A. B. joint pub. 8, 1-79. halvhrets frostkador a svenskodlade trod och buskar. Sevensk. Roberts, R.H.,1949. Theoretical aspects of graftage. Papp. Tidn.43, 28 1-285.(Plant Breeding Abstracts XIII, Bot. Rev. 15, 423-443. 334). Rodger, G. J.,1954. Ann. Rep. For, and Timber Bur., Thimann, K. V., 1956. Promotion and inhibition: twin Australia. themes of physiology. Amer. Nat. XC (852), 145-162. Rogers, W. S. and A. B. Beakbane, 1957. Stock and scion and J. Behnke-Rogers, 1950. The use of auxins relationships. Ann. Rev. P1. Phys. 8, 217-236. in the rooting of woody cuttings. Maria Moors Cabot Found. Rohmeder, E.,1957. Altersphasenentwicklung der Wald- Pub. 1, 1-344. bäume und ForstpflanzenzUchtung. Silv. genet. 6, 136-142. Torrey, J. G., 1956. Physiology of root elongation. Ann. Rohrig,E., 1959.Untersuchungen Uber das Jugend- Rev. P1. Phys. 7, 237-266. wachstum von Schwarzpappelhybriden auf verschieden Stan- Tranquillini,W.I.,1954.DieLichtabhangigkeitder dorten. Silv. genet. 8, 24-30. Assimilation von Sonnen-und Schattenblätterneiner Buche Ruden, T., 1954. Om valbjØrk og endel andre unormale unter okologischen Bedingungen. Proc. 8th Tnt. Bot. Cong., veddannelser hos bjØrk. Norske Skogsfors. Medd. 43, 455-505. Sax, R., 1958.Experimental control of tree growth and Paris, Section 13, 100-102. reproduction. The Physiology of Forest Trees, ed. Thimann, , 1955. Die Bedeutung des Lichtes und der Ronald Press, N. Y., pp. 601-610. Temperatur für die Kohlensäure-assimilation von Pin us cern bra Schaffalitzky de Muckadell, M., 1959. Investigations on -Jungwuchs an einem hochalpinen Standort. Planta, 46, 154- ageing of apical meristems in woody plants and its importance 178. in silviculture. Det. forsti. ForsØgs. i Danmark, XXV (4), 310- Trendelenburg, R. and H. Meyer-Wegelin, 1955. Das Holz 455. als Rohstoff. Hanser Verlag, Munich. Scheffer, T. C. and H. Hopp, 1949. Decay resistance of Turnbull, J. M., 1947. Some factors affecting wood density black locust heartwood. U. S. D. A. Tech. Bull. 948. in pine stems. J. S. A. For. Ass. 16, 22-43. Schmidt, W., 1930. Forstliche Pflanzenzuchtung. Zflchter Ulmer, W., 1937. Uber den Jahresgang der Frosthärte 2, 189-195. einiger immergrüner Arten der AlpinenStufe,sowieder , 1938. Die Klima-Rassendiagnose bei Pinus Zirbe und Fichte,unter Berucksichtigung von osmotischen silvestris. C. R. Ass. mt. Ess. Sem. 10, 256-258. Wert, Zuckerspiegel und Wassergehalt. Jahrb. wiss. Botanik, , 1941.Erbforschungsfragen.Allg.Forst.-u. 84, 553-592. Jagdztg. 117 (1), 1-15. Vaartaja, 0., 1954. Photoperiodic ecotypes of trees. Can. Schober, R.,1958. Ergebnisse von Lärchen-Artund Pro- J. Bot., 32, 392-399. venienzversuchen. Silv. genet., 7, 137-154. Varty, I. W., 1956. Adelges insects of silver firs. F. C. Schdnbach, H., 1956. Untersuchungen über Cellulosegehalt (Britain), Bull. 26, 1-75. und Raumgewicht von Pappelhölzern im Rahmen der Zuchtung. Vegis, A., 1955. Symbolae. Bot. Uppsaliensis, 14,1. (Not Deuts. Akad. Landwirtschaftswiss, Wiss. Abh. 16, 1-32. seen. Cited by Wareing, 1956). Schönhar, S., 1957. EmBeitrag zur Frage der Anfälligkeit Wahlenberg, W. G., 1950. Epicormic branching of young Verschiedener Pappelarten und Pappelsorten gegen Dothichiza yellow-poplar. J. For. 48, 417-419. populea. Mitt. Ver. forstl. Standort skunde Forstpfl.-Zuch. 6, Wareing, P. F.,1956. Photoperiodism in woody plants. 59-62. Ann. Rev. P1. Phys. 7, 191-214. Schreiner, E. J., 1957. The possibilities and limitations of , 1958. Reproductive development in Pinus selectionand breeding forpestresistanceinforesttrees. sylvestris.The Physiologyof Forest Trees,ed. Thimann, Proc. Soc. Am. For., Syracuse, N. Y., 50-52. Ronald Press, N. Y., pp. 643-654. , 1958. Possibilities for genetic improvement , l958a. The physiology of cambial activity. in the utilization potentials of forest trees. Silv. genet. 7 (4), J. Inst. Wood Sd. 1, 34-42. 109-136. , 1958b. Interaction between indoleacetic acid Schrock, 0., 1958. Die Untersuchung der phototropischen and gibberellic acid in cambial activity. Nature 181, 1744-1745. Reaktion als Auslesemethode bei Kiefernsamlingen auf Grad- , 1959. Problems of juvenility and flowering in schäftigkeit. Zllchter 28, 320-323. trees. J. Linn. Soc. Lond. LVI (336), 282-289. Schulenburg, A. F., 1953. Die spättreibende Tieflandsfichte: Wassink, E. C., Richardson, S. D. and G. A. Pieters, 1956. 740 Fifth World Forestry Congress Proceedings Photosynthetic adaptation to light intensity in leaves of Acer certaine,ilest indispensable de mettre au point des méthodes pseudoplatanus. Acta bot. néerlandica 5 (3), 247-256. d'échantillonnage pour effectuer des comparaisons génotypiques, Wershing, H. F. andI. W. Bailey,1942. Seedlings as par exemple de la densité du bois et de la dimension des éléments. experimental material in the study of "redwood" in conifers. Technique de l'amélioration des essences forestières. Les J. For. 40, 411-441. problèmes techniques poses par Ia production de graines sont Willstätter, R. and A. Stoll,1918. Untersuchungen über considérés comme d'ordre physiologique,et nous passons en die Assimilation der Kohlensäure. Springer, Berlin. revue certaines des recherches qui sont actuellement en cours Wright, J. W., 1955. Directory of forest genetics research dans ce domaine. Nous arrivons a la conclusion que notre compré- and education in the United States and Canada. Pub. Soc. hension de ces phénomènes ne pourra progresser de facon satis- Amer. For. (mimeographed). faisante que par une cooperation étroite entre le généticien, le Zabel, R. A.,1956. Decay resistance variations within physiologiste et le biochimiste. Northeastern forest tree species. Proc. 3rd N. E. Forest Tree L'examen des problèmes poses par l'amélioration génétique des Improvement Conf., 13-17. essences forestières nous amène a la conclusion que la physiologie Zak, B., 1956. Experimental air-layering of shortleaf and est un domaine qui n'a pas encore été suffisamment exploité par loblolly pine. U.S. For. Ser. S. E. For. Exp. Sta., Sta. Pap. les forestiers. Les raisons peuvent en être imputdes aux difficultés 69, 1-12. rencontrées lorsqu'on expérimente avec des arbres, mais aussi en and R. G. McAlpine, 1957. Rooting of short- partie aux lacunes qui existent dans les politiques forestières et leaf and slash pine needle bundles. U.S. For. Ser. S. E. For. dans Ia formation universitaire des sylviculteurs. Nous sommes Exp. Sta., Note 112, 1-2. heureux toutefois de constater qu'à l'heure actuelle, les questions Zeller,0.,1951. TJber Assimilation und Atmung der relatives a la dendrophysiologie semblent susciter un intérêt de Pfianzen im Winter bei tiefen Temperaturen. Planta 39, 500- plus en plus marqud. 526. Zobel, B.J.,1956. Genetic, growth and environmental El Papel de la Fisiologla en el Mejoramiento de los factors affecting specific gravity of loblolly pine. For. Prod. J., 6 (10), 442-447. A rboles Forestales , 1957. Inheritance of wood properties in pine. Este trabajo seflala que los fisiólogos pueden contribuir a la Proc. 4th Southern Conf. on For. Tree Improvement, 27-29. solución delos problemas del mejoramiento de losárboles ,Barber, J., Brown, C. L. and T. 0. Perry, forestales con un estudio y dilucidacidn de los procesos de desa- 1958. Seed orchards-their concept and management. J. For. rrollo dentra del árbol que se desee modificar. Se dan ejemplos 56 (11), 815-825. de lo expuesto, en los siguientes campos: and R. R. Rhodes,1957.Specific gravity Mejoras en el crecimiento y Ia fornia. Se enumeran los indices for use in breeding loblolly pine. For. Sci., 3 (3), 281- problemas de Ia determinación de los árboles progenitores con 285. alta eficiencia fotosintética y la evaluación fisiológica de resis- Zurbin, A. I., 1951. Breeding new poplar hybrids. Trud. tencia contra sequlas, contra la escarcha y la adaptabilidad de Inst. Lesa 8, 78-84. (Russian-seen in Plant Breeding Abstracts lugares. Se tratan brevemente los fenómenos fotoperiódicos rela- 25, 556, 1955). cionados con la mejora de los árboles y la posibilidad de emplear reacciones fototrópicas como Indice de la formación de troncos. Le role de la physiologie dans l'amélioration des essences Selección y cultivo de especies que resisten las enfermedades. forestières Se recalca la importancia que tiene el comprender el mecanismo genetipico de la resistencia contra los insectos y las enfermedades II ressort du present rapport que le physiologiste peut apporter y se sugiere que podrIan emplearse más eficazmente los recientes une contribution importante a l'amélioration des essences fores- descubrimientos de los investigadores fisiológicos en este campo. tières en apprenant a reconnaitre et a élucider les processus Selección y cultivo para madera de calidad y extracciones. internes de l'arbre que l'arboriculteurdesiremodifier.Cette En este caso, lo primero es comprender los procesos integrantes affirmation est illustrée en ce qui concerne les domaines suivants: del desarrollo de la parte leñosa y crear mayor interés en los Amelioration en matière de croissance et de forme. On estudios de la anatomIa fisiológica de Ia madera. Para estar en trouvera id une discussion des problèmes relatifs au repérage des posición de demostrar, sin género de duda, Ia variación heredable arbres semenciers ou des jeunes sujets ayant des qualités élevées de ciertas propiedades es necesario antes crear métodos técnicos de photosynthèse, ainsi que de l'évaluation physiologique de Ia de muestreo adecuados en lo tocante, por ejemplo, a la densidad résistance a la sécheresse et aux gelées, et de la faculté d'adapta- de la madera y tamaflo de elementos. tion au site forestier. Nous examinons rapidement les phénomènes MCtodos técnicos para el mejoramiento de drboles forestales. de photopériodicité relativement a l'amélioration de l'arbre et Se estudian los problemas tecnicos de propagación vegetativa, nous mentionnons la possibilité d'utilisation des reactions photo- considerando el florecimiento y la producción de semillas desde tropiques comme indice de forme du tronc. el punto de vista fisiológico y también algunas de las investiga- Selection et reproduction pour la résistance aux maladies. ciones actuales. Se sostiene la conclusion que para hacer progresos Nous soulignons l'importance qu'iI y a a bien comprendre le en Ia comprensiOn de estos fenómenos será necesaria una estrecha mécanisme de la résistance génotypique aux insectes nuisibles et cooperación entre los genetistas, los fisiólogos y los bioquImicos. aux agents pathogènes; et nous suggérons que les progrès accomplis Cuando se consideran los problemas referentes al mejoramiento récemment dans les techniques de recherches physiologiques soient de los árboles forestales, se liega a la conclusion de que los exploités plus a fond dans ce domaine. silvicultores no han hecho todo el uso que deben de la fisio- Selection et reproduction pour Ia qualité du bois et pour logIa. Las razones para esta indiferencia no solamente residen en les produits extraits du bois. Ici, la comprehension des processus las dificultades que se encuentran en los experimentos con árboles, entrant en jeu dans le développement du xylème est la premiere sino también, en parte, se deben a ciertas deficiencias en las condition indispensable, ainsi qu'un intérêt accru dans l'anatomie normas de investigaciOn y en los estudios universitarios de los physiologique du bois. Avant que les variations héréditaires de silvicultores. El autor termina expresando su calurosa acogida a! ces propriétés puissent être démontrées de facon absolument creciente interés que se nota en los estudios de fisiologla forestal.

Genetics and Tree Improvement 741 The Role of Exotic Species in Forest Tree Improvement

JOHN M. FIELDING Forestry and Timber Bureau, Commonwealth of Australia, Canberra, Australia

Definition of exotic. In this paper the term "exotic" is SouthernHemisphere,wheretheconiferousfamily used in the sense employed in the questionnaire on Abietaceae (the pines, firs, spruces, larches, pseudotsugas, exotics of the Seventh British Commonwealth Forestry etc.) does not occur naturally.Also, the climates not Conference. The definition of exotic in the British Com- being influenced by a large high-latitude land mass, are, monwealth Forest Terminology is: "Not native to the area latitude for latitude, milder than in the Northern Hemis- in question." However, in the case of a species that has phere and favourable over wide areas for eucalypts, which been grown in a country for several centuries and has are extensively used as exotics. Where soils are unsuitable become part of its natural forest associations, it need no for pines, as on the pampas of South America, eucalypts longer be regarded as an exotic. And, if, within a large are widely grown. Countries in which exotics take only a country like the sub-continent of India, a species is planted minor or insignificant place in forestry are either those well outside its natural range, it might here be regarded well endowed with coniferous forests or those with a as an exotic. small requirement of wood and with adequate forest areas The universal use of exotic forest trees. As far as is to supply it. known, every country in the world that practices forestry The planting of exotic trees probably extends back grows exotic foresttrees,either commercially or ex- beyond the beginning of recorded history. Certainly, some perimentally. They are used for every purpose to which trees, such as the Lombardy poplar, have been planted forest trees are putsawn timber of all kinds, including extensively for a very long time. It is, however, with the furniture, , , fuel, poles, soil stabiliza- European colonization of America, Africa, Australia and tion, shelterbelts and protection, fodder and shelter for other countries over the last few centuries that the transfer livestock, aesthetic purposes, and so on. of tree species throughout the world by man has been car- In some countries, forestry is based almost exclusively ried out on a large scale. Extensive introductions of trees on exotics. South Africa, whose indigenous forest is very from these lands were made to Europe, and one of the first small in area (probably due largely to thousands of years tasks of the early colonists was the introduction of trees. of firing by primitive men) and very low in yield, has For example, only four years after the settlement of the obtained great economic benefits through their use.It is Cape of Good Hope by the Dutch East India Company estimated that by 1980 there will be approximately three in 1652, European trees were reported as thriving in the million acres of exotic plantations in the Union.In Company's garden1, and in 1958, almost 1,000 species South Australia, practically all the timber produced comes and varieties of trees were undergoing trial in plantations from forests of exotic pines, a position likely to hold for and arboreta in South Africa2. all time. In , it has been estimated that by about The choice between exotic and native species. Foresters, 2025 A.D. 97 per cent of the total Chilean production of in general, prefer to grow native trees. When they find it timber (in board feet) will come from planted forests, the desirable to change the species of a forest or to create a great bulk of which will undoubtedly consist of exotic new forest on treeless land they generally give first con- species. And, in Denmark, the excellent conifer forests sideration to species native to the same general region. are comprised entirely of exotic tree species. In Europe and Japan particularly, hardwood forests have On the other hand, some countries use exotic trees on been converted to more valuable softwood forests by the a very smallscaleor only experimentally.Sweden, planting of native conifers.This work has taken place although making use of exotic poplars and possessing trial over a long period of time and is still proceeding. plots of other exotics, relies almost entirely on native Exotic forest trees, however, are often preferred to trees for its large .Japanese forests are native species in the following areas: comprised, almost without exception, of native species. a. Many regions either lack native species suitable for Finnish forestry, except for experimental plots of exotics, the purpose for which the plantations are grown, or uses only indigenous trees. And in some tropical countries exotic species have been found to be more satisfactory with valuable forest areas, such as Malaya, practically all the timber needs of the country are supplied by native than the native onesbecause of their greater value, forests. greater yield, greater profitability, greater ability to take Countries that rely almost exclusively on exotics are those which are poorly endowed with, or completely lack- 1Zahn, G. A. and Neethling, E. J., 1929. S. Al. Jour. Sci. XXVI: 211-234. ing in coniferous forests. Thus, the outstanding examples 2 Poynton, R.J.,1957. Paper. Brit. Comm. For. Conf. 1957. of countries that rely on exotic forest trees are in th (Govt. Printer, Pretoria.)

742 Fifth World Forestry Congress Proceedings advantage of varying conditions or their superiority on Some species possess additional characteristics which other grounds, such as their value for shelterbelts, farm enhance their value to the foresterfor example, the forestry or soil stabilization or the ease with which they resistance of many eucalypts to fire and the ability of teak can be grown. to grow from coppice shoots. The establishment of extensive forests of exotic pines Monterey pine (P. radiata D. Don) is an example of a in southern Australia is an example of the use of exotics softwood that possesses all the basic requirements of a in an area possessing no suitable native species. Softwood successful exotic.It is for this reason that it is planted forests being a vital need in the economy of the country so extensively. It produces wood that is in high demand; and there being a complete absence of native conifers its rate of growth and yield are high; it produces seed at (except for several inferior forestry species of the genera an early age and in adequate quantities; it can be raised Callitris and Podocarpus), there is no choice in southern very easily and cheaply (good planting stock can be Australia but to use exotics. produced in nine to ten months after sowing); it can be Kenya is an example of a country possessing a number easily and cheaply established and grown in plantations; of valuable native forest trees but which, nevertheless, successful growth is not prevented by insects or disease finds it desirable to concentrate on exotics. The question in the climates and on the soils to which it is adapted; of whether to use native or exotic trees has occupied the itis highly variable; and its silvicultural characteristics forestry administration of Kenya for about half a century, are fairly well known and documented. and a serious attempt has been made to grow plantations Susceptibility to disease or insect attack or difficulties of the native trees. Recently, an extensive plantation pro- in obtaining adequate viable seed restrict the use of some gramme based mainly on exotics, was adopted. Kenya species that might otherwise be planted extensively as is of particular interest because it was probably here that exotics. Red cedar (Cedrela won/A Roxb.) would cer- the first conscious use was made of mycorrhiza-infected tainly be a popular plantation tree in the sub- and soil in introducing exotic pines. tropics but for the depredations of the cedar twig borer. b. In some regions of the world where forestry has The araucarias would be planted more extensivelyif made little progress, the silvicultural characteristics of all adequate supplies of viable seed were available.They the valuable forestry species are not well known. Con- produce a very superior softwood and possess a favour- sequently, some of them cannot yet be used in plantations able rate of growth. Araucaria cunninghamii Ait., in par- even if it were desirable and practicable to do so. Thus, ticular, is a most promising softwood for sub-tropical and in such regions, exotic trees are probably being used on possibly tropical plantations. The ability of A. excelsa sites where native species(if sufficient were known of R. Brown to grow straight and vertically and to develop them) could be employed with equal or greater success for a symmetrical crown on sites exposed to strong winds the same purpose. and sea spray is remarkable. However, seed of these The properties of successful exotics. Exotic trees are species is not readily available in large quantities, and it not used by foresters merely because they are foreign. loses its viability quickly unless kept under cold storage. There are very good reasons why they are grown so The pines of Mexico and Central America would have extensively.Species vary widely in their forestry value, been planted more extensively if seed of these species and, just as in agriculture, there are crop plants of excep- could be easily obtained. tional value widely used throughout the world, so, in The importance of taking exotics into account in a forestry, there are tree species of outstanding value. breeding programme. In planning a breeding programme The exotic trees that are used extensively throughout for any tree species (native or exotic), it is vital to give the world possess a number of special characteristics. careful consideration to exotic species both as possible Those grown in commercial forests for the production of substitutes for, and for hybridization with, the species to wood have the following properties: be bred. Failure to do this may cause much wasted effort, Their produce is of high value; because, after many years of work, an improved strain Their rate of yield is high. may be developed, only for it to be found either that an Those grown for special purposes such as shelterbelts, exotic species is more satisfactory or that hybridization soilstabilization and farm forestry possess particular with an exotic should have been a basic part of the adaptation to the environments or particular value for programme. the purpose for which they are used. The value of introducing exotic trees in improving local In addition, these exotic trees have the following prop- species through hybridization is shown in the history of erties in common: the cultivation of poplars.Hybrids between American Adequate supplies of seed (or cuttings)are and native poplars are planted very extensively in Europe. available; Eucalypts provide an outstanding example of the They are easy to raise in the nursery; importance of taking exotic species into account in breed- They are easy to establish and grow in planta- ing programmes. Hybridization in the genus Eucalyptus tions; offers wide possibilities, and, for any country conducting Their successful growth is not prevented by a programme of eucalypt planting andbreeding, itis insects or disease; highly desirable that all species of likely value be intro- They possess considerable physiological varia- duced and brought into the programme and that the best bility and are thus adapted to growth over a available genotypes be obtained as early as possible. wide range of environments; and The genus Pinus includes a number of good illustra- Information is available on methods of growing tions of the value of exotic trees in breeding programmes them and on their rate of growth and yield. Work on the breeding of blister-rust resistant white pines

Genetics and Tree Improvement 743 in North America involves hybridization with exotic Arboreta for testing the exotics are highly desirable. white pines.In the breeding of slash pine (P. elliottii They should be as representative as possible of the Engeim.), the use of Caribbean pine (P. caribaea More- ecological conditions under which the trees, if successful, let) must be considered both as a possible substitute for would be grown in the region.It is desirable that each slash pine in warmer regions and from the viewpoint of progeny in an arboretum should consist of a plot of at hybridization. In the breeding of Monterey pine, hybridi- least 80 to 100 trees in order that it may contain con- zation with knobcone pine (P. attenuata Lemmon) must siderable variability, that the trees should be able to be included if the work is to be systematic and thorough. develop under reasonably representativeforest condi- Knobcone pinecoversa widerclimaticrange than tions and that it may be satisfactorily thinned.In the Monterey pine and thus probably possesses greater phys- Australian Capital Territory, arboreta consist of plots iological variability. Hybridization between the two species one chain square, separated from each other by open yields fertile hybrids and thus a large amount of varia- spaces one-half chain wide. A one-chain square plot tion as raw material for the breeder. Pinus patula Sch. contains 81 trees spaced 8 ft. x 8 ft. or 144 trees spaced and Cham. can be readily hybridized with its close rela- 6 ft.x 6 ft.The provision of the half-chain space tive P. gre ggii Engeim., and any planting or breeding between plots allows them to develop without undue programme involving P. patula should take into account interference from neighbouring plots. In the case of trees the possibility of obtaining improved stock through this exhibiting distinct geographic variation, the inclusion of hybridization. different provenances in the arboretum is highly desirable. The introduction and testing of exotics.The object The present world position regarding exotics.There of a programme for introducing exotics is to obtain trees is no doubt that the expansion of forests of exotic trees, for direct use in plantings and for hybridization with which has been a feature of forestry during the last half- native and other exotic trees. century, will continue in the future and probably at an The introduction and testing of forest trees is a very accelerated rate.There is,at present, a deficiency of long-term programme of work and must be planned from highly productive forests close to many centres of popu- this point of view. All species and. varieties considered of lation. As the world population increases, the demand for potential use in forestry in the region during the foresee- all kinds of wood products must increase greatly. Exotics able future should be introduced.The decision as to can be expected to have an important role in trying to whether or not a given species should be introduced has satisfy this demand. to be based on what is known of its value for the purpose Despite the present and future importance of exotics in for which it is needed and on its climatic and edaphic world forestry, the position with regard to the introduction requirements and limits.The available information on and testing of exotic forest trees cannot be regarded as most species is scanty, and decisions as to which species satisfactory. should be introduced have to be made with this fact in Monterey pine provides an outstanding example of mindActually, as regards climatic requirements and this unsatisfactory state of affairs.In order to conduct a limits, it must be remembered that an exotic may thrive planting programme properly with a species, a knowledge over a much wider range than its natural distribution of the growth and characteristics ofitsvarieties and would suggest, and hybridization with other species may provenances is necessary. This knowledge is obtained by further increasethis range.Also, introductions from introducing and testing them in plantations. To conduct summer to winter rainfall areas are more likely to be a breeding programme properly on a species, carefully successful than the reverse. And, latitude for latitude, it planned introductions of any species with which it can is easier to transfer a species from the Northern to the be hybridized are also necessary. In view of these essen- Southern than from the Southern to the Northern Hemis- tial requirements, it is almost incredible that it was over phere, becauseofthegenerallysmaller temperature 100 years after Monterey pine was first planted outside variations at a given latitude in the Southern Hemisphere. California, and long after it had become apparent that it The introduction and testing of an exotic forest tree was destined to be one of the most important trees in a species passes through two stages before it can safely number of Southern Hemisphere countries, that trial plots enter commercial planting. of the variety P. radiata var. binata Engeim. were first Firstly, the exotic is planted in arboreta or as individual established in 1959. Also, although knobcone pine forms trees in parks and other places.Generally, considerable fertile hybrids with Monterey pine, some of which have information is available on exotics introduced by private shown considerable promise, yet itis only recently that persons and variousauthoritiesgovernmental,semi- the first systematic attempts were made to introduce this governmental and others.In countries such as Great species into countries where Monterey pine is extensively Britain, a very large amount of information isto be planted. A similar position holds with respect to bishop obtained from these plantings. pine (P. muricata D. Don), the other species with which Secondly, the species showing promise in arboreta or as Monterey pine can be hybridized. individual trees are tested in trial plantations. The interval Introductions from Mexico, Central America and the between the initiation of these stages need not necessarily West Indies are particularly unsatisfactory. This is a very be long. In the case of a fast-growing species, a period of rich field for foresters seeking exotic conifers. Only three eight to ten years may be sufficient. However, an exotic pines from the region are planted commercially as exotics cannot safely be planted on a large scale until it has been P. patula Sch. and Cham., P. caribaea Morelet and P. grown in trial plantations over a major part of the rota- pseudostrobus Lindley; the latter two, only in the last few tion.Thus, the period of testing is a long one and, for years.It is probable that other species of the region will this reason, needs to be carefully planned and controlled. find a place in forestry in the warmer parts of the world.

744 Fifth World Forestry Congress Proceedings But, because it has been very difficult to obtain seed of enquiriesadvice, for example, on species recommended the trees of this area, their introduction has been seriously for introduction. neglected.Indeed,a number ofpinesof particular Recommending research(including arboreta and interest to foresters have been planted oniy rarely out- provenance trials)that is desirable in order to provide side the region. For example, Pinus pringlei Shaw has information on these trees. The primary object of these not yet been introduced into Australia, and other valu- recommendations would be to fill in gaps in the available able species, such as Pinus ayacahuite Ehrenb. and P. information. pseudostrobus Lindley, have been introduced only in The work of this section would be a basis for the recent years and on a very small scale. accumulation of detailed information on the nature of The introduction of the tropical pines of southeast trees used in forest plantations and should be directed Asia has also been unsatisfactory because of the difficulty with this aim in view. of obtaining seed.It is likely that these trees will find The actual research on which the information is based considerable use as exotics when they are more available would be conducted by individual countries. and better known. Indeed, the whole position of exotics b. A centre for seed collection. within the tropics and sub-tropics is unsatisfactory. Very Itis recommended that a centre be established,if few species in these regions are well known outside their possible, at Mexico City, to organize seed collections in native countries, teak being an outstanding exception. Yet Mexico, Central America and the West Indies, a region there are excellent forest trees native to the areas; among which contains a large number of conifers, many of which the conifers, species of the genera Araucaria and Agathis, are little known and the seed of which is difficult to intro- and among the hardwoods, such little-known species as duce.Itis desirable, however, that such a section, if Queensland maple(Flindersia brayleyana F.v. M.) required, should also try to provide for seed collection in which produces an excellent wood and is well adapted to neighbouring areas. nursery and plantation practices. Such a centre could provide a nucleus of staff from Recommendations. In view of: which other centres could, if desired, be established later The importance of exotic trees in forestry and in Asia, for example. the probability that their future use will increase The tasks of the centre would be: greatly; To obtain information on the variation of the trees The basic importance of carefully planned and of forestry value in the region in relation to the climates controlled programmes for introducing forest tree and soils of their natural distribution, their economic value, times of seeding and means of collecting seed; and species,particularlyinthecasesofcountries To organize supplies of seed from the region, and, deficient in forests; where necessary, collect, store and sell seed. The paucity of readily available information on The two sections should work in close co-operation. many species of forestry value that are either used Their staffs should include workers with sound back- or have potential use as exoticsinformation on grounds in genetics and forestry. their variation; climatic and edaphic requirements It is further recommended that the Division should try andlimits;silviculturalcharacteristics,including to arrange for a eucalypt seed collection centre to be set seeding and nursery and plantation methods; and up as soon as possible in Australia to supplyseed of desir- uses; able trees of different provenances and ecotypes. The difficulty of obtaining seed of many species, Acknowledgements. The writer wishes to acknowledge including that of obtaining a satisfactory range of the assistance given by Dr. M. R. Jacobs and Mr. C. D. genotypes possessing valuable characters such as Hamilton, who read through the manuscript and sug- resistance to disease, drought and cold; and gested a number of alterations which have been incor- The losses and inefficiency resulting from this porated in this paper. lackofinformation and from thisdifficultyof obtaining seed; RESUMES it is recommended that the Forestry and Forest Products Le role des essences exotiques dans l'amélioration de Division of F.A.O. should consider setting up the follow- l'arbre sylvestre ing two sections. Autant que l'on sache, tous les pays pratiquant la sylviculture a. An information section on forest trees having actual utilisent des essence exotiques, soit commercialement, soit ex- or potential use as exotics. périmentalement. Certains pays font appel presque exciusivement The functions of this section would be as follows: a ces essences pour leur sylviculture, l'exemple le plus marquant Co-ordination of information on forest trees with étant fourni par l'hdmisphère Sud oui les conifêres de la famille des abiétinées(pins, sapins, épicéas,etc.)ne poussent pas a actual or potential use as exoticsinformation on their l'état naturel,et oii les conditions climatiques sont favorables natural distribution in relation to climate and soils; varia- a l'eucalyptus dont l'utilisation comme essence exotique est trés tion; silvicultural characteristics, including seed, seeding, répandue. and nursery and plantation methods; diseases and insect L'utilisation généralisée des essences exotiques bien connues, de préférence aux essences indigènes, s'explique par de très bonnes enemies; nutrition; uses; results of arboreta and proven- raisons. De méme que l'agriculture a certaines récoltes de valeur ance trials, etc. exceptionnelle, ii y a en sylviculture des essences ayant également The questionnaire on exotics conducted by the Seventh une valeur exceptionnelle. Cette valeur découle du prix élevé de British Commonwealth Forestry Conference would be leurs produits et de leur rendement élevé, ou de leur valeur particulière pour certains usages, comme par exemple comme useful in planning this work. rideaux protecteurs; d'autres particularités peuvent également con- Dissemination of information on such trees. tribuer a leur popularité, comme par exemple le fait que leurs Provision of advice and information in response to graines sont faciles a obtenir et qu'elles sont d'une culture facile. Genetics and Tree Improvement 745 Lors de la preparation d'un programme de selection et de no crece de por sI. Alll, las condiciones climáticas favorecen el reproduction pour une certaine essence d'arbre(indigène ou crecimiento del eucalipto que también se planta como árbol exotique),iiest de la plus haute importance d'accorder une exótico. attention particulière aux essences exotiques, tant comme éléments Hay fundadas razones para el empleo generalizado de los possibles de remplacement que pour l'hybridation avec l'essence exóticos más conocidos en preferencia a los árboles indigenas. que l'on se propose de reproduire. De la mismá manera que en la agricultura hay plantas cose- L'introductionetl'essaid'essences exotiques constituent un chables de excepcional valor, también las hay en la silvicultura. programme a long terme qui demande une preparationat- La notable utilidad de estos árboles se debe al alto valor de sus tentive et une surveillance étroite et continue. productos y su elevado rendimiento o en su valor especial para En ce qui concerne l'introduction d'essences exotiques, la situa- ciertos propOsitos, como por ejemplo, arboledas de resguardo. tion actuelle, sur le plan mondial, n'est pas satisfaisante. Les También poseen otras propiedades propias, tales como Ia abun- renseignements dont on dispose actuellement sur les caractéris- dancia de semillas y la facilidad con que éstas se plantan y tiques d'un grand nombre d'arbres d'une utilisation effective et crecen. potentielle en tant qu'essences exotiques sont insuffisantes pour Al planear un programa de cultivo para cualquier especie de queleurintroduction puissefairel'objetd'unepreparation árboles (ya sean indIgenas o exóticos) es de vital importancia adequate. De même, les difficultés rencontrées pour l'obtention prestar cuidadosa consideración a las especies exóticas tanto desde d'approvisionnements satisfaisants de graines d'un grand nombre el punto de vista de su empleo como posibles sustitutos de ciertas d'essences constituent un problème de premiere importance. Etant otras que se proyecte cultivar, como para la hibridizaciOn con las donné que pratiquement toute essence exotique présente de l'intérêt mismas. pour nombre de pays, c'est là un domaine dans lequel la coopéra- La introducción y ensayo de las exóticas es un programa a largo tion internationale s'impose. En consequence, nous recommandons plazo que requiere un cuidadoso planeamiento, asi como una a la Division des Forêts et des Produits Forestiers de la FAO estrecha y continua regulación. d'envisager la creation des deux sections suivantes: La presente actitud mundial respecto a lasexóticas no es Une section d'informations ayant pour mission de coordon- satisfactoria.Actualmente, la información disponible sobre las ner etde distribuerlesrenseignements surlesarbres caracteristicas de muchos árboles que pueden o podrlan emplearse sylvestres de valeur effective et potentielle en tant qu'essences como exóticos resulta insuficiente para la formulación de un exotiques, de fournir sur demande tons renseignements sur plan eficaz que permita introducirlas en un nuevo ambiente. ces essences, et de recommander les recherches qu'il convient Otro problema de importailciaesladificultad con que se d'effectuer pour combler les lacunes existant actuellement tropieza para obtener un suministro satisfactorio de semillas de clans les renseignements dont on dispose a leur sujet. ciertas especies. Considerando que casi todas las especies exOticas Un centre pour Ia collecte des graines pour aider a assurer son de interés para cierto nCmero de paises, éste es claramente lesapprovisionnements en graines d'arbres sylvestres en un campo propicio para la cooperación internacional. Por lo provenance de la region du Mexique, de l'Amérique centrale tanto, se recomienda que la Division de Silvicultura y Productos et des Antilles. Forestales de la FAO estudie el establecimiento de las siguientes Nous recommandons également a la Division d'essayer d'établir secciones: aussi rapidement que possible en Australie un centre pour la col- Una sección de informaciOn que coordine y disemine lecte des graines d'eucalyptus. información sobre árboles forestales de probado o posible valor para ser usados como éxoticos; que suministre informa- El Papel de las Especies Exóticas en el Mejoramiento ción sobre dichos árboles a los que la pidan y que recomiende estudios de investigación destinados a suplir de Arboles Forestales cualquier deficiencia de información existente. Por lo que Se sabe, todo pals que se dedica a la silvicultura Un centro de recolección que facilite la obtenciOn de un emplea árboles forestales exóticos para fines comerciales o simple- suministro adecuado de semillas de árboles forestales de las mente como experimento. Algunos paises basan su silvicultura regiones de Mexico, Centroamérica y las islas del Caribe. exclusivamente en ellos y los ejemplos más notables de esta También se recomienda a la DivisiOn que lo antes posible trate práctica se encuentran en el Hemisferio Sur, region en que la de establecer en Australia Un centro para Ia recolección de familia conIfera de las abetáceas (los pinos, abetos, piceas, etc.) semillas de eucalipto.

746 Fifth World Forestry Congress Proceedings SPECIAL PAPERS Sex Ratio in Quaking Aspen and Possible Sex-Related Characteristics

DEAN W. EINSPAHR The Institute of Paper Chemistry, Appleton, Wisconsin, U.S.A.

Forest geneticists who have searched extensively for and were limited to the dominant or codominant trees flowering, phenotypically superior aspen have very fre- nearest the center of each plot.Selected trees were quently found that such trees tend to occur in ratios of measured in detail and the sex determined by examining about three male (staminate) to one female (pistillate). the flower buds. No attempt was made to determine the Several possible explanations have been offered for occurrence of bisexual trees in the population sampled. this large deviation from the usually expected 1: 1 ratio of Tree measurements includeage,d.b.h.,totalheight, males to females. The most obvious explanation is that height to a three-inch top, height to the first live branch, male trees are superior in vigor and form. Another pos- and diameter inside bark at the top of the first sixteen-foot sible reason is the occurrence of a greater proportion of log.In addition, measurements were made of crown male trees in natural stands, due possibly to a genetic diameter,straightnessof stem, crown exposure, and modification of the usual 1:1 sex ratio or to some sex- branch angle and weight.Soil and site information was associated survival differential. recorded, and trees that were not flowering were girdled Still other alternatives that should be considered are in an effort to induce flowering, for observations the the possibilities that male trees flower more abundantly following year. and/or more frequently and that male flower buds are Five survey lines were established during the 1957 enough larger than female buds to be more easily detected field season, and measurements were completed on 45 from the ground.Each of these circumstances, and trees.Four additional survey lines were established in 1958, bringing the total number of measured trees to 91. especially a combination of them, would favor selection Data from a number of additional trees were obtained of more male than female trees. but excluded from the study because flowering was not Previous Observations induced by the girdling treatment. Until a recent study by Pauley and Mennell (1957) in Results which they reported a male: female sex ratio of 3: 1in A summary of the sex determinations and measure- quaking aspen, no intensive investigations on the sex ments is presented in Table I. These data were analyzed ratio in the genus Populus or the possibility of sex- statistically with two objectives in mind. The first objec- related characteristics in the genus Populus have been tive was the investigation of the possible existence of a conducted. sex ratiosignificantly different from the expected 1:1 A number of observations have been reported which ratio. The second objective was to determine if there are indicate male superiority in several species of popiars may any significant differences in growth and form between exist. Also suggested in the literature is the occurrence, the two sexes.Sex ratio was tested by means of a chi- in certain natural populations, of deviations from the square test, the results of which are presented in Table normal 1: 1 sex ratio. These observations are best sum- II. The analysis shows that neither the over-all sex ratio marized by Pauley (1948, 1949). nor the sex ratio of the individual lines differ significantly Because of the importantsilvicultural and genetic from the expected 1: 1 ratio. implications of sex ratio and sex-related differences in An analysis of variance was used to determine whether quaking aspen, a study was established to. further investi- the differences in growth and form between the two sexes gate these possibilities. The report that follows describes was significant. The method of analysis used is outlined the results of this study conducted in several natural by Snedecor (1946), and shown below are the details stands in Northern Wisconsin and Upper Michigan. of the analysis for selection index, one of the characteris- tics investigated. Methods Since the numbers in the classes are different, the A series of survey lines was established in quaking analysis becomes rather complex and was therefore car- aspen stands near Bruce Crossing, Michigan, and Eagle ried out on the IBM 610 electronic computer. The River, Ashland, and Cornucopia, Wisconsin.Sample results of this analysis are presented in Table III. None trees were located every 150 feet along the survey lines of the properties showed a significant difference between Genetics and Tree Improvement 747 the two sexes taken as a whole. The analysis shows also where branch angle is concerned. In this case, most lines that thereis,in general, no interaction present.This have distinct differences in branch angle between sexes, means that individual survey lines follow the same pattern but the differences are in opposite directions in various as the over-all analysis and exhibit no significant differ- lines making the over-all comparison without statistical ences between the two sexes. An exception must be made significance.

Table I.Average measurements for each sex summarized by transects No. of Selection Tree Form Branch Branch Natr. Cr. Line trees Sex indexa volume Height D.b.h. Age classb angle wt. prun.' Vol.e

1 5 F 9.1 4.5 44 5.8 41 74 68 2 1.6 102 3 M 6.0 5.7 48 7.7 38 72 63 2 2 211 2 3 F 13.4 7.0 51 7.9 43 80 63 2 2 167 4 M 13.3 8.3 53 8.6 40 76 60 2 2 196 3 5 F 11.9 12.8 62 9.8 38 78 53 2.4 1.4 338 8 M 11.4 9.8 58 8.8 35 78 65 1.6 1.9 268 4 4 F 10.4 6.7 54 7.8 34 76 60 2 1.5 126 4 M 16.1 9.3 56 8.4 34 77 66 2 2 234 5 5 F 15.9 16.5 67 10.4 43 79 64 1.8 1.6 246 1 M 8.6 11.9 68 9.8 43 77 60 2 1 331 6 6 F 9.8 9.3 61 7.9 34 76 62 2.2 2.2 222 5 M 13.0 8.1 59 8.0 35 77 64 1.4 2.0 135 7 5 F 14.6 7.6 54 7.7 42 78 59 2 1.8 97 6 M 16.2 11.4 57 9.9 44 78 59 2.3 1.8 161 8 2 F 11.9 18.6 64 12.6 56 83 58 2 2.0 1049 9 M 19.4 27.4 74 13.7 53 80 66 2 2.1 528 9 7 F 12.8 13.9 64 11.1 50 76 65 1.7 2.3 398 9 M 10.2 13.0 58 10.7 48 78 68 1.7 1.8 393 Over- 42 F 12.2 10.4 58 8.9 42 77 62 2.0 1.9 265 all 49 M 13.6 13.3 60 10.0 43 78 64 1.9 1.9 293 Empirical Tree Selection Index based upon volume/age, tree volume/crown volume, and tree form with adjustments for excessive crown size and . b Form class= d.i.b. 17½ ft./d.o.b. at 4½ feet x 100. Branch weight-Trees were rated from 1 to 5 for branch weight. Trees with excessive branch weight were rated as 1. dNatural pruning-Trees were rated from 1 to 5 for natural pruning. Trees with poor natural pruning were rated as 1. Crown volume in cubic feet.

Table H.Chi-square test sex ratio study

Number of frees Observed Observed Expected Expected Adjusteda Unadjusted" Degiees of Line Total male female male female chi-square chi-square freedom

1 8 3 5 4 4 .125 .500 1 2 7 4 3 3.5 3.5 .000 .014 1 3 13 8 5 6.5 6.5 .307 .692 4 8 4 4 4 4 .000 .000 1 5 6 1 5 3 3 1.500 2.667 1 6 11 5 6 5.5 5.5 .000 .091 7 11 6 5 5.5 5.5 .000 .091 1 8 11 9 2 5.5 5.5 3.273 4.45 1 9 16 9 7 8 8 .062 .25 I Sum of 9 chi-squares 8.755 9 Total 91 49 42 45.5 45.5 .396 0.538 1 Interaction chi-square 8.217 8 Yates' correction for small expected numbers has been used to determine whether a particular line has a sex ratio significantly deviating from a 1:1 ratio. This is the case if chi-square is larger than 3.841. "No correction is applied in determining the significance of the interaction chi-square. The interaction chi-square has 8 degrees of freedom and needs to be larger than 15.507 to be significant at the 5% level.

748 Fifth World Forestry Congress Proceedings Analysis of Variance of variance was based upon a limited number of trees, but the very low "F" values obtained indicate that a Selection index larger sample of the population very likely would not d.f. SS MS F influence the validity of the conclusions drawn. The rate Preliminary analysis of growth and the overall form of a tree appear to be Subclass means 17 94.8 influenced by a number of factors, including climate, soils, Sexes 44.0 position and sizes of crown, as well as the genotypic con- Lines 8 668.0 stitution of the tree. In view of reports in the literature, Individuals 1290.0 17.67 it is possible that there may be sex-related differences in Interaction 8 271.73 34.0 l.92 aspen, but the control exercised by sex is overshadowed (SWD ) 2/SW 8.79 by the influence of other genetic and environmental factors. Correction for Replicated progeny tests conducted under carefully con- disproportion 35.21 trolled field conditions could conceivably be employed to Completed analysis isolate sex-related differences if they exist. Sexes 8.79 8.79 .2585" Lines 8 633.00 79.00 Summary and Conclusions Interaction 8 271.73 34.00 Nine survey lines were established in natural quaking Individuals 73 1290.00 17.7 aspen stands in Upper Michigan and Northern Wiscon- = 2.06 sin.Sample trees located every 150 feet along the sur- bF = 5.32 vey lines were measured, described in detail, and girdled to induce flower bud production when the trees did not Table III.Summary of "F" values for analysis of variance flower naturally. on sex-related characteristics A statistical analysis of the data was made and briefly the results can be summarized as follows: "F" value for "F" value for interaction For the stands studied, the overall sex ratio and sex Characteristic sexesa (sex x lines)' ratio of the individual survey lines did not differ signifi- cantly from the expected 1: 1 ratio. Selection index .259 1.92 None of the growth and form characteristics studied, Volume .632 .64 with the exception of branch angle, differed significantly Height .003 .76 between male and female trees. D.b.h. 1.167 .79 Age 3.885 .33 Branch angle differedsignificantly between male Form class .017 .54 and female trees for most of the individual survey lines, Branch angle 1.3 64 18.1 but the differences were in opposite directions for the Branch weight .739 1.21 various lines, making the overall difference without statis- Natural pruning .057 .78 tical significance. Crown volume .273 1.57 References SF05 = 5.32 Pauley, Scott S.,1949. Forest tree genetics research: Populus bF = 2.06 L. Econ. Botany 3(3):299-330. 1948. Sex and vigor in Populus. Sci. 108: 302-3. and Mennel, Geo. F., 1957. Sex ratio and herma- Discussion phroditism in a natural population of quaking aspen. Minn. For. Notes No. 55. In contrast to the results of the studies of Pauley and Snedecor, George W., 1946. Statistical methods. 4th ed. Ames, Mennel (1957) and the apparent fact that the majority Iowa, Iowa State College Press. of commercially important clones are male, this investiga- tion fails to show either morphological differences between Acknowledgment pistillate and staminate aspen trees or deviations from The author is indebted to Drs. J. P. Van Buijtenen and Philip the commonly occurring 1: 1 ratio. The differences in the N. Joranson for their assistance in preparation of the manuscript results of this study and those of earlier workers might and in the statistical analysis. be explained by different genetic constitutions in the populations, by more prolific flowering or by more notice- RESUMES able flower buds among male aspen trees. The methods Proportion d'arbres males et d'arbres femelles chez le employed should be given careful consideration and may peuplier tremble et caractéristiques pouvant étre en account for the differences in results obtained, since this rapport avec le sexe study made use of a girdling technique to promote flower- Des recherches ont éteffectuées en vue de determiner la ing, while previous studies involved only trees which were proportion d'arbres a fleurs males et d'arbres a fleurs femelles flowering naturally. Also worthy of mention in this con- existantdanslespeuplementsnaturelsde peuplier tremble (Populus tremuloides Michx.). Un total de neuf lignes d'inventaire nection are the repeated observations in this study and ont été établies dans les peuplements de peuplier tremble de Ia other selection work that the least abundantly flowering region nord du Wisconsinet du haut Michigan. Des arbres trees and the trees with the least conspicuous flower échantillons ont été marques tous les 150 pieds le long de ces buds often were female. lignes et ont eta limités a l'arbre dominant ou co-dominant situé le plus près du centre de chaque placette. Les arbres sélectionnés None of the characteristics measured were significantly ont été mesurés en detail(age, hauteur, diamètre, dimensions different between sexes taken as a whole. The analysis de la couronne, forme, etc.) et leur sexe déterminé par examen

Genetics and Tree improvement 749 des boutons de fleurs. Les arbres qui n'étaient pas en fleur ont Se dispusieron nueve hileras de ensayo en bosques de este tipo été cernés pour inciter la floraison et laissés de côté pour étre de alamo en el norte de Wisconsin y de Michigan. Los árboles examines l'année suivante. de muestreo estaban a 46 metros de distancia unos de otros, a On a procédé a une analyse des données obtenues en utilisant lo largo de dichas lIneas, y se limitó a aquellos árboles dominantes des tests au carré khi et une analyse de variations. Les tests au o condominantes situados más cercanos al centro de cada parcela. carré khi ont révélé que ni la proportion générale des sexes, ni Se observaron detalladamente los árboles escogidos (edad, altura, Ia proportion des sexes dans chaque ligne, ne different de facon diámetro a 1.37 m. del suelo, tamaño de Ia copa, forma, etc.) appreciable de la proportion attendue de 1: 1. Les renseignements y se examinaron los capullos de las fibres para determinar el obtenus de l'analyse des données de variation indiquent qu'aucune sexo. Los árboles que no estaban fioreciendo se anillaron con el des caractéristiques de croissance et de forme étudiées, a l'excep- objeto de inducirlos a que fioreciesen para ser observados el año tion toutefois de l'angle des branches, ne different de facon ap- siguiente. préciable entre les arbres males et femelles. On a observe que Los datos obtenidos se estudiaron utilizando el diseño de xi- l'angle des branches différait de facon marquee entre les sexes pour cuadrado y se hizo un análisis de variación. El xi-cuadrado presque chaque ligne d'inventaire, mais les differences étaient en demostró que ni Ia proporción general de sexo, ni Ia proporción directions opposées pour les diverses lignes, rendant ainsila de sexo de cada una de las hileras variaban notablemente de la difference d'ensemble peu appreciable du point de vue statistique. proporción de 1:1 esperada. La información obtenida del análisis de los datos sobre variación probó que ni el crecimiento ni las La Proporción de Sexo, en el Alamo Temblón y las caracterIsticas de la forma, con la excepción del ángulo de las ramas, diferlan mayormente en los álamos de uno u otro sexo. Posibles CaracterIsticas Relacionadas con su Sexo El ángulo de las ramas era notablemente diferente entre los sexos En bosques naturales de alamo temblón (Populus tremuloides en la mayor parte de las hileras separadas, pero las diferencias se Michx.) se investigó la proporción de árboles estaminIferos y presentaron en direcciones opuestas en cada hilera, lo cual repre- pistilados y las diferencias relacionadas posiblemente con el sexo. sentaba en conjunto una diferencia sin importancia estadIstica.

Selection and Testing for Sugar Yield in Acer saccharum L.

HOWARD B. KRIEBEL Associate Professor of Forestry, Ohio Agricultural Experiment Station, Wooster, Ohio, U.S.A.

For the production of maple syrup, sap of the sugar maple (Acer saccharum L.) is concentrated by boiling to bring it to a standard weight of 11 pounds per gallon, or 1.32 kilograms per liter. The amount of sap required to 80 produce a given volume of syrup depends on the initial sugar content of the sap as it comes from the trees. Figure 1 shows how many gallons of sap of various concentra- 70 tions are required to produce one gallon of finished syrup. The pronounced effect on this ratio of an increase in sugar content can be readily noted. Only half as much 60 sap of 5 percent sugar content is required to produce a gallon of syrup as is required if the sap has a 2.5 percent sugar content, for example. Because of the considerable 50 labor charge involved in sap collection and boiling, a significant cost reduction is obtained by producing syrup from sap of high sugar content. : 40 Extensive studies have been made of factors affecting the sugar content of maple sap. It is now known that the tree with the highest sugar content has a very full crown, 30 characteristic of open-grown trees.Trees of this type frequently average over 3.5 percent sugar content.In contrast, forest-grown trees usually average 2 to 2.5 per- 20 cent sugar content (4, 5, 6) * Environment, therefore, has an important influence on sugar content. For reasons still unknown, the sugar content of an individual tree 10 fluctuates by as much as 1.0 percent from day to day and even from hour to hour. 0 In spite of this fluctuation, an individual tree which is 2 3 4 5 high in sugar content in relation to its neighbors main- Sugar percentage of sap

* Numbers in parentheses denote the references listed at the end Figure Relationship of sugar content of sap to volume of sap of this paper. required per gallon of finished syrup. 750 Fifth World Forestry Congress Proceedings tains this relative position from one year to the next, and Because of this problem of obtaining rooted cuttings, a tree low in sugar content tends to remain low in rela- a program of clonal testing based on grafting was started tion to its neighbors (7).This is true both in forest in 1955 at the Ohio Agricultural Experiment Station. stands and in the open and has every indication of being The influence of rootstock sugar content on that of the an inherent characteristic, because of the consistent varia- scion was not known a priori. Any such influence, if it tion among morphologically similar individuals,either existed, would not affect the suitability of such clonal within a forest stand or within a group of roadside trees. stock for a seed orchard, providing the characteristic Tests of several hundred mature trees have been made were actually inherited, although it would influence sugar repeatedly over a period of years in Vermont, New yield of the grafted trees themselves. However, it was Hampshire,Massachusetts, New York,Pennsylvania, considered quite possible that there would not be such an Ohio, and Michigan. These records provide an excellent effect.If enough ramets are tested of each clone on a basis for a program of genetic selection and testing by reasonably homogeneous group of rootstocks, statistical both sexual and vegetative propagation. Such programs principles of randomization and replication can be used are currently under way in New Hampshire, Vermont, as they are in testing height and other environment- Massachusetts, and Ohio. Ease of measurement makes sensitive variables.Unless scion influence is completely sugar content a very suitable characteristic for selection overshadowed by the influence of the stock, the mean and progeny testing. Measurements are made either with sugar percentage and the distribution of measurements a sap hydrometer or with a hand refractometer having a around the mean will be higher for a genetically "sweet" scale which reads directly in percent solids. In maple sap tree than for a tree of low sugar content. Many of the these solids are 96 percent sugars (8), meaning that the grafts were made high enough on the stock to permit reading can be considered a direct reading of sugar per- testing sap of both rootstock and established scion. As a cent for all practical purposes. Only one drop of sap is further test,a series of double grafts were made, by required for a reading.This must be taken during a grafting scions from a high- and a low-test tree on the period of sap flow, which occurs when the air temperature same rootstock. Tests at three points will be possible on rises to about 5 degrees Centigrade following a period of these trees. below-freezing weather. Sap is best taken when flowing The grafting program was conducted both in the directly from the tree, either from a taphole or from a greenhouse on potted rootstocks and in the nursery on small hole made with a pocket knife or other sharp instru- lined-out stock. The program included intensive investi- ment. gations of technique and factors affecting survival and Tests can be made on small saplings as well as large growth of grafted and budded trees; as a result the per- trees. However, sap flow is difficult to obtain from trees centage of success was greatly increased.Vigor of the less than 3 centimeters in diameter just above ground scion was found to be the most critical factor in survival. level.Occasional readings can be obtained from trees 1 In 1958, a seed orchard was initially laid out, using to 2 centimeters in diameter at an age of 3 or 4 years. 20 of the best clones. Table 1 lists the ortets, with per- Trees grown from seed often attain testing size at an age tinent data concerning origin and sugar records, also of about 7 years, and by the time trees are 10 years old, female and male parents used in progeny tests. In com- nearly all can be tested. The relation between sugar con- paring yields of these individual trees, it is important to tent of young trees and that of old trees is not yet firmly keep in mind the lower sugar yield of forest-grown trees established, although the progeny tests which we are now than open-grown trees.Thus, a tree in a dense stand making in Ohio indicate that there is no relationship averaging 2.5 percent sugar (e.g., tree number 272 in between age and sugar content. Sugar content of small Table 1) may be genetically superior to a roadside tree saplings appears to be just as high as that of old trees, averaging 4.0 percent sugar (e.g., tree number 576). provided that the young trees are grown in the open The seed orchard was planted on a 30' x 30' triangular where thereis freedom for crown development. We spacing, using Langner's design (3) with some modifica- have obtained numerous readings of 2 to 4 percent in tionsnecessitated by irregularplot shape.First-year 10-year-old trees, and one reading of 6.6 percent on such mortality was quite high, especially of trees budded the a tree, the highest on record for the state of Ohio. previous summerReplacements have been made when- ever possible by grafting in the orchard on established Clonal Testing stocks, or by using well-established grafted trees. Because Close cooperation between research centers in the of intensive management, initiation of sap testing in the northeastern part of the United States has resulted in the orchard will be possible in about two years. exchange of branch cuttings and open-pollinated seed, collected from about 30 of the best trees for which Progeny Testing long-term records are available. One obstacle to clonal A second phase of the selection program is actual testing has been the extreme difficulty of rooting cuttings progeny testing.Open-pollinated seed collected from as taken from theselectedmaturetrees.Considerable many selected phenotypes as possible was used for the research at the University of New Hampshire and more establishment of test plantations in Ohio. This type of recently in Vermont has produced satisfactory techniques testing is also being conducted in Vermont. Sap testing for obtaining initial rooting, but the problem of extremely will begin on a significant scale in about three years high overwintering losses of rooted cuttings has not yet in Ohio on progenies of about 20 Ohio and Massa- been solved (1, 2). Air layering is also being tried in chusetts mother trees for which detailed performance Massachusetts. records are on hand. Genetics and Tree Improvement 751 Table 1. Records of sugar maple trees under clonal or progeny pattern, if such a pattern exists. Larger provenance tests, tests at the Ohio Agricultural Experiment Station. including more seed origins, were established three years Range No. later.These plots will provide a more sensitive test of Type Mean of years No. geographic variation, from which it can be determined Tree of sugar tests of of whether any correlation exists between winter hardiness no. Source tree1 % % tests tests and sugar content of the sap. Such a relationship is sug- 272 Ohio F 2.5 4.1-1.5 4 19 gested by the lower average sugar percentages and syrup 273 Ohio F 2.2 2.8-1.7 4 19 yields obtained in Ohio than in northern New England 354 Ohio R 3.1 4.1-2.2 4 18 and New York. 356 Ohio R 3.3 4.9-2.5 4 20 358 Ohio R 3.9 6.1 -2.9 4 19 Conclusions 359 Ohio R 3.0 4.3-2.1 4 19 In conclusion, several considerations make sugar con- 360 Ohio R 2.7 4.0-2.0 4 20 tent of Acer saccharum an excellent character for genetic 361 Ohio R 1.7 2.5-1.0 3 15 selection and testing.First, the intensive studies of tree 362 Ohio R 2.6 3.8-2.0 4 20 variability in sugar content during the past decade or so 366 Ohio R 2.7 4.3-2.1 4 20 throughout the commercial maple sugar producing region 368 Ohio R 2.8 3.9-2.1 4 18 have provided the basic information for selection and 390 Vt. F 2.0 3.0- 1.4 10 128 testing.Second, sugar content of young trees in experi- 397 Vt. F 2.5 3.6- 1.6 10 138 mental plots appears to be comparable to that of mature 489 Vt. F 3.9 5.8-2.3 10 137 trees,thusmakingearlyparent-progenycorrelations 003 N.H.' R 6.0 feasible.Third, the simplicity of measurement and the 005 N.H.' R 8.0 likelihood of obtaining sufficient sap tests for an accurate 545 Mass. R 4.7 6.0-3.6 7 20 assessment of filial performance by the tenth or twelfth 572 Mass. R 5.3 11.4-3.4 6 19 year are favorable to heritability estimation. Simultaneous 573 Mass. R 4.7 6.2-3.6 6 19 clonal propagation and seed orchard establishment partly 575 Mass. R 3.9 5.6-2.8 7 18 overcome the obstacle of a long reproductive cycle. Fur- 576 Mass. R 4.0 6.0-2.6 7 18 ther study will be needed to develop economical methods 583 Mass. R 4.9 7.0-3.4 6 17 of vegetative propagation for rapid commercial utilization 585 Mass. R 4.0 5.6-3.0 6 17 of elite trees. 619 Mass. R 4.9 6.2-3.6 6 16 624 Mass. R 4.6 6.0-3.6 5 16 References 632 Mass. R 4.1 6.0-2.8 7 20 Dunn, Stuart and Russel Eggert, 1959. Propagation of woody 640 Mass. R 3.8 5.2-2.8 7 20 plants. N. H. Agric. Expt. Sta., Bull. 645. 662 Mass. R 4.4 6.2-3.0 8 20 Gabriel, W. J., 1959. Personal communication. 664 Mass. R 4.4 6.0-2.8 6 18 Langner, W., 1953. Die Klonanordnung in Samenpiantagen. Zeitschr. Forstgen. und ForstpflanzenzOchtung 2:119-121. 669 Mass. R 4.3 5.2-2.0 7 15 Moore, H. R., W. R. Anderson, and R. H. Baker, 1951. 385 N.Y.' R 4.0 7 Ohio maple syrup. . . some factors influencing production. 386 N.Y.' R 4.8 4 Ohio Agric. Expt. Sta. Bull. 718. Morrow, Robert R.,1955. Influenceoftree crowns on 1 R= roadside; F = forest. maple sap production. Cornell Univ. Agric. Expt. Sta. Bull. 2 Reported approximateaverages over several years; detailed 916. records not obtained. Stevenson, D. D. and R. A. Bartoo,1940. Comparison of the sugar percent of sap in maple trees growing in open and dense groves. Pa. State Forest School Res. Paper 1. In 1955, we made controlled pollinations on six road- Taylor, Fred H., 1956. Variation in sugar content of maple side trees at Wooster, Ohio, using 21 different cross com- sap. Vermont Agric. Expt. Sta. Bull. 587. binations, includingselfing,open pollination, and no Willits, C. 0.,1958. Maple sirup producers manual. U. S. pollination.The crossing included trees of high, inter- Dept. Agric. Handbook 134. mediate, and low sugar content. Seed yields were good, RESUMES and in 1959 a progeny test was established which will begin to yield information in 1961. Some of the parents Selection génétique et essais de l'Acer saccharum L. pour are also included in both the open-pollinated progeny le rendement en sucre tests and the clonal tests, so that some information on C'est tin fait établi que la teneur en sucre de la sève de 1'Acer heritability and combining ability should be forthcoming. saccharuni L. vane de facon rdgulière d'un arbre a l'autre. Une In addition to the individual tree selection, variability légère augmentation de la teneur en sucre représente une économie importante en Ce qu'elle réduit la quantité de sève nécessaire pour in sugar content is being studied in replicated provenance la production d'une unite de sirop d'érable, en raison du moindre tests of Acer saccharum. The first of these tests was degré de cuisson ndcessaire. Dans le nord-est des Etats-Unis, la established in 1954 and now has many trees five meters selection génétique de l'érable repose sur de fréquentes vériflca- tions au réfractomètre de la teneur en sucre de la sève, effectuées or more in height. Most of the trees in this plantation au cours d'une période de plusieurs années. Ces selections font have already been tested several times during the past l'objet d'essais au moyen de greffes; une pépinière pour la produc- three years, although sap flow is still rather irregular and tion de graines et renfermant 20 clones a été établie dans l'Ohio. not as extensive as it is in mature trees. These trees have En outre, des essais sont actuellement effectués avec des plants been permitted full crown development to date, and tests provenant de reproduction sexuée et asexuée. Les jeunes arbres peuvent étre soumis a un essailorsqu'ilsatteignent3centi- indicate that sugar content is just as high as it is in mature metres de diamètre et parfois plus tot. D'ici deux ou trois ans, trees. Data are not yet sufficient to define any regional on commencera a disposer de renseignements sur les caractéris- 752 Fifth World Forestry Congress Proceedings tiques transmises héréditairement. En outre, les arbres croissant cuanto mayor es el contenido tanto menos tiempo se necesita dans des plantations de provenance font l'objet d'essais visant a para hervirlo. En el Nordeste de los Estados Unidos la selección determiner sila teneur en sucre de la sève vane suivant la de árboles se hace a base de las pruébas refractométricas del region géographique oil l'érable croit. porcentaje de azt'scar, realizadas durante un periodo de varios años. Estas selecciones se comprueban por medio de injertos. En Ohio Selección y Análisis del Contenido de Azcar del Acer se ha establecido un huerto para semilleros que incluye 20 clones. Además, se han hecho experimentos de progenies de una o dos saccharum L. plantas madres. Los árboles nuevos ya pueden estudiarse cuando El contenido de azilcar de la savia del Acer saccharum L. ha tienen 3 centImetros de diámetro y algunas veces antes. Dentro demostradoserdiferenteenárbolesindividuales.Cualquier de dos o tres años será posible obtener datos sobre los factores aumento pequeño del porcentaje de azdcar en la savia representa hereditarios. A la vez, están realizándose estudios en plantaciones una considerable econcmIa en la cantidad de ésta, necesaria para experimentales para determinar si existe alguna variación geográ- La producción por unidad del jarabe de arce azucarero porque fica en el contenido de azilcar de la savia.

Karyological Notes on the Genus Eucalyptus

C. RUGGERI Central Experimental Station of Agriculture and Forestry Rome, italy

From a strictly karyological point of view, very little E. elaeophora F. Muell. 2n=22 (Ruggeri, 1960) is known of eucalypts. Apart from the diploid number E. fastigata Deane & Maiden 2n=22 (Ruggeri, 1960) E. ficifolia F. Muell. 2n=22 (Smith-White, 1942) 2n=22, little or nothing is known concerning the chromo- E. flocktoniae Maiden 2n=24 (Ruggeri, 1960) some morphology of this genus. E. globulus Labill. 2n=22 (McAulay, 1936) In a significant study (which was, however, limited to E. gomphocephala DC 2n==22 (Ruggeri, 1960) E. goniocalyx F. Muell. 2n=22 (Ruggeri, 1960) the simple determination of the chromosome number), E. gummifera Hochr. 2n=22 (Smith-White, 1942) Atchison (1947) examined 25 species of Eucalyptus, of E. gunnii Hook, f. 2n=22 (Atchison, 1947) which two wereapparentlyaneuploid with 2n=24, E. haemastoma Sm. 2n=22 (Smith-White, 1942) namely, E. redunca and E. corynocalyx. E. incrassata Labill. 2n=22 (Smith-White, 1942) E. johnstoni Maiden 2n=22 (McAulay, 1936) More recently, Ruggeri (1959-60) took up thisre- E. kirtoniana F. Muell. 2n=22 (Atchison, 1947) search on a further 28 species, with the intention of also E. lehmanni Preiss. 2n=22 (Ruggeri, 1960) throwing some light on the chromosome morphology. E. leucoxylon F. Muell. 2n=22 (Ruggeri, 1960) Thus, it has once more been possible to observe the E. linearis Dehn. 2n=22 (McAulay, 1937) high constancy and homogeneousness of the chromosome E. longifolia Link & Otto 2n=22 (Atchison, 1947) E. macarthari set, and furthermore, another species, E. flocktoniae, was Deane & Maiden 2n=22 (Ruggeri, 1960) identified as having a chromosome number of 24. Thus E. maculata Hook. 2n=22 (Atchison, 1947) the number of eucalypts having 2n = 24 is raised to three. E. maidenii F. Muell. 2n=22 (Ruggeri, 1960) E. melanophloia F. Muell. 2n=22 (Ruggeri, 1960) We summarise below the present karyological situation E. obliqua L'Her. 2n=22 (McAu!ay, 1937) of the genus by listing the species which have been studied E. occidentalis End!. 2n=22 (Ruggeri, 1960) karyologically. E. ovata Labi!l. 2n=22 (Ruggeri, 1960) E. paniculata Sm. 2n=22 (Smith-White, 1942) Eucalyptus: x 11. E. pauciflora Sieb. 2n=22 (McAulay, 1937) E. aggregata E. paulistana 2n=22 (Atchison, 1947) Deane & Maiden 2n = 22 (Ruggeri, 1960) E. polyanthemos Schauer 2n==22 (Ruggeri, 1960) E. alba Reinw. 2n22 (Krug, 1949) E. pulverulenta Sims 2n=22 (Atchison, 1947) E. albens Miq. 2n = 22 (Ruggeri, 1960) E. redunea Schauer 2n=24 (Atchison, 1947) E. angulosa Schauer 2n=22 (Atchison, 1947) E. resinifera Sm. 2n=22 (Atchison, 1947) E. astringens Maiden 2n22 (Ruggeri, 1960) E. rubida Deane & Maiden2n=22 (Atchison, 1947) E. behriana F. Muell. 2n22 (Smith-White, 1948) E. rudis Endi. 2n=22 (Atchison, 1947) E. bicostata Maiden, E. saligna Sm. 2n=22 (Krug, 1949) Bl. & Sim. 2n=22 (Ruggeri, 1960) E. sideroxylon Benth. 2n=22 (Smith-White, 1942) E. botryoides Sm. 2n = 22 (Atchison, 1947; E. staigeriana F. Muell. 2n=22 (Smith-White, 1942) Ruggeri, 1959) E. steedmanii Gardn. 2n=22 (Atchison, 1947) E. bridgesiana Baker R. T. (Atchison, 1947; E. tereticornis Sm. 2n=22 (Ruggeri, 1960) E. stuartiana F. Muell. 2n = 22 Ruggeri, 1960) E. tetraptera Turcz. 2n=22 (Smith-White, 1950) E. brockwayi Gardn. C. A.2n22 (Ruggeri, 1960) E. torquata Luehm. J. G. 2n=22 (Atchison, 1947) E. calophylla Br. R. 2n = 22 (Atchison, 1947) E. trabutii Vi!m. 2n=22 (Ruggeri, 1959) E. camaldulensis Dehnh. 2n=22 (Atchison, 1947; E. triantha Link. 2n=22 (Atchison, 1947) Ruggeri, 1959) E. vim inalis Labill. 2n=22 (Atchison, 1947) E. cinerea F. Muell. 2n=22 (Ruggeri, 1960) E. citriodora Hook. 2n = 22 (Atchison, 1947) E. cladocalyx F. Muell.- (Atchison, 1947; The are found in a fossil state from as far E. corynocalyx F. Muell. 2n=24 Ruggeri, 1960) back as the Lower Cretaceous period (Andrews, 1913). E. cornuta Labill. 2n = 22 (Ruggeri, 1960) AccordingtoHerbert(1929)and Blake(1953), E. dalrympleana Maiden 2n=22 (Ruggeri, 1960) E. diversicolor F. Muell. 2n=22 (Atchison, 1947) eucalypts appeared in that geological period in a region E. dives Schauer 2n=22(Smith-White, 1942) of Australia which possessed a moderate climate with high Genetics and Tree Improvement 753 rainfall and, during the Tertiary period, they apparently References spread into Tasmania and New Guinea, with a great dif- ferentiation of species. Atchison,E.,1947. Chromosome numbers in the Myrtaceae. We do not yet know the phylogenetic evolution of the Amer. J. Bot. 34:159-64. genus. But we cannot refrain from asking how the Blakely, W. F., 1955. A key to the eucalypts. Forestry Timber eucalypts, with such a large distribution range and long Bureau, Canberra. geological history, have been able to maintain such a Crocker, R. L. and Wood, J. G., 1947. Some historical influence contant chromosome number. on the development of the South Australian vegetation com- munities and their bearing on concepts and classification in In our opinion, therefore, great importance attaches to ecology. Trans. Roy. Soc. S. Austr. 71(1):11-136. the fact that Eucalyptus redunca, E. corynocalyx and E. Darlington, C. D. and Wylie, F. D., 1955. Chromosome atlas of flocktoniae are all species which originated in southwest- flowering plants. Allen & Unwin Ltd., London. ern Australia, that they are very similar morphologically de Philippis, A.,1954. Gli eucalittivisti in Australia. Ann. and grow in a belt which has more or less the same Acc.Sd.For. 2:73-108. environmental conditions, consisting notably in summer F.A.O. (Metro, A.), 1954. Les eucalyptus dans le reboisement. drought and moderate or low winter rainfall. Rome. It is true that the three species are not found in contig- Maiden, J. H., 1909-29. A critical revision of the genus Eucalyp- uous areas, but it must be remembered that during the tus. Government Printer, Sidney. Tertiary period an inland sea separated western Australia Messeri, A. and Ruggeri, C., 1959.II numero cromosomico di from eastern Australia, which might be the cause of the E. x trabutii Vilmorin (Myrtaceae).Proc. Tnt. Bot. Congr. gaps between their distribution areas.Initially they may Abs. Montreal 2:260-1. have been continuous, or, alternatively, without going so Renier, H. J., 1953. Les eucalyptus en Australie Ct en Tasmanie. far back in geological time,thediscontinuity in the Publ. Direction Agriculture Forêts et Elevage, Bruxelles. present-day distribution of E. corynocalyx E. flocktoniae Rugged, C., 1960.II numero cromosomico di E. x trabutii Vil- and E. redunca, and of many other species, might date morin (Myrtaceae). In press. from relatively modern times, namely to the xerothermic 1960. Studio cariologico sul genere Eucalyptus (Myr crisis of about 5,000 years ago, when the desert climate taceae). In press. which invaded a large part of the continent caused a Wood, J. G., 1959. The phytogeography of Australia (in relation great impoverishment in the flora.Subsequent to this to radiation of Eucalyptus, , etc.) In: Keast, A., Crocker, period, with the arrival of a wetter period, the genus R. L. & Christian, C. S., Biogeography and Ecology of Aus- Eucalyptus showed marvellous powers of ecological adap- tralia. Junk, Den Haag. tation and reconquered the dominating position which it at present holds among the arboreal vegetation of Aus- RESUMES tralia, evincing a wide range of species and biotypes suited for the colonisation of very different environments. Notes karyologiques sur le genre Eucalyptus These three species thus, in all probability, bear witness L'auteur fait une breve description de la situation actuelle du to a differentation, which went no further, in the evolu- point de vue karyologique du genre Eucalyptus et énumère toutes tion of the family, or else prove the existence of individ- les espèces étudiées jusqu'à present. uals which external or internal influences caused to differ II a été également établi que E. flocktoniae, E. redunca et E. from the original pattern. corynocalyxles seuls chezlesquels on a découvert jusqu'à present Ia presence d'un groupe diploIde de 24 chromosomes- sont tous des espéces provenant du sud-ouest de l'Australie, très semblables du point de vue morphologique, et croissant dans iine zone dont les conditions ambiantes sont plus ou moms les mêmes, a savoir sécheresse en été et pluviosité modérée ou faible en hiver. Selon la théorie de l'auteur, ces espèces constituent peut-être, an cours de l'évolution de Ia famille, l'indication d'une variation ou la preuve de l'existence d'individus qui se sont écartés du type original a la suite d'influences ambiantes ou internes.

Notas Cariológicas sobre el Género Eucalyptus Se resume la situaci6n cariol6gica actual del género Eucalyptus y se da una lista de todas las especies estudiadas hasta la fecha. Ha quedado probado por este estudio que E. flocktoniae, E. redunca y E. corynocalyx, las ilnicas que se han hallado hasta ahora con una serie diploide de 24 cromosomas, son todas especies originariasdel Sudoeste de Australia, morfológicamente muy similares y que crecen en una zona con las mismas condiciones ambientales, o sea, una época de sequla veraniega y un Indice pluviométrico entre bajo y moderado en el invierno. En este trabajo se propone la teorIa que dichas especies quizás representen, en la evoluci6n de la familia, la prueba de una variación o de la CLimatic regionsof AustraLia (from Renier) and distribution rangeof existencia de individuous a los cuales el ambiente o influencias E. redunca E. corynocatyx andE. fLocktoniaeUflllffi internas les han hecho salirse de la norma original. 754 Fifth World Forestry Congress Proceedings Variation and Heritability Of Physiological and Morphological Traits In Norway Spruce

FRANçOIS MERGEN Professor, Yale University School of Forestry, New Haven, Connecticut, U.S.A.

Forestgeneticsisconcerned withsimilaritiesand When Lush used the term "heritability in the broadest differences between related trees.It is important to know sense" he included as hereditary differences the variations the range in variation and the amount of similarity in caused by epistases and dominance, as well as the non- various traits, and how they are transmitted to succeeding linear interactions between heredity and environment. generations. Until recently, very few estimates for heritability had Individual tree differences within a species are the been made for traits of forest trees, mainly because the result of mutations, genetic combinations, and modifica- proposed techniques for calculating these values deal with the type of progeny tests and parent-progeny knowl- tions by the environment. A segment of genetic investiga- edge that is scarce for forest trees. In the field of forestry tion is concerned with the measurement of genetic poten- we have few experiments that lend themselves tothe tials of individuals, groups or populations of trees, in an strict mathematical treatments. The results from vegeta- attempt to evaluate these in relation to modifications by tively propagated clones can be of value in this respect different environments. When a character is unaffected by and should be used when applicable. It should be realized changes in the environment and remains stable over a that the term "heritability," as it is being used today by wide range in conditions, the trait is under rigid genetic plant breeders, refers to different ways of estimating vari- control.If, on the other hand, small changes in the ance, and, therefore, needs to be defined foreach case. environment are reflected by pronounced modifications in In this paper are described estimates of the existing varia- the phenotype, the trait is under loose genetic control. tion for certain traits in clones of Norway spruce, and The concept of "rigidity of genetic control" is quite their degree of genetic control. valuable.It permits one to make predictions for selected trees and define gain potentials. "Rigidity of genetic con- Experimental Approach trol" is concerned only with the current generation.It Norway spruce, Picea abies, occurs naturally in Europe has only limited application in explaining the performance over a considerable geographic area, and treesof this of successive generations, because it does not isolate and species have been planted widely in the United States. define the various genetic components. Considerable attention has been given toitsgenetic The genetic components are composed of additive gene improvement, including attempts to propagate it vegeta- effects, non-additive gene effects, epistatic factors, and tively.Past studies reported tree to tree differences in nonlinear interactions between environment and genotype. variousattributes,without,however,attemptingto Lush (1958)* used the term "heritability," to describe describe the range in variation and partitioning this varia- tion into genetic and environmental components. Two the part of the total phenotypic difference that is caused characteristics were chosen for this study: (1) flushing by the additive effect of the genes, and proposed the after dormancy had set in; and (2) ability to produce following formula: roots on cuttings. a Thirty trees, fifteen years old, that were growing in a H= plantation wereselectedfor uniformityofsize and .2 + .2 +.2 + o2 + 2 apparent vigor.Three hundred cuttings were collected where = additively genetic variance, o = variance due from the upper part of the crown during August and November to obtain estimates for two periods of growth. to dominance deviations, cr= variance due to epistatic In August, the trees were growing actively, while in interactions, g2= variance due to nonlinear interactions November they were dormant. One-half of the cuttings were placed in a propagation bench withoutchemical of heredity and environment, and = variance due to pretreatment, while the other half were treated with environmental variations. 0.5% indolebutyric acid in talcum powder. A randomized block design with five replications was used. Observations on flushing, made only on the cuttings *Lush,J.L.,1940.Intra-sire correlations or regressions of offspring on dam as a method of estimating heritability of char- from the November collection, were taken during Jan- acteristics. Amer. Soc. Animal Prod. Proc.: 293-301. uary. A cutting was considered tohave flushed if the Genetics and Tree Improvement 755 bud scales had separated and the new green needles were November, the estimated values for heritability are very visible. The formation of roots on the cuttings from the similar. August collection were evaluated after 12 weeks, while those from the November collection were lifted and Table 1.Heritability and the Range in the Variation and Average evaluated after 16 weeks. For the observations on root of Rooting Response formation, the number of roots, as well as the length of the longest root was recorded. Controls only Controls and treated Results on flushing. The data on flushing were trans- Date of Herit- Herit- formed into angular values for the analysis of variance. collectionRange Mean abilityRange Mean ability There was a considerable range in the flushing response % % % % % % (10% -53%). The statistical analysis of the data showed August 0-7 0.5 73 0-14 0.8 38 that the difference between trees was highly significant November 12-97 61 70 10-97 54 71 and that the chemical treatment had no effect. To obtain an estimate of the proportion of the genetic variance in flushing, Lush's (1956) formula with the variance com- Volume of roots. An estimate of the volume of roots ponents from the analysis of variance was used. The value for each cutting was calculated by multiplying the number for heritability obtained was 56%. This can be inter- of roots by the length of the longest root. These values preted to mean that 56% of the between-trees component were used without transformation in the analysis, and of variance represents genotypic variance in the "broad the results obtained paralelled the observations on the sense," or that 56% of the variation in flushing between number of cuttings that rooted. The levels of significance were the same with the exception of the effect of chemical the trees was due to genetic differences between the trees, treatment that was significant only at the 5 percent level and 44% was due to direct environmental conditions or of probability. There were highly significant differences from interactions with the environment. between trees and between seasons of collection, and the Results on rooting. For the analysis of the number of values from the August collection were much more cuttings that rooted, the percentage values were trans- variable. formed into angular values. The analysis of variance gave the following results:(1) there was a highly significant Using the same formula for volume of roots as was differenceinrooting between the 30 trees, and the used for percentage of cuttings that rooted, estimates of difference was present in both the August and November heritability were obtained (Table 2). collections;(2)theoverall rooting was significantly Table 2.Heritability and Range in Variation and Average greater in November than in August; (3) by calculating Volume of Roots the variance ratio for the effect of trees, using either the mean square of the "Trees X Chemical Interaction" or Controls only Controls and treament the "error" term, highly significant values were obtained, Date of Herit- Herit- indicating that the 30 trees were different whether they collection ability ability were untreated, or treated with indolebutyric acid or any Range Mean % Range Mean % similar chemical; and (4) there was a highly significant August 1-122 4.4 37 1-122 6.5 40 overall effect from the chemical treatment, as well as a November 1-121 42.0 75 1-121 40.3 69 highly significant interaction between season and treat- ment. The chemical stimulated rooting in the cuttings collected in August, but was detrimental for the cuttings Discussion collected in November. Heritability,as defined by Lush, has been used in The average phenotypic expression in rooting of an different ways by plant breeders, and therefore needs to individual treeis composed of the following factors: be defined precisely whenever there are complications P= G + B + BG + C + IC + D,whereP = pheno- present. After the limitations of the design are defined, it type of the root, G = genotypic value of the tree, B = willstill remain a useful expression of the genotypic deviation due to effect of the block in the plantation, variance components. As used in this analysis, it prob- BG = deviation due to interaction between genotype ably could be best defined as the "degree of rigidity of and block, C = effect of chemical, IC = interaction genetic control." However, the substitution of a new term with chemical, and D = random element.Using the will not help to clarify matters greatly. The main points of interest are the fact that the 30 formula where heritability is expressed as the values as trees were chosen at random from a large population in regard to their ability to flush, or to produce roots. Noth- P ing was known of these factors a priori, and it can be indicated in Table 1 were obtained. assumed that variants from both extremes of the range The interaction between the chemical treatment and were sampled.The existing spectrum of variation in date of collection caused a much greater range in rooting both flushing and rooting was wide enough, and the response in the August collection.This increase in the within-tree variation in the five blocks, as well as the tree environmental effect accounts for the lower value for X block interactions were small enough to give an expres- heritability that was obtained for the "controls + treated" sion of heritability. Although the absolute magnitude of cuttings of the August collection.It is of interest to note rooting response was quite different in the two collec- that, although the level of rooting of the untreated August tions, the estimates for heritability varied only slightly. cuttings was only a small fraction of that obtained in This would indicate that the parameters were similar in 756 Fifth World Forestry Congress Proceedings these two experiments, which would lend confidence to only demonstrated considerable tree-to-tree variation in the heritability estimates obtained. rooting, but also a strong genetic control of both percent- Because heritability is composed of two components, age of cuttings that rooted and volume of rootsproduced. the effect of the environment and that of the genes, it is possible to change the numerical value for heritability by RESUMES changing the environment. This fact was well illustrated Variances et hérédité des caractéristiques physiologiques for the August collection when heritability for rooting of et morphologiques de l'épicéa the controls is compared with heritability for the control Deux caractéristiques observées chez 30 arbres de Picea alba and treated cuttings. When only the controls were used, ont été choisies pour l'étude de la rigidité du contrôle génétique: a value of 73% was calculated, while for all the cuttings (1) redéveloppement de la pousse après commencement du repos hibernal;et(2)capacitéde développement de racines aux a value of 39% was obtained. By treating the cuttings boutures.Les données fournies par la repousse des bourgeons with a chemical,inessence,a more heterogeneous indiquaient une très vaste échelle de reactions (10%-53%) et on environment isprovided which increases the variance obtenait une valeur de 56% pour la transmission héréditaire. La component of the error term. In general, it can be stated capacitd de prendre racine était tout a fait variable et modifiée par les differences individuelles des arbres, Ia saison pendant laquelle that the more uniform the environment under which the les boutures étaient prélevées, et le traitement au moyen d'un progeny or propagules are being tested, the greater will produit chimique.La capacité d'enracinement retransmise aux be the value for heritability. boutures non traitdes était de 73% pour les dchantillons prélevés In this evaluation, heritability is used in the "broad en aoüt, et 70% pour les échantillons prélevés ennovembre. La quantitb des racines formées, suivait de très près l'ensemble des sense" and included are variations due to "maternal" rdsultats obtenus pour le nombre d'échantillons qui avaient pris effects, or nongenetic properties of the trees, e.g., health racine. of the tree, insolation of the tree, past history of insect La notion de l'hérédité, sa méthode de calcul, de méme que and disease attack, general fertility level under which a son application a la génétique forestière, sontexaminées a la particular tree is growing, etc. By selecting trees with a lumière des résultats obtenus. similar past history, it is felt that the variance components for these factors was minimized Most of the variance in Variación y Heredabilidad de Cualidades Fisiológicas y the error term was made up of nongenetic causes of Morjológicas del Abeto de Noruega variation within and between blocks, physical differences Para el análisis que se describe en este trabajo se seleccionaron between cuttings, and possibly also nonlinear interactions dos caracterIsticas, bajo rIgido control genético, de 30 abetos de Noruega: (1)el renuevo después de sobrevenido el letargo; between genotypes and blocks. y (2) la habilidad de producir raIces en las estacasde plantar. Although the characters that were considered were not Los datos relacionados con los renuevos indican una gran variedad chosen for their practical importance, a knowledge of en los resultados (10-53%) y se obtuvo unaheredabilidad de their range in variation, as well as their degree of genetic 56%. La habilidad de crecer raIces resultó muy variable, depen- diendo de las diferencias individuales de los árboles, la época de control will be useful.Early flushing and susceptibility recolección y los tratamientos quImicos.La heredabilidad del to late spring frosts or insect attack are closely correlated crecimiento de raices en las estacas de planta no sujetas a trata- in certain species. These results indicate that the amount miento fue de 73% para las recolectadas en agosto y 70% para of variation in flushing is wide enough, and under rigid las recogidas en noviembre.El nfimero de raIces producidas guardaba bastante la proporción con el nfimero de estacas que genetic control, which would make it feasible to select crecieron raIces. either early- or late-flushing trees. The ability to root, Usando como base los resultados obtenidos, este trabajo trata per se, is not an important criterion, except if it is present ci concepto de la heredabilidad, los métodos de calcularla y in trees that show desirable attributes.This study not también su aplicación a la genética forestal.

The Role of Cytology in Forest Genetics Research

M. B. RAIZADA Chief Research Officer and Head, Division of Botany, and S. KEDHARNATH Forest Geneticist, Forest Research Institute and Colleges, Dehra Dun, India

As is well known, the individual organism is the result generations. For itis these genes which are passed on of the action of genes, the ultimate hereditary particles. from parent to offspring and which are responsible for These genes interact with each other as well as with the the more or lessclose resemblance between the two generations.Extensive studies have shown that in con- environment, and the sum total of these interactions sonance with the important rolethe genes play, the determines the external appearance or phenotype of the mechanism of their distribution to the cells which ulti- individual. These ultimate hereditary particles also con- mately give rise to the gametes is very precisely controlled. stitute the narrow bridge which connects the successive The study of the way in which these hereditary units are Genetics and Tree Improvement 757 organized in the cells and the way in which their dis- fertile true breeding forms which are qualitatively and tribution is effected during the process of cell division quantitativelydifferent from both theparents.The forms the subject matter of the discipline of cytology.It hybrid chestnut, Aesculus carnea isa successful true is clear, therefore, that the genetical behaviour of a popu- breeding polyploid. Upcott (1936) showed that A. carnea lation or a succession of populations cannot be clearly had 2n= 80 chromosomes and that it was an amphiploid understood unless detailed knowledge of the cytological derived from the F1 hybrid A. pavia (2n=40) A. hippo makeup and behaviour of such populations and their (2n40). The earliest demonstration of the occurrence progenitors is available. of such a phenomenon was that by Muntzing (1932), One of the basic items of cytological knowledge which who showed that Galeopsis tetrahitis an amphiploid is indispensable before a rational programme of genetic derived from G. speciosa x G. pubescens. It is generally studiesforthe improvement of foresttreescan be considered that this process has played a leading part in chalked out is precise information as to the chromosome the evolution of the plant kingdom (Stebbins, 1950). If number in the particular species and also the closely one compares the chromosome numbers of some of the allied species or genera. Even within the same species it economic plants and their closely related wild species, one might happen that different ecological or geographical often finds considerable evidence for the occurrence of races constitute different chromosomal biotypes, i.e., they this phenomenon.However, only detailed cytological may differ in their chromosome makeup.Thus, there study of the hybrids between the presumptive allo-poly- may exist a polyploid series, some being diploid while ploid and its putative parents can give definitive informa- others may possess higher chromosome numbers and be tion as to the presence of such relationship between these indistinguishable from thediploids on morphological taxa. In such cases, it may be possible to reconstitute criterion (Barlow, 1958).If such a situation exists, it the economic plant, using superior forms of the parents must be clear that the genetical behaviour of these races so that any undesirable quality can be eliminated. will vary to a very large extent.Again, even though Such an approach to the improvement of the existing the number may be the same in two races, the order in speciesis known as the genome approach to plant which the genes are located on the chromosomes may be improvement and hasoflatereceivedconsiderable different in the two.If such structural differences do emphasis in the improvement of many crop plants such exist, then hybridisation between these two races in order as wheat, cotton and tobacco.There is no apparent to combine their desirable traits may be hindered by the reason why such an approach should be less fruitful in resulting sterility. The existence of such structural differ- forestry improvement.It may even be possible to create ences can, however, be brought to light only by a critical new types unknown to nature. For it has been found examination of meiosis in the hybrid. that, utiising the technique of embryo culture, hybrids Mention has already been made of the possibility of can be obtained from crosses which do not normally the existence of races with different chromosome num- succeed in nature. Though such hybrids are likely to be bers.Experience with crop plants has shown that in sterile as a consequence of lack of chromosomal homol- some cases, especially where weed fertility is not of prime ogy, fertile, true breeding forms could be obtained from concern,more vigorousforms can beobtained by such hybrids by chromosome doubling.The utility of increasing the chromosome number.This process has this technique is, of course, not quite clear as yet, but become especially facile with the discovery and stand- theexperience with crop plantsseems to be quite ardisation of colchicine technique. For a rational appli- promising. cation of this technique also, a knowledge of the chromo- Normal genetical behaviour depends upon the occur- some number of the material isessential,since such rence of sexual reproduction, i.e., in the case of higher artificially induced polyploidy is of greater value when plants, the alternation between the haploid male and the original material has a low or basic chromosome female gametes and the diploid sporophyte.Reassort- number. If, on the other hand, the material is already in ment of the chromosomes during the process of gamete a high polyploid condition, i.e., it has a large number of formation results in reshuffling of the genes contributed chromosomes, then it is likely to have reached the limits by the parents, and this process brings to light a good of improvement through increased chromosome number deal of variation from which both nature and the breeder and, therefore, may not respond favourably to any fur- can select desirable plants. In some cases, however, per- ther increase in chromosome number. The utility of this haps due to an inherent instability of the genetic system type of improvement is shown by the following examples: or to the lack of suitable environmental conditions, this Morus, Populus, Cryptomeria, etc. process appears to have been short-circuited, and embryos If triploids are found to be superior, then techniques develop without the participation of female and male will have to be evolved for checking the chromosome gametes. Such apomixis is, of course, disadvantageous in number of the progeny resulting from 4n x 2n matings the sense that recombination and the release of variation so that only triploid seedlings could be saved and prop- is prevented.However, in the short run, under stable agated. conditions of environment too much variation may prove So far, we have been considering the utility of auto- more disadvantageous to the species concerned than the ploids,i.e., where the chromosome number of a pure production of identical or more or less unaltered individ- species has been doubled.In nature, however, another uals by suchapomicticorvegetativereproduction. form of polyploidy is much more frequently met with Especially under conditions ofartificialculture as in where the chromosome number of a more or less sterile plantations, where more or less similar conditions can be hybridbetweendistantlyrelatedformshasbeen made to prevail year after year, the advantages of sexual doubled.This process often results in the evolution of reproduction may be outweighed by the heterogeneity

758 Fifth World Forestry Congress Proceedings of such a sexually produced population.It would be RESUMES necessary, therefore, that the life history of the material Le role de la cytologie dans les recherches portant sur should be studied to determine where apomictid forms la génétique forestière are present and, if so, to determine the genetic control of La connaissance precise du nombre de chromosomes constitue this character with a view to incorporating this trait into l'un des éléments cytologiquos fondamentaux qu'il est essentiel de posséder pour mettre en oeuvre un programme rationnel d'étude selected desirable lines.Another useful technique which génétique tendant a l'amélioration des arbresforestiers.Des may be mentioned in this connection is the study of the biotypes chromatiques ou des series polyploides, ou une combinai- son de ces deux caractères, se rencontrent dans quelques espèces. growth of the pollen tubes in the process of fertilisation. Ti existe également des cas dans lesquels deux races dotées du Very often, even though pollination occurs, true fertilisa- memo nombre de chromosomes présentent des differences struc- tion does not take place, but the stimulus of pollination turelles. Ceci a des consequences importantes dans un programme d'hybridation.L'existence de ces differences structurelles n'est is enough to start the embryo developing.Depending rdvélée que par un examen minutieux de la méIose de l'hybride. upon the constitution of the egg, it may develop into a Certaines formes polyploides présentent do grandes promesses haploid or a diploid sporophyte. The former is likely to dans quelques genres tels que Morus, Populus, Cryptomeria. On n'a pas encore explore a fond l'utilité des amphiploides en matière be weak and unthrifty, but it is of great interest to the d'amélioration des arbres forestiers par hybridation entre espèces. geneticist as well as the breeder, inasmuch as doubling Ii est bien connu que les amphiploides ont joud dans la nature un the chromosome number in such a haploid could give, at role important dans l'évolution du règne végétal. La technique de l'embryoculture, par laquelle on arrive a de nouveaux hybrides one step, a completely homozygous plant. Such homozy- a partir do croisements qui normalement no réussissent pas dans gous plants are, as is well known, essential for the exploi- la nature, et la production de noyaux haploides qui favorisent la creation de plantes contenant des homozygotes et qui permettent tation of hybrid vigour and are usually obtained only d'exploiter la vigueur propre aux hybrides, sont autant d'outils qui after a number of generations of inbreeding. The occur- pourraient êtreutilisésdans le perfectionnement des arbres. rence or the artificial induction of such haploids would, L'apomixie, si elle présente d'ordinaire quelques inconvénients en ce qu'elle empéche la recombinaison et la liberation des variantes, therefore, prove very beneficial for a programme of peut néanmoins avoir des avantages indéniables dans certains cas. forestry improvement by exploiting heterosis. Une bonne connaissance du contrôle génétique de ce trait est par In conclusion, it may be pointed out that the knowl- consequent utile si l'on desire l'incorporer aux lignes sélectionnées. Les auteurs suggèrent qu'un Comité de Correspondance soit edge at present available on the cytology of different dtabh, comparable a ceux qui fonctionnent dans lo cadre du species of forest plants is rather meagre. Concentrated Congrès do la Sylviculture du Commonweaith, qui serait chargé effort will be required if this gap in our knowledge is to del'échange,surleplaninternational,desrenseignements provenant d'études n'ayant pas encore atteint le stade de la be bridged in a reasonable time, and this will require the parution dans los revues scientifiques. cooperation of forest cytologists and geneticists all over the world. In view of the urgency of the problem, suit- Papel de la Citologia en la Investigación Genética Forestal able arrangements need to be made for the quick exchange Uno de losrequisitos básicos del conocimiento citológico, esencial a todo programa cientIfico do estudios genéticos para el of information between workers in this field. The process mejoramiento de los árboles forestales, es disponer do informa- of publication in scientific journals is likely to take a long ción precisa sobre el ndmero de cromosomas do los mismos. Los time, in view of the pressure for space in such journals. biotipos y poliploides cromosómicos so encuentran a veces en ciertas especies.Pero también hay casos en que dos razas con It is therefore suggested that a "Corresponding Commit- idéntico nilmero do cromosomas muestran diferenciasestruc- tee," similar to ones functioning under the Commonwealth turales.Esto suele tenor consecuencias de importancia en un Forestry Congress, be set up and that each interested programa de hibridización. La existencia do tales diferencias son reveladas sólo mediante un examen crItico do Ia meiosis del country be requested to nominate a representative. Sum- hIbrido. maries of discussions, review of work in progress, etc., Las formas poliploides han probado ser muy prometedoras en may be circulated once in four or six months to the ciertos géneros como ei Morus, Populus y Cryptomeria.La utilidad de los anfiploides para el mejoramiento do los árboles members by the Secretary. The Secretary may be chosen forostales, mediante la hibridizacnin do las especies entre si, no from among the nominees of the countries. In addition, ha sido totalmente explorada todavIa. Esto a pesar de que so the members may request information on special topics sabe bien quo en la naturaleza los anfiploides han hecho un papel do importancia en la evolucidn del reino vegetal. La técnica de la or problems of interest. embriocultura, para conseguir nuevas combinaciones hIbridas de cruzamientos, que no ocurren normalmente en la naturaleza, y lainducciónhaploidicaparadesarrollarsubsiguientemente References plantas homoroicas destinadas a la explotación de la heterosis, Barlow, B. A., 1958. Australian J. Bot. 6:38. son, sin embargo, otros do los medios quo podrian utilizarse con Muntzing, A., 1932. Hereditas, 16:105. éxito para el mejoramiento do los árboles. La apomixis, aunque por lo general desventajosa en el sentido do quo impide la re Stebbins, G. L., 1950. Variation and evolution in plants. Columbia combinación y la libertad do variación, resulta beneficiosa en Univ. Press. New York. determinadascircunstancias.Por consiguiente,esdoutilidad Upcott, M., 1936. J. Genet. 33:135. conocer elcontrol genético en este campo cuando so desea incorporar este tipo a lIneas seleccionadas. Acknowledgment A fin de facilitar el rápido intercambio internacional de datos, obtonidos en investigaciones que tal vez no hayan sido publicadas We are grateful to Shri R. N. Datta, I.F.S., President, Forest todavia en las revistas cientificas conocidas, so sugiere la creación Research Institute and Colleges, Dehra Dun, for his encourage- de una "Comisión de Corresponsales" similar a las quo funcionan ment to contribute this paper. en el Congreso Forestal do la Comunidad Británica.

Genetics and Tree Improvement 759 The Flowering of Some Clones of Beech (Fagus sylvatica L.)

J. D. MATTHEWS Forestry Commission of Great Britain, London, England

Introduction seed collections have shown these to be capable of pro- In 1951 a programme of selection and breeding in ducing viable nuts. Tree 170 was only 23 years old and beech was begun in Britain.Controlled pollination on has not borne viable nuts. mature beeches in the forest is often not practicable and, as a first step towards making controlled crosses possible, The Grafted Plants scions were taken from thirty-six plus trees and grafted The grafts fall into two groupsthose grafted in 1951 on to young seedling rootstocks to form clones genetically and 1954, respectively. In all cases branches two to three identical to the parents. The performance of the grafts feet long were taken from the middle part of the crowns derived from thirteen plus trees of various origins, ages of the parent trees. The method of grafting was the whip and sizes has been observed to determine their flowering and tongue graft using three- or four-year-old scion wood, behaviour, devise methods to bring beech grafts into about the thickness of a pencil and bearing two or more flower quickly and learn how to establish and manage seed dormant buds.The larger foliage buds were generally orchards of beech. removed from the scions. The rootstocks used in 1951 were three- or five-year-old transplants of mixed origin. The Parent Trees The successful grafts were lifted at the end of 1951 and planted at a spacing of ten feet x ten feet on a site close The location, ages and dimensions of the parent trees to the Alice Holt Research Station, Surrey. The grafts are given in Table 1. of 1954 were made on rootstocks also planted in 1951 on the same site. The scions were top worked at five to Table 1.Origins and dimensions of the parent trees six feet using the whip and tongue graft. Age Height Girth Using the performance of juvenile and mature beeches Tree No: Origin (in 1951) (ft.) (ft: in.) in the immediate neighbourhood as a guide, it is evident that the climate and soil conditions are favourable for 6 Kingscote Estate, Gloucestershire 135 109 4-10 both growth and initiation of flower buds in beech. 7 Kingscote Estate, The total number of grafts observed is 100, and the Gloucestershire 135 108 6-5 observations have extended from 1951 to the end of 1959. 20 Popes Wood, Gloucestershire 120 98 5-4 Flowering of Whole Clones 33 Cirencester Park, Table 2 shows the production of female flowers by the Gloucestershire 215 98 6-3½ 41 Goodwood Estate, Sussex 170 100 7-10 clones planted in 1951. 51 West Dean Estate, Sussex 125 95 5-0 65 Slindon Estate, Sussex 200 to Table 2.Total number of female flowers produced annually 230* 114 8-7 by whole clones. All were planted in 1951. 84 Penn Wood, Year of flowering Buckinghamshire 90 103 4-2 Clone 90 Maiden Bradley Estate, no. 5253 54 55 56 57 58 59 Totals Wiltshire 145 105 6-1 100 Ffrydgrech Estate, 6 0 0 0 0 0 0 10 0 10 Brecknockshire 135 90 10-5 7 00 0 0 0 0 0 0 0 107 Amberley Court, 20 0 0 0 0 0 0 4 0 4 Gloucestershire 135 * 100 8-0 33 0 0 23 6 134 9 1,120 391,331 160 Castle Bolton, Yorkshire 120 100 7-6 41 0 0 0 0 22 0 134 0 156 170 Micheldever Forest, Wiltshire23 24 - 51 0 0 15 15 22 8 1,655 85 1,800 0 97 *These trees were selected and measured in 1954. 84 0 2 2 0 0 0 101 90 0 0 0 0 7 0 537 0 544 100 0 0 0 0 0 0 6 0 6 All were good phenotypes, selected on a variety of sites 160 0 0 0 0 0 0 0 0 0 for their vigorous growth, good growth habit and freedom 170 0 0 0 0 0 0 0 0 0 from the important diseases and insect pests which attack beech. With one exception, all the trees were mature, and Totals 0 2 40 21 185 173,563 1243,952

760 Fifth World Forestry Congress Proceedings The growth of the grafts was slow in the year of graft- The effects of weather on flowering. Previous work by ing and also in the following season, but improved greatly Matthews (1955) on the flowering of mature beeches in in 1953.In spring 1953, clone 84 bore two female Britain pointed to the importance of temperature, rainfall flowers, and in 1954, in the fourth season after grafting, and sunshine in June, July and August of the year prior clones 33 and 51 began to flower. These two clones have to flowering.The appropriate meteorological data for since flowered every year. Clones 6, 20 and 100 did not South-east England is given in Table 3, and it will be seen bear flowers until the eighth spring after grafting, and that the above-average temperatures and duration of sun- clones 7, 160 and 170 have remained barren throughout shine and below-average rainfall during the summers of the nine years of study. 1955 and 1957 are reflected in the increased number of Following Schaffalitsky (1959), who found that the fruitful clones and heavier flowering by those clones in retention of dead leaves during winter is a feature of the 1956 and 1958. juvenile growth phase in beech, it can be said that those Table 3.Meteorological data from District 5, South-east parts of the grafts above the graft union were, with the England.(Derived from the monthly weather reports exception of clone 170, in the adult phase, i.e., the leaves of the meteorological office.) were not retained during the winter. By contrast, those Air temperatureRainfallSunshine shoots of the rootstocks which were allowed to develop duff, from percentagepercentage Flowering of below the graft union were markedly juvenile in this Month average ofaverage of average the grafts respect, the dead leaves being strongly retained during (°F.) (%) (%) 1954.3 clones: winter after all those of the crown above the graft union June 1 -0.1 90 83 July l953 -1.4 145 100 40 female had been lost. The lack of flowering in clone 170 may be August J +0.8 92 124 flowers partly explained on the basis of the young physiological June 1 -1.8 158 73 1955.2 clones: age of the parent tree and scions, but other factors must July l954 -3.6 123 72 21 female August -2.2 141 79 flowers be considered to explain the behaviour of the other clones. J June 1 -0.4 116 82 1956.4 clones: Among the more obvious are size of graft, the weather of July p1955 +1.8 50 124 185 female the season before flowering and effect of rootstock. August 1 +3.4 42 107 flowers

The effects of size of graft. After two seasons of slow June 1 -2.0 96 69 1957.2 clones: July 1956 -0.7 152 86 17 female growth the scions grew much more rapidly, and height August -3.4 150 90 flowers growth increased to an average of two feet each year. By J June 1 -2.3 63 134 1958.8 clones: the fourth season the grafts had developed a relatively July p1957 -1.3 173 85 3563 female simple shoot system consisting largely of long shoots, Augustj -0.4 126 91 flowers often of considerable vigour. After the grafts had attained June 1 -0.9 223 71 1959.2 clones: July 4958 -0.8 82 99 124 female a height of six feet or so, short or spur shoots* of limited August J -0.3 154 65 flowers growth became plentiful in the lower part of the crowns. In the case of most clones the increase in age and size Artificial stimulation of flowering. In early May 1957, was associated with a rapid increase in the complexity of pairs of grafts of the same or similar size in height and the shoot system and especially in the proportion of stem basal diameter were marked, and on 24th May, the branches bearing short or spur shoots. As will be shown stem of one graft of each pair was partially girdled-two later, the majority of the flowers, both male and female, half-girdles being made one inch apart.If the clone had are borne on these short shoots of limited growth. previously been fruitful, the girdling did increase male The clones varied greatly in the numbers of short and female flowering in 1958 by from four to eight times. shoots. In 1958, counts were made on sample branches, If the clone had not flowered previously, the girdling did and the numbers ranged from four short shoots per long not bring it into flowering in 1958. shoot in a barren clone, through six per long shoot on a clone which had just come into flowering, to thirteen per Flowering Within Clones long shoot on a heavily flowering clone, The preponder- Clones 33 and 51 have flowered regularly since 1954, ance of short shoots gives a characteristic appearance to and a record has been kept of the female flowers produced the flowering clones. by each graft. The figures are given in Table 4. That size is important is suggested by the performance The individual grafts have varied greatly in the age at of the 1954 grafts on which scions of clones 107 and 85 which they began flowering and in total production of were top worked on to large established rootstocks. By flowers. Within clone 33, the regular production of graft 1957,thesegrafts had developed crowns not much B is in marked contrast to the biennial flowering of grafts smaller than those of the 1951 grafts, and flowering in A, D and H. Grafts C, E and J have been relatively less 1958(in the fifth season after grafting) was prolific, productive than the remainder. In 1956 and 1958, all especially on clone 107. the grafts of clone 33 flowered. It appears, therefore, that to become fruitful, the grafts In clone 51, there is again extreme variation in the must attain a certain age or size, or both, this being flowering of the individual grafts.In both clones, some linked with the development of a complex shoot system. of this variation is related to the dimensions of the grafts, Then, external stimuli are required to cause the initiation the largest grafts having borne the most flowers and nuts. of flower buds, and one stimulus is provided by weather Ifthepartially-girdledtreesaredisregarded,three- conditions. quarters of the female flowers have been borne by the three biggest grafts of clone 33 and one-half by the three *A short shoot is one having an annual growth in length of biggest grafts of clone 51. 0.5 cm. or less (Muller, 1947). This picture of variable production is similar to that Genetics and Tree Improvement 761 in fruit orchards before the use of selected standard root- flower buds could be identified during the late summer stocks, and much of the variation in size and flowering of 1957.In anticipation of their development in 1958, of the grafts is probably due to the rootstocks. For beech diagrams were prepared of the branch systems of all the seed orchards this lack of uniformity in flower production grafts. As the flowers appeared in the spring their position is not desirable, and, in the long run, some selection and and numbers were plotted, and in this way a picture of standardisation of rootstocks will be necessary. To study their distribution was obtained. Table 5 summarises the the selection of rootstocks, scions of two clones were results. grafted in 1954 on to rootstocks in a replicated trial of On grafts eight to ten feet tall the generalised pattern several seed origins of beech; and in 1958, a possible of growth and flowering consists of: method of propagating desirable standard rootstocks was An upper zone of vegetative growth, corresponding tried. The root system of a ten-foot-tall graft was bared, roughly to the upper one-third of the crown, in which and the horizontal roots were severed at two feet from vigorous long shoots are plentiful and short shoots are the stem. Sucker shoots developed from the intact parts relatively few. Flowers are also relatively few. The pro- of the roots, and these shoots have been rooted. portion of male to female flowers is about three to one. A middle zone of moderate vegetative growth and Table4.The female flowers produced by individual grafts moderate flowering, corresponding roughly to the middle within two clones. one-third of the crown, in which the long shoots are less vigorous and short shoots are more plentiful. Here male Graft Clone 33 Cirencester and female flowers develop in the proportion of four to no. 53 54 55 56 57 58 59Totals one. A 0 2 0 27 2 306 11 348 A lower zone of heaviest flowering, corresponding B 0 6 3 6 5 68 4 92 roughly to the lower third of the crown, in which short C 0 0 0 1 1 49 0 51 shoots are plentiful and vigorous long shoots are relatively D 0 6 1 43 0 165 12 227 few. Here male and female flowers are produced in the E 0 0 0 1 0 42 6 49 proportion of four to one. F 0 1 1 0 0 0 0 0 Table 5 shows that flower distribution varies from G 0 0 0 39 0 2339 5 383 clone to clone (and it also varies from graft to graft with- H 0 9 0 15 0 120 0 144 in clones). Clone 84 flowered well for the first time in J 0 0 2 2 1 31 1 37 1958, and virtually all the flowers were borne in the Totals 0 23 6 134 91,120 391,331 lower one-third of the crown. Clone 33 had flowered for some years, and the upper vegetative zone was relatively small; one graft bore flowers right out to the tops of all Graft Clone 51 West Dean the branches, and the leading shoot also bore female no. 53 54 55 56 57 58 59Totals flowers.The lower crowns of some grafts of clone 6 A 0 0 0 0 3 45 46 94 became partially shaded from 1957 onwards and this B 0 0 5 0 4 124 0 133 reduced flower production in the lower crown. C 0 0 0 0 0 7 3 10 Conclusions D 0 4 5 0 0 133 14 156 E 0 0 0 0 7 7 It appears that, in Britain, the first good flowering of F 0 0 0 0 0 55 1 56 beech clones which are in the adult phase of development G 0 0 0 3 0 135 3 141 cannot be expected until the grafts are between five and H 0 11 0 17 1 292 10 331 eight years old and from eight to twelve feet tall.The J 0 0 5 2 0 2864 1 872 graftsshould therefore be encouraged to reach big dimensions quickly, and the methods which suggest them- Totals 0 15 15 22 8 1,655 851,800 selves are: 1 These grafts died in 1954 and were replaced in 1956. The Scion material should be taken from vigorous, well- scion material was collected from another graft in the clone. grown and fruitful branches in the middle or upper crowns 2 These grafts were subjected to a partial girdling treatment in of the parent trees. May 1957. If possible, graft the scions on to vigorous estab- lished rootstocks eight to ten feet tall. Flowering Within Individual Grafts When grafting on small rootstocks, employ cultural In spring 1958, fifty of the 100 grafts bore male and techniques which lead to strong vegetative growth, e.g., female flowers, some of them in great numbers. Because grafting under glass and using supplementary light and of their greater size, and in particular their fatness, the heat.

Table 5.The distribution of male and female flowers on grafts of six clones (expressed as percentages of total flowers).

All clones Proportion of Clone: 6 33 41 51 84 90 males to Position M F M F M F M F M F M F M F females Upper crown 0 0 6 9 2 4 1 1 0 0 1 1 2 3 3:1 Middle crown 59 70 31 31 23 17 27 29 0 1 27 25 29 29 4:1 Lower crown 43 30 63 60 75 79 72 70 100 99 72 74 69 68 4:1

762 Fifth World Forestry Congress Proceedings 4. Encourage the development of a complex shoot a dté observée afin de (a) determiner leur comportement en cours de fioraison,(b)mettre au point des méthodes permettant system in the lower part of the crown. Retain and favour d'accélérer la fioraison des greffes de hêtre, et (c) constituer des the lower branches of the scion by keeping the grafts at pépinières de graines. a wide spacing and allowing plenty of light to reach the Il existe une grande variation entre les clones, a la fois en lower crown. ce qui concerne le moment de la premiere floraison et la pro- portion de fleurs males et femelles. Itisclear that seed orchards of beech should be Ii semble qu'afin de devenir fécondes, les greffes doivent established on sites favourable to both the growth and atteindre un certain age ou une certaine taille, ou encore une flowering of the grafted plants. Spacing is important, and combinaison de ces deux facteurs, ce qui demande un système for a satisfactory early yield, ten by ten feet appears to complexe de boutures. De nombreuses fleurs des deux sexes apparaissent sur de be a suitable initial spacing. The arrangement of the "petites pousses" situées a la partie inférieure et médiane de la clones should permit removal of half the seed trees when cime. they have attained a height of fifteen feet and a further La floraison de la plupart des greffes a eu tendance a être thinning to achieve a final spacing of at least forty feet. biennale et fonction des conditions météorologiques des mois de Finally, it must be pointed out that five of the thirteen juin, juillet et aoftt de l'année la précédant. Une incision circulaire partielle du tronc a accru la pro-- clones studied have not yet flowered, and observations on duction de fleurs des clones ayant déjà eu une fioraison antérieure. them continue.Additional treatments being studied are L'auteur, en se fondant sur ces etudes, avance quelques proposi- geotropic manipulation of the branches, choice of root- tions relatives a la creation de pépinières de hétres producteurs de stock and, later, the application of fertilisers. graines. References Florescencia de Algunos Clones de Haya (Fagus sylvatica Matthews, J. D., 1955. The Influence of weather on the frequency L.) of beech mast years in England. Forestry 28, 2, 107-116. Se ha observado la fiorescencia de trece clones de haya (pro- Muller, D., 1947. The short shoots of beech. Dansk Skovforen- ducidos por el injerto de renuevos de árboles adultos en árboles ings Tidsskrift 32, 11, 363-365. jóvenes) con el fin de a) determinar el proceso de la fiorescencia, Schaffalitsky,M.,1959. Investigationsonagingofapical b) idear métodos para que los injertos de haya fiorezcan con más meristems on woody plants and its importance in silviculture. rapidez y c) establecer huertos para semilleros. Reprint from Det Forstlize ForsØgvaesen i Danmark 25, 4, Los clones varlan muchIsimo en cuanto al tiempo de la 310-455. Copenhagen. primera fiorescencia y la cantidad de fibres hembra y fibres macho que producen. Acknowledgment Parece que para ser productivos, los injertos deben alcanzar cierta edad y tamaflo, o ambas cosas, lo cual se relaciona con el Thanks are given to Professor P. F. Wareing and Mr. desarrollo de un sistema complejo de renuevos. K. A. Longman of University College of North Wales, Muchas fibres de ambos sexos brotan de "renuevos cortos", Aberystwyth, for reading and commenting on this paper. situados en las partes baja y media de la copa. La fiorescencia de la mayorIa de los injertos tendió a ser RESUMES bienal y relacionada con las condiciones del tiempo en los meses de junio, julio y agosto del aflo anterior. La floraison de quelques clones de hétre (Fagus sylvatica Los anillados parciales aumentaron la producción de fibres L.) en clones que habIan fiorecido antes. La fioraison de treize clones de hêtre (produits par greffage de De estosestudiossederivanalgunasproposicionespara scions provenant d'arbres adultes sur des porte-greffes très jeunes) establecer huertos para semilleros de haya.

Resultados Obtenidos con la Introducción de Semillas De Especies Forestales Exdticas

HECTOR R. MANGIER! Ingeniero Agrónomo, Administración Nacional de Bosques, Secretarla de Agricultura y Ganaderla, Reptiblica Argentina

La base principal para plantar y resolver el problema mental en toda la amplitud de nuestro vasto territorio. forestal en nuestro pals, es la aclirnatación e implantación Considerando quenuestrosuelorednetodoslos de las especies más adecuadas a nuestro suelo, a nuestro requisitosparacultivarárbolesdelgénero Pinus y clima y a las perspectivas de nuestro comercio, procu- teniendo en cuenta que este revestIa una gran importan- rando para ello que la introducción de aquellas esencias cia desde el punto de vista forestal y económico, tanto en inexistentes constituyan a Ia vez una fuente de riqueza, el ndmero de especies que lo integran como por las a! evitar la salida de millones en divisas al exterior. distintasaplicaciones de su madera, se introdujo por Fué asI que desde el comienzo de Ia creación de los primera vez en el año 1938 de Estados Unidos, el Pinus servicios forestales en la Repdblica Argentina se promovió elliottii,ilamado incorrectamente Pinuscaribaea.Su La introducción e intercambio de semillas con entidades cultivo se extendió en nuestra zona del litoral, abarcando forestales del extranjero, a fin de iniciar la etapa experi- grandes superficies, principalmente en Misiones y Delta Genetics and Tree Improvement 763 del Paraná, donde ha demostrado buen crecimiento y otras especies de gran valor que por sus caracterlsticas de marcada plasticidad, como ser resistencia a la excesiva crecimiento y propiedades de aplicaciOn de sus maderas, humedad del suelo, en lugares bajos, temporariamente resultaban ser las más indicadas para nuestras necesi- inundables, asI como resistencia a la sequIa. Es de cre- dades. cimiento rápido y muy resistente a los ataques de enfer- En ndmero de más de 200 especies diferentes se intro- medades o plagas coino asImismo a la acción del fuego. dujeron del continente australiano desde la fecha indicada Pinus patula. En Misiones donde se está encauzando, hasta nuestros dIas, donde cada vez es mayor el inter- tiene un crecimiento muy rápido siendo atacado algo por cambio, canje y adquisición de semillas con todos los Ia larva que destruye Ia parte apical de los brotes. Las Servicios Forestales de aquel pals. primeras semillas, que no fueron muchas, se trajeron de Entre las especies introducidas indicaremos las más Mexico, cultivándose en la provincia de Buenos Aires importantes, y las que principalmente nos conviene incor- donde parece no aclimatarse, dado que muchos ejem- porar a las ya existentes: E. regnans, se trata de un árbol plares sucumben después del quinto y sexto año. sumamente interesante que estamos cultivando con todo Pinus palustris. Los primeros ensayos con esta especie exito en la regiOn austral, su crecimiento es bastante productora de excelente madera y resina, se efectuaron en rápido y ha demostrado ser resistente a los frlos y bajas la region de nuestro Delta del Paraná, con semilla intro- temperaturas; en idénticas condiciones se viene compor- ducida del Sudeste de los Estados Unidos. Los pocos tando el E. gigantea en la misma zona. Estos dos árboles ejemplaresobtenidoscrecieron muy deficientemente, tienen un crecimiento vigoroso en su lugar de origen. descartando toda posibilidad de asegurar su aclimatación Existiendo otras especies de eucaliptos que podrian económica en esa zona. En Misiones, plantaciones reali- reemplazar a nuestro quebracho colorado, para ser utiliza- zadas posteriormente han demostrado que hasta los 10 dos en Ia elaboraciOn de durmientes, sin previo trata- años, su desarrollo es lento pero pasado ese tiempo se miento preservativo, se introdujeron especies del grupo acelera notablemente, alcanzando grandes dimensiones. "Ironbark."Este grupo que comprende los Eucalyptus Otras especies de pinos, el Pin us merkusii y ci Pinus crebra,siderophloia,paniculata,sideroxylon,etc.,se khasya, intrOducidas hace poco tiempo, aün en ensayo, vienen ensayando en nuestros establecimientos de experi- no permiten hacer enunciado alguno sobre su adaptación. mentaciOn,destacándosecon gran sucesoestosdos Taxodium mucronatuni. El Servicio Forestal de Mexico iiltimos por su rapidez de crecimiento,el primero en nos hizo llegar en el año 1938 semillas del famoso Ahue- Misiones, el segundo en Mendoza, Córdoba, San LuIs, huete, árbol nacional de dicho pals. Esta especie que se etc. ha plantado en la region del Delta del Paraná, ha alcan- Otra especie de eucalipto que ha despertado nuestro zado mayores dimensiones que el ciprés calvo (Taxodium interés es el E. macrorhyncha, habiendo observado que distichum). Estos árboles se han aclimatado rápidamente tiene un crecimiento inferior a las otras especies, pero su en la region señalada. valor reside en el follaje que contiene RutIn, substancia Agathis robusta o "Kauri". En los parques y plazas de cristalina de color amarillo, de propiedades antihemo- La ciudad de Buenos Aires, existe un árbol esbelto de rrágicas.Esta especie está siendo experimentada con aspecto piramidal que posee follaje permanente, color buenos resultados. verde oscuro o brillante, se trata del Agathis robusta o Para explotar industrialmente como productoras de "Kauri," planta del grupo de las conlferas. Esta especie aceites esenciales, se introdujeron las especies macarthuri, sOlo ha sido multiplicada por injerto sobre Araucaria dives, australiana, etc., como asi también otras para ser angustifolia, por cuanto pertenece a la familia Araucaria- utilizadas en la elaboraciOn de postes, construcciones cea;seintrodujosemilla procedentedel Estado de civiles,parquets, envases, pavimentos,etc.,E. ovata, Queensland (Australia) de donde es originaria, después E. maideni, E. pilularis, E. grandis, E. deanei, E. manni- de multiples gestiones.Se encuentra sometida a ensayo fera, E. alba, E. propin qua, E. deglupta, E. algeriensis, en Ia region litoral argentina, dado que es apropiada E. diversicolor, E. marginata, E. gunni, E. punctata, E. para clima templado, no pudiéndose emitir juicio sobre obliqua, etc. su comportamiento dado el corto tiempo transcurrido Con respecto a estas especies, no obstante los buenos desde su importaciOn. Otra especie, el Agathis australis, y alentadores resultados obtenidos en lostrabajos de conocido como "Kauri de los neozelandeses," introducido investigaciOn realizados hasta la fecha, dado el corto recientemente, también se halla en experimentaciOn. lapsodesdesuintroducciOn,laexperimentaciónes Araucaria cunninghamii. Desde hace aproximadamente todavla discontlnua e incompleta. 4 afIos tenemos esta esencia cuya semilla se importO del Alamos.Resulta sumamente interesante destacar la EstadodeQueensland(Australia).Losresultados importancia adquirida en la Argentina por el cultivo de obtenidos son satisfactorios.La aclimatación de esta las Salicáceas, destacándose en forma notable los álamos especie seria factible en la provincia de Misiones, donde (género Populus). A raiz de la desfoliaciOn sufrida en desarrolla bien. el alamo criollo (Populus nigra cv. itálica), en la zona del Eucaliptos. En lo que se refiere al género Eucalyptus, Delta por la acciOn de las royas, se introdujo a nuestro fueron introducidos en nuestro pals, a partir del aflo 1856. pals en 1937 el alamo hIbrido italiano "A M" (P. xeura- La iniciación y adaptación en la Argentina, de los eucalip- mericana cv 1-154). Este árbol demostrO desde su prin- tos, data de más de 100 años.Las especies de más cipio gran resistencia a Ia enfermedad citada y extraor- antigua introducciOn, boy mayormente difundidas por sus dinario desarrollo.Su cultivo se difundiO ampliamente aptitudessilvicolasy elevados rendimientosson:E. entre los cultivadores isleños, sin embargo, boy después camaldulensis, E. viminalis, E. tereticornis, E. glob ulus, de más de 20 años de su introducciOn, debido a la presen- E. saligna, etc., A partir del año 1949 se incorporaron cia de la Septoria (chancro del tronco) se le está reem-

764 Fifth World Forestry Congress Proceedings plazando por otros tipos, entre ellos, el alamo 214 (P. zando en Misiones, con esta esencia productora de una xeuramericana cv 1-214), introducido hace pocos años, de las mejores maderas de Brasil, están fundamentados que se adapta a diferentes clases de suelos y crece muy por el hecho de disponer en ci pals con condiciones vigoroso, poseyendo una mejor conformación, menos ecolOgicas similares a la de su habitat. susceptible al ataque de Septoria y con madera de mejor calidad que el A.M. RESUMES Robinia pseudoacacia var. rectissima. En el año 1937 Results Obtained by Introducing Seeds of Exotic Forest desde los Estados Unidos de Norte America fué introdu- Species cida a! pals la Robinia pseudoacacia var. rectissima. El To introduce, experiment with, and distribute throughout the material recibido no eran semillas sino trozos de raices, country the greatest possible number of exotic forest species hav- por cuanto la citada especie no las produce fértiles. Las ing an economic value has always been one of the goals we plantasobtenidasdesarroilaron muy bien con fustes have proposed to achieve for the benefit of our forest economy. rectos y altos sin ramificaciones. Su difusión no alcanzó All types of soils and a varied climate are found in the Argentine Republic, which has enabled us to introduce a diverse las caracterlsticas de otras especies en razón del motivo number of exotic forest species. Beginning with the genus Pin us, señalado,perolospocos cultivosrealizados que se Pin us elliottii, palustris, khasya, ,nerkusii, and patula were intro- encuentran actualmente en la provincia de Buenos Aires, duced into the country, these being trees of great forest and han demostrado su alto valor forestal, superior a la de la economic value. A large number of species of eucalyptus have also been imported; since 1949, our collection has increased to propia acacia blanca (Robinia pseudoacacia). more than 200 species, among the principal of which are E. . A pesar de contar con una especie regnans and gigantea. Other outstanding species are E. sideroxy- tanante de primer órden como es nuestro quebracho Ion and E. paniculata, because their wood has natural durability colorado (Schinopsis balansae), hemos prestado siempre and need not be treated with preservatives. Among the poplars, the "Arnaldo Mussolini" was introduced La atención por aquellas otras especies exóticas produc- to be cultivated in place of the native poplar in our Paraná toras de tanino.Si bien se cuenta en el pals con plantas Delta, but recently it has been replaced by poplar 214. de Acacia mollissi,na, excelente árbol curtiente, se intro- Other species of incalculable value and known results are the dujo por primera vez la Acacia pycnantha originaria de Ulmus pumila, Taxodium niucronatum, A.M. and 214 poplars, La region sud de Australia. Hasta el presente, a pesar de and Robinia pseudoacacia var. rectissima. A great deal of re- search has been carried out concerning Acacia pycnantha, Ocolea cultivársela en regiones similares a la de su habitat, no porosa, Agathis rob usta, Agathis australis, Araucaria cunning- parece acomodarse, creciendo con relativa lentitud. ham ii,and various species of eucalyptus, in order to ascertain Acer saccharum. No existiendo en ci pals ejemplares their results in an ecological site similar to that of their natural de sugar maple (Acer saccharum), especie muy valiosa habitat. ampliamente difundida en Estados Unidos de Norte America y Canada, se consideró la posibilidad de intro- Résultats obtenus grace a l'introduction de semences ducir esta especie con el objeto de ensayarla en la region d'espèces forestières exotiques de los bosques subantárticos. A lines de 1958 se obtuvo Introduire, experimenter et propager sur toute l'étendue du pays le plus grand nombre possible d'espèces forestières exotiques, una pequefla remesa de semillas las que se sembraron en telle a toujours été l'une des tâches a la rdalisation de laquelle nuestra Estación Forestal General San Martin, en Rio nous avons apporté nos plus grands efforts, dans l'intérêt de notre Negro.Los resultados obtenidos han sido de lo más économie forestière. promisorios, alcanzándose un alto poder germinativo y un Du point de vue édaphique, on trouve, dans la République rendimiento elevado de plantitas de aspecto lozano y argentine, des sols de tous types, comme aussi des climats varies, ce qui nous a permis d'y introduire une grande varibtd d'espèces vigoroso. forestières exotiques. En commencant par le genre Pinus, on a Ulmus pumila. Procedente de los bosques de Siberia, introduit dans le pays Pinus elliottii, palustris, khasya, merkusii et fué adoptado por nuestros Servicios Forestales en 1944. patula, qui constituent des arbres de grande valeur forestière et économique. Les eucalyptus ont dgalement joué une role d'une Su cultivose extendió, principalmente a lasregiones très grande importance, en ce qui concerne le nombre des espèces semiáridas de las provincias de San Luls, Córdoba, y La irnportées, notre collection s'dtant accrue depuis 1949 de plus de Pampa, donde ha demostrado condiciones muy sobresa- 200 espèces parmi lesquelles les principales a mentionner pour- lientes y un crecimiento regular, aim en épocas de sequlas raient être E. regnans et gigantea. D'autres espéces notables sont prolongadas. E. sideroxylon et E. paniculata, du fait que leur bois remplit les En las observaciones practicadasse ha conditions de durabilité naturelle, ce qui rend inutile un traitement constatado que crece en toda clase de tierras, tanto corn- au moyen de substances préservatrices. pactas como arenosas. En médanos se han visto cre- Parmi les peupliers, on a introduit l'Arnaldo Mussolini, pour cimientos extraordinarios, comprobándose un perfecto de- êtrecultivé, au lieu du peuplier natif,dans notre Delta du sarrollo en tierras salitrosas. Parana, mais dernièrement on a commence a le remplacer par le peuplier 214. Ocotea porosa. De los Estados Unidos del Brasil se Parmi losautres espèces d'une valeur inappreciable et d'un gestionó en ci año 1950 Ia introducción de un árbol que rendement connu, iifaut noter I'Ulmus pitmila, Jo Taxodium crece en los Estados de Paraná y Santa Catalina, en con- mucronatum, les peupliers AM. et 214, le Robinia pseudoacacia sociaciones con el pino paraná (Araucaria angustifolia), var. rectissima. Un travail approfondi de recherche est en voie de réalisationsurlesespèces Acacia pycnantha, Ocotea porosa, La Ocotea porosa, conocida vulgarmente con el nombre Agathis robusta, Agathis australis, Araucaria cunninghamii et de "imbuia."Esta especie crece bien rápidamente, las diverses espèces d'eucalyptus afin d'en connaitre le rendement posibilidades de éxito en los ensayos que se vienen reali- dans des milieux écologiques semblables a leur milieu naturel.

Genetics and Tree Improvement 765 Especies Forestailes Exóticas en Experimentación En La Repüblica Argentina

Fi&NcIsco JUAN CERsosIMo ingeniero Agrónomo, Administración Nacional de Bosques, Secretaria de Agricultura y Ganaderla, Repáblica Argentina

En distintos establecimientos dependientes de Ia Direc- Corn portamiento:Las han dado resultado ción de Investigaciones Forestales, de la Administración negativo, por helarse fácilmente.Sobre la Araucaria Nacional de Bosques, se ileva a cabo una serie de expe- bidwillii, por ser reciente su plantación, no se puede aün riencias y ensayos silvIcolas, comentándose en este informe opinar. Los Cupressus se desarrollan bien, destacándose los relacionados con especies exóticas. ci C. lusitanica. Entre los Eucalyptus, los mejores resul- Con ellas se han formado parcelas experirnentales a tan E. sideroxylon (for blanca y rosada), E. viminalis, fin de conocer sus grados de adaptabilidad y poder E. tereticornis y E. leucoxylon; y los de menor adaptación efectuar luego estudios de crecimientos e incrementos son E. saligna, E. globulus, E. pilularis y E. crebra. Las volumétricos. restantes especies son de resultados poco satisfactorios, Se mencionarán a continuación las parcelas de especies con excepción de Melia azedarach y Ulmus purnila que exóticas existentes en algunos de esos establecimientos y presentan una buen crecimiento. los resultados obtenidos, describiéndose asImismo breve- Estación Forestal Leandro N. Alern (provincia Misio- mente la posición geográfica de cada uno de ellos y los nes). Ubicación: 55° 20' longitud Oeste; 27° 35' latitud factoresclimáticosyedáficos más importantesque Sur; altitud de 220 metros. Region fitogeográfica de la infiuyen sobre las plantaciones. Selva Misionera.Clima:subtropical, cálido y hümedo. Estación Forestal Presidencia de la Plaza (provincia Precipitación media anual de 1.700 milImetros, distribui- Chaco). Ubicación: 590 50' longitud Oeste; 27° latitud dos más o menos regularmente a través de todo el año. Sur;altitud de 80 metros sobre nivel mar.Region Temperatura media anual de 21° C.; maxima absoluta fitogeográfica del Parque Chaqueno, en la zona de transi- de 41° C. minima absoluta de 6,6° C. PerIodo con ción entre la oriental y occidental, es decir, entre la heladas de mayo a septiembre, con una frecuencia media region hümeda y semiárida.Clima: subtropical, con de 10 dIas en el aflo. Suelo: formado a partir de meláfiros variaciones bruscas de temperatura. Precipitación media y areniscas rojas intercaladas; textura arcillosa y arcilo- anual de 900 milImetros; inviernos secos (12 mm. en arenosa; preponderantemente rojo, laterItico y ácido. agosto) y veranos lluviosos (200 mm en febrero). Tern- Especies en ensayo:Ailanthus altissima; Casuarina peratura media anual de 21° C.; maxima absoluta de 43° cunningharniana; Cupressus macrocarpa, C. sempervirens C. y minima de 6,5° C.Son frecuentes las heladas var. horizontalis; Elaeagnus angustifolia; Eucalyptus al- de efectos desastrosos sobre la vegetación. Suelo: proce- geriensis, E. carnaldulensis, E. globulus, E. leucoxylon, E. dente de material loésico; textura arcillo-areno-humIfera; rob usta,E. sideroxylon, E.tereticornis, E.virninalis; carácter podsólico pardo. Fraxinus americana, F. excelsior; Me/ia azedarach; Pinus Especies en ensayo: Acacia aneura, A. mollissima, A. hale pensis, P. pinea; Populus a/ba var. bolleana, P. betuli- pycnantha; Araucaria bidwillii; Cupressus lusitánica, C. folia,P.canadensis,P.caroliniana,P. euramericana macrocarpa; Eucalyptus algeriensis, E. Astringens, E. 1-154, P. eurarnericana 1-214, P. laurifolia, P. nigra var. bosistoana, E. camaldulensis, E. cinerea, E. citriodora, E. italica, P. tremuloides; Quercus suber; Robinia pseudoa- crebra, E. diversicolor, E. globulus, E. kirtoniana, E. cacia; Salix alba var. coerulea; Ulmus pumila. leucoxylon, E. marginata, E. melliodora, E. paniculata, La mayoria de las parcelas son de un cuarto de E. pilularis, E. punctata, E. redunca, E. Resinif era, E. hectarea, datando las primeras de 1949, habiendo estado rudis, E. saligna, E. sargenti, E. siderophloia, E. sideroxy- las mismas supervisadas por los sucesivos directores del lon (for blanca), E. sideroxylon (for rosada), E. tereti- establecimiento, Ings. Agrs. Roberto V. Carretero, Juan cornis, E. viminalis; Fraxinus americana; Me/ia azedarach A. Araujo y Armando C. Leytes. var. gigantea; Pinus elliottii, P. taeda; Quercus suber; Comportamiento:Los mejoresresultadossehan Tectona grandis; Ulmus pumila. obtenido con los Pop ulus y Eucalyptus, destacándose entre Las plantaciones se iniciaron en el año 1949, pero la ellos el P. euramericana 1-214, que se ha difundido por mayorIa de ellas, especialmente de Eucalyptus, se efec- toda la zona, y E. camaldulensis.El E.tereticornis tuaron en 1955, bajo la supervision del actual Director del creció bien durante los primeros años, pero luego se ha establecimiento, Ing. Agr. John Henry Ewens, a cuyo mantenido estacionario, y el E. sideroxylon al contrario, cargo se halian los ensayos. La superficie de cada parcela mejoró notablemente después de los dos primeros años es variable, siendo en su mayor parte orientativas, con de crecimiento regular. Las especies restantes se compor- reducido námero de ejemplares. tan poco satisfactoriamente,excepto Salixalbavar.

766 Fifth World Forestry Congress Proceedings coerulea de muy buen desarrollo, y Robinia pseudoacacia. var. latifolia, P. griffithii, P. jeffreyi, P. nigra var. aus- Estación Forestal Fernández (provincia Santiago del triaca, P. ponderosa, P. radiata, P. rigida, P. thunbergii; Estero).Ubicación: 63° 55' longitud Oeste; 27° 55' Pseudotsuga menziesii; Quercus robur, Sequoiadendron latitud Sur; altitud de 160 metros. Region fitogeográfica giganteum, Thuja gigantea; Ulmus pumila. del Parque Chaqueno, zona occidental. Clima: tipo con- Las primeras plantacionesse efectuaron en 1953, tinental, templado o templado-cálido, seco, con grandes aunque muchas parcelasson dereciente formación, variaciones diurnas de temperatura. Precipitación media especialmente las de Eucalyptus. Los ensayos se efectuan anual de 520 milImetros; inviernos muy secos (2 mm en en dos clases de parcelas distintas, unas de "experimenta- agosto); veranos más hümedos (103 mm. en febrero). ción" de un cuarto de hectárea, y otras de "orientación" Temperatura media anual 21° C.; maxima absoluta de de menor superficie, con una cabida de aproximadamente 44° C. y mInima de 6° C. Heladas de mayo a septiem- 400 plantas, bajo ba supervision del Director del estableci- bre, con una frecuencia media de 12 dIas en el año. miento, Ing. Agr. Ricardo Jungwirth. Suelo: formado por materiales sedimentarios, con pre- Comportamiento:Los mejoresresultadossehan dominio de bess,limos y arenasdeIa formación pampeana. obtenido con las Piceas (excepto P. excelsa) y con los Especies en ensayo: A cacia pycnantha; Casuarina cun- Pinus contorta var. latifolia y P. ponderosa, y con Pseu- ninghamiana, C. montana, C. stricta, C. torulosa; Cupres- dotsuga menziesii.Entre los Eucalyptus se destacan el sus sempervirens var. horizon talis, Eucalyptus botryoides, E. viminalis, E. regnans y E. gigan tea, aunque, como casi E. camaldulensis, E.citriodora, E. crebra, E. hemi- todos son de reciente plantación, no se puede emitir aim phloia, E. macrorhyncha, E. maideni, E. paulistana, E. un juicio definitivo. Igual sucede con las especies restan- resinif era, E. robusta, E. rudis, E. saligna, E. tereticornis, tes, que en la actualidad presentan un estado de desa- E.viminalis;Fraxinusamericana;Meliaazedarach, rrollo regular. Pinus halepensis; Populus angulata, P. canadensis, P. nigra, Estación Forestal Castelar (provincia Buenos Aires). P. nigra var. stella; Quercus suber; Robinia pseudoacacia; Ubicación: 58° 40' longitud Oeste; 34° 40' latitud Sur; Ulmus pumila. altitud de 30 metros. Region fitogeográfIca de Ia Estepa Las experiencias, que están a cargo del Director del Pampeana. Clima:templado y huimedo. Temperatura establecimiento Ing. Agr. Julio Alonso, se efectñan en media anual de 16° C.; maxima absoluta de 40° C. y tres diferentes clases de parcelas: (1) de orientación, con mInima de 6° C. Precipitación media anual de 970 100 ejemplares; (2) de observación, con casi mil indivi- mm, con inviernos secos (42 mm. en julio) y veranos- duos; v (3) para ensavos de distancias, con nümero varia- otoños lluviosos (120 mm. en marzo). Heladas de abril a ble de árboles. Se iniciaron en ci año 1944, siendo en octubre, con frecuencia de 10 dias en el año. Suelo: tipo su gran mayorIa posteriores a esa fecha. chernozem, desarrollado sobre material boésico; es pro- Comportamiento.De lasCasuarinas,laque más fundo y de textura areno-arcillosa. rápido crece es la C. cunninghamiana (a los 5 años, 8 metros de altura y 12,5 cm. de DAP), habiendo fracasado Especies en ensayo y comportamiento: Existen nu- casi totalmente la C. montana. Casi todos los Eucalyptus merosas parcelas, en su mayorIa de pequena superficie, las han adquirido buen desarrollo, siendo uno de los géneros primeras de las cuales datan de 1949; la formación de las que más se adapta a la zona, destacándose E. camaldulen- mismas ha estado a cargo del señor Juan R. Barriero, cx sis, E. resinif era, E. macrorhyncha, E. tereticornis, E. Encargado y actual Jefe de Plantaciones del estableci- viminalis y E. robusta. El Ulmus pumila crece muy bien miento. En verdad constituyen un arboretum, y asI las (a los 5 años, 8 m. de altura y 15 cm. de DAP). Las agruparemos, no dando la nómina completa por ser dema- demás especies no se han destacado, y algunas práctica- siado extensa: (1) Eucalyptus; con 170 parcelas de dis- mente han fracasado, como por ejemplo A cacia pycnan- tintas especies, incluidas las variedades. Las de mejor tha, Fraxinus americana, Quercus suber y los Populus. comportamiento son E.algeriensis,E.amplifolia, E. Estación Forestal General San Martin (provincia RIo camaldulensis, E. cinerea, E. deanei, E. goniocalyx, E. Negro). Ubicación: 71° 37' longitud Oeste; 41° 58' lati- leucoxylon, E. longifolia, E. macarthuri, E. maideni, E. tud Sur; altitud de 310 metros. Region fitogeográfica de ovata, E. rubida, E. sideroxylon, E. stuartiana y E. vimina- los Bosques Subantárticos, zona Norte Valdiviana. Clima: us, en especial esta Ultima (a los 7 años, 17,80 metros de hémedo y frIo.Precipitación media anual de 970 mm; altura y 0.23 m. de DAP). La gran mayorIa de los veranos secos (enero 18 mm ); inviernos hémedos (junio restantes Eucalyptus de la colección no se adaptan a las 180 mm) con nevadas.Temperatura media anual de condiciones climáticas del lugar; (2) Coniferas; principal- 10° C.; maxima absoluta de 37° C. y minima de 9,5° mente Cupressus y Pinus, con un total de 25 parcelas, C. Heladas en todo el año, con una frecuencia media de 89 dIas en el año. Suelo: de carácter podsólico, responde destacándose C. lusitanica, C. sempervirens var. hori- en general al tipo humIfero, humifero-arcilloso y humI- zontalis, P. patula, P. pinaster, P. radiata y P. halepensis. fero-arenoso, con profundidad término medio de 40 cm. (3) Latifoliadas; existen unas 20 parcelas, con Acacias Predomina el relieve montañoso. varias (la mejor A. dealbata, que a los 8 años ha alcan- Especies en ensayo: Acacia melanoxylon; Betula alba; zado 8,60 m. de altura y 0,10 m. de DAP), Castanea Castanea sativa; Eucalyptus australiana, E. cinerea, E. sativa y Gleditsia triacanthos de buena resistencia a los coriacea, E. dairympleana, E. dives, E.fastigata, E. factores climáticos, Fraxinus americana y F. excelsior fraxinoides, E. gigantea, E. obliqua, E. ovata, E. regnans, (comportándose mejor éste ültimo), y finalmente Ulmus E. viminalis; Fraxinus excelsior; Picea alba, P. engelman- pumila, Meldia azedarach, varios Quercus y Casuarinas, nii, P. excelsa, P. pungens, P. sitchensis; Pinus contorta todos los cuales desarrollan lenta e irregularmente. Genetics and Tree Improvement 767 RESUMES Espèces foreslières exotiques faisant l'ob jet d'expérimen- Exotic Forest Species Being Tested inthe Argentine tation dans la Republique argentine Republic Afin d'éprouver ledegré d'adaptabilité des diverses espèces exotiques et de pouvoir ensuite procéder a l'étude des croissances To prove the degree of adaptability of different exotic species etdesaccroissementsvolumétriquesdanslesdtablissements and then to make studies of their volumetric growth and increase relevant de la Direction des Recherches forestières (Administra- in the stations under the Division of Forestry Research (National tion nationale des Foréts), on a formd des parcelles expdri- Forestry Administration), experimental plots were established. mentales.Les résultats que l'on y a obtenus font l'objet des In this report, comments are made on the results obtained. observations exposées dans la présente communication. For each forestry station the geographical location, the phyto- Afin de donner une idée des conditions dans lesquelles sont geographical region (according to the Lorenzo R. Parodi classi- placées les espèces exotiques a l'essai, on y passe brièvement en fication), and the main characteristics of the climate and soil revue, pour chaque station forestière, la position géographique, are described briefly, to give an idea of the conditions encountered la region phytogéographique (selori la classification de Lorenzo by the exotic species tested. R. Parodi) et les principales caractéristiques du climat et du sol. Get exposé est suivi d'une nomenclature de ces espèces, sous Such species are then indicated, but not all the species tested reserve, toutefois,qu'elle renferme non la totalité des espèces are mentionedonly those on the experimental plots; that is to étudiées, mais seulement celles qui ont servi a la formation des say, in addition to those specified, there are other exotic species parcelles, c'est-à-dire qu'en dehors des espèces exotiques mention- with which experiments are being conducted, but they are still in nees, il en existe d'autres qui font l'objet d'expérimentations, mais seed beds or nurseries. qui se trouvent encore en pépinière en forêt ou en dehors de la Next, the area in general of the experimental plots, in what year forêt. the trees were planted, and the names of those who conducted On indique ensuite quelle est, d'une facon générale, la surface the experiments are indicated. de ces parcelles et l'année de leur plantation, comme aussi le Lastly, comments are made on the results obtained. It may be nom des personnes qui, dans chaque établissement, se livrent a concluded from those results that the species whose behavior was ces essais. the best are as follows for each forestry station: Pour conclure, on commente les résultats obtenus et l'on en "Plaza":Eucalyptus sideroxy ion, E. viminalis, E. tereticornis, déduit que les espèces dont le comportement s'est avéré le meilleur E. leucoxy ion, Cupressus iusitanica, Melia azedarach, and Ulmus dans chacune des stations forestières, sont les suivantes: pumila. "Plaza":Eucalyptus sideroxylon, E. vim inalis, E. tereticornis, E. leucoxylon; Cupressus lusitanica; Melia azedarach et Ulmus "Alem":Eucalyptus saiigna, E. botryo ides, E. citriodora, E. pumila. rob usta, E. resinifera, F. microcorys, Pinus elliottii, Araucaria "Alem": Eucalyptus saligna, E. botryoides, E. citriodora, E. bidwiiiii, and Tectona grandis. robusta, E.resinif era, E. microcorys; Pinus elliottii; Araucaria "Rivadavia": Populus euramericana 1-214, Eucalyptus camaldu- bidwiliii et Tectona grandis. lensis, and Salix alba var. coerulea. "Rivadavia":Populus euramericana 1-2 14; Eucalyptus carnal- "Fernández":E. camaldulensis, E. resinif era, E. tereticornis, duiensis et Salix aibu var. coerulea. E.viminalis,E.robusta, Ulmus pumila, and Casuarina cun- "Fernández": E. carnaldulensis, E. resinifera, E. tereticornis, E. ninghamiana. vim inalis, E. rob usta; Ulmus pumila et Casuarina cunninghamiana. "General San Martin": Pinus contorta var. iatifolia, P. ponder- "Général San Martin": Pinus contorta var. latifolia, P. ponde- osa; Pseudotsuga menziesii, Picea aiba, P. engelmannii, P. pungens, rosa;Pseudotsugamenziesii; Piceaalba,P.engelmannii,P. P. sitchensis, Eucalyptus vim inalis, E. regnans, and E. gigantea. pungens, P. sitchensis; Eucalyptus viminalis, E. regnans et E. gigan tea. "Castelar":Eucalyptus algeriensis, E. amplifolia, E. camaldu- "Castelar":Eucalyptus algeriensis, E. amplifolia, E. camaldu- lensis, E. cinerea, E. deanei, E. leucoxylon, E. macarthuri, E. lensis, E. cinerea, E. deanei, F. leucoxylon, E. macarthuri, E. maideni, E. ovata, E. rubida, E. stuartjana, E. vim inalis, Cupressus maideni, E. ovata, E. rubida, E. stuartiana, E. viminalis; Cupressus lusitanica, Pin us radjata, and Acacia deaibata. lusitanica; Pinus radiata et Acacia dealbata.

Resultados Obtenidoscon Plantaciones Forestales en la Zona Montañosa de San Martin de los Andes-Neuquén

ROBERTO SANCHEZ ACOSTA Técnico Forestal, Administración Nacional de Bosques, Secretaria de Agricultura y Ganaderia, Repdblica Argentina

La Adrninistración Nacional de Bosques posée en de las especies en el valle de San MartIn de los Andes en Neuquen a 1.500 rn/s/n/rn y a unos 10 krn. del pueblo un vivero ex-profeso próximo al Lago Lacar; posterior- de San Martin de los Andes, sobre el carnino que lieva al mente al 30 y 40 año de obtenidas las plantas se pro- cerro Chapelcó, una modesta plantación experimental de cedió a su plantación definitiva en la altura. unas 15 has. denominada "Plantación Forestal Lote 69." Luego de observaciones recogidas a los 6-14; 10-18; y Esta se inició en el año 1937 con algunos "pinos" 13-21 años respectivamente para las plantaciones de los exóticos y posteriormente, en el año 1949, alcanzó la años 1937 y 1949 se concreta en la recornendación fores- totalidad de unas 23 especies en ensayos entre pinos y tal de unas 14 especies para zonas similares y aun con otras (indIgenas y exóticas). un margen de seguridad ecológica algo menor. La plantación en montana demandó la crIa preliminar Asimismo, en el presente, se anotan observaciones co-

768 Fifth World Forestry Congress Proceedings EstanciaTipiliukeSan Marlin de los Andes-Nequén. Corfinas de Cupressus macrocarpa y C. Iusitanica de 8 aiios de edad: aIura promedlo, 8m.; diámetro promedlo 6cm. rrespondientes a especies forestales ensayadas en estable- temporada iluviosa. En la altura se forman campos de cimientos ganaderosde la misma regiOn (planilla No. 2) nieve que desaparecen en verano. Prácticamente la Iluvia con el mérito a sufavor de corresponder a un mayor se hace presente durante los doce meses del año, pero su nümero de aflos ensuelos algo diferentes, variando en intensidad es bien manifiesta entre los meses de abril a altitud a la par que concurriendo a los mismos distintas noviembre, correspondiéndole al invierno el mayor grueso temperaturas y precipitaciones, lo que amplIa en cierto pluviométrico. modo Ia labor experimental de la "Plantación Forestal Lote 69." Tern peratura Aun cuando Ia razón de la plantación fué inicialmente Anotamos como referencia las correspondientes a la forestal, hoy a los 22 años, se encuentra vinculada a la vecina localidad "Las Taguas": actividad pastoril al igual que sus similares particulares, Medias anuales: Maxima:22° C. puesto que es uno el problema existente: proteger el Minima: 6,1° C. suelo contra Ia erosion, repoblar la masa boscosa, incre- Amplitud: 28,1° C. mentar laspasturas naturales y posibilitar actividades agrIcolas menores, como es la horticultura. Vegetación A fin de ubicarnos mejor en las condiciones ecológicas En directa concordancia con los variados factores de imperantes en la zona de San MartIn de los Andes suelo, topografIa y clima existen dentro de la region pra- diremos que: dos con hierbas cespitosas, bosques de conIferas, montes Conforme con estudios orográficos y fitogeograficos arbustivos, matas xerOfilas, en fin, varia en razón de la Ilevados a cabo por distintos investigadores como Hau- humedad y conforme esté presente la montana el valle, man, Khun, Frenguelli, Feruglio, Cabrera, Parodi, etc., cañadón, la estepa, el prado y/o la meseta. entre un largo (N. a S.) deUflOS350 km. y un ancho (0. a E.) de unos1 80 km., se presentan en el territorio Vientos cinco regiones fIsicas, tres a cuatro formaciones fitogeo- Siendo un factor climático importante, creemos con- gráficas, dos regiones naturales con una zona hOrneda y 3 veniente mencionar que predominan los del Oeste, siendo áridas y cuatro regiones climáticas. de gran intensidad y presentándose con más frecuencia Lo expuesto evidencia la gran variedad topográfica, en los meses de primavera y verano. climática y natural existente en Neuquen, lo que justifica en cierto modo la ausencia de datos precisos sobre su Clirna suelo y clima, redundando en la dificultad para cualquier La "Plantación Forestal Lote 69" está en una zona de acción forestal. clima hümedo y frIo, con un Indice hIdrico 60 de poca No obstante lo expresado, puede anotarse lo siguiente: deficiencia de agua. Precipitacián Suelo y Relieve Para la zona de San Martin de los Andes pueden con- Relieve extremadamente accidentado, ocupado en par- signarse unos 2.000 mm anuales, siendo el invierno Ia tes por lagos, alternando con mesetas y pampas altas y

Genetics and Tree Improvement 769 faldeos montañosos de fuerte declive, lo que da en conse- horizonte b:10-35 cm.; humIfero, arcno-arcffloso cuencia suelos acumulados y profundos como otros super- (poca arcilla), suelto, flojo, permeable. ficiales y eminentemente minerales e incluso pobres en las horizonte c: 35-45 cm.; areno-arcilloso, suelto, flojo, pendientes rápidas. Combinándose con el relieve peculiar permeable. de la montana es comün la existencia de microclimas, ya horizonte d1: 45-120 cm.; arenoso, con cenizas vol- en función de la altitud como de la orientacion e inclina- cánicas, algo tenaz. ción de la montana, ancho de sus valles, regimen de las horizonte d2: 120-200 cm.; areno-arcilloso, fresco, iluvias, fuerza de los vientos, iluminación, etc. tenacidad media, permeable, raIces hasta más o menos Para la zona en general han de mencionarse suelos que 160 cm., rocas. van del hürnedo al semiárido, árido y desértico, es decir suelos podsóiicos, forestales, depósitos eólicos, arenosos, Planillas No 1 y No 2 etc. Complementa la prescnte dos pianillas (No 1 y No 2) En consecuencia de lo dicho, existen las más variadas las que concretan los datos propios de las especies alturas sobre ci nivel del mar, las que van desde los 200 recomendadas. a los 1.500 m., alternando estas con los distintos acci- En la planilla No 1 solo se citan aquellas especies dcl dentes topográficos presentes(valles, montañas, caña- "Lote 69" que por su buen comportamiento, mcrecen dones, mesetas, lomas, etc.). realmcnte que se les preste atenciOn alguna. Plantación Forestal Lote 69" En la planifia No 2 (a yb) en cuadro resumido se ano- tan aigunas exigencias, prcferencias. tolerancias,resisten- Dentro del panorama descripto a grandes rasgos, se cias, etc., de las principales especies tratadas. encuentra la "Piantación Forestal Lote 69" como se dijo, Las exigencias, tolerancias, etc., deben ser consideradas sobre un terreno onduladoa unos1.500 rn/s/n/rn, o tenidas en cuenta mientras no sean decisivas, siempre y expuesto a los vientos de los cuatro puntos cardinales, por cuando se trate de ejecutar plantaciones en lugares abier- lo que, dada la altura y falta de protección y reparo por tos, pués Ia densidad posterior y Ia radicación sucesivas parte de algün cerro vecino o formaciones boscosas, ci de nuevas masas forestales van mejorando las condiciones frIo es rnás intenso, Ia precipitación más frecuente y la del medio y en consecuencia disminuyendo en importancia caIda de nieve más copiosa y persistente, liegando a los factores adversos, que en más son limitantes rempora- estacionarse con un prornedio de 70 a 100 cm., alcan- les. que excluyentes definitivos o absolutos. zando a veces los 200 cm. de altura. El gran poder de acomodación y aclimatación que Asimismo, ci so! caiienta más, ya sea por fa!ta de la poseen las plantas para desarrollarsc en lascondiciones protección señalada como por la exposición tan variada (ambiente-suelo) más variadas, a veces contradictorias del suelo extremadamentc ondulado, que durante ias y aparentemente opuestas, ya sufriendotransformaciones horas de luz ci so! se proyccta continuamente sobre él, fisiológicas y somáticas, ya cambiando suestructura secándolo fácilmcnte, favorecido do por su naturalesa (interna y externa) o simplemente regulando su creci- csencialmente humIfera arenosa y la evidente escasez de miento (en más o en menos) hace evidente el hecho de que arcilla. hay en ellas facultades especiales e intrinsecas no bien La falta de arcila aludida da, en consecuencia, un sue!o conocidas y precisadas que determinan una exigencia flojo que se prolonga la rnás de las veces hasta casi dos minima de condiciones forestales adccuadas y convenien- metros de profundidad.Por lo dicho, algunas especies ternente armonizadas para su supervivencia. cxigentes en agua requieren riego en verano y aquellas Es decir que en Ia radicación exitosa de una especic con sistema radicular de poco desarrollo o expansion no habrá que atenerseal rnenosa ese mInimo de ambiente prosperan, tal ci caso, por ejemplo, del Pinus insignis que forestal adecuado y a partir deéI, a reforestaciones habiéndo llegado a los 3 rn. de altura se tumba por tener futuras y a Ia acción racional derivada de una observación, poca base en rclación a! gran desarrollo de su parte aérea. experiinentación e investigación constante. Considerando en términos generales ci suelo boscoso, podemos dar su cornposición aproximada, que para ci RESUMES caso de la acción forestal que nos preocupa es suficiente, Results Obtained From Plantations in the Mountainous por cuanto ci hecho de variar en más o en mcnos no Area of San MartIn de Los Andes in Neuquén afectará los fines perseguidos por la presente comunica- ción. Para que realmente sea notable una variación de Forestry in the Patagonia area (an area with mountains,valleys, suelo habrá de buscársela bién lejos del "Lote 69," donde plateaus,etc.) has been made difficult by the following factors: A grear climatologic and topographic diversity. ya no sOlo cl suelo ha variado sino las demás condiciones Theneed for selecting the most appropriate typesof trees de arnbiente, por lo que planteadas las cosas asI, la labor for such different environments. forestal que se llevará a cabo, deberá ajustarse, entonces, Evident regression of forests and the difficulty with which the a esas nuevas condiciones y al estudio de las mismas. species recover. Grazing, erosion.and fires. Lapresente csunainformacióneminentemente The difficulty ofreconciling forest development with forestry, técnica-práctica, basándose en observaciones generales, agricultural, andcattle-raising activities. análisis del cuadro ecolOgico descripto y en la sIntesis Lack of water, in some cases. Maturity and overmaturity of forests. lógica provenientc del espIritu que priva en la misma. The need for overall scientific and technical studies on the subject. En términos generales ci suelo del "Lote 69" presenta: 9. Scant forest consciousness in the rural population. horizonte a: 5-10 cm.; mantillo forestal con restos Nevertheless, the following14 species of trees can be grown in naturales. thc area of San MartIn de losAndes, in the province of Neuquen:

770 Fifth World Forestry Congress Proceedings Planifia 1.Comportamiento de las principales especies y su estado actual en "Lote 69"

Crecimiento Progreso en: Especies Fecha Edad a Estado (fecha de siembra) Plant. los aiios: Altura Diam. Altura Diam. act. (m.) (cm.) (m.) (cm.) 195 1-14 1,80-3,00 3-5 Pinus strobus-1937 1937 195 5-18 4-6 10-12 2-3 7 MB 1958-21 5-7,50 12-17 1-1,50 1951-14 3-6 10-17 Pinus murrayana-1937/45 1937/49 1955-18 5-7 10-17 2-3 7 MB 1958-21 5-9-11 14-18 2-4 1-4

195 1-14 3 6 Pinus pinaster-1937 1937 1955-18 7 16 4 10 MB 1958-21 3-8,60 22 1,60 6 1951-6 0,80-1,20 1-3 Pinus contorta var. latifolia-19451949 1955-10 3,60-5,50 4-8 2,70-4,70 3-5 MB 1958-13 6,00-6,30 10-13 0,80-2,40 5-6 195 1-6 3-4 5 Pinjis banksiana-1945 1949 1955-10 3,50-7,00 5-13 3 8 MB 1958-13 3,50-8, 15 14-17 1,10 4-9 195 1-6 1-3 2 Pinus monticola-1945 1949 1955-10 1,50-5,00 2-9 3,50 7 B 1958-13 1,6 3-12 2,00 3 1951-6 0,20-1,40 5 Pinus ponderosa-1945 1949 1955-10 1,50-4,60 3-9 1,30-3,20 4 B 1958-13 2,35-5,70 4-12 0,80-0,90 3 195 1-6 1,60 2-3 Pjnus insignis-1945 1949 1955-10 3-6 8-16 1,40-4,50 4-12 MB 1958-13 3-9 6-28 3 12 195 1-6 0,30-2,00 Betula verrucosa-1945 1949 1955-10 2,00-5,20 2-5 1,70-3,20 2-5 RIB 1958-13 2,30-6,70 3-6 0,30-1,50 1951-6 0,60 Juniperus comm unis-1 945 1949 1955-10 0,60-1,60 1-3 1 3 MB 1958-13 1,30-2,10 2-3 0,50-0,60 1

A claración: Solo en los ahos indicados se efectuaron mediciones de losárboles más representativos; no existiendo registro de observaciones periódicas de ninguna naturaleza. Pinus:strobus,murraycina,pinaster,contorta,banksiana, zone montagneuse de San Martin des Andes en monticola, ponderosa, and insignis. Cupressus: arizonica and lambertiana. Neuquén. Beta/a: a/ba. L'action forestière dans la zone patagonique se heurte a des Juniperus: comm unis. difficultés par suite de: Sequoia: gigantea. La grande varidtd du climat et de la toographie. In general, the environmental factors favorable for these species La nécessité de préciser les essences forestières convenant a are the following: des milieux très divers. Soil: preferably humid, although dry soilis tolerated; deep, La regression évidente de la forêt et la récupération difficile usually with humus, loose, slightly sandy and/or sandy clay. des espèces. Terrain: Le pâturage, l'érosion et l'incendie. flat and/or mountainous, subject to the reservations La difficulté de concilier l'action forestière avec les exploita- mentioned in table No. 2. tions agricoles, d'élevage de bestiaux et forestiéres. Temperature:thetreesendure temperatures below 0° and Dans certains cas, le manque d'eau. above 20° Centigrade. La maturité et l'excès de maturitO des massifs boisés. Rainfall: they thrive with rainfall ranging from 400 to 1,500 or La nécessitéd'étudestechnico-scientifiquesintégrales in- 2,000 millimeters per year. hérentes ausujet. Origin: usually from the western part of the United States. Un intérêt peu développd chez les ruraux en matière de Other factors:usually these trees are not sensitive to the sylviculture. australsun, snow, wind, and frosts.They require light and Néanmoins, on indique, pour la region de San Martin des Andes humidity, growing at altitudes ranging from 400 to 1,500 meters en Neuquén (R.A.) quatorze espices forestières de bon com- above sea level. portement: Pinus: strobus,murrayana,pinaster,contorta,banksiana, Résultats obtenus avec les plantations forestières dans la monticola, ponderosa, et insignis.

Genetics and Tree Improvement 771 Planila 2a.Algunas exigencias, preferencias, etc., de las especies tratadas Terreno Suelo requendo preferido/aceptado a a Especies a 2 2 a a a a E - a E a 'a © a ; a a Pinus strobus X X X X X. X. X. X X X. - - - Pinus murrayana X X - - - X. X X X. X. - - X. Pinus pinaster X - X X X. X - X. X - - X. X. - Pinus contorta X X. X X X X X. X. X - X. - X X Pinus banksiana X. X X X - X. X. X X X. X. - - Pinus monticola X. X X X. X X X. X Pinus ponderosa X. X X X X X. - X X. X. X Pinus insignis X. X X X X X. X X. X X. - - - - Pseudotsuga douglasii - X X X X X. X. X X X - - Cupressus arizonica X. X X X X. X. X. X. X X - - - - Cupressus lambertiana X X X X X. X X. X. X X X. X. X Juniperus communis X. X X X X. X. X. X X X X. - X. - Sequoia gigantea - X X X X - X. X X X - - - - Betula alba X. X. X. X X X X. X X - X. - A breviaturas usadas: Suelo requerido: X = afirmativo; X. = también o indistintamente; - = negativo. Terreno preferido ybaceptado: X preferido; X. = tolerado; - = sin dato.

PJanilla 2b.Algunas exigencias, preferencias, etc., de las especies tratadas Agentes climaticos: su resistencia y sensibilidad Exigencias Alturas a Pals de Especies FrIo Alcanzadas origen Sol Nieve Hela- Vien- Bajo S/N/M da to Cero aE

Pinus strobus R Sn R Sp Si x. 800 E.U. (E) ( 400 Pinus murrayana - R.P (1200 E.U. (0) Pin us pinaster Sn.P Sn " R.P Su " No 600 Europa (S) Pinus contorta " Sn.P NoSn R Sp " " 1200 E.U. (0) (1000 Pinus banksiana - R " R.P Si (1200 EU. (N.E.) Pinus monticola Sn.P " x.x 3000 E.U. (0) (1000 Pinus ponderosa - NoR " R (2500 Pinus insignis NoSn R.P " Sn ,, x.x 1000 Pseudotsugadouglasii Sn NoR NoSn R No Si 2000 Cupressus arizonica NoSn ? poco x.x 2000 Cupressus lambertiana Sn.P R.P R.P Si - 400 Juniperus communis NoSn " NoSn x.x 1000 Europa, A Sequoia gigantea - R " R Si 1500 E.U. (0) lietula alba NoSn " " Sn 1000 Europa, Asia

Abreviaturas usadas: Agentes climáticos: R resiste; NoR = no resiste; Sp soporta; Su = sufre; R.P = resiste poco; Sn = sensible; Sn.P poco sensible; NoSn = no sensible. Exigencias: Si = exige; No = no exige; x.x indistintamente; x. = algo exigente. PaIses: A = Asia; E.U. = Estados Unidos de Norte America.

772 Fifth World Forestry Congress Proceedings Cupressus: arizonica et lambertiana. Des temperatures: elles supportent le froid au-dessous de zero, Betula: alba. et des temperatures supérieures a 200 C. Des précipitations pluviales: elles prospèrent avec un régime de Juniperus: communis. précipitations allant de 400 a 1.500 et 2.000 mm par an. Sequoia: gigantea. Origine:d'unefacong'nérale,l'ouestdesEtats-Unisde Lesquelles, en règle générale, se développent dans l'Amérique du Nord. Un Sol:de préférence humide, avec tolerance du solsee; Autres observations: ne sont généralement pas sensibles au profond, meuble, légèrement sablonneux ou argilo-sablonneux. soleil austral, a la neige, ails vents et aux gelées. Croissent a des Un terrain: plat ou accidenté, compte tenu des reserves formu- altitudes variant entre 400 et1.500 mItres, et exigent de la lees au tableau n° 2. lumière et de l'humidité.

L'Amélioration de la composition des hétraies Dans la République Populaire Roumaine

GR. POPA, M. MADEA, ET AL. IONESCU Roumanie

Le hêtre est l'espèce forestière la plus répandue en sols a squelettes) a produit une plus grande masse lig- R.P.R. dans les regions de collines et de montagnes. Elle neuse, et d'une qualitd supérieure a celle du hêtre. couvre environ 35% de la superficie boisée du pays. Mais Dans de telles circonstances il peut être adopté dans une très grande partie des peuplements de hêtre n'a pas toute la sous-zone du hêtre. une productivité correspondant au potentiel de la sta- Le chêne rouvre associé au hêtre, produit une bonne tion.Par des recherches effectuées sur ce problème, on qualite de bois, très indiquée a des usages supdrieurs est arrivé a la conclusion que l'augmentation de la pro- spécialement pour le placage.Ii pourra être introduit ductivité des forêts de hêtres doit être fondée principale- dans le tiers inférieur de la sous-zone du hêtre, sur la ment sur l'amélioration de la composition actuelle, par partie supérieure des versants ensoleillés (au sud et au l'introduction dans une proportion allant jusqu'à 30% sud-est) dans des sols riches, profonds et suffisamment d'espèces plus productives ou d'une qualité supérieure. humides. Les plus indiquees sont: Parmi les espèces exotiques cultivées dans notre pays Especes indigènes: des la fin du XIXème siècle, on en trouve des exemplaires l'épicéa (Picea excelsa Link.); qu'on peut introduire avec succès dans la sous-zone du le sapin (Abies alba Mill.); hêtre pour augmenter sa productivité. Ainsi: le mélèze (Larix decidua Mill.); Le douglas vert, a l'âge de 50 ans, a l'altitude de 500- le pin sylvestre (Pinus sylvestris L.); 700 m., planté dans des sols profonds suffisamment le rouvre (Quercus petraea L.). humides, a l'abri des vents froids, a réalisé une quantité Espèces exotiques: de bois deux fois plus grande a celle du hêtre et d'une le douglas vert (Pseudotsuga taxif olia Britt. var. qualité supérieure. La plus grande partie de ces peuple- viridis Asch. & Gr.); ments sont purs et seulement un petit nombre reste le pin Weymouth (Pinus strobus L.); associd aux espèces indigènes. Même dans la sous-zone le chêne rouge (Quercus borealis Michx.). du hêtre, a une altitude inférieure a 200-300 m., le En ce qui concerne l'utilisation de ces espèces dans douglas souffre dans une certaine mesure du manque l'amélioration des hêtraies, on a tirelesconclusions d'humidité. suivantes: Dans la moitié ouest du pays, ii peut être introduit dans L'épicéa peut être étendu au tiers supérieur de Ia sons- des hêtraies jusqu'à l'altitude de 700 m., dans des stations zone du hêtre; au-dessous de cette limite, le peuplement favorables out l'on realise un minimum de 600 mm. de qui en résulte est d'une qualité inférieure et exposé aux précipitations atmosphériques annuelles. chablis de neige. Le pin Weymouth a l'âge de 50 ans, cultivé dans de Le sapin peut trouver une extension plus large dans le bonnes stations, a l'altitude de 200-300 m., a produit une tiers moyen de la sous-zone du hêtre, dans des stations masse ligneuse deux fois plus grande que celle du hêtre. correspondantes, dans des sols riches, profonds et suffi- L'extension de Iaculture de cette espèce devra étre samment humides, a l'abri des gelées tardives. dirigée selon les nécessités, parce que dans certaines cul- Le mélèze peut être introduit dans toute la sous-zone tures leurs troncs présentent de grands noeuds, assez du hêtre dans les stations aux sols fertiles, profonds, et nombreux, qui nuisent a la qualité du bois. suffisamment humides, sur des versants ensoleillés et bien Le chêne rouge a été cultivé dans la partie inférieure aérés, afin que le bois garde toutes ses propriétés tech- de Ia sous-zone du hétre, jusqu'a l'altitude de 500 m., dans nologiques. des stations favorables, aux sols riches, profonds et suffi- Le pin sylvestre utilisd dans des hêtraies dont la pro- samment humides. ductivité est inférieure (dans des sols acides et dans des La masse ligneuse obtenue a été de 1,5-2,8 lois plus Genetics and Tree Improvement 773 grande que celle du hêtre. On recommande son introduc- Comments tion dans Ia partie inférieure de la sous-zone du hêtre, a l'ouest du pays. Mark Johannes Hoist (Canada): Toutes ces espèces exotiques ont a leurs debuts une The two papers which we have just heardone on croissance plus rapide que le hêtre et des le premier age, cytology and one on physiologyare fieldsof basic des atteignent les dimensions exigées par les nécessités research which are of immense importance to the tree industrielles.Des recherches ultérieures doivent établir breeders.Most treebreeders haveat one time or la dynamique de la croissance de ce peuplement jusqu'à anotherdone some work related to these fields, but to un age plus avancé. be good in any of them is a full-time job. We therefore L'introduction de ces espèces pour l'amélioration de la appreciate having these surveys made available to us and composition du peuplement du hêtre, devra être pratiquée having our problems clarified. dans lestrouées ou lesvides, quand la régénération As a tree breeder of spruce and hard pine, I found Prof. naturelle fait défaut. Mehra's survey very interesting. It points out that specia- Pour les superficies complètement régénérées de hêtre, tion in conifers has been on the ecospecific level as indi- dans des stations aux conditionsidéales,lesespèces cated by normal pairing of chromosomes inspecies amélioréescouvriront jusqu'à 30% de lasuperficie hybrids; and that species hybridization appears especially améliorée en trouées ou en bandes après l'élimination du promising because species differences are mainly due to semis de hêtre. gene mutationstherefore a large gene pooi is available Pour les hêtraies a productivité inférieure, situées dans in related species. des sols trop acides ou a squelettes, on recommande The other point madethat we, by inbreeding, should l'introduction du pin sylvestre comme espèce principale en get rid of recessive deleterious genesis a very valuable association avec le hêtre sur toute lasuperficie pour one.Dr. C. Syrach Larsen has shown pictures of out- l'amélioration du sol et pour assurer au pin un bon elagage crosses which are remarkably uniform and vigorous, and naturel. Dr. F. I. Righter also suggests a similar approach. At the Petawawa Forest Experiment Station we have established RESUMES a number of inbreed lines of white spruce (Picea glauca) Improvement of the Composition of Beech Stands in the plus trees to rid them of deleterious genes. Rumanian People's Republic Dr. Richardson's survey of physiology as related to The beech is one of the most important species in the forest forest tree breeding is an excellent one. We surely need economy of the Rumanian People's Republic.It occupies 35% more basic research on tree physiologyand the time of the total forest land. will come when a physiologist is an integrated part of any Research conducted up to the present demonstrates that produc- tivity of beech stands can be increased by improving their com- tree breeding program. position through the introduction of more productive and higher It is true that tree breeders are prone to make "pepper- qualityspecies,including(a)native species, and (b)exotic pot" experiments in physiologyi.e., empirical experi- species. ments. However, some of us do know something about All these species must be introduced in optimum sites meeting their ecological requirements throughout the area where there plant physiology, but we cannot spend all our time on are blanks and empty spaces, in an amount equal to 30% of the physiological problems.One example:In 1951 we areas regenerated naturally. wanted a fertilizer that would give pines a shock, and With respect to beech stands of inferior productivity, situated on thus perhaps stimulate flowering. We selected ammonium acid or skeletal soils, the introduction of the Scots pine as the principal species throughout the area is indicated in association nitrate.By further empirical experimentation, we have with the beech, to improve the soil and guarantee pruning of found that ammonium nitrate will double female flowering the pine. and reduce male flowering by half, provided the ammon- ium nitrate is applied before the flower primordia are Mejoramiento de la Corn posición de los Hayales en la formed. We are now repeating these experiments to find Repáblica Popular Rurnana out what is happening to auxins, amino acids, and major El haya es una de las especies más importantes de la economIa elements in various age classes, various locations in a forestal de la Repáblica Popular Rumana y ocupa el 35% de Ia tree, and at various times during the growing season. superficie de bosques del pals. Las investigaciones hechas hasta el presente demuestran que la Another important problem is plant forcing or the productividad de los hayales se puede aumentar mejorando su acceleration of growth to produce large plants in a short composición con la introducción de otras especies más pro- time.It seems that intolerant species, such as birch and ductivas y de calidad superior como: a) las especies indigenas; y larch, are easily grown to a large size on long days, and b) las especies exóticas. at least birch will produce flowers within 14 months. The Todas las especies se deben introducir en un sitio óptimo que corresponda a sus exigencias ecoiógicas en toda la superficie de northern species are much more difficult, as they seem to espacios vaclos, no regenerados y en proporción de alrededor del deteriorate if grown continuously at high temperatures. 30% en las superficies regeneradas por medios naturales. We are therefore trying to find out what the minimum En los hayales de productividad inferior, situados en suelos chilling requirements are for keeping our spruces healthy. ácidos o agotados, la introducción del Pinus sylvestris como especie principal, es la más indicada junto con ci haya para Combined with long-day treatment we hope to accelerate mejorar el suelo y garantizar la poda del pino. growth considerablythus shortening our breeding cycle.

774 Fifth World Forestry Congress Proceedings Session C .

Improvement Through Racial Selection and Testing

WOLFGANG WETTSTEIN-WESTERSHEIM Forstliche Bundesversuchsanstalt, Schönbrunn, Vienna, Austria and HANS HUFNAGL Director of Forestry, Landwirtschaftskammer, Linz, Austria

Introduction to History and Theory of Racial Research the important forest influences were heavily impaired by monocultures with provenances from other climatic zones, The forest communities of the earth have undergone and that the use of non-controlled provenances led to constant changes due to climatic oscillations.Certain yield and quality losses.During the second decade of tree species have remigrated from warmer zones to those this century the biological concept of silviculture made which had become vegetationless by glaciation.Quite its appearance. The forest was recognized as a "life- naturally, a considerable quantity of races have formed, community," including mankind. Its value for protection being best adapted to the site conditions encountered. In of climate and water balance and other so-called forest most cases, several tree species have been present in mix- influences were recognized ture,and seldom in pure stands.Utilization of the In1936, Langlet (Sweden) and Kalela (Finland) forests then resulted in management according to human published an extensive survey of the many hundreds of judgment. Man's heavy interventions in the forest com- provenance tests then existing.The results, frequently munity resulted in serious damages within a few centuries. documented by high significance, indicated that there are Very soon it was to be found that seed artificially har- differences in cold resistance, growth rate, growth period, vested could not be transferred to other sites or else led needle or leaf size, resistance to fungal infection, and to failures.In fact, there were races that were not suit- various responses when trees are planted under various able for all conditions.Changed environmental factors climatic conditions. Thus we are concerned with chemico- gave rise to the occurrence of insect outbreaks, and physical races, climatic races, physiological forms, and diseases, snowbreaks, and windfalls occurred in increased measure. ecotypes. The most impressive instance of this was the use of General Application Central European Scots pine seed for reafforestation of extensive clearcut areas in Sweden during the late 17th The conclusion is that attention should be paid to the and throughout the 18th century.Thousands of acres use of autochthonous races or, in the purchase ofseed, were cleared prematurely. Enormous sums of money were at least of provenances grown under similar environmen- wasted. tal conditions.Fully effective stands should be certified with a statement of site conditions, and their seed should Forestry had suffered a failure and gave way to the be used only under equal or similar conditions.Fre- need for a new course in planning. The forester was quently, we shall have to use a mixture of several races. faced with the task of improving the forest again, and First of all, we must distinguish climatic, site, and altitu- science's task was to supply the foundations. The first dinal races. The legislative bases necessary for the use of hint of the existence of tree races was made in literature proper seed should be created. about the middle of the past century by the Frenchman, Vilmorin. Engler (Switzerland), Cieslar (Austria), Op- Itis generally held that in Europe, by paying full permann (Denmark), and Schotte (Sweden), at the Con- attention to natural racial characters, we can count upon gress in Vienna (Mariabrunn Research Institute), sug- an average volume yield increase of 1 cubic meter per gested large-scale seed-origin (provenance) tests to be hectare annually. made by the IUFRO. Very soon, these tests clearly Racial Improvement of Stands demonstrated the urgency of the problem. It was recog- nized additionally that conservation of soil power and The case occurs relatively seldom that whole stands Genetics and Tree Improvement 775 are constituted of unfit tree races. Such stands are mostly to plant and animal pests. Thus, there are forms of Pinus of short duration, being eliminated by Nature, herself. sylvestris which, having a higher sugar content in their If undesired supplementary tree species are to be dis- needles, are preferred by game, and, on the other hand, carded, this is often very uneconomical, but yet necessary there are forms of broadleaved trees that are avoided by if inferior races have been introduced. Removal must be game because of high tannin content. We should wel- done in good time to prevent unfit races from fructifica- come a testing method allowing conclusion from seedling tion, or else undesired pollination of trees with good growth as to the later development of a tree. Perhaps the hereditary traits,and multiplication of unfit races by graft orchard will give some information by cultivating natural regeneration will occur. We must also consider several ages of the same tree side by side. what tree species we have to deal with. Pine and larch As already indicated, the best phenotypes have been are particularly sensitive in this respect, while spruce has marked in practice and preserved as long as possible for a wider amplitude.Broadleaved trees are more often seed-harvesting purposes.In many respects, the fore- affected from youth by climate. ster does better than the agriculturist in preserving an elite The forester is often faced with difficult tasks. As a for many decades and even centuries, since the selected rule, it will be a matter of conducting to early regenera- tree is preserved through vegetative propagation, either tion an opened-up stand freed from racially unfit individ- directly by rooting of its own progeny, or indirectly by ual trees. It should be considered in each instance whether grafting on stocks of the same species.Grafted seed or not one should proceed by stages in consolidating the orchards have already been laid out in many countries remaining stand.This largely depends on the distribu- and have given good results.It could be stated that for- tion of trees to be removed from a stand. According to mation of chemical constituents, such as tannin, cellulose this, a decision will be made whether emphasis is to be composition, fiber length, and resin production, depends laid on the tending of the stand or on the additional on hereditary factors and is thus inherent to the individual regeneration. plant.In orchards, itis thus possible to preserve such Finally, the size of the total area is essentially decisive. elite quality trees for an unlimited time. In the small difficulties are greatest, and here It is not always easy to distinguish between progenies only management by the selection system is possible. In from cultivated stands and those from the unadulterated medium-sized and large-scale forestry, any regeneration stands of nature, for in Europe, at least, mixtures have felling system will be possible: open-stand system, group- long since arisen by seed traffic from one site to another. selectionsystem, shelterwood-compartment system, or The need for a test of physiological response to environ- selection system properand regeneration may as well ment has become urgent.Also, the inheritance of a take place under shade. number of single characters, by which the selected pheno- There isand it will be unavoidable in most cases types differ, is realized in this way. Testing during the an undesired fertilization which renders illusory seed har- first development stages, say, from seedlings up to the vesting from elites.Even within site-conforming races third or fourth year of age, supplies a good differentiation there will be individual differences as to yield and quality in the response to environment.It appears particularly of individual trees. Improvement of the racial constitu- interestingtostudy the thermo- and photoperiodical tion of a stand means its tending by well-managed thin- responses: Sprouting, or sap-flow, cannot start until the ning. Conversion of non-natural pure stands into mixed soil is thawed, and assimilation through chlorophyll needs stands with fit races will be the most important task of the a sufficient daylength or sunshine duration.Thus, in near future.The trend must be to pursue a constant northern latitudes and on elevated sites there will be racial improvement of given tree races. High-yield trees shorter cycles of vegetation than in southern zones and of any race should be preserved for seed harvesting as on low valley sites. Interesting experiments in this respect long as possible. have been conducted in Pinus sylvestris, Betula verrucosa and Populus. No adaptation to changed environment Exact Choice of Races could be observed.Thus, genetical factors account for The practical possibilities of obtaining an increase of this response to daylength. Just this selection for thermo- yield from among a natural or artificial mixture of races and photoperiodical response is of decisive importance within a stand are thus narrowly limited.Out of this for increment and volume yield. For example, a poplar awareness, further improvement possibilities, of a biologi- type having its maximum increment under short day cal, physiological, and genetical nature, were pursued, length will be prematurely compelled by frost to stop and this led forcibly to individual tree selection.The growing, and the parts not yet lignified must die. successes attained by this method inagriculture and In broadleaved species easy to propagate vegetatively, fruit growing leave no doubt that we shall obtain further such as Salix and Populus, the testing of progenies from improvements through individual selection. The selected individuals has already shown success. We also know tree shows the genotype in its environment, thus, in its from breeding research that individual selection enables modified variability. We have to examine what the tree us to restrict considerably the range of variation of single owes to its heredity and what to environment or to tend- races. Since we have essentially to deal with allogamy, we ing. Detailed scientific tests are needed in order to choose need several elites as similar to each other as possible in valuable genotypes from among the phenotypes. order to avoid inbreeding. Choice of individuals and progeny tests have more than once given good results; thus,it has been possible to Selected Races as a Basis for Combination Breeding realize single features of phototropic behavior.Particu- Combination or cross breeding enables us to attain an larly good experience has been gained with the resistance increase of ecological responding capacity. This has also

776 Fifth World Forestry Congress Proceedings proved successful in trees.In many cases, interspecific La distinction des races nous amène inévitablement a tine combination breeding results in heterosis. Syrach Larsen's selection individuelle et a des contrôles de descendance compares qui, a leur tour, nécessitent des analyses génétiques et l'étude de Larix hybrids may be cited as an example, and so may facteurs physiologiques particuliers. En ce qui concerne Ia pro- the interspecific hybrids of Pinus, Eucalyptus and poplars duction d'hybrides, l'emploi de l'effet d'hétérose, et Ia mutation giving a 30 percent or more increment increase.Seed provoqude, des méthodes permettant une utilisation rentable sont harvesting from such F1 hybrids can be achieved artifi- en voie d'élaboration.Des jardins de porte-graines composes d'arbres greffés jouent un role important. cially as well as naturally in special orchards.Let us Ainsi, ce qui précède resume brièvement l'dtat actuel de notre mention especially the possibility of crossing on grafts and science. Une selection des races est indispensable si l'on veut cut twigs in the greenhouse during the winter months, obtenir une production forestière accrue.C'est la base de tout allowing artificial production of crosses even from extreme programme de selection futur. provenances independently of both season and site. Nous insistons auprès des organismes nationaux et internatio- naux a ce que les marchands de graines et les pépiniéristes soient It is also possible this way to combine proterogynous amenés, au moyen de mesures législatives, a ne distribuer et and proterandrous trees (or to induce selfing by which vendre que des races et espèces expérimentées et provenant de restriction of characters is possible), since species differ- zones certifiées, ou ayant fait l'objetd'essais rigoureux, pour ing in flowering time by several weeks may be made to Ctre plantées dans un milieu favorable a leur développement. flower simultaneously in the greenhouse.It also becomes possible to conduct progeny tests on seed of a tree grown MejorasPOTMedio de las Pruebas y la Selección Racial from uncontrolled pollination along with and in the same Este trabajo presta especial atención a Ia gran variedad de year as seed from controlled pollination. posibilidades de mejorar la silvicultura por medio de la selección racial. Se resumen la historia y teorIa de la investigación racial. Se Production of New Races demuestra que las causas de muchos de los fracasos de la silvicul- The method of polyploidization, too, has had a good tura del siglo pasado no se averiguaron hasta que se descubrió, por medio de estudios sistemáticos, que las especies más importan- measure of success in forest trees. In this respect, results tes de los árboles forestales están divididas en razas climáticas o from Sweden are most remarkable. By artificially triplica- ecoidgicasque no puedendesarrollarsesino en sussitios ting and quadruplicating the chromosome number, they apropiados. have succeeded in obtaining gigas forms of Populus tre- Hoy, usando como base estas razas naturalmente formadas mula, securing an increment increase of 20-30 percent. (autóctonas),lapericiaforestal puede ejercer una selección Good results were also obtained through natural muta- metddica valiéndose de las pruebas de origen hechas en diversos lugares. tions such as the Finnish flamy and curly birches. Mediante métodos de trabajo y cuidado bien estudiados puede esperarse un aumento en la producción de madera calculado en RESUMES un metro ctThico por hectárea. Normalmente, será cuestión de Amelioration par des essais et la selection des races producir la regeneración prematura de un rodal en producción, libre de todo árbol racialmente defectuoso, y plantar la raza La grande gamme des possibilités d'amélioration de la forêt apropiada. El método de tratamiento silvicultural dependerá de au moyen d'une selection des races est mise en evidence. los árboles indeseables que han de sacarse, y de la magnitud del L'histoire et la théorje de la recherche des races est résumde. area forestal. L'auteur montre que les causes des nombreux échecs en sylvicul- ture, au cours du siècle dernier, n'ont pas été déterminées jusqu'au La distincidn de razas conduce forzosamente a la selección jour oü l'on a découvert, grace a des etudes systématiques, que les individual y a las pruebas comparativas de progenie. Esto, a su espèces des essences forestières les plus importantes se divisaient vez, requiere análisis genéticos y el estudio de los factores fisio- en races climatiques ou écologiques qui ne peuvent se développer lOgicos especiales.Están ensayándose métodos que permiten Ia que sur l'emplacement qui leur convient. utilización econdmica para la producción de hIbridos, el empleo Aujourd'hui, la pratique forestière, partant de ces naturelles de losefectos heter5sicos y la mutación inductiva. También (autochtones) est a même d'effectuer une selection méthodique resultan titiles los huertos para semilleros utilizando injertos. basée sur le contrôle de l'origine effectué dans de nombreux Lo dicho más arriba resume brevemente el presente estado de endroits. nuestraciencia.Laselecciónracialesindispensable pam Grace a des méthodes de travail et d'entretien bien étudiées, on acrecentar el rendimiento y sienta las bases fundamentales para petit s'attendre a une augmentation de Ia production forestière todo objetivo de cultivo en el futuro. évaluée a tin metre cube par hectare.En règle générale,ii El autor termina dirigiéndose a las entidades nacionales e s'agira d'amener a une régénération rapide un peuplement com- internationales para que insistan en la obtención de medidas plètement débarrassé des arbres de races indésirables et de les legislativas que obliguen a los productores y vendedores de semilla remplacer par des individus d'une race desirable. L'aménagement y semillones a transmitir y vender solamente razas y especies dépendra en grande partie de la manière dont les arbres a arracher probadas de areas certificadas, o especies probadas como adap- sont répartis, et de l'étendue de la zone forestière. tables a cierto sitio apropiado de crecimiento.

Genetics and Tree Improvement 777 Improvement Through Individual Tree Selection and Testing Seed Stand, and Clonal Orchards

WOLFGANG LANGNER Director, Institute for Forest Genetics, Schmalenbeck über Ahrensburg, Holstein, Germany

The topic of the paper has been broadened insofar as it is possible that under uniform site conditions, one part the problem of "seed stands" has been put at the begin- of a population (seed stand) may perform better than flingFurthermore, I am going to discuss the problem of another partof the same population.Economically testing, not only of single-tree selection but also of seed important characteristics may have accidentally had a stands and seed orchards.I feel that it is necessary to selection advantage in a certain subpopulation but not in consider testing for all three items. another. This means that after a sufficient number of gen- erations, two completely different subpopulations grow- Seed Stands ing in the same environment may have developed. The When seeds are collected from a stand of a natural performance of stands originated from one of these population and this seed is used for the establishment of groups, then, depends on which subpopulation waschosen new stands, a very important change with regard to the to serve as the seed source. genetical composition oftheforest takes place:the But subpopulations normally do not show whether natural distribution of the genotypes is eliminated. We their economically favorable characteristics are based only have to consider that populations have been formed in the upon a distinct influence of environment. This means that natural range of a given species which differ in respect to by a simple phenotypic selection of the best seed stands their genotypic variation. This variation is due not only in a natural tree population, an economical advantage can to site and other environmental factors but also to acci- be expected only for the sum of these stands but not, in dental factors. These populations are also in themselves every case, for the single stand.It follows that progeny not homogeneous, i.e., they are subdivided, due to the testing becomes a necessity, if improvement or a higher same reasons, into subpopulations.And, finally, there productivity is in mind. Since the frequency of finding are still smaller units within subpopulations which will be subpopulations of particular value is relatively high, that called populations of interbreeding individuals or progeny kind of progeny testing should be used more frequently. units. On the other hand, it is understandable that the prob- The origin of such progeny units in tree populations ability of obtaining highly productive stands is not to be becomes understandable if one considers the fact that a considered high if the selection is limited to relatively tree normally becomes fertilized by its neighbors. This small areas of uniform environment. The best chances for means that the seed originated from a particular mother finding economically valuable seed stands do exist by and a limited number of fathers is closely related, and, in selecting as many different population units on as many the case of natural reproduction, most of the offspring different sites as possible over the whole natural range grow near the mother tree. Therefore, groups of trees in and by testing these, using a wide range of different site natural reproduction are closer in their genetic position to conditions.This leads to large provenance-testing series the surrounding trees than to trees a greater distance which enable us to find those populations which are best away. suited to the local environment. The greater the site differ- The selection of seed stands and the seed collection ences of the selection area are, the greater the reason not from them lead to the establishment of artificial stands. to base the selection itself upon the phenotype, because In these artificial stands the balance between genotypes it is impossible to draw any conclusions from the pheno- and environment created by nature during many tree gene- type formed on a special site as to its behavior on another rationsisdestroyed.Therefore,thequestionarises site.It is also most likely that many chances of finding whether or not by leaving the natural regeneration, an superior strains will not be realized when researching improvement in forest productivity is possible. only for stands in a particular environment similar or In answering this question we must not only consider identical to that which will be used for planting. The the choice of the seed stands, but also the site on which planting site and seed stand site are most likely to be only the seedlings will be used.Whether the result differs approximately similar.Itisalso likely that seemingly depends on the degree and kind of the differences between small site differences occasionally have greater resulting the new planting site and the one of the seed stands. The effects than do larger site differences. same productivity can be expected only if both sites are From the standpoint of population genetics another identical. On the other hand, due to accidental variation consideration with regard to the selection of seed stands in genotypes in different populations and subpopulations, and their results in the following stand is of importance.

778 Fifth World Forestry Congress Proceedings It is evident that the size of the indigenous seed stand area and that hybridization between different populations does in a natural forest is an important factor.This means not occur.This type of seed stand is also favorable that important positive results can be expected only if because of the low probability of inbreeding occurring. the selected seed stand is of such a size that its members Since the high light intensity in which the trees are grow- are more remotely related.If they are related, this could ing stimulates flowering and seed production, not only on result in inbreeding depressions on the next generation a few trees but rather on a high number, this also facili- or on following generations. At all events, seed collected tates seed harvest of all seed-producing trees, which is from very small stands or groups of trees should be difficult in normal small-spaced stands. If such stands are mixed with seed from genetically similar stands.Har- of unknown origin, conclusions from the tree-improve- vesting seed from a very few trees in a stand might result ment point of view, concerning seed or the use of these also in selfing depressions. This disadvantage is particu- seeds in different sites, can be drawn only after progeny larly given when seeds are collected from standing trees. testing. Preferably, the few trees with a large amount of seed are picked for seed harvest, but in most years only a relatively Individual Tree Selection few of them flower. This can be prevented only by apply- Similar to the above-mentioned selection of very small ing controls during the flowering season as well as during seed stands or groups of trees is the selection of single seed collection. On the other hand, it must be remem- trees for seed production.If the seed of the one-parent bered that if the seed stand is not too large in size, several progenies is kept and used separately for the establish- different population units might be involved which, used at ment of new stands, it is impossible to judge the results a certain site, would mean that the members of one or in the F1 generation upon the phenotypic appearance of another population group would show up one year but the mother trees. There are great chances for inbreeding not the next.Seed which has been collected over the depressions in the F2all parents of this F2 material are entire range of a species might give extremely disadvan- at least half sisters if not full sisters and selfed progenies. tageousresults.Doing this would destroy the given It follows that this type of seed harvest is wrong. This equilibrium of population groups. type of seed harvest, by the way, has already been prac- On the contrary, the choice of seed stands of suitable ticed. The danger of inbreeding in the following genera- size at least results in the preservation of higher groups of tions is the highest if the seed trees were isolated trees. In genotypes, which is quite desirable. Although their local this case, inbreeding depressions as a result of selfed off- arrangement is changed compared with that found in spring may already occur in the F1.The more trees natural reproduction, the different genotypes are preserved involved in a seed stand in which seed trees are harvested in the plantation. This preservation is especially important the less the chance of getting selfed offspring. When when thinking of new stand selection in the artificially mixing seed of several single trees there is a gradually produced stands. A continuous selection of seed stands decreasing chance of obtaining selfed material in the F1, in new generations is also more difficult, because it will and particulary in the F2 progeny. Stem has shown that be very hard to find stands in which hybridization by the seed of at least 10 trees of a larger stand have to be strange populationswill not occur.The further we mixed before the danger of inbreeding can be eliminated. depart from the natural genotype grouping, which is the Here, however, complete panmixia is a prerequisite. Since case on many of the forests in Germany, the more caution a complete panmixia is unlikely to occur, the number of is required, and the designation of stands of this nature trees has to be increased considerably. Comparing pro- should be made only after progeny testing.Stands of ductivity of stands originating from seed harvested from unknown origin, however, have to be progeny tested in single trees, and then kept separate or mixed, with the, every case.Their phenotypic appearance does not tell progeny of whole seed stands or natural populations in much aboutthegenetical composition of theseed. which selections were carried out, we may say that the Inbreeding depression as well as hybrid-weakness might former may be improved, but this is not to be assumed. occur. Definite figures on performance can be obtained only after Important suggestions are available with regard to seed- completing the progeny testing of the seed stands and the stand treatment. Here, I might refer to the Swedish pro- selected single trees in this stand on different sites. posal of the so-called "living seed magazine" which has Progeny testingof selected single trees for harvesting been further developed, particularly in the U.S.A.In seed of superior quality was strongly recommended, par- such seed stands, seed production is the primary objective. ticularlyat the beginning of forest tree improvement Timber production is of very little or no interest, and all research. Great expectations with regard to an increase in techniques applied to such stands serve the purpose of timber production were connected with it.It can also be promoting frequent and abundant flowering and fruiting said that there is a certain similarity with regard to the of all members of the stand.This is accomplished first later recommended methods of plus-tree selection and of all by wide spacing, and all trees of little economic with regard to enthusiasm. However, single-tree selection value are removed. Only trees of good form and volume for seed production and selection of plus trees are two are kept, and greater spacing gaps are tolerated. completely different things. The former is directed toward The seed collection of such treated stands for cultiva- improved seed production after progeny testing. The lat- tion on the same site must be considered positively from ter goes a step further, as it is the basic step for future the improvement point of view, when sufficiently large breeding procedures.Seed harvested from plus trees is indigenous stands or stands of their progenies are selected. not normally used for the establishment of new stands. Furthermore, itis necessary that a sufficient number of Testing of single-tree progenies was thought to be seed trees remain to eliminate the chances of inbreeding simple. One felt that it was sufficient enough to raise

Genetics and Tree Improvement 779 seedlings from these trees from a few seed years and to propagatedvegetatively(i.e.,grafting)andplanted plant them out.So, after a certain number of years, randomly in clonal mixture, the seeds provided in this results would show which trees provided the best off- seed orchard are probably superior to average seed har- spring. Trees which continue to produce promising young vested in the same origin area, and also to seed collected offspring over a number of years should be used for the from the plus trees. But the present practice of establish- establishment of future seed stands. It was thought that ing seed orchards can be improved in the future by con- fertilization of a given tree was always done by the same sidering the following items. First, a problem of import- pollen mixture.It was thought that panmixia did exist. ance is whether only superior F1 material is wanted or We know today that panmixia normally does not exist, also superior material in the following generations.If and a given tree in different years is fertilized by different only superior F1 material is required, no special precau- neighbors.This can result, year for year, in different tions have to be taken, except that the orchards be parent combinations and different progenies. Furthermore, isolated from strange pollen and that a sufficient number of importance is the fact that early fast growth is not of clones be included to give the desired amounts of seed. indicative of the growth rate when a tree is becoming If, however, the F2 material and the following generations mature. We can also expect that normally only such have to show superiority, a higher clonal number is neces- trees as show a good to high seed bearing capacity will sary, and a size of seed orchard is required in whichall be selected.This is because only these trees produce the theoretical combinations are made possible on a high enough seed to make a repeated progeny test possible. frequencybasis.Considering the number ofclones Even the most enthusiastic proponents of this method involved, one has to keep in mind that all the selected think that only a few trees will be left over. So it will be clones do not flower at the same time. In fact, some of very likely that there will be an increasing possibility of them do not flower in the same year, and certain clones inbreeding depressions. We know today that the most show a poorer flower production or no flowers at all.It pessimistic estimates about the number of trees providing must also be considered that there are possibly trees superior offspring are still too optimistic because of the which, if a small amount of pollen of other clones is polygenous nature of most of the economically important available, have a high tendency to be self-compatible. characteristics(for instance, growth rate).The result The number of clones, therefore, has to be so great that would bthat only offspring from a few trees could be in a given year so many cross combinations are produced raised, and this, in turn, would increase the chances of in order to avoid inbreeding depressions. A lower number inbreeding. Furthermore, this would result in less seed, is, of course, possible if we can increase flower and fruit which makes this method useless for practical purposes. production by artificial means for certain clones, thus Based upon this way of thinking,, new ways had to be improving crossability chances. The clonal number sug- found to solve the problem. Therefore, the establishment gested by Stern (30-50) seems reasonable. But also, if of seed orchards was proposed. The basis for the seed the number of clones involved is still higher it is necessary orchards is also single-tree selections; the selection pur- to make an inspection during the flowering seasonand pose is, however, different. And so it seems suitable to another shortly before the seed harvest. discussthese problems in connection with the seed It is possible, of course, to obviate these dangers by orchards themselves. testing the flowering time and fertilization conditions and combination chances before establishing seed orchards. Clonal Seed Orchards For this purpose, so-called clonal test plantations could Under certain conditions, and aside from special breed- be established in which controls and controlled crosses ing methods, the establishment of seed orchards seems to could be carried out over a number of years.It is a be the best way to obtain significant improvement. matter of economics as to whether or not to increasethe The seed orchard idea has been most systematically number of clones and to forget about clonal test planta- developed in Sweden. A discussion of the techniques and tions. procedures which we have to follow to fulfill the neces- Furthermore, plus trees selected in indigenous stands sary requirements for improvement of seed quality should give, at the present, the most promising material for seed follow the Swedish line of thinking. orchards in respect to further improvement. Quite a bit The method consists of the following.First, areas of of effort is also being made in Sweden to find,through most uniform environmental conditions in the natural testing, those trees which produce genetically superior range of a given species are carefully selected. We might offspring by flowering together.For one thing, clonal call these uniform areas "origin areas." Their limits are tests of each selected plus tree were carried out;for formed vertically as well as horizontally. In these origin another thing, the result of different plus-tree combina- areas a great number of so-called plus trees are carefully tionsistested. Due to the time limit itis, however, selected with the help of a special selection index. This impossible to discuss this important matter further in index has been prepared in such a way that with a certain detail. degree of security, combinations of these plus trees are The discussion about the selection of plus trees and produced which, when planted in the same origin area, their use in seed orchards would be incomplete if we did would result in phenotypes equally as good as the plus not discuss whether or not selections of plus trees in non- trees which have been chosen. This possibility has been indigenous stands are worthwhile, and also in which way shown by research results which demonstrated clearly that such selected trees have to be used. some importantquantitativecharacteristicsare most First, it seems necessary to emphasize that a selection likely the result of an additive gene effect. of plus trees, i.e., trees which are superior to trees of the If the selected plus trees of a given origin area are same population, in non-indigenousstands cannot be

780 Fifth World Forestry Congress Proceedings made except when these stands are progenies of a single Conclusion population unit.If, however, a plantation consists of many different population units in which many different Concluding thediscussionof the above-mentioned genotypes of unknown origin are included, an objective problems, the following might be pointed out. selection of plus trees is the more impossible the more A prerequisite for a not merely accidental improvement the populations are different. of our forest trees through the selection of seed stands Therefore, it must be said that particularly in Germany and single trees, as well as through the establishment of many of the selected trees are in this sense not plus trees. seed orchards, is the consideration of population genetics. It is certainly possible to use these trees in seed orchard In order to be on the safe side, selections made in indig- establishment.It is, however, impossible to predict as to enous populations and subpopulations are to be pre- whether the seed of the orchard is better than the seed ferred.Similarity and dissimilarity of site of origin and harvested from these plus trees or seed harvested from the site to be used for planting influence the results con- selectionstands.Progeny testing should be required siderably. The possibility of inbreeding depressions and before the seed is permitted to be used. The risk of this hybrid-weakness in the F1 and following generations has type of seed orchard lies in the fact that probably already to be checked and considered.If such hazards are likely in the F1 material the effect of hybrid weakness might to occur, and if it is unknown whether or not we are show up.It can also happen in the mixture of the dealing with selections originating from natural stands, provenances of artificial stands that the selected trees are clonal and progeny testing are strongly recommended. F1 progenies of only one narrow population which were Testing, however, is required if economically elite types successful in the new environment.Using these trees are to be discovered. would result in inbreeding depressions.Therefore, seed orchards established with such tree material present many RESUMES unknown and doubtful factors. Amelioration par selection sur une base individuelle el Care must be exercised also in seed orchards where essai des peuplements semenciers, et au moyen de the selections are made in provenance trials.It is very pépinières de porte-graines issus de clones seldom known from how many trees the seed of a given Si l'on procède a la selection des peuplements semenciers dans provenance of these trials has been collected.If only a le but d'obtenir des plants génétiquement améliords, les condi: few mother trees have been harvested for a particular tions génétiques de la population doivent être considérées aussi provenance, inbreeding depressions may appear already in bien que le site de ces peuplements, par comparaison avec le site devant être utilisé pour leurs descendants.C'est seulement en the F1 progeny.Progeny testing, which certainly gives procédant a l'essai de ces descendants qu'il est possible de se results in a relatively few years, seems, therefore, neces- renseigner sur la valeur économique, déterminée génétiquement, sary in doubtful cases. d'un peuplement semencier, sur la base de son phenotype, dans une zone oà la composition normale de la population a été Reference has to be made also to the so-called hybrid altérée.Ii en va de méme pour les peuplements semenciers dent seedorchards.Insuchestablishments members of les graines seront utilisées dans un milieu complètement different. different origin areas or different species of a certain genus Ii ne semble pas qu'il soit nécessaire de procéder a l'essai des are planted together. The objective is to produce "hybrid descendants dans lecas de peuplements semenciers indigènes sdlectionnés dans leur region d'origine, lorsque le site devant être seed," particularly in such cases where heterotic material utilisé pour planterleursgrainesestanalogue.Iiesttrès is expected. vraisemblable que les graines recueillies dans des peupiements At present, only hybrid seed orchards of the genera semenciersphénotypiquementsupérieurs,croissantdansune Larix and Pinus seem economically important. In such region dont les conditions de milieu sont analogues, sont en général supérieures aux graines obtenues de l'ensemble de l'habitat establishments one must realize that there is, first of all, de l'essence considérée.Ccci ne s'applique probablement pas a only the question of producing F1 material, because F2 tel ou tel peuplement déterminé, a des peuplements sélectionnés, material normally does not reach the productivity of the dans une population réduite, a la selection de zones plus étendues F1. This is particularly the case when the hybrid parents avec des conditions de site variées, et enfin a des selections portant sur l'ensemble de l'habitat naturel. Dans ce dernier cas,ii est are related. Because in all interspecific crosses the pro- recommandé de procéder a des essais systdmatiques de provenance ductivity of the hybrids depends upon the choice of the en utilisant différentes conditions de site,car cela permet de crossing partners,it seems necessary to carry out test trouver des peuplements tout particulièrement productifs. Lors- crosses beforehand. After this, the crossing partners with qu'on sélectionne les peuplements pour les essais de provenance, ii convient d'accorder au nombre et a la repartition des sites une good hybrid effect are planted side by side.There is, importanceplusgrandequ'àl'apparencephdnotypiquedes however, also another procedure possible by which as peuplements. En outre, les peuplements ne doivent pas être d'une many breeding trees as possible of different population superficie trop restreinte, sans être toutefois trop étendus, de units of both species are selected. Only a few grafts or facon que l'on n'ait pas a choisir un nombre trop élevé d'unités de population. Un mélange de graines provenant de l'ensemble only one graft of each breeding tree is chosen for planting de l'habitat naturel d'une essence donnée est considéré comme in such a way that the different species are planted in étant de peu de valeur. Tous les facteurs mentionnés ci-dessus mixture.F1 material obtained from such an orchard prennent de l'importance lorsque non seulement la génération F1 involves a wide spectrum of different hybrid types under doit être utilisée, mais aussiles gdnérations suivantes.On a déjàfait mention de lapossibilité de "depressions" dues a which presumably a satisfactory number of valuable l'endogamie et de défectuosités dues a l'hybridation. La méthode plants can be expected. Since there is also a high number consistant a sélectionner les peuplements semenciers exclusive- of intraspecific combinations of different genetic makeup ment pour la production des graines et non pour celle de bois involved, the risk for the use of the unselected F1 offspring d'oeuvre est considérée comme présentant de trés grands avan- tages. is considerably reduced. On the other hand, it seems La méthode consistant a sélectionner des arbres sur une base possible to consider the production of interspecific hybrids individuelle dans le but de récolter les graines doit être considérée instead in seed orchards by controlled cross-pollinations. comme peu satisfaisante.Etant donné qu'ilest extrêmement

Genetics and Tree Improvement 781 improbable que l'onpuisse trouver des arbres ayant chaque individuales,parasemillerosseleccionados en una población année des descendants excellents,iiserait très difficile de re- pequeña de árboles, para la selección de zonas más grandes que cueillir assez de graines, et des "depressions" dues a l'endogamie acusan condiciones distintas en sus diversas partes y, finalmente, ont toutes chances de se produire dans les générations suivantes. para selecciones que abarcan el conjunto de la extención natural. La selection d'arbres "plus" pour l'établissement de pépinières En este dltimo caso se recomiendan pruebas sistemáticas de origen, de porte-graines est considérée comme une méthode trés importan- utilizando para ello las diversas condiciones que prevalecen en te par laquelle la qualité de la semence peut étre améliorée du sitiosdistintos,lo cual permite identificar semilleros que son point de vue génétique, L'utilisation d'un indice de productivité especialmente productivos.Al seleccionar semilleros para las pour Ia selection d'arbres "plus", dans des populations de peuple- pruebas de origen, debe darse más consideraciOn al ndmero y a ments naturels de conditions uniformes de site, est une considéra- la distribución de los sitios, que a sus condiciones fenotipicas. tion importante. Les selections effectuées dans des peuplements Además, los semilleros no deben ser demasiado pequeños pero non indigènes ne présentent un intérét que si ces peuplements ne tampoco excesivamente grandes, para no seleccionar un nilmero sont pas composes de trop nombreuses essences différentes. Lors- demasiado grande de unidades de la población. Se estima que la qu'on établit une pépinière de porte-graines, les arbres "plus" d'une semilla, mezclada de una determinada especie proveniente de seule region d'origine particulière doivent seuls être utilisés. Une todas partes de la extenciOn natural, es de muy poco valor. Todas telle pépinière de porte-graines ne doit pas être de dimensions las consideraciones anteriormente indicadas revisten importancia trop réduites et doit renfermer un nombre aussi 'levé que possible cuando no solamente ha de utilizarse la generaciOn F1,sino de clones, afin d'éviter les effets de l'endogamie au cours des también las generaciones subsiguientes. Ya se ha hecho menciOn générations suivantes. Un nombre de 30 a 50 clones ne semble de las posibles depresiones en los cultivos sin mezcla de familias pas être trop élevé en raison également des différentes conditions y de la debilidad hIbrida. Se considera que el método de selec- de floraison.Pour cette même raison, les pépinières de porte- cionar rodales para semilleros con el fin exclusivo de obtener graines doivent être inspectées pendant la floraison et peu de semillas y no para la producción de árboles, ofrece grandes temps avant larécolte des graines.Sil'ona préalablement ventajas. procédé a l'essai des clones et de leurs descendants, ii se peut La selección de árboles individuales con el objeto de obtener qu'un nombre moms élevé de clones soit suffisant, et ii est possible semillas es una práctica que ofrece resultados poco satisfactorios. dans ce cas d'établir des pépinières de porte-graines de dimensions Dado que es poco probable encontrar árboles con excelentes plus réduites.L'essai des descendants est également nécessaire a descendientesanuales,resulta sumamente difIcilobtenersufi- l'élimination des clones indésirables ou pour l'établissement de ciente semilla y posiblemente se produzcan en las generaciones nouvelles pépinières avec des clones de qualité éprouvée. subsiguientes depresiones en el cultivo sin mezcla de familias. Se considera que la selecciOn de árboles "positivos" para el Si l'on utilise des arbres "plus" choisis dans des plantations, ou establecimiento de huertos para semilleros constituye un método croissant dans des placettes d'essai établies a l'aide de graines sumamente importante por medio del cual puede mejorarse la provenant d'un nombre limité de peuplements, le danger des calidad de la semilla desde el punto de vista genético. El empleo effetsde l'endogamieetdes faiblesses dues al'hybridation de indices de productividad para la selección de árboles "positi- existera pour la génération F1 et les suivantes. L'essai des arbres vos" en poblaciones de existencias naturales, reviste suma im- sélectionnés devient donc une nécessité. portancia. La selección en existencias no indIgenas será eficaz Ce que nous entendons par "pépinières pour la production de dnicamente en el caso en que los árboles existentes no constituyan semences hybrides" constitue un cas special. L'essai des différentes una variedad excesiva de poblaciones. Al establecer un huerto combinaisons possibles est recommandé, mais la question de savoir para semillero deberán utilizarse árboles "positivos" provenientes Si cet essai doit être effectué depend de l'objectif a atteindre. de una determinada zona de origen. El huerto para semillero no debe ser excesivamente pequefio y debe incluir la maxima canti- Mejoramiento Mediante Selección individual y Pruebas dad posible de clones para evitar los efectos del cultivo sin de Arboles, Semilieros y Viveros de Variedades que mezcla de familias en las generaciones subsiguientes. El nOmero de clones de 30-50 no parece ser excesivo teniendo en cuenta las se Reproducen POT Medio de Estacas distintascondicionesdefloración.Porigualesrazoneses Si los rodales para semilleros se seleccionan con el objeto de necesario vigilar los huertos para semilleros durante la floraciOn obtener material genéticamente mejorado, deberán tenerse en y también poco tiempo antes de la cosecha de las semillas. Si los cuenta las condiciones genéticas de la población de árboles, asI clones y sus descendientes han sido examinados de antemano, como también la ubicaci6n del semillero en comparación con el podrá utilizarse un mlmero más reducido de clones y podrán sitio que se utilizará para la procreación. La información sobre establecerse huertos para semilleros más pequefios.El exarnen el valor económico genéticamente determinado de un semillero de los vástagos es necesario para eliminar clones indeseables o seleccionado a base de su fenotipo, en una zona en la que la paraestablecerhuertos parasemillerosnuevos conclones composición normal de Ia población de árboles ha sido destruIda, probados. solo puede ser obtenida por medio de pruebas de procreación. Cuando se utilizan árboles "positivos" seleccionados en las Igual criterio es aplicable en el caso de semilleros cuyas semillas plantaciones o criados durante pruebas de origen y establecidos serán utilizadas en un medio ambiente completamente diferente. con semillas de solamente unos pocos viveros, existe el peligro Las pruebas de procreación no parecen ser necesarias en el caso de los efectos causados por el cultivo sin mezcla de familias y el de semilleros de especies indigenas seleccionadas en los lugares de Ia debilidad hIbrida, en la generaciOn F1 y subsiguientes. Por de origen, cuando el sitio que se utilizará para el transpiante de lo tanto,es necesario someter a pruebas a los árboles selec- los vástagos es de caracterIsticas similares. Es muy probable que cionados. las semillas obtenidas en semilleros fenotIpicamente superiores En los "huertos para semillas hIbridas" se presenta un caso que crecen en una zona cuyas caracterIsticas son similares, sean, especial.Se recomienda someter a pruebas a las distintas corn- por lo general, mejores que las semillas obtenidas en toda la binaciones, pero la necesidad de tal procedimiento depende del extención.Probablemente, esto no es aplicable para semilleros objetivo que se desea lograr.

782 Fifth World Forestry Congress Proceedings Forest Tree Improvement Through Inbreeding And Intraspecific and Interspecific Hybridization

FRANCIS I. RIGHTER Forest Geneticist, Institute of Forest Genetics, Pacific Southwest Forest and Range Experiment Station, Berkeley, California, U.S.A.

In1924the Oxford Paper Company set up the first As the method of producing hybrid corn through single comprehensive program in the United States for a sus- and double crossing is well known, I shall not describe it. tained and systematic application of genetic principles to Rather I shall touch on the use of its products in forest- the improvement of forest trees. At that time, skepticism tree breeding and suggest modifications that might be about the practicability of such work was widespread. In used. consequence, practical interest in such work was slow to The method produces homozygous lines, low in vegeta- develop, and programs that were started had to bump tive and reproductive vigor. When such lines are crossed, along over some long stretches of very rough road. Today, populations of F1 hybrids, remarkable for uniformity and the situation is very different. The "proud full sail" of with vegetative and reproductive vigor fully restored, are optimism has replaced the early skepticism, and programs obtained. Because of the reproductive weakness of the in the field of forest genetics research and tree breeding maternal parent, however, seed-yield per plant is too low have increased, particularly since World War II, in seem- for practical purposes, except for products, like sweet ingly geometric progression under the sponsorship of corn, which bring a relatively high price. The cornbreeder educational, business, and government institutions in this therefore crosses two F1 lines derived from crossing four and many other countries. To one who has spent almost inbred lines. As the F1 plants are fully vigorous repro- three decades in this field of work, that revolution seems ductively, an abundance of seed is obtained at the cost very remarkable, indeed, and it is heart-warming in the of an acceptable reduction in the uniformity and yield. highest degree. The F1 lines must be produced annually. A crop may The assumptions which gave rise to so much skepticism consist entirely of the progeny of a single line of F1 35years ago were eventually shown to be erroneous, hybrids. wholly or in part; and we may as well assume that the Applied without modffication to pines and other genera advancement of knowledge and the dynamism of breeding of forest trees that are capable of self-fertilization, this will bring further changes in concepts and procedures. method would be slow in yielding results, since five or This seems certain to me because some formidable bar- more generations might be required to obtain homozygous riers confront us. These barriers challenge science. But lines. Once the F1 hybrids were produced, however, they the power of science is such that we may well expect might yield seed crops for a hundred years or more. The those barriers to yield to it. When they give way, new time required would vary with the reproductive precocity possibilities will be at hand. In view of these considera- of the species and the effect of inbreeding on precocity. tions, I shall discuss the topic assigned to me as might a Another possibility is that other results of breeding might mildly skeptical optimist. make the expected results obsolete long before they can be obtained. This, however, is a risk that most long-term Improvement Through Inbreeding projects must take. Inbreedingincludes"selfing"andcrossingclosely Many species of pine, when grown under favorable related individuals.Backcrossing of hybrids to parental conditions, attain to reproductive activity early in life. At plants may also be included in the second category. Both Placerville, California, Scotch pine has produced strobili of these kinds of inbreeding are powerful analytical and of both sexes at the age of5years, and19other species synthetic tools. They are being used to some extent in and varieties of pine have demonstrated equal or greater forest genetic research, and their routine use as an essen- precocity(Righter,1939). Inbreds, however, would tial step in the synthesis of improved forms based on probably be less precocious. In view of the precocity of exact knowledge is to be expected. many species and the probability that artificial meansof Presumably, selfing, which is used with great success in stimulating flower production even in inbreds will be producing hybrid corn, can be used with similar effect found, double crossing may prove to be well worthwhile in producing crops of forest trees of many species. The in many species. Moreover, as genetic uniformity is not method is now being used in England for the production necessary in silviculture, enough roguing of undesirable of improved crops of Pinus sylvestris (Matthews and genes might be effected before homozygosity isobtained, McLean,1957).Applied to forest trees, the method is say, by two or three selfings instead offive or more, to capable of yielding returns beyond those obtained from providesuitableseedforinterimusein producing hybrid corn.It therefore merits special consideration. improved crops.Since the inbreds may develop into Genetics and Tree improvement 783 fairly large trees capable of producing many seeds, it may selves are presently determining their utility.In many prove posible to plant the F1's.This would eliminate a cases, perhaps in most, the difficulty of mass producing generation of waiting, and the F1 hybrids would excel the the hybrids is the crucial factor. For although it is easy double crosses in uniformity and yield. to produce a single, particular, interspecific hybrid tree, Finally, the inbreds might, and the F1 lines certainly it is very difficult to demonstrate that mass production would, serve very well as parents in intervarietal and of that particular hybrid iseconomically feasible.In interspecific hybridization.Offhand,Ishould rate the many instances, so few seeds are obtained per pollination F1's as good as, if not better than, most of the proposed bag that mass production of the hybrid could be justified elite selections for such purposes. only by an enormous superiority of the hybrid over its Rigid control of pollination in making the selfings is parental species in yield. essential.Otherwise good-looking non-inbreds in the The difficulties of mass production will gradually be inbred lines might be selected, with the result that the reduced or overcome.Costs can be reduced through benefit of one or more selfings would be lost. establishment of breeding orchards containing representa- If the trees in the inbred lines of female parents are tives of numerous races of a species. Last year, the United not genetically identical when the F1's are to be produced, States Forest Service established near Placerville a breed- interpollinating among them will have to be prevented. ing orchard consisting of 50 trees of each of 26 proven- This can be done through (1) removal of catkins from ancesof knbcone pine.Sincethisspeciesbegins the female parent line; (2) use of pollination bags; or (3) reproductive activity at about 3 years of age, and since isolation of pairs of parents. Similarly, control would have the yield of hybrid seed per pollination bag is high, it to be applied to the F1 line of female parents. If isolation will soon be possible to mass-produce the knobcone- in pairs can be arranged, both inbred lines and both F1 monterey hybrid at low cost in accordance with an aimed lines could be used as female parents. This would double breeding program that will serve various parts of Cali- the crop. The amount of natural selfing would probably fornia and Oregon. The F1 hybrid begins to produce be negligible. A fourth possibility is that by the time flowers at 4 years of age, and many of the F2 plants are homozygous lines are produced, a method of inhibiting very vigorous. Therefore, plantations of the F1 hybrid will pollen production may be available. become valuable seed orchards early in life, yielding seed To reduce the danger from too much uniformity, a in abundance at low cost.At the Institute of Forest dozen or more F1 lines should be established for pro- Genetics, the F1 hybrids at 11 years are about equal in ducing seed for reforestation in a specified zone, at least height to 22-year-old ponderosa pines growing adjacent until silviculture becomes highly agriculturalized. to them; and in a field planting on the Eldorado Na- tional Forest, the F2 is well ahead of ponderosa pine at Improvement Through Intraspecific and the age of 7 years. Interspecific Hybridization Mass production problems may also be solved by other Technically, intraspecific hybridization refers to cros- means. Research into flowering phenomena may lead to sing between (1) genotypically different individuals of the information that will enable tree breeders and silvicul- same ecotype or geographic race; and (2)different turiststostimulate and controlflowering.Similarly, ecotypes or geographic races of the same species. For research into vegetative propagation through rooting of convenience, I shall use the terms "hybridization" and cuttings of many species and through rooting of fascicles "wide outcrossing" to include interecotypic, interracial, of pines may provide a breakthrough that will make such and interspecific crossing. propagation commercially feasible. Hybridization between individuals of the same ecotype Other barriers to tree improvement through hybridiza- or geographic race does not fall within the scope of this tion are found in particular species or races themselves. part of my discussion, since my assignment is to enlarge Many crossings fail altogether or are obtainable only on improvement through production of new forms. How- through taking special measures. Hybrids of sugar pine, ever, it is obvious that the ultimate in improvement for a for example, are highly desired. But sugar pine is a lordly particular purpose through wide outcrossing eventually snob that will have nothing to do with other species comes down to the use of the best individuals within par- except through extreme compulsion (Stone and Duffield, ticular ecotypes or races.Hence, when individuals bet- 1950). To straighten up Digger pine would be a major ter than the average of their ecotype or race are produced accomplishment. But Digger pine is a deformed outcast, or found, they will be used in producing hybrids. One shunned by even its closest relatives.Similar situations aspect of the use of products of crossing individuals of the are to be found in most other genera. Difficulties of this same ecotype or race was touched on under inbreeding. kind may be overcome in some cases when the barriers to crossing are understood. Studies of reproductive phenom- Some Difficulties ena, long ago foreseen, but only recently undertaken, Before venturing into the future, it is customary to look are beginning now to show up in the literature. at the past so that one's evaluation of possibilities may Another kind of roadblock is the fact that most hybrids benefit from what has been done. In the field of wide have been produced so recently and without aiming at crossing among forest trees, so much has been done that particular sites or zones that their adaptability to any there is an apparent embarrassment of riches. Many particular area on which planting is to be done is un- seemingly incredible results of such hybridization have known. This difficulty can be overcome for the present been observed; yet very few practical applications are through aimed breeding and interplanting the resultant being made.It therefore is quite evident that factors hybrids with the parental or other species native to the other than the observed characters of many hybrids them- site (Righter, 1946), if mass production through either 784 Fifth World Forestry Congress Proceedings I sexual or vegetative reproduction is relatively inexpensive races or species are crossed.In general, hybrids are and if the hybrid has shown sufficient promise. In such intermediate between the parents, but occasionally hybrid an operation,loss of the hybrid because of lack of vigor or heterosis in various characters is obtained. adaptability would mean loss of the cost of producing Thus, the cross between the relatively slow-growing but the hybrid seed. The potential loss can be calculated, frost-hardy knobcone pine of the lower west slopes of but the yield, in the event that the hybrid proves success- the Sierra Nevada of California and the extremely vigor- ful, cannot be calculated. ous, but frost-tender, Monterey pine of the central Cali- If a fertile F1 hybrid should prove successful, the in- fornia coastal region is intermediate in frost-hardiness, crease in yield from it might be only a partial measure vigor, and season of flowering.Similarly, the hybrid be- of its value, since highly valuable seed might regularly tween western white pine of the High Sierra of California be obtained at small cost from the mature trees before and the eastern white pine of Massachusetts is intermedi- they are harvested. This possibility has been envisioned ateindrought-hardiness.Most hybrids produced at (Anonymous, 1955), and a report by Clausen and Hiesey Placerville and elsewhere have been intermediate in vigor (1958) gives its importance added emphasis. Concerning under the conditions where they were tested. the relation to environment of hybrid vigor in F1 and F2 Hybrids intermediate in vigor can be used to increase hybrids between contrasted ecotypes, Clausen and Hiesey crop yield within the distribution range of the weaker report: parent if they are otherwise adapted. They may also be "Hybrid vigor changes with the environment, for the used in the distribution range of the stronger parent or of gene-controlled growth-promoting and growth-inhibiting another vigorous species if they have an important endow- processes vary inintensity with the environment, and ment, such as resistance to a disease or to an insect, otherwise inactive genes may become activated in new which the stronger parent or other species lacks. Finally, environment. An especially striking example was reported since hybridization may release hidden or latent genes in the F2 of the cross between subspecies borealis and (Clausen and Hiesey,1958), they may prove to be gigantea of Achillea borealis (Clausen, Hiesey, and Nobs, superior in habitats to which the parents are not native. 1955). At the lowland station at Stanford there is no An interesting example of such possibilities is the early conspicuous hybrid vigor in the F2 of this cross. At the performance of a F1 hybrid (produced at Placerville) mid-altitude Mather Station, however, the high-latitude on a longleaf pine site in southern Louisiana. The hybrid borealis parent tends to die during the summer, and the is a cross between a single shortleaf pine of Oklahoma low-latitude lowland gigantea tends to become killed dur- provenance and asingleloblolly pine of Louisiana ing the winter. The F1 plants survive with great vigor, and provenance. It is intermediate in vigor at Placerville, and more than 50 percent of the F2's are even more vigorous it probably would be intermediate in the habitats of the than the F1. The parental characters complement each parental species. At Bogalusa, on a longleaf pine site, it other in both the F1 and part of the F2, producing more is resistant to fusiform rust (Henry and Bercaw, 1956), vigorous growth and greater tolerance to both winter and and I have been told that it is about as vigorous there as summer seasons in this environment." loblolly pine to which it is superior in several other im- Various other factors impose limitations on the kinds portant characters.Because loblolly pine, which is in and degrees of improvement that can be obtained through extensive use at Bogalusa, suffers seriously there from hybridization. In some instances, hybrids can be readily fusiform rust, the hybrid appears to hold much promise. obtained without fully obtaining the objectives of hybridi- In crossings between shortleaf and loblolly pines, seed zation, as in crossing the American and Chinese chestnuts yield per pollination has been high. Hence it should be for the production of an acceptable timber tree resistant economically feasible to mass-produce numerous disease- to the chestnut blight.Resistant hybrids have been pro- resistant lines of shortleaf-loblolly hybrids which will be duced, hut they lack the desired properties of the Ameri- adapted to numerous longleaf sites. can chestnut.After many years of work, the objective If adapted, heterotic hybrids may be used to "increase" still seems to be obtainable only in the very distant future, yield in the distribution ranges of both parents as well if at all. as on intermediate sites, as indicated by Clausen and It may appear that I have unwittingly put the cart Hiesey (1958). The literature contains numerous reports before the horse by enlarging on the difficulties of produc- of hybrids which have displayed hybrid vigor in early ing crop improvement through hybridization before deal- testing.Several such hybrids have been produced at ing with the possibilities of obtaining improved trees Placerville. Few heterotic hybrids are in use, however. through such means, but I hold that the chief problem in Another important result of hybridization is the com- effecting a wide application of hybridization in forestry is bining of two or more important characters not possessed not that of obtaining acceptable genetic improvements, by both parents.The F1 hybrid between Jeffrey pine but rather the difficulties of using such improvements with and Coulter pine is more frost-hardy than Coulter pine, economic success once they have been produced. For that more vigorous than Jeffrey pine, and it is highly resistant reason I have given the difficulties priority in my discus- to the pine reproduction weevil which has ravaged planta- sion. tions of Jeffrey and ponderosa pines in northern Cali- fornia. The average yield of hybrid seed per pollination Improvements Commonly Obtained bag is low, and the hybrid is not yet in use. A single Through Hybridization Jeffrey pine has given a high yield per bag, however, and Most characters that determine the utility of trees are doubtless other trees of similar yielding capacity will quantitativeones;and we already know what may eventually be found. Then this hybrid will be widely used reasonably be expected of such characters when contrasted in California, since it is equal to the best ponderosa pine

Genetics and Tree Improvement 785 in vigor and is highly resistant to the reproduction weevil. greater vigor and better quality, the extra cost of produc- Meanwhile the so-called Jeifrey-Coulter backcross hybrid, ing it is more than justified. Pinus jefjreyi X (P. jeff reyi X P. coulteri) is under mass To producethe hybridatlessexpense, breeding production for use in the range of Jeffrey pine and part orchards of the parental species have been established of the range of ponderosa pine in California because it along the warm, southern coast where loblolly pine is not is more easily produced. It has less vigor than the F1 and injured by frost. Control of pollination will be effected by is less resistant to the weevil than the latter. In 9 years of removing the pollen catkins from the pitch pines.This testing in northern California, however, it has surpassed is probably one of the first instances in which a completely Jeffrey pine in vigor and weevil resistance (Hall, 1959). exotic hybrid has been used on a truly large scale, halfway Large populations of progenies of hybrids offer excep- around the world from the habitats of the parental species. tional opportunities for highly effective selection.Such Even more impressive than the pitch-loblolly hybridiza- populations exhibit an enormous amount of genetic tion project in Korea, in number of hybrids involved, is the diversity resulting from segregation and recombination. production and use of the hybrid Populus tremula X P. The growing of large populations of such progenies under tremuloides in northern Europe (Syrach Larsen, 1956). natural conditions, as Stebbins (1950) has noted, sets the Seed of this vigorous and disease-resistant cross is readily stage for natural, and artificial, selection which can speed produced in great numbers in the laboratory. An interest- up the rate of evolution very strikingly. Because individ- ing account of a small commercial project for the pro- ual selection among economically important species is at duction of hybrid aspen is given by Heimburger (1952). best very difficult in California, the hybridization program A match company produces about 30,000 hybrids per of the Institute of Forest Genetics has long envisioned use year and sells them to State and private forest districts of a breeding procedure that may give rise to accelerated to be grown into trees suitable for match stock which selection. Judging by small populations of different F2's the company hopes to buy later on for its own use. The now being grown in different places in the Sierra Nevada operation does not pay for itself directly, but it is less and Mountains, future tree breeders will be confronted with an less unprofitable as the years go by, and valuable ex- embarrassment of riches when selecting among large perience in growing the hybrids to the match-stock stage populations of F2's. is accumulating. The company is confident that the in- The procedure used in this program provides for inclu- vestment will be very profitable in the long run. sion in F1 populations of a great deal of the variability of the parental races or species to insure that the F2 popula- The example of the Danish Match Company shows tion will include a great diversity of new types.Thus, that some forest owners are willing to invest in projects numerous individuals of the female parent species or race of uncertain financial outcome.Others are not.Both are pollinated with a mixture of pollen from numerous attitudes are helpful. One gives the tree breeder opportu- individuals of the male parent species or race. Informa- nity to test breeding products in large observation plots; tion presented by Dimpflmeier (1959) indicates that this the other requires him to adhere scrupulously to scientific procedure would be very effective in breeding hybrid procedures.Thetreebreeder may sometimestake larches. advantage of opportunities to test products in use when improvements in nursery tests are so great as to appear obvious; and such an expedient may be very helpful.It Some Large Scale Applications has been in the past. Thus, the mule is obviously superior of Breeding Results to its parents for certain kinds of work. As the mule has been a valued animal for centuries, its superiority was not One of the most impressive applications of hybridiza- determined by scientific methods. On the other hand, if tion results has been under way in Korea for several years. current scientific standards had been in use when the mule There the hybrid between pitch pine and loblolly pine was first produced, the world would be very different (Pinus rigida x P. taeda) is being mass-produced through today. The mule did not change the world very much, hand pollination on a most impressive scale(Hyun, but it was useful. There is no doubt about what scientific 1956). This hybrid was first produced in 1943 at Placer- method would have done; nevertheless, testing in use may ville, where Dr. Hyun, Who was conducting an investiga- be helpful. tion there at the time, saw it.It is more frost-hardy than My discussion has been of methods.As Duffield loblolly pine and has greater vigor and better form than (1954) has stated, no one breeding method or procedure pitch pine, which had been planted extensively in Korea is best in all situations. In a rapidly changing world, who for a number of yearsabout 50 million seedlings per can predict what method will be used in a particular region yearbecause of its superiority over the native Korean fifty years hence? I cannot. In 100 years, if not sooner, red pine in growth and insect resistance. Pitch pine is too low in quality to produce good lumber in Korea. The papers on forest genetics will very likely resemble those young pitch pine plantations make excellent breeding on chemistry and physics in being largely pages of formu- orchards, and hence they are being used in breeding the lae interspersed with short sentences.In that distant hybrid. From a modest beginning in 1953, when 672 time, projects to improve forest trees will still be under- hybrid seeds were produced, the project has grown very taken,and forestgeneticiststhen,as now, will be rapidly. In 1955, 11,666 pollination bags were used, and speculating about the future while working out solutions 339,000 hybrid seeds were obtained from the work. In to their own particular problems. But by that time many later years more than 30,000 bags were used. The cost of our forests will begin to look very different from those per thousand of the hybrid seedlings was $1.52 more than we see today. Much of that change will come about the cost per 1,000 pitch pine seedlings. In view of the through hybridization.

786 Fifth World Forestry Congress Proceedings References RESUMES Anonymous, 1955. Forest research in California. Hybrids show Amelioration des essences forestières par propagation promise as seed orchards. U. S. Forest Serv. Calif. Forest and d'une espèce et par hybridation dans le cadre d'une Range Expt. Sta. Annual Report 1954: 19-20. Clausen, Jens, and William M. Hiesey, 1958. Phenotypic expres- espèce et par croisement d'espèces sion of genotypes in contrasting environments. Scottish Plant Le scepticisme qui régnait ii y a trente-six ans en ce qui con- Breeding Sta. Report 1958: 41-51. cerne le caractère pratique de la selection des essences forestières Dimpflmeier, R., 1959. Die Bastardierung in der Gattung Larix. a maintenant fait place a l'optimisme, et les travaux dans ce (Hybridization in the genus Larix).Beihefte Forstwiss. Cbl. domaine ont marqué une evolution rapide au cours des dernières 1959. No. 12: (Reviewed in Plant Breeding Abstracts. 29(4): années. L'auteur du present rapport passe en revue les possibilités 919-920. Abstract No. 4717). etlesdifficultés relatives a lacreation de nouvelles formes Duffield, J. W., 1954. The importance of species hybridization and améliorées par reproduction entre espèces proches et par croise- polyploidy in forest tree improvement. Jour. Forestry. 52(9): ment entre espèces éloignées du même genre.Ii examine, a la 645-646. lumière de certaines modifications et limitations, la méthode de Hall, Ralph C., 1959. Field tests of resistance of hybrid pines to dihybridation employee dans la selection du mais.Ii passe en thepine reproductionweevil.U. S.Forest Serv.Pacific revuelesdifficultésrencontrées pour améliorerlesessences Southwest Forest and Range Expt. Sta. Tech. Paper 33. forestières par croisement entrevariétés éloignées,ainsi que Heimburger, C., 1952. The Fourth International Poplar Congress lesmoyens pouvantlesrésoudre.Iiprésentelesrésultats in Great Britain and forest tree breeding in Denmark. Forestry généraux pouvant être attendus de ce type de croisement et en Chron. 28(3): 6-23. donne quelques applications courantes. Henry, B. W., and T. E. Bercaw, 1956. Shortleaf-loblolly hybrid pines free from fusiform rust after 5 years' exposure.Jour. Mejoramiento de Arboles Forestales por Medio del Forestry. 54(11): 779. Cultivo Hyun, S. K., 1956. Forest tree breeding work in Korea. Institute sin Mezcla de Familias y Mediantela paper No. 1.Institute of Forest Genetics, Central Expt. Sta., Hibridización Intraespecifica e Interespeclfica Suwon, Korea. Elescepticismosobrelaposibilidaddecultivarárboles Matthews, J. D., and C. McLean, 1957. Improvement of Scots forestales, que imperó durante lostiltimos 36 afios, ha sido pine in Britain by selection and breeding.Seventh British substituIdo por el optimismo y en aflos recientes han evolucionado Commonwealth Forestry Conference1957:2-14.Australia considerablemente los trabajos en este aspecto de la silvicultura. Sand New Zealand. Se consideran lasposibilidades y dificultadesexistentes para Righter, F. I.,1939.Early flower production among the pines. producir nuevas especies mejoradas por medio del cultivo sin Jour. Forestry 37(12): 936938. mezcla de familias y mediante cruzamientos extensos. La aplica- 1946. New perspectives in forest tree breeding. ción del cruzamiento doble en el cultivo del maiz se considera a Science 104(2688): 1-3. la luz de ciertas modificaciones y limitaciones. Se analizan las Stebbins, G. Ledyard,Jr.,1950.Variation and evolution in dificultades para el mejoramiento de árboles forestales por medio plants. New York. Columbia University Press. de cruzamientos extensos, juntamente con las posibles medidas Stone, E. C., and J. W. Duffield, 1950.Hybrids of sugar pine que permitan reducir dichas dificultades.Se hace mención de by embryo culture.Jour. Forestry 48(3): 200-201. los resultados generales que pueden esperarse de los extensos Syrach Larsen, C.,1956.Genetics in silviculture.Edinburgh cruzamientos y se citan ejemplos de algunas de las aplicaciones and London. Oliver and Boyd. de dicho método.

Mass Production of Control-Pollinated Seed of Conifers

SIN Ku HYUN Professor, institute of Forest Genetics, College of Agriculture, Seoul National University, Suwon, Kyunggido, Korea

The superiorities of the progenies of F1 hybrid between out such test plantations, large-scale control pollination Pinus rigida Mill. and Pinus taeda L. to the open-pollin- has been carried out every year since 1954. ated progenies from their maternal stands have been From the practices carried out during the four years, clearly demonstrated in their juvenile performances. the rate of fertile seed production and the cost of polli- The pitch pine, which is extensively used for reforesta- nation, seed, and seedling production were calculated, and tion in Korea, is to be replaced by x Pinus rigitaeda as the data obtained are presented. soon as the consistency of their superiorities is proven in Material and Method the different type of soil and climate of south Korea. Test plantations of F1 hybrid of P. rigida x taeda at different Maternal Stand sites are therefore needed in order to reveal their perform- In control pollination, the maternal stand should be ances at the respective sites, and a method of mass pro- composed of highly selected individuals which have proven duction of F1 hybrid seed of x P. rigitaeda should be through progeny tests to be genotypically superior. How- devised to meet the immediate need of the hybrid seed. In ever, as a provisional measure, pitch pine plantations of order to observe their performances under different site collegeforestsinSuwon havebeen employedas conditions, test plantations of F1 hybrid of P. rigida x maternal stands. taeda are being laid out at various localities in south In order to facilitate the bagging and pollinating work, Korea, and in order to produce F1 hybrid seed for laying around 10-year-old plantations of pitch pine, which are

Genetics and Tree Improvement 787 not more than 16 feet in height, were employed as around absorbent cotton to the branchiets. In case many maternal stands (with one exception, in 1954, when a 35- female buds appeared in one bag, only five were retained, year-old plantation was used). Further details of maternal and the rest of them were taken off, and, at the same time, stands employed are as follows. care was taken to remove all pollen catkins appearing in the bag. Description of maternal stands used About 20 pollination bags were mounted on each tree of 30-year-old pitch pine, whereas about 2 to 8 pollina- Year of Approx. pollina- height tion bags were mounted on each 10-year-old tree. tion Origin Age (ft.) Site Location When the female strobili arrived at the optimum stage (scales and bracts equal in size, scales widely separated), 1954 Plantation35 20-22gentle Suwon college the pollinations were made. The isolation of flowering slope forests twigs was done by middle-school children, and portable 1955 do 8-12 8-13 do do wooden ladders were used to reach the tops of the trees. 1956 do 8-12 8-13 do do 1957 * On an average, one hundred man-days were needed to coppice 10-11 10-13 do do isolate 10,000 flowering twigs of 10- to 15-year-old pitch 1958 plantation 10-14 10-16 do do pine by bagging. *Coppice originated from stumps which were Pollination.Pollination was effected by using a hypo- cut at the age of twenty-five. dermic syringe fitted with a rubber bulb and pollen agita- tor,as recommended by Duffield.The needle of the These stands were thinned before pollination to the syringe was forced into the bag, and the pollen was extent that crowns of seed trees do not overlap. expelled toward the female strobili by one or two quick squeezings of the bulb, and the holes made by the Pollen needle were sealed with Scotch tape. Two to three polli- Pollen to be used for control pollination should be nations were needed for each bag to complete pollination, collected from superior individuals, but the pollen pro- as the female flowers do not all reach the receptive stage vided by various institutions in the U.S.A. was collected simultaneously. from several individuals, which seemed to be better than On an average, 0.3 cc. (0.1 gram) of pollen was used average in their respective localities, and was mingled. for each pollination bag to complete the pollination, and The sources from which pollen was supplied are as sixty-seven man-days were needed to pollinate the flowers follows: in 10,000 pollination bags. Removal of pollination bags. Bags were removed as soon as the flower closed completely and there was no Species Source of Pollen Supplier longer any danger of foreign pollination. The bags would Pinus taeda Eddy Arboretum, Placer-F. I. Righter soon be too small to hold the rapidly developing shoots, ville, Calif. so it was common practice to remove the bags 5 to 7 Kwangjoo, Chullanamdo days after pollination. Texas H. Brix Waterproofed pyranin tags were fastened to the branch- Gainesville, Fla. Wang, Chi-Wu Raleigh, N.C. Bruce Zobel lets at the places where the bags had been fastened to Jones County, Ga. W. H. Mann indicate that all cones maturing on the stem above it had Bainbridge, Ga. F. C. Cech been pollinated. On an average, one hundred man-days Pearl River, Miss. B. H. Henry were needed for removing 10,000 bags and fastening that Pin us radiata Eddy Arboretum, Placer- F. I. Righter number of tags.The synthetic sausage-casing bag is yule,Calif. usable for two years. Pinus elliottii Gainesville, Fla. Wang, Chi-Wu Results Obtained *CoIlected from one living specimen of Pinus taeda standing in the Arboretum of Chullanamdo Provincial Forest Production of Fertile Seed Experiment Station in Kwangjoo. Data obtained in the course of four years' experience with large-scale pollination of Pinus rigida x taeda, P. All pollen imported was transported by air and kept in rigida x elliottii, and P. rigida x radiata are given in the refrigerators until use.The germination percentage of following tables. pollen was tested immediately prior to using in order to Production of fertile seed differs in each year, mostly confirm the viability of the pollen. due to the difference of viability of pollen used and the amount of pollen used per bag, and it is believed that the Method of Hybridization poor seed production of Pinus rigitaeda in 1957 is to be Isolation of female flowers. Flower buds of pitch pine ascribed to insufficient pollen for fertilization. start to develop from early May in 10-year-old stands However, it is shown that twenty seeds per cone or and from late May in 35-year-old stands. thirty seeds per pollination bag are the average rate of The flowering twigs were bagged with synthetic sausage seed produced from a rate of 0.12-0.15 gram of pollen casings, 20 cm. x 50 cm. in size, when the flower buds per pollination bag in the crossing of Pinus rigida x taeda. were in stage I (flower buds expanded, but female strobili In the crossing of Pinus rigida x radiata, from two to not yet visible).Twigs bearing more than two female twelve fertile seeds per cone and from one to seven fertile flower buds were bagged, and the bags were securely tied seeds per pollination bag were produced, though the rate

788 Fifth World Forestry Congress Proceedings pollination Year 0/ Maternal stand Pollen source Results of control-pollination of Pinus rigida x radiata by year Numberpollination of bags harvestedNumberof cones pollinationNumbercones of per bag volumeof seedTotal(cc.) of seedsnumberTotal of soundNumber seeds Percentageof Numbersound 0/ of soundseed seeds per seeds per pollina-cone Number of seeds ofcone sound non bagNumber tion bag Numberper seeds perpollina- 1955 ests,plantation8- to Suwon12-year-old in College pitch For-pine MixtureKwangjoo,Eddy Arboretum, of Chullanamdoabove Placerville,two Calif. Total or average 11,624 2,9242,5296,171 26,26912,387 7,2856,597 2.262.492.612.01 16,9804,7204,2608,000 1,176,630 297,780322,840556,010 330,030173,50072,56083,970 28.026.024.431.2 4544.844.345 12.611.51114 101110117 90 28.328.628.1 1956 do EddyKwangjoo, Arboretum, Chuflanamdo Placerville, Calif.5Calif. Total or average 13,38510,078 3,8226,256 23,10013,405 7,5355,870 0.91.71.31.9 17,25510,6105,5105,100 1,139,550 715,544366,800348,744 214,260868,080117,00097,260 7630.026.533.5 49.35448.659.3 37.51612.919.9 85719656 25.464.721.218.7 1957 coppice10- to 11-year-old in Collegeuwon pitch Forests, pine MixtureGainesville,Texas of aboveFla. two 10,0883,6002,700 833 15,886 1,9785,5804,695 2.3t.51.71.5 1,4203,7002,9509,840 273,100112,100210,100732,300 160,70025,20076,00031,100 222815 49564046 121410 7 75.877.872.513.4 30.121.111.515.9 1958 10- to 14-year-old pitch HitchitiKwangjoo,Raleigh, Exp.NC. Chullanamdo For., Jones County, Total or average 18,039 818 29,417 1,278 1.51.63 18,860 950 1,402,700 75,100 310,600 17,600 312224 49.547.559 15.510.514 104.5 77.791.8 32.717.225.5 * Pollen was collected from P. rigida x taeda F, hybrid, and backcross to P. rigidaForests,pine was plantationmade. Suwon in College PearlBainbridge, River, Ga. Miss.Ga. Total or average 22,54413,828 3,4175,299 42,07129,231 5,5737,267 1.731.631.362.1 28,88520,500 5,0353,350 2,048,2001,445,700 247,900354,600 452,760659,460121,60085,100 3334 47.34448.5 15.61516.5 66.990.872.5 22.929.224.9 Results of control-pollination of Pinus rigida x elliottii by year Number of seeds of sound Number Number pollination Year of Maternal stand Pollen source Numberpollination of Number bags harvestedof cones Numberpollinationcones of per bag volumeof seedTotal(cc.) 57 ofnumber seedsTotal4,760 of soundNumber Percentageseeds Number o/ of sound760 of sound seed16.0 seeds per seeds per pollina-19cone cone 3 tion bag tion bagper 13.6 seeds perpollina- 2.7 19581957 ests,plantation10-Suwoncoppice to Suwon 14-year-old11-year-old in Collegein College pitch Forests, For-pine HitchitiGainesville, Exp. For., Fla. Jones County, Ga. 3,818 350 2,680 243 0.70.6 690 54,250 5,950 11.0 20.2 2.2 14.2 1.55 Results of control-pollination of Pinus rigida x radiata by year Number Number pollination Year of 1955 8- to 12-year-old pitch pine Maternal stand Eddy Arboretum, Placerville, Calif. Pollen source Numberpollination of bags 107 harvestedNumberof cones 152 pollinationNumbercones of per bag1.42 ofvolume seed Total(cc.) 60 of seedsnumberTotal3,505 ofNumber sound seeds 702 Percentage Numberof sound of of soundseed20.0 seeds per seeds per23.1 polltna-cone Number of seedscone of sound4.6 tion bag lion bag per32.7 seeds perpollina- 6.56 19571956 plantation10-ests, to Suwon 11-year-old in College pitch For- pine do do 1,8801,845 1,312 559 0.20.7 150440 44,26013,600 16,100 3,100 22.036.0 25.033.7 12.2 6 23.9 7.23 1.60.87 00 1958 ests,plantationSuwoncoppice10- Suwon to in 14-year-old Collegein College Forests, pitch For- pine do 1,599 780 0.5 75 6,200 1,550 25.0 8 2 3.8 0.96 of pollen per pollination bag was larger than in the cross- Cost of Seed Production ing of Pinus rigida x taeda. The costs calculated for seed production of Pinus rigida In the crossing of Pinus rigida x elliottii, fertile seeds x taeda in each year are as follows: were produced at the rate of from two to three seeds per cone and from one to two seeds per pollination bag.

Calculation of pollinating cost for Pinus rigida x taeda

1955 (11,624 bags) 1956 (10,078 bags) Wages Preparing of pollination bags 26 man-days x 200 11W x ½ = 2,600 11W 22 man-days x 200 HW x ½ = 2,200 Stapling, inserting cotton 38 " x 200 " = 7,600 38 " x 200 " 7,600 Bagging 116 " x 300 " = 34,800 100 " x 300 " 30,000 Pollinating 77 " x 300" = 23,100 67 " x 300 " 20,100 Removing bags 116 " x 300" = 34,800 100 " x 300 " 30,000 Cone collecting 46 x 300" = 13,800 40 " x 300" 12,000 Cleaning of seed 14 " x 200" 2,800 12 x 200 " 2,400 Sub total 119,500 104,300 HW

Material Pollination bags 11,600 x 50 11W x ½ = 290,000 HW 10,000 x 50 11W x ½ 250,000 HW Cotton 8 kwan x 500 11W = 4,000" 7 kwan x 500 HW 3,500 String 14 rolls x 300 11W 4,200" 12 rolls x 300 11W = 3,600 Pollen 4 lbs. x 10,000 HW = 40,000" 3 lbs. x 10,000 11W = 30,000 Tags 11,600 x 2 HW = 23,200" 10,000 x 2 HW = 20,000 Scotch tape 6 rolls x 100 HW 600" 5 rolls x 1,000 HW = 5,000 Colored paper 230 sheets x 2 HW 460" 200 sheets x 2 11W 400 Paste 2 seung x 280 11W 500" 2 seung x 250 HW = 500 Ladders 16 x 1,400 HW x ¼ = 5,600" 14 x 1,400 11W x ¼ = 4,900 wire hooks l6xlOOI{Wx¼ 400" l4xlOOHwx¼ = 350 Syringes 46 x 800 HW x ¼ = 9,200" 40 x 800 HW x1/4 8,000 Gloves 12 pairs x 300 11W x ½ 1,200" 10 x 300 11W x ½ 1,000 Sub total 379,360 11W 327.250 11W Total 498.860 11W 431,550 11W Number of seeds produced 330,030 214,260 Production cost for one grain of seed 1.51 HW 2.01 11W

1957 (18,039 bags) 1958 (22,544 bags)

45 man-days x 200 HW x ½ 4,500 HW 56 man-days x 200 HW x ½ = 5,600 HW 60 " x 200" 12,000" 74 " x 200" 14,800 180 " x 350 " 63,000" 225 " x 350 " 78,750 120 " x 350 " 42,000" 150 " x 350 " 52,500 180 " x 350 " = 63,000" 225 " x 350 " 78,750 72 " x 350 " 25,200" 80 " x 350 " 28,000 22 " x 200 4,400" 30 " x 200 " 6,000 214,100 11W 264,400 11W

18,000 x 50 HW x ½ = 450,000 HW 22,500 x 50 HW x ½ = 562,500 11W 9 kwan x 600 11W 5,400" 22,500 x 50 11W x ½ = 7,700 22 rolls x 400 HW = 8,800" 25 rolls x 500 11W = 12,500 6 lbs. x 10,000 HW 60,000" 7 lbs. x 10,000 11W = 70,000 18,000 x 3 11W 54,000" 22,500 x 4 11W = 90,000 9 rolls x 1,000 11W = 9,000" ii rolls x 1,000 HW = 11,000 4 sheets x 250 11W = 1,000" 5 sheets x 300 11W = 1,500 2 seung x 360 11W = 720" 2 seung x 450 HW = 900 27 x 1,400 11W x ¼ = 9,450" 30 x 1,500 HW x ¼ = 11,250 27 x 100 HW x ¼ = 675" 30 x 100 HW x ¼ = 750 72 x 800 11W x ¼ = 14,400" 90 x 1,000 11W x ¼ = 22,800 18 x 400 11W x ½ = 2,400" 23 x 500 HW x ½ = 3,830 615,845 11W 794,430 11W 829,945 11W 1,058,830 11W 310,600 659,460 2.67 11W 1.60 11W

790 Fifth World Forestry Congress Proceedings In the same manner, the costs of seed production for pine for producing one unit of planting stock.This Pinus rigida x radiata and Pinus rigida x elliottii were amounts to HW 660 (approximately $1.00) more for the calculated, and the data obtained are as follows: production of each 1,000 units of hybrid planting stock. On the same basis, the production costs of one unit of Pollinating cost for Pinus rigida x radiata planting stock of pitch-monterey and pitch-slash hybrid 1956 (1,845 bags) 1957 (1,880 bags) pines were computed, and the results were HW 4.17 for Wages 18,400 HW 22,129 11W pitch-monterey hybrid and HW 19.15 for pitch-slash Materials 58,500 64,332 hybrid, respectively. Total 76,900 86,461 Number of seeds 16,100 3,100 Applicability of Controlled Pollination in Production cost for one Mass-Producing Hybrid Seed grain of seed 4.77 11W 2.79 HW The factors which will affect the applicability of con- Pollinating cost for Pinus rigida x elliottii trolled pollination in mass-producing hybrid seed are: 1957 (350 bags) 1958 (3,818 bags) Rate of production of fertile seed. The cross ability Wages 4,045 HW 45,045 11W between parental species, viability of pollen used, rate of Material 11,749 134,136 pollen applied to female strobii, and the correctness of Total 15,804 179,361 pollinating time are considered to be the principal factors Number of seeds 760 6,000 affecting the productivity of fertile seed. Production cost for one Uniformityinhybridprogeny.Uniformityof grain of seed 20.70 HW 29.89 11W hybrid progeny varies, owing to the heterozygosity of parental species. The F1 hybrid progenies of Pinus rigi- The cost of production of one grain of fertile seed taeda have shown diversities in their performances to be ranges from HW 1.51 to HW 2.67 for pitch-loblolly of no greater extent than in those of the open-pollinated hybrid pine, from HW 2.79 to HW 4.77 for pitch- progenies from the same maternal stand, whereas the F1 monterey hybrid pine, and from HW 20.70 to HW 29.89 hybrid progenies of Pinus rigida x radiata have shown for pitch-slash hybrid pine. considerable diversities. Due to the high heterozygosity of parental species, the crossings between two highly Cost of Seedling Production selected parental clones would offer better promise in The costof production of nursery stockslargely producing heterotic progenies of less diversity in their depends upon the tree survival percentage.The four performances. years' experience of raising nursery stock with pitch- Rate of labor cost. The average rate of labor cost loblolly hybrid pine has shown 65% survival at the end to the cost of material used for pollination work in four of the first year in the seed bed. And the cost calculated years' experience of large-scale control pollination was for pollination work for one unit of 1-0 stock of pitch- thirty-two percent.Such a relatively low labor cost, loblolly hybrid pine ranged from HW 2.30 to HW 2.40. which is available in Korea, is primarily responsible for This is the extra expense for pollination procedure to be making large-scale control-pollination work economically added as additional cost of production of one stock of feasible. hybrid pine seedling. From 60 to 70 out of 100 pitch-loblolly hybrid seed- References lings are large enough for field planting at the end of the Cumming, W. C. and F. I. Righter, 1948. Methods used to control pollination of pines in the Sierra Nevada of California, USDA first year in the seed beds, whereas only 20 out of 100 Circular No. 792. ordinary pitch pine seedlings are large enough for field Duffield, J. W., 1952. Relationships and species hybridization in planting as 1-0 stock. On this basis, the production cost the genus Pinus. Zetschr. Forstgenetik. 1: 93-100. per unit of planting stock would not be greatly different Hyun, S. K., 1956. Forest tree breeding work in Korea, Institute between hybrid pine and ordinary pitch pine. Paper No. 1. Wright, J. W. and W. J. Gabriel, 1958. Species hybridization in the hard pines.Series Sylvestres.Silvae Genetica 7. Heft 4. Pitch-lobloily 65 (hand-pollination + (production cost hybrid pine: cost per 1-0 seedling) per ordinary RESUMES 1-0 seedling) ± 35 (production cost per 1-1 transplant)+ 100 Production en masse de semences de résineux pollinisés artificiellement 65 (2.40 HW -1- 1.00 11W) + 35 x 3.00 11W En raison de l'énorme potentiel économique de l'hybride du 3.26 11W Pinus rigida x Pinus tueda, on procède depuis quatre ans a la 100 production en masse de semences hybrides par la pollinisation Pitch pine:20(production cost + 80(production cost artificielle effectuée sur une grande échelle. On procède également per 1-0 seedling) per 1-1 transplant) a la production en masse de semence hybride de Pinus rigida x + 100 radiata et de Pinus rigida x elliottii par la pollinisation artificielle. Des plantations de pitchpin de 10 a 14 ans ont été utilisdes Entre 11.000et30.000sacs 20 x 1.00 11W + 80 x 3.00 11W comme peuplements maternels. = 2.60 11W isolateurs ont été montds sur les arbres et l'isolation des ramilles 100 fleuries a été effectuée par des écoliers. En moyenne, 100 journées de travail-homme ont été ndcessaires pour isoler par l'ensachage 10.000 ramilles fleuries de pitchpins de 10 a 14 ans. Consequently, pitch-loblolly hybrid pine costs HW 0.66 Le pollen a été importé par avion des Etats-Unis. On a utilisé more (the difference between 3.26 and 2.60) than pitch en moyenne 0,3 cc. (0,1 gramme) de pollen par sac pour assurer Genetics and Tree Improvement 791 Ia pollinisation, et 67 jours de travail-homme ont été nécessaires Ia producción en gran escala de semilla hibrida de Pinus rigida pour polliniser 10.000 sacs. x radiata y Pinus rigida x elliottii, también se efectCa mediante Les sacs ont été enlevés aussitôt que Ia fleur femelle était la polinización regulada. complètement close et qu'il n'y avait plus aucun danger de pol- Como arbolados maternos se han empleado plantaciones de linisationindirecte.Desfichesde pyranine imperméabilisée Pinus rigida de diez a catorce años. En los árboles se colocaron furent attachées aux ramilles aux endroits oü les sacs avaient de 11.000 a 30.000 bolsas de polinización y el aislamiento de los été montés. Ii a fallu en moyenne 100 journées de travail-homme tallosfioridos lo efectuaron niflos de escuela secundania.Por pour enlever 10.000 sacs et attacher les fiches a leur place. Et término medio se necesitaron 100 dIas-hombre para aislar con les sacs faits d'une enveloppe synthétique (du type généralement bolsas 10.000 tallos fioridos de Pinus rigida de 10 a 14 aflos. utilisé pour les saucissons) ont Pu servir pendant deux ans. El polen se importó de los Estados Unidos por la via aérea. On a constaté que le taux moyen de production de graines Por término medio se emplearon 0,3 cc.(0,1 grm.) de polen fertiles était de 20 graines par cone et de 30 graines par sac en en cada bolsa de polinización para completar ésta, y se necesitaron ce qui concerne le croisement de Pinus rigida x taeda. Toutefois, 67 dIas-hombre para polinizar 10.000 bolsas de polinización. pour ce qui est du croisement de Pin us rigida x radiata, Ia pro- Las bolsas se retiraron tan pronto como las fibres hembra se duction a été de 2 a 12 graines fertiles par cone et de 1 a 7 cerraron del todo y no hubo peligro de polinización extraña. En graines fertiles par sac. De même, pour le croisement de Pinus las ramas, en los lugares donde se colocaron las bolsas, se fijaron rigida x elliottii, la production de graines fertiles a été de 2 a 3 etiquetas impermeables de pyranin. Por término medio se necesi- graines par cOne et de 1 a 2 graines par sac. taron 100 dias-hombre para fijar y retirar las etiquetas de 10.000 Le prix de revient de Ia production d'une graine fertile vane bolsas. La cubierta sintética cilindrica se pudo usar por dos años. de 1,51 a 2,67 HW pour l'hybride resultant du croisement pitch- En lo referente a resultados, se demostró que 20 semillas por pin/loblolly,de2,79a4,77 HW pourl'hybridepitch- cono y 30 semillas por bolsa de polinización fue la producción pin/Monterey, et de 20,70 a 29,89 HW pour l'hybride pitchpin/ media de semilla fértil en el cruce de Pinus rigida x taeda. En el Caraibes. cruce de Pinus rigida x radiata se produjeron de dos a doce semi- has fértiles por cono y de una a siete semillas fértiles por bolsa Le prix de revient unitaire des operations de pollinisation de polinizaciOn. En el cruce de Pinus rigida x elliottii, las semillas calculé pour 1-0 plant d'hybride pitchpin/loblolly vane de 2,30 fértiles se produjeron a razón de dos a tres semillas por cono y a 2,40 HW. Cette dépense supplémentaire pour les operations de de una a dos por bolsa de polinización. pollinisation est a ajouter au prix de revient d'un plant de pin El costo de producción de un grano de semilla fértil varIa de hybride. HW 1,51 a HW 2,67 en el pino hibrido "pitch-loblolly;" de HW Etant donné que sur chaque centaine de jeunes brins d'hybride 2,79 a HW 4,77 en pino hThrido "pitch-monterey" y de HW pitchpin/loblolly, 60 a 70 sont assez grands au bout d'une année 20,70 a HW 29,89 en pino hibrido "pitch-slash." dans la pépinière pour être transplantés, par comparaison avec El costo calculado del trabajo de polinizaciOn para una clase une proportion de 20 seulement sur 100 pour les jeunes brins de de cepa de pino hIbrido pitch-loblolly 1-0 varIa de HW 2,30 a pitchpin ordinaire, ii en découle que le prix de revient unitaire HW 2,40.Este es el gasto extra de polinizacain que se añade des graines de semence ne diffère pas sensiblement entre le pin como costo adicional de producción de una cepa de arbolillos de hybride et le pitchpin ordinaire. En consequence, Ia production pino hIbrido. du pin hybride pitchpin/loblolly coOte 660 HW (environ 1,00 $) De 60 a 70 de cada 100 arbolillos de hibrido pitch-loblolly han de plus pour chaque millier de plants hybrides. crecido lo suficiente para plantarlos en el campo al fin del primer De même, la production des hybrides pitchpin/Monterey et aIio en el semillero, en tanto que solo 20 de cada 100 arbolillos pitchpin/CaraIbes coOte 2,40 et 25,46 $ de plus respectivement de Pin us rigida han crecido lo suficiente para plantarlos en el que le pitchpin ordinaire pour chaque millier de plants hybrides. campo como cepa 1-0. Con esta base, el costo de producciOn por La possibilité d'appliquer Ia pollinisation artificielle pour Ia arbolillo listo para plantan no es muy diferente entre el pino production en masse de semences de pin hybride est examinée hIbnido y Pinus rigida ordinario. En consecuencia, el pino liIbrido des trois points de vue suivants:(1) taux de production de pitch-loblolly cuesta HW 660 (Ca: $1.00) más para producir semences fertiles;(2) uniformité des hybrides ainsi obtenus; et cada 1.000 arbolillos de hIbnido para plantar. (3) coOt de la main-d'oeuvre. Asimismo,elpino hIbrido pitch-monterey yelpitch-slash cuestan $2,40 y $25,46 más, respectivamente, que el Finns rigida Producción en Gran Escala de Semillas de Coniferas de ordinario para producir cada 1.000 arbolillos hibnidos listos para Polinización Regulada plantar. El empleo de Ia polinizaciOn regulada para producir semilla de En vista de las grandes posibilidades económicas del hIbrido pino hIbrido en gran escala se trata desde los tres puntos de vista Pinus rigida x Pinus taeda, la producción en gran escala de siguientes:(1) proporciOn de producciOn de semilla fértil; (2) semilla hIbrida se ha llevado a cabo durante cuatro ailos mediante uniformidad de progenie hibrida; y (3) proporción del costo de Ia polinización regulada, igualmente en gran escala. Asimismo, mano de obra.

792 Fifth World Forestry Congress Proceedings Polyploidy and Mutagenesis in Forest-Tree Breeding

AKE GUSTAFSSON Professor, Forest Research Institute of Sweden, Stockholm, Sweden

Introduction populations,hybridization,recombination,and back- All planned plant breeding is based on the multitude crossing will be the principal methods in tree breeding. of forms found in nature or 'released in experimentation. Notwithstanding, artificial mutation and polyploidy, too, Natural variation is still the main source of the genes and will prove fruitful under certain conditions, and in the genotypes needed for the successive improvement of a long run they may be methods needed also when forest cultivated species. New variation continually arises by trees are dealt with.Under all circumstances a plant various processes:(1) hybridization, followed by gene breeder has to know the population structure of the recombination; (2) the occurrence of gene mutations and species he is working with. For this reason the basic chromosomal changes of various kinds; and (3)the chromosome number, the occurrence of polyploidy, and increase or decrease in chromosome number. the karyotype are outstanding features which must be The methods used in present-day plant breeding may considered also in ordinary plant breeding. be summarized in the following manner: Chromosome Number, Polyploidy, and Mutation Selection:in materials found in the region where the selection is carried out, or in materials intro- Basic number (x). According to the Raukiaer classi- duced from other areas. Selection is an outstanding ficationsystemof"life-forms"(1937),foresttrees and necessary principle and it is generally applied belong to the Phanerophytes. These comprise species the also in methods 2-6. buds and apical shoots of which are destined to survive F, heterosis:obtained through the crossing of the unfavorable period of the year, since they are formed differentspecies,varieties,or lines.These are on stems which live for several, often many, years.In either heterozygous or homozygous. In the latter many plant genera there is a definite connection between case they are homozygotized by spontaneous selfing, the ecological adjustments of a species, its life form, and forced inbreeding, or a doubling of the chromosome itsintrinsic qualities of chromosome size and number. number in haploids. Matters of this kind have been considered by Stebbins F2 . . .F,, recombination and transgression:the (1950) in his "Variation and evolution in plants," as breeder sorts out single useful biotypes from a large well as by Gustafsson (1948) and Gustafsson and Nygren offspring. (1956). With regard to species of woody genera, Steb- Simple or repeated backcrossing (F1 x parent strains bins (1938; 1950) concludes that the occurrence of high or reciprocally): special characters are transferred basic chromosome numbers often indicates their ancient from one variety to another by planned back- origin through hybridization and subsequent polyploidy. crossing. The gymnosperms disregarded for the moment, high basic 5Induced mutation: which consistsof gene and chromosome numbers of this kind are encountered, for chromosome (also karyotype) changes, infrequently instance, in with a decrease or increase in the chromosome Tilia, where x = 41, number. It is obtained by: Fraxinus x = 23, hybridization Platanus x = 21, (whichincreasesthegeneral Aesculus x = 20, mutation rate), or by special "mutator" genes; Populus and Salix ' x = 19, a deficiency of minerals or other nutrients in Crataegus and Sorbus x=17, the soil; Carya and Juglans x 16, irradiation, ionizing or nonionizing; or Alnus, Betula and Ulmus x=14. chemical mutagenesis. The presumably very ancient woody genera of the 6.Polyploidy. i.e., the increase in chromosome num- order Ranales, for instance, Magnolia, Liriodendron and ber, caused either by: Cercidiphyllum, have basic numbers of x= 19.Many hybridization and subsequent doubling of the other woody representatives of this order exhibit numbers chromosomes (amphi- or alloploidy); or by starting from x = 12 or 14. Herbs have basic numbers of artificial doubling of the chromosome number x = 5, 6, 7, 8, 9, etc. Other woody genera with relatively of zygotes and gametes (autoploidy) through high basic numbers consist of: Erythrina, x= 21; Ilex, x= the application of drugs (for instance, coichi- 18, 20; Phoenix, x= 18; Gleditsia, x= 14; Morus, x= 14; cine), heat treatment, twin-formation (with the Acacia and Albizia, x= 13; Ficus, x= 13; Cinnamomum, fertilization of unreduced egg cells). x= 12; Quercus, x= 12; Corylus, x= 11, 14; Casuarina, In this article methods 5 and 6 will be specially con- x=8, 9, 10, 11, 12, 13, 14; and Cornus, x=10, 11. sidered.For long times to come selection in natural It remains to be settled whether a genus like Bambusa Genetics and Tree Improvement 793 (), with high chromosome numbers in different numbers seem to occur, x= 11,14, but no polyploid species (70-72), has a basic number of 12 or 36. Any- species are found, Ficus, where 39 species have 2n=26, how, the closely related genera and species of the tribe hex, with the diploid series of 2n= 36 and 40, Juglans, Bambuseae have somatic chromosome numbers of 48, where all species have 2n = 32, and Populus (all species, 54?, 70, and 72, that indicate a common polyploidy and except for some triploid and tetraploid aberrants and possibly an ancient origin of the high numbers. autoploids, have 2n = 38). Low basic numbers are found in the tree genera: The genus Carpinus is interesting, since all its species Cassia with x=6, 7, 8, 13; Carpinus and Ostrya, x=8; have 2n= 16, except for the European hornbeam, C. Hevea, x=9; as well as in a number of genera, single betulus, which has 2n = 64. Often considered a variety of species of which have been examined C. betulus, the related species C. carpinizza has 2n= 16 All the high basic numbers mentioned above cannot and differs largely by its small leaves (Johnsson, 1942). be primitive but should be considered secondary and Spontaneous autoploids have been detected in several derived, possibly having arisen in the way suggested by hardwood species,forinstance,in Acer platanoides Stebbins. Turning to the gymnosperms, which date even (Meurman, 1933), Populus tremula (Nilsson-Ehle, 1936; farther back than the angiosperms, we find a basic number Mtintzing,1936), Quercus robur(Johnsson,1946), of 7 in Ephedra and the basic numbers of 8 and 9 in Betula verrucosa (Johnsson, 1944), and Robinia pseu- several genera of Cycadaceae. Basic numbers of x= 11, doacacia (Kanezawa, 1948). These cases will be discussed 12, and 13 are encountered in Cycas and Microcycas, and further. x = 10 is found in Sciadopitys, a genus of Taxodiaceae (as Turning to the gymnosperms, we must state that each listed in Darlington and Wylie, 1955) or Pinaceae (in genus is remarkably constant cytologically.Occasionally Rehder, 1947).Otherwise, the basic numbers of the some spontaneous polyploids arise, however, e.g., in Larix gymnosperms generally are 11,12, and 13, except in (a triploid in the cross L. decidua x occidentalis, Larsen Podocarpus, where x= 19 and 20, too, are found (see and Westergaard, 1938; a tetraploid individual in L. below). Thus, if not very high, the basic numbers of decidua, Christiansen, 1950), in A bies firma (a tetraploid gymnosperms certainly are higher than those common individual, Kanezawa, 1949), in Picea abies (tetraploid among angiospermous herbs. individuals, Kiellander, 1950), in Juniperus virginiana Polyploidy. Natural polyploidy is found in several tree (triploid individuals, Stiff, 1951), in Cryptomeria japon- genera. The following cases may be listed for hardwoods: ica (a tetraploid individual, Zinnai and Chiba, 1951), in Tilia 2n 82, 164 Pinus densiflora (Zinnai, 1952, tetraploid seedlings), in Fraxinus 2n=46, 92, 138 P. elliottii (so-called mixoploid seedlings with diploid, tn- Erythrina 2n=42, 84, ±126 ploid, and tetraploid tissue, Mergen, 1958), and in P. Magnolia 2n=38, 76, 114 Salix 2n=38, 76, 114, 152 (also some sylvestris (Johnsson, 1959). Most of the spontaneous other numbers) polyploids have been detected in nurseries. A few (in Crataegus and Sorbus2n 34, 51, 68 Larix and Pinus) are represented by full-grown trees. Carya 2n = 32, 64 The genera Ephedra, Gnetum and Welwitschia contain Alnus 2n = 28, 42, 56 Betula 2n = 28, 42, 56, 70, 84 regular polyploid series (2n= 14 and 28, 24 and 48, 42 Morus 2n = 28, 56, 84, 112, 308 and 84, respectively). One species of Juniperus (J. chin- Cordia Zn = 28, 32, ±72, ±80 ensis, 2n=44), too,is polyploid. A special problem Acacia 2n = 26, 52 relates to the genus Podocarpus, where 2n-numbers of 22, Acer 2n = 26, 39, 52, 78, 104 Quercus 2n = 24, 48 24, 38, and possibly 40 seem to occur.The species Eugenia 2n = 22, 44, 66 (also 28, ±42,45, examined represent two of the five sections of the genus, ± 54) viz, Stachycarpus and Eupodocarpus, the former with Casuarina 2n = 22, 33, 44, also 16,18,20, 2n=24 and 40, the latter with 2n=22, 38, and 40 24, 26, 28, 39, 56 Hevea 2n = 18, 36, 54 (Mehra and Khoshoo, 1956b). These numbers are not Carpinus 2n 16, 64 true multiples but may probably hide some sort of ancient Thus it can safely be assumed that polyploidy is fre- amphiploidy. The single species of Pseudolarix (P. ama- quent in the angiospermous tree genera, independent of bilis, Chinese golden larch) occupies a derived position the basic number.Compare, for instance, the genera with 2n = 44, a number decidedly higher than that of the Tilia and Fraxinus, having the basic numbers of 41 and Larix species (2n=24). This case, too, may be the result 23, with Hevea and Carpinus, having x=9 and 8. of an ancient amphiploidy, or of secondary autoploidy. Nevertheless,inseveralgeneralisted,polyploidy, Intriguing are the chromosome numbers of Sequoia, although present, is rare.Such is the case in Quercus, Metasequoia and Sequoiadendron (Stebbins, 1948), three where most species are diploid and only one is tetraploid related genera, two of which (Sequoia and Sequoiaden- (the East-Asiatic Q. dentata, Japanese silkworm oak). dron) are often united into one genus. Arranging the SimilarlyinUlmus, where most species arediploid, relationships of these genera mutually and with other although Ulmus americana(white elm)istetraploid members of Taxodiaceae, Stebbins found the following according to Sax (1933a), and spontaneous autotriploids order of resemblance with regard to 27 distinct properties: of Ulmus glabra were found in certain offspring (Eklundh- Between Metasequoia Ehrenberg, 1959). and Resemblances Differences In just a few genera only diploids occur, for instance, in Sequoia 18 9 Eucalyptus, where 36 species have 2n = 22 and 2 species Taxodium 14 13 2n=24. Also in Cinnamomum (7 species: 2n=24), Glyptostrobus 12 15 Cornus, with 2n=20 and 22, Corylus, where two basic Sequoiadendron 11 16 794 Fifth World Forestry Congress Proceedings The chromosome numbers of the five genera are, The apomictic mode of reproduction is often accompanied respectively, 2n = 22, 66, 22, unknown, 22. Sequoia by polyploidy, especially when parthenogenetic reproduc- sempervirens is exceptional with 2n = 66 (±), evidently tion prevails.The employment of apomixis in forest a hexaploid genus (species) originated through crosses trees, either by hybridization or mutation, would no doubt between two or perhaps three different species in com- facilitate the breeding and distribution of single outstand- bination with a subsequent polyploidization. Metasequoia ing genotypes that show hybrid vigor.Certain data glyptostroboides (or a species related to it) was possibly indicate that part processes of parthenogenetic reproduc- one member oftheoriginalcross.A conspicuous tion can arise de novo by mutation.The ability of homology seems toexist between the various basic propagation by means of rooted cuttings is sometimes chromosome sets (genomes) of the proposed hexaploid. caused by specific genes transferable from one species to This possibly indicates a partial autopolyploidy. another, like the remarkable case when the rooting ability Stebbins (1950, p. 470) pointed out a feature char- of Salix viminalis was transferred to after acteristicof numerous woody angiosperm genera, viz, hybridization (Nilsson, 1941). Indeed, methods of vege- the small chromosome size (Fig. 1). In the corresponding tative reproduction have become of utmost importance herbaceous genera both small and large sizes are repre- in the breeding of all useful tree species and they will sented.According to Stebbins, this difference depends steadily increase in value. on two facts:first, the angiosperm wood contains fiber A special mode of parthenogenesis concerns the de- cells which, being small in their transverse dimensions, velopment of reduced egg cells without fertilization, i.e., have originated from small-sized cambium initials; sec- haploid parthenogenesis.Complete homozygosis is im- ond, the longevity of the woody plants requires a genetic mediately obtained by the artificial doubling of such system with a maximum amount of recombination, this haploid chromosome numbers. In a crop plant like maize being favored by many and small chromosomes. Having inbred lines are raised suddenly and quickly in this way. cambium initials all about equal in size and lacking wood The artificial production of haploid individuals by irradia- fibers, the principal gymnosperms, the Coniferales, cer- tion of pollen or egg cells, use of aged pollen, or distant tainly have a fairly high but still distinctly low basic num- hybridization should be of great importance in forest-tree ber and large-sized chromosomes.It is likely, Stebbins breeding. A few examples of haploid trees have been argues, that the phylogenetic reduction of the chromosome reported in literature:in Prunus (Pratassenja, 1939), size occurred early in the evolution of woody angiosperms. Robinia (Kanezawa, 1948), and Populus (Tralau, 1957). Fragmentary as this analysis no doubt is, we may never- In Ulmus, antipodal embryos (with the haploid chromo- theless conclude that in flowering plants, beginning with some number) are not rare (Ekdahl, 1941), although the primitive gymnosperms and ending with the most haploid plants have not yet been recovered. derived angiosperms, there exist numerous variations as Mutation. Few data have been gathered with regard to to the rate of polyploidy, the size of chromosomes, and spontaneous mutation in forest trees. However, it is worth the basic number.Possibly these features stand in a stressing here that mutationsincluding different kinds of certain relationship to the ecological conditions: the type chromosomal and gene changesare instrumental in in- of environment, or, according to the Raunkiaer termi- creasing variation."Spontaneous" mutations are caused nology, the life-form system of the family, genus, or by some of the following influences: background radiation species. (approximately 3 roentgens per 30 years), chemical com- Apomixis. Certain tree species are characterized by a pounds formed in metabolism, temperature-conditioned replacement of normal sexual reproduction by various instabilitiesof the gene molecules, or errors in their forms of apomixis,This term simply means that no reduplication. In long-lived organisms like tree species the "mixis"(fertilization) normally occurs.Embryos may background radiation may appear relatively important stillbe formed by agamospermy (parthenogenesis or and responsible not only for a few but perhaps for forty adventitious embryony), or,if there is a complete or or fifty percent of all mutations that occur. prevailing seedsterility,a vegetative propagation by Most of the variability caused by mutation is of the means of stolons, runners, bulbils, etc.In horticulture, recessive type.In cross-fertilizing species this recessive where triploids or otherwise seed-sterile types are often (or hidden) variability is generally very profound and it used, a mass propagation may be applied artificially by can be detected after appropriate matings. This implies means of cuttings or graftings. that such organisms often are conspicuously heterozygous. No conifers are known to reproduce regularly by In some cases heterozygosity of a gene locus may, per se, apomictic methods like parthenogenesis or adventitious lead to increased vigor (heterosis) of the heterozygotes in embryony. Some,however,likespeciesofThu/a, relation to that of the homozygotes, owing to some sort of Chamaecyparis, Cupressus, etc., are easily propagated by gene interaction or "over-expression" of a trait (super- means of cuttings.Suckers will form from the base of dominance). the stems in other species. Such is the case in the poly- This hidden type of variability is common in tree ploid Sequoia sempervirens in contrast to the diploid species, too. Some instances will be mentioned below. Sequoiadendron. Chlorophyll lethals constitute a characteristic mutation However, regularapomixisbyseedformation type that is frequent in higher plants.In homozygous, (agamospermy), or tendencies in this direction, is found occasionally also in heterozygous condition they cause a in angiospermous shrubs and trees. (Cf. Gustafsson, 1947, breakdown of the chioroplast structure and the pigment pp. 306-320.)Such isthe case in Alnus, Casuarina formation, to the extent of suppressing photosynthesis. (Barlow,1959a,b),Celastrus,Crataegus,Eugenia, The fine structure and development of chloropiasts has Euonymus, Garcinia, Sorb us, Ulmus, and Zanthoxylum. been elucidated considerably by means of such chlorophyll Genetics and Tree Improvement 795 b

Rgure I.Chromosome siZe and number in (a) Pinus sylvestris (with 12 partiallyasynaptic' bivalents), (b) Populus robusta and (c)P. tremula (both with 19 bivalents), (d) Morus nigra (with 154 bivalenis) and (e) Alnus incana (above: 14 bivalents at first meiotic metaphase, below: 14 chromosomes at second meiotic metaphase). Magnification circaI, 500 x (a-c after v. Wettstein et al.,1959; d after Darlington and Ia Cour, 1942; e after Gram et al.1941.)

796 Fifth World Forestry Congress Proceedings mutants (von Wettstein, 1959). These are of various ap- sq 48. 0y pearance: albina, without pigments, purely white; xantha, containing carotinoids and traces of chlorophyll, yellow- 150 ish; viridis, with carotinoids and chlorophyll in changed proportions and quantities, yellowish green, light green, 140 etc.; as well as some less frequent typesalboviridis, tigrina, zonata, striata, etc. (Gustafsson, 1940). Chloro- phyll deviations of this kind have been registered for 20 several genera of conifers and hardwoods. A detailed 110 study with regard to population structure and provenance 00 behavior was published by Eiche in 1955. In some popu- lations of Pinus sylvestris such lethals are frequent. In go open-pollinated progenies of 1,016 individual trees from 80 43 different provenances at one field station (Bogesund) 00 and 1,015trees from 43 standsatanother station (Sundmo), a generally low, but in some instances a high 60 rate of lethals was found. The average rate observed at 50 Bogesund was 1.4 chlorophyll lethals and at Sundmo 1.7 40 lethals per 1,000seedlings.Figure 2 illustratesthe various rates of lethals from one station (Bogesund), summarized in the following table. 20

Minimum Rates of chlorophyll lethals &' .&.. - number of x 10-2 36 40 45 50 55 85 on' No. of trees heterozygous A--4--- 5 Station analyzed trees 0.5 5-10 10-84 Bogesund 1,016 410 332 = 81%41 = 10% 37 9% Figure 2a. Distribution of 410 heterozygous mother frees Sundmo 1,015 295 209 = 71% 51 17% 35 = 12% (----0----) end of 1,368 chlorophyllmutants (- -. - - - - -) found in the progeny of these trees in the field trial af Bogesund and also the distribution of 43 stands (- - - - X -. - -) from which the mother In these instances the hidden variability was exposed frees originatedallclassified on the basis of mutant rates(class in open-pollinated offspring. We may safely presume that interval = one 10°). artificial selfing should have revealed many more heter- ozygous trees, possibly the great majority of the trees examined. A controlled pollination of this kind has been applied on a minor scale, and it has actually unveiled a high number of trees heterozygous for chlorophyll lethals, as well as other morphological and physiological aber- rations. The complex heterozygosity in nature is evident also from the fact that two or more chlorophyll lethals occur in every population studied, in fact, 29 percent of allstandsshowlethalsrepresentingfourdifferent chlorophyll deficiencies. This figure, too, would certainly increase conspicuously if artfficial selfing was applied. Most of the chlorophyll aberrations studied by Eiche were definitely lethal,i.e., they died at an early stage. Some may survive, however.Cases where they reach maturity are frequently reported in forestry literature. Several years ago Swedish botanists began a careful inventory of outstanding trees and they also found cases of viable chlorophyll aberrants (for instance, Hesselman, 1906; Sylven, 1907). In recent years, Langner (1953) described so-called aurea types in Picea abies. They are characterized by a yellowish-green color of their needles. Both recessive and dominant chlorophyll genes are in- volved.In homozygous condition the dominant gene causes the appearance of fully lethal albina seedlings. Langner suggested that clone individuals of the yellow- green heterozygotes be used as indicators of pollen con- tamination, especially when evaluating the location of 20 40 60 80 iooZ seed orchards. The heterozygous aurea types are suitable for such a judgment, because they produce two types of Figure 2b.Distribution of relative frequencies of stands, classified on the basis of the percentage of the mutated trees in stands ( )in offspring when foreign pollen dominates: aurea aberrants the field trials at Bogesund and (------) at Sundmo (class interval= and normals, in equal proportion. When no foreign pollen 10 percent).

Genetics and Tree Improvement 797 ispresent, rare self-pollination may occur, and white constancy of the karyotype over long periods of time but homozygotes, too, will then be formed. it also leaves some indications of the phylogenetic develop- Freak types of morphological aberrants are not seldom ment. encountered in nature. The parallel variations occurring Figure 3 shows the karyotypes of (1) Taxus and in a large number of tree species (the Vavilov law) con- Cephalotaxus (family Taxaceae according to Rehder), stitute examples of this kind, e.g., growth characteristics of the stem, excessive or reduced number of branches, color of leaves and needles, and lobation of leaves. For conifers, interesting cases have been reported by Hessel- CEPHALOTAXTJS PORTUNI man (1907), Sylven (1909; 1951), Wittrock (1914), and Holmgren (1959), and they are recorded under various names in the taxonomical literature, e.g., Rehder's monograph (1947). Note also the interesting oak-like mutant quercina of Juglans (Babcock, 1916). I In the cases discussed above, the genes responsible for the freak characters may go back to events that occurred TAXUS BACCATA generations ago. New mutations are difficult to trace, if they are not recovered as bud mutations (sports). Such instances are well known in the horticultural litera- ture, especially with respect to fruit trees.In fact, many cultivated varieties of apples, oranges, peaches, etc., have I originated as sports and are now propagated on a large I'HI Hli scale.Following Shamel and Pomeroy (1932; 1936), Granhall (1954) especially stressed this point. In other LARIX DECIDUA trees, too, cases of bud mutations have been reported, forinstance,in Alnus (Soderberg, 1917), Elaeagnus (Pomeroy, 1921), Eucalyptus (Chevalier, 1942), Euony- mus (Shame!,1917), Ilex(Schwanitz,1953), Olea (Morettini,1955), Phoenix(Mason,1930;Shamel, 1930), and Picea (Langner, 1954). Often the so-called I tI t dichotypic pines or spruces are caused by spontaneous back-mutations to the normal status ("reversions"), both PSEUDOLARIX AMA.BILIS types appearing on the same tree.In fact, we may pre- sume that old trees often are chimerical for mutations arisen during ontogenesis. Although mutations are the driving force in evolution, remarkably little is known about the mutation process in IIHIIIIIIE[IItIiFItII forest trees.Our knowledge on this point isactually almost nil. PINUS PARVIFLORA Karyotype analysis. Chromosomes can be broken and remodelled in various ways, spontaneously as well as experimentally. Such changes may concern single chromo- somes or comprise two or more chromosomes simul- taneously. Often they cannot easily be detected in mitosis, although they are frequently seen at meiosis. Occasion- ally, however, a close scrutiny of mitosis also reveals PICEA ABIES these changes.Unfortunately, few studies of this kind have been carried out in forest trees.This is partly due to the small chromosomes in many hardwood genera and our imperfect cytological technique in gymnosperms. Here, as in numerous other instances, K. Sax (cf. Sax and Sax, 1933) performed a pioneer analysis, which ought tutuHIj to be repeated and extended to other species and genera ABIES CEPHALONICA by means of methods. Also, Mehra and Khoshoo (1956a and b) have reported similar studies. Roughly speaking, chromosomes may be divided into three categories: (1) chromosomes with the centromere- the "moving center" of a chromosomelocated in the middle (median); (2) chromosomes with the centromere I between the middle and the end (submedian or sub- terminal); and (3) chromosomes with the centromere Figure3. Schemaficalpictures of the karyotypesin seven conifer species (after Sax and Sax,1933).The horizontal lines denote the very close to the end (subterminal or terminal). Such relative positions of the individual centromeres, the vertical lines the an analysis of the centromere position often illustrates the lengths of the respective chromosome arms.

798 FifthWorld Forestry Congress Proceedings (2) Larix and Pseudolarix (Pinaceae), and (3) Pinus, in gymnosperms, too. This is evident from the fact that Picea and A bier (also Pinaceae). The analysis of Sax and certain trees of this species from a special locality show Sax, as well as that of Mehra and Khoshoo, indicates that multipartiteconfigurations(quadrivalents,hexavalents, Taxus baccata has 10 chromosomes with median or sub- etc.) at the first metaphase of meiosis (Sugihara, 1940). median centromeres, 1 chromosome with subterminal, and Changes in chromosome structure and centromere posi- 1 chromosome with an almost terminal centromere.In tion can be induced by three processes: (1) chromosome Cephalotaxus, at least 11 chromosomes have median and breakage at the centromere region; (2) so-called pen- submedian centromeres and only 1 chromosome has a centric inversions, with a shift in centromere position; and subterminal centromere. (3) unequal reciprocal chromosome translocations.It In Larix, 6 chromosomes have median or submedian remains to be decided which process has been the most centromeres,and6 chromosomes havesubterminal important one in nature.In crop plants, like barley or centromeres.In Pseudolarix, on the other hand, the maize, experimental remodelling of the karyotypes is an karyotype is remarkably different. Only 2 chromosomes established procedure, of great importance theoretically have median centromeres, the remaining 20 chromosomes as well as practically. have subterminal or terminal centromeres. Induced Polyploidy and Mutation The three genera, Pinus, Picea, and A bies, are mutually less deviating in chromosome structure. In Pinus, all the As mentioned in the introduction, high chromosome centromeres are median, in Picea, 9 out of 12, and in numbers can arise by means of two processes: (1) am phi- Abies, 7 out of 12, the remaining chromosomes having or alloploidy (also called interspecificpolyploidy), involv- subterminal centromeres. ing hybridization between different populations, often In Ginkgo biloba (x = 12), according to Lee (1954), species or even genera, in combination with a subsequent special sex chromosomes are to be found. The karyotype, doubling of the chromosome number; and (2) autoploidy (intraspecificpolyploidy), the functionof unreduced as illustrated by him, is seen in Figure 4.In the female side or trees, two pairs of satellite chromosomes occur: a large gametes in fertilization, on the male or the female pair with median centromeres, and a smaller pair with on both of them, or the direct doubling of thechromosome subterminal centromeres. In the male, only one member number. The two processes may be visualized in the fol- of the "satellite pair" with subterminal centromeres pos- lowing manner: sesses a satellite, the other lacks it (to the extreme left of the figure).Of the remaining ten pairs, one shows a Amphiploidy median or submedian centromere,all the others have Species A Species B subterminal centromeres.In contrast to thisanalysis, Chromosome sets Chromosome sets however, Newcomer (1954) considers that the two large (genomes) (genomes) chromosomes determine the sex. AA BB F1 hybrid: chromosome constitution AB more or less seed sterile, F2: rare individuals with a chromosome constitution AABBmore or less fertile and constant. Auto ploidy IIii ii II II ii 1111111111 Species AA: Unreduced egg cells or pollen grains(AA) fi are formed. After fertilization,individuals with the con- stitution AAA (triploid)or AAAA (tetraploid)can appear.In bud mutation a tetraploidstate may be reached immediately: AA - AAAA. In the case of amphiploidy, the hybrid AABBbreeds true or almost true from the beginning. The morethe IIIII ,IIIIII chromosome sets (genomes) of species A and B deviate from one another, the more constant the hybrid. Nu- merous natural polyploid species haveoriginated in this II II Iiii 1111111111 II'' way. Examples of this kind are given intextbooks and monographs (Stebbins, 1950; also Clausen, 1951). As Figure 4.Karyotype of Ginkgo biloba (after Lee,1954).Note the exemplified above with regard to the origin of Sequoia four satellite chromosomes of the female individuals (above) and the sempervirens,itis probable that not only hardwood three satellite chromosomes of the male individuals (below). According to Lee the dissimilar chromosome pair to the extreme left represents species and genera but also conifer species have arisen thesex chromosomes. in such a way. A doubling of chromosome number after species hybridization is often attained by means of un- Consequently, karyotypedifferencescertainlyexist, reduced egg cells and pollen grains, originated through but a detailed analysis is still required. Studies of meiosis some failure at meiosis. The more distant the parents, in Cephalotaxus drupacea (x = 12), for example, reveal the lower isthe frequency of pachytene pairing and the occurrence of spontaneous chromosome translocations chiasma formation and, in consequence, the more pro- Genetics and Tree Improvement 799 flounced are the success of chromosome doubling and the developed by von Wettstein (1937). The scheme is as true-breeding character of the amphiploid. follows: The polyploidizing of species and genus hybrids that 2x - 3x (by partially unreduced gametes), or already exist is a fascinating but largely neglected field. 2x -* 4x (after the application of colchicine) Certainly, many diploid species hybrids of treesare 3x x 2x or 2x x 3x -p 4x (partially unreduced remarkably fertile, e.g., Platanus acerifolia. This product gametes) isa diploid hybrid of P.orientalis and occidentalis, 4x x 2x (or 2x x 4x) -* 3x (normal gametes) probably arisen before 1700 and cultivated on a large The scheme worked as planned.In many cases the scale in Europe and the USA. The parent species have triploids are decidedly superior to the diploids, but the been separated from one another over tens of thousands tetraploids are inferior to the triploids and the diploids. of years (Sax, 1933b; Stebbins, 1950). Such a case is Definite improvements can certainly be gained also on exemplified also by the hybrid of the Chinese Catalpa the tetraploid level by planned crossing and selection. ovata and the eastern North American C. bignonioides (Such is the case in sugar and fodder beets, where the (Smith, 1941; Stebbins, 1950). The newly discovered order of production has become: 3x > 4x > 2x.) Ac- hybrid between Cupressus macrocarpa and Chamaecyparis cording to early studies (Johnsson, 1942), however, the nootkatensis (Osborn, 1941) is even more striking. Being tetraploids of Populus tremula definitely represent a stage highly fertile, it segregates for its parental characteristics. beyond the point of peak production. Species hybrids are not uncommon among the conifers, The finding that certain species hybrids manifest hybrid and a doubling of their chromosome numbers is a highly vigor (heterosis) in the F1 generation, e.g., in the cross tempting task. Also here, numerous hybrids are remark- Populus tremula x tremuloides, seemed temporarily to ably fertile. This has been pointed out by Sax (1932) for shift the interest from polyploidy to species hybridiza- Larix hybrids, where possibly the number of chiasmata tion.It was soon found, however, that both effectspoly- (an index of chromosomal affinity) is somewhat reduced. ploidy and heterosiscould be united in one and the same A triploid hybrid, with 2n = 36, arose in the F1cross of offspring,for instance,in tetraploid Populus tremula L. decidua and occidentalis, both of which have 2n = 24. crossed with diploid P. tremuloides. The latest data avail- As in Platanus and Catalpa, the parent species have been able were discussed by Johusson (1959). Figure 5 is separated geographically over long periods of time.It taken from an earlier publication (1953). According to is a characteristic feature in this cross that onlyone hybrid the recent survey by Johnsson the triploid species hybrid plant arose, viz, the triploid mentioned.Its discoverers shows a higher production than the diploid one. In Figure (Larsen and Westergaard, 1938; see also Larsen, 1956) 5 this comparison has been carried through to a hybrid pointed out that the triploid could be used for the produc- age of 16 years. tion of tetraploids just like those found in Populus. Ac- The fact that this triploid hybrid seems to be more cording to Larsen (loc.cit.) this has not succeeded yet. resistant to the aspen crownbrand (Valsa sp.) than the Species hybrids occur also in Picea, Pinus, and Abies, diploid one is even more important. This is not especially which are uniformly diploid except for a low percentage remarkable, since there are two genomes from the resistant of autotriploid individuals.Whether polyploids arise in (or, at least, less susceptible) Populus tremula and only the hybrid offspring is unknown, however. Similar is the one genome from the usually susceptible parent tree of case in Carya, Ulmus, Betula, Juglans, Populus, and P. tremuloides. In the diploid hybrid the proportion of Salix crosses. A methodical production of species (and genomes is just one to one. genus) hybrids, with a subsequent chromosome doubling In his paper of 1959, Johnsson also mentioned some (for instance, by means of colchicine), would certainly autoploid hardwoods recently studied, for instance, Betula be of interest phylogenetically and would provide im- verrucosa, where four spontaneous triploid individuals portant information also on the value of artificially pro- (3x = 42) have been discovered, one of them very duced new species in forestry. In fact, such a program is vigorous. Triploid aberrants (3x = 36) have also been slowly under way with a view of outcrossing the autoploid found in twin seedlings of Quercus robur. A remarkable products arisen spontaneously or produced artificially. case was recorded in Ulmus glabra (Eklundh-Ehrenberg, The triploid or giant aspen (Populus tremulavar. 1949). A vigorous "triploid-looking" tree was diploid gigas), detected by Nilsson-Ehle (1936) and first analysed (2n = 28) but produced triploid and tetraploid individ- cytologically by Muntzing (1936), was the first instance uals in its offspring, owing to a weak chromosome pairing of an autoploid aberrant and its concrete use in plant at meiosis ("asynapsis"). Later on, trees with the same breeding. Later on, a great number of such triploid find- peculiarity were discovered (seven out of thirty examined, ings were reported not only in Sweden (see Johnsson, Gustafsson, 1952, p. 257). The cross of "asynaptic x 1959), asynaptic" produced tetraploid and triploid progeny, the butalsoinFinland, the USSR, and other cross "asynaptic x normal" yielded triploids only. By countries. Nilsson-Ehle (1938) immediately grasped the this method triploids can be obtained at will, not only importance of his finding. Like the case in fruit-tree and within the species but with other species as well. Although crop-plant breeding, the triploids could be used for the the tetraploids generally are inferior, definite triploid com- production of tetraploids. The outstanding value of these binations might prove valuable. teraploids lies in the possibility of a mass production of This is definitely the case in Alnus. When the colchi- triploids by the hybridization of tetraploids and diploids. cine method was used, some tetraploid specimens or In Populus, such a mass hybridization is facilitated be- chimeras ("mixoploids") of A Inus glutinosa were raised cause pollen can easily be forced, and pollination is con- by C. Ehrenberg (see Johnsson and Eklundh, 1940). veniently carried out in greenhouses, according to methods After tetraploid x tetraploid as well as tetraploid x diploid 800 Fifth World Forestry Congress Proceedings 17 useful polyploids. Regarding forest trees the yield of wood and wood products is clearly the outstanding matter. More- 16 over, most of the forest trees have a high degree of allo- gamy in reproduction, although certain biotypes of a 15 Ptremtdold.sft.muIa species may give rise to some progeny after forced self- 31; fertilization (Plym Forshell, 1953), or even whole popu- 14 21; lations, like Picea omorika, or species characterized by --4-_Iis self-compatibility,likeLarix europaea and leptolepis 13 (Langner, 1959; Larsen, 1956). The low chromosome 12 number required is difficult to encounter in many hard- wood genera, where the basic number is derived, e.g., in 11 Populus and Salix (x= 19) or in Betula and Alnus (x= 14). On the other hand, many genera or species of -10 # this kind have a small chromosome size, which counter- acts the damaging influence of an increase in cell size in 9 the case of autoploidy. In the genera mentioned, intra- specific tetraploidy seems to represent a stage past the 8 1,11/i point of viability optimum: production decreases beyond the triploid stage. This can be expected also for many 7 Ptr.muia 3z conifer species, where polyploids are but accidentally pro- I 2.1;- duced in nature, the triploid number would lead to maxi- mum production (timber, wood products, rubber, excretes $ and secretes, chemical compounds). The production of autoploids also in pine, spruce, fir, oak, etc., and their 4 backcrossing to various diploidswithin or beyond the species limitsis, in fact, a fascinating large-scale task. This work has to be greatly accentuated and must proceed E parallel to experiments on forced early flowering and increased vegetative regeneration. Finally, it should be pointed out here that many high- polyploid species complexes in nature are the result of

1 2 3 45 6 7 8 910 111213 14 1516 combined processes of amphi- and autoploidy. The prob- years able case of Sequoia sempervirens has already been referred to. Many more instances are known. In the case Figure 5.Height-growth of hybrid aspen and Populus tremula with 38 and 57 chromosomesin a 16-year-oldexperimentalplantaflonat of amphiploidy (alloploidy)Stebbins (1950, p. 371) Ekebo, Sweden. After Helge Johnsson (1953 and unpubl.). suggests that the viability optima are more flexible and the levels of chromosome number higher than those obtained crossings,2x-,3x-, and 4x-individuals of A. glutinosa with autoploidy.This idea is,I consider, substantially could be compared as to their growth properties. The correct.Stebbins refers to the chromosome numbers of triploid showed a striking growth capacity.It even grew Kalanchoe (2n= circa 500) and Buddleia (2n= 300). so rapidly that its growth became harmful to the plant. Morus nigra, too, (with 2n= 308) may be mentioned Tetraploid individuals are inferior.The triploid species here. More examples of complex high-polyploid species hybrid (Alnus rubra 2x x Alnus glutinosa 4x) is of special and genera are cited in Gustafsson's monograph on apo- interest. Like the triploid aspen hybrid, referred to above, it reaches a maximum in growth rate and vigor owing to mixis and polyploidy (1947). the combination of hybridization and polyploidy.It is Here it may also be mentioned briefly that manyspecies more harmonious in development than the pure auto- do not intercross on the diploid level or they tend toform triploid.The diploid hybrid itself shows a pronounced highly sterile diploid hybrids. On the tetraploid orhigh- degree of heterosis (Ljunger, 1959). In birch (Betula polyploid level, however, they may form large complexes, verrucosa), colchicine-produced autotetraploids (4x = with the original diploids interlaced morphologicallywith 56), too, have been obtained.Their triploid progeny, polyploid forms and backcrosses.Huge complexes of raised after back-crossing with diploid B. verrucosa, per- this kind are encountered, especially in apomictic groups form well in yield experiments. of Crepis (in which genus Babcock and Stebbins,1938, Certain rules have been established for agricultural outlined this concept), Rubus, Sorbus, Potentilla, Poa, crops as to the relative performance of autopolyploids and so on. (Levan, 1945; Gustafsson, 1947; MUntzing, 1953). Three The experimental remaking of tree species and genera properties are especially important for the success or to fit human demands has just recently begun, onboth failure of a recently obtained autoploid: (1) the chromo- the diploid and the polyploid level. As stated inthe intro- some number; (2) allogamy contra autogamy; and (3) duction, selection and hybridization are tools necessaryfor the purpose ofcultivation,viz,vegetative production applied contra seed yield. Low chromosome number of a species, all progress in tree improvement, whether they are pronounced allogamy, and vegetative production are con- in connection with gene recombination, F1heterosis, ditions that facilitate the origin and selection of practically polyploidy, or mutation. Genetics and Tree Improvement 801 Mutation. The famous Hugo de Vries, founder of the tion 50 percent of the control) were as follows (cf. also mutation theory, pointed out in 1904 (see Blakeslee, Fig. 6). 1935) that X- and a-rays could possibly be utilized also X-rays y-rays for a production of new variations (mutations) of crop for embryo class II 500 r 1,200 r plants.Not until the late twenties, however, did H. J. for embryo class III 1,000 r 1,300 r Muller and L.J.Stadler show that the genes (and for embryo class IV 1,500 r 2,300 r chromosomes) of flies and plants really are changed after irradiation.Muller stressed the potential importance of and for seeds of Picea abies (embryo class IV), with a this method in plant breeding, but Stadler was definitely water content of skeptical with regard to its practical implications, possibly 2.8% 600 r X-rays with the exception of vegetatively propagated species. 5.9% 2,200 r X-rays Since then much work has been carried out in various 25.4% 2,200 r X-rays plant and animal species. Especially with respect to dip- bid self-fertilizing organisms we now know that some cm mutations may be induced that definitely increase produc- tion in the homozygous as well as in the heterozygous condition. Induced mutations have become an additional 3 tool in plant breeding.Their importance will steadily increase in the same degree as we know how best to apply the mutagenic agents and, which is no less important, how 0 best to screen out the mutations desired. Several kinds of mutagenic agents are known: (1) the 2

non-ionizing radiations like ultraviolet(or even visible 4

light, ultrasonic waves, etc.), preferably applied to pollen S grains; (2) ionizing radiations like y-rays from various radioactive isotopes(like cobalt-60), X-rays from the ordinary Coolidge tube, neutrons of various qualities from COMROL 2MX r 30 r 4800 r cyclotrons or atomic pilesall these and other radiations Figure 6.The effect of X-irradiation on seeds of Pinus silvesfris (1960, applied to pollen grains, seeds or vegetative buds; and provenance Sweden: Malfeshoim, latitude 56°N, 50 m. above sea level, (3) different chemical compounds, some highly mutagenic seedlingsize30 days after germination). ones, e.g., ethyl methanesulphonate, ethylene imine, ethy- lene oxide, etc., are preferably used on seeds but appli- Disregarding the difference in X- and y-dosages (which cable also to pollen grains, probably also effective in is in part environmentally conditioned) it is obvious that fully developed pine seeds (embryo class IV) are twice induced bud mutation (this has not been tried as yet). or thrice as resistant to irradiation as undeveloped ones It is a most interesting fact that the action of many (embryo class 11). As in numerous crop plants, resting mutagenic agents has turned out variable with regard to wet seeds are decidedly more resistant to irradiation than the production of chromosomal rearrangements versus dry ones. The theory behind this difference has been gene mutations, i.e., chromosome breakage (with conse- developed by L. Ehrenberg and co-workers (1955 and quentchromosometranslocation)versusintragenic later). changes. Ionizing radiations cause high rates of chromo- Few investigations have been carried out in forest trees some breakage with subsequent changes of the karyotype, with regard to irradiation of vegetative parts.Experi- often drastic in appearance, whereas chemical mutagens ments in comparing y-ray sensitivity were started by predominantly lead to gene changes and deficiencies, and myself (see Gustafsson and Simax, 1958; and von Wett- less frequently to gross rearrangements. The high rates of stein et al., 1959). Rooted cuttings of poplar varieties visible mutations that appear in radiation experiments can (Populus robusta, serotina, clone "297," obtained through the courtesy of Dr. H. van Vloten, Wageningen, Holland) be widely surpassed after appropriate treatments with were irradiated, together with three- to five-year-old graft- ethyl methane sulphonate, ethylene imine,diethylsul- ings of Pinus sylvestris and Picea abies. The poplar cut- phate, and so on. The most efficient compound detected tings received dosages from a few hundred up to 200,000 so far (ethyl methanesulphonate, CH3SO2OC2H5, Heslot r-units. All plants of Populus serotina exposed to dosages et al., 1959; L. Ehrenberg, 1960; Gustafsson, 1960) is not above 50,000 r had succumbed two years after the irrad- causing any noteworthy amount of chromosome fragmen- iation. In P. robusta, all plants exposed to 500-16,000 r tation and translocation (Favret, 1960, unpubl.). were still alive two years after the treatment.In clone With regard to forest trees, ionizing radiations (and "297" also, plants having received up to 100,000 r were chemical mutagens) can be applied to seeds as well as to able to grow, although this very high dose produced weak shoots and abnormal leaves. Only secondary cuttings of vegetative buds and shoots.The dosages of ionizing the treated materials exposed to less than 8,000 r rooted radiations suitable in seed treatments of Pinus sylvestris so far. and Picea abies (Gustafsson and Simax, 1958) depend on C. Ehrenberg made some irradiation experiments using embryo and endosperm development and on water con- graftings of alder, Alnus glutinosa, in order to produce tent.In a special set of experiments with seed of Pin us haploid individuals. She found that dosages above 32,000 sylvestris the approximate DL50 doses causing a germina- r-units killed the irradiated material. At 20,000 r the 802 Fifth World Forestry Congress Proceedings graftings developed badly and their leaves fell off.Also Finally,it ought to be mentioned here that induced at 10,000 r some influence of irradiation was noticeable as bud mutations have definitely proved of practical impor- to leaf development, but the graftings were not killed at tance in the breeding of fruit trees and berries. Gröber this and lower dosages. (1959)hasrecently described a red-fruitedvariety In five clones of pine, three-year-old graftings were obtained from "Weisser Klarapfel," a goal long aimed for exposed to doses ranging from 1,000 to 19,000 r. Treat- by German apple growers.Similarly, Bauer (1957) ments with 2,000, 4,000,6,000,8,000, 10,000, and showed that the improvement of black currant (Ribes 18,500 r were invariably lethal. The single graftings sur- nigrum) may proceed easier by means of induced small viving a year after the treatment had received dosages of mutations than that obtained with the ordinary crossing 1,000 and 1,600 r. In spruce, five-year-old graftings were and selection methods. given dosages ranging from 250 to 16,000 r. Treatments Seed treatments will be of very restricted value for with 250, 1,000 and 2,000 r produced a normal type of species with a long rotation period, like the northern con- development, with plants healthy up to six months after ifers.In species with a rotation period of ten or twenty years, however, this kind of treatment, too, may appear irradiation.The striking contrast in tolerance between (like growing poplars, alder and conifers probably is associated handy, especially with regard to dominant traits many types of disease resistance).For numerous intro- with pronounced differences in chromosome size (Fig. 1). duced species ("exotics") a rapid increase in variability Several authors (Sparrow and Christensen, 1953; Nybom, Here, seed treatments using 1956) postulate a parallelism between large chromosomes may be of great value. and low tolerance. irradiation or chemical mutagens may be performed alone or combined with hybridizationand selection. Finally, in Few otlher studies concerning forest trees have been ornamental shrubs, or trees of complex hybrid origin like carried out: Alnus glutinosa(Simak and Gustafsson, many poplar varieties, mutationexperiments using the 1953); Betula pubescens (Scholz, 1957); Juglans species vegetative system may finally lead to amazing results. Here, (Traub and Muller, 1934; Barlow, 1953); Olea europaea as elsewhere in experimentation,carefully planned screen- (Petri, 1930); Pinus (Sato and Yoshio, 1951; Toyama, ing methods, sufficient economic assistance and, above all, 1954, also other conifer species); Populus (Bogdanov, unwearied patience will be amply repaid in the long run- 1948; Euler, in cooperation with C. Ehrenberg, 1949). from both a theoretical and a practical point of view. See also Nikitin (1934) and Nishina and Sato (1943). Few induced bud mutations in forest trees have been References described up to now. Some examples are given by Scholz Babcock, E. B., 1916. Studies in Juglans III.(1) Further evi- (1957) for Betula verrucosa and pubescens, where chi- dence that the oak-like walnut originates by mutation.(2) A meras with regard to chlorophyll defects and delayed leaf parallel mutation in Juglans hindsii (Jepson) Sargent.Univ. Calif. Publ. Agr. Sci. 2(3): 71-80. development were found. Whether his "Verzweigungsmu- and G. L. Stebbins, Jr., 1938. The American species tanten mit fächerartiger Kronenbildung" (changed type of of Crepis: their relationships and distribution as affected by ramification) really originate in induced mutation, cannot polyploidy and apomixis. Carnegie Inst. Wash., Publ. 504. be judged by his description.Also Bogdãnov (1948) Barlow, A.L.,1953.Thomas walnut seed treatment with radioactive cobalt.44th Ann. Rep. North. Nut. Grow. Ass., described some artificially produced chimeras in Populus. Roch., N.Y.: 56-59. Irradiation experiments with forest trees may have the Barlow, B. A., 1959a. Chromosome numbers in the Casuarin- following chief purposes (in addition to theoretical con- aceae. Austr. Journ. Bot. 7(3): 230-237. 1959b.Polyploidy and apomixis in the Casuarina siderations) distyla species group.Austr. Journ. Bot. 7(3): 238-251. to increase variation, Bauer, R., 1957. The induction of vegetative mutations in Ribes nigrum. Hereditas 43: 323-3 37. to induce disease resistance, Blakeslee, A. F., 1935. Hugo de Vries 1848-1935.Science 81: and, generally seen, to induce changes in 58 1-5 82. ecolLogical requirements, Bogdanov, P. L., 1948. Experiments with X-irradiation in poplar growth properties, breeding. Bot. Zurnal 33: 438-440. various quality characters. Chevalier, A.,1942.Un Eucalyptus resistant au froid, venu probablement par mutation.Rev. Bot. Appl. 26: 232-234. In species which are easily propagated by vegetative Christiansen, H., 1950. A tetraploid Larix decidua Miller.Det means, especially by cuttings, bud mutations may obtain Kgl. Danske Videnskab.Selsk., Biol. Medd. 18 (9):1-8. direct practical value, especially with respect to disease Clausen, J., 1951. Stages in the evolution of plant species. Cornell Univ. Press. Ithaca, New York. resistance. Recent studies of barley and other crop plants Darlington, C. D. and L. F. La Cour, 1942. The handling of (see, for instance, Favret, 1960, reviewed also by Gustafs- chromosomes. George Allen & Unwin Ltd., London. son, 1960) indicate that biotypes which are susceptible Darlington, C. D. and A. P. Wylie, 1955. Chromosome atlas of tomildew (Erysiphe species)can acquire resistance flowering plants. George Allen & Unwin Ltd. London. Ehrenberg, L.,1955.Studies on the mechanism of action of through mutations in certain segments of definite chromo- ionizingradiationsin plantseeds.Sv.Kern.Tidskr.67: somes.Prerequisites for successful mutation work are, 207-224. quite simply, controlled mass infections and large popu- 1960. Chemicalmutagenesis:biochemicaland chemical points of view on mechanisms of action."Erwin lations tested. A similar induction of resistance would be aur-Gedachtnis-Vor1esungen 1959," Gatersleben. possible also in tree materials, which can be propagated Eiche, V.,1955.Spontaneous chlorophyll mutations in Scots in thousands of individuals and easily inoculated with Pine (Pin.us sylvestris L.).Medd. fr. Stat. skogsforskn. inst. spores of the damaging fungus. The problem is of an 45(13): 1-69. Ekdahl, I., 1941. Die Entwicklung von Embryosack und Embryo economic nature only. How valuable are resistant bud bei Ulmus glabra Huds. Sv. Bot. Tidskr. 35: 143-156. mutations, and which expenses of production are war- Eklundh-Ehrenberg, C., 1949.Studies on asynapsis in the elm, ranted? Ul,nus glabra Huds. Hereditas 35: 1-26. Genetics and Tree Improvement 803 Euler, H. von, 1949. Biochemische Untersuchungen an Diploiden Larsen, C. Syrach, 1956.Genetics in silviculture.Transl. by und Triploiden Espen aus normalen und rontgenbestrahlten Mark L. Anderson. Oliver & Boyd, Edinburgh & London. Pollen. Arkiv f. kemi, mineralogi o. geologi. 26A(30): 1-19. and M. Westergaard, 1938.Contributions to the Favret, E.A.,1960.Spontaneous and induced mutations of cytogenetics of forest trees.I. A triploid hybrid between Larix barley for the reaction to mildew. Hereditas 46: (in press). decidua Miller and Larix occidentalis Nutt.Journ. of Gen. Gram, K., C. M. Larsen, C. Syrach Larsen, and M. Westergaard, 36(3): 5'23-530. 1941.Contributions to the cytogenetics of forest trees.Joint Lee, C. L., 1954.Sex chromosomes in Ginkgo biloba. Amer. Rep. Arboretum, Lab. Gen., Lab. System. Bot.II.Alnus Journ. of Bot. 41: 545-549. studies.Royal Vet. & Agr.Coll., Copenhagen, Yearbook Levan,A.,1945.Aktuelle Probleme der Polyploidizuchtung. 1941: 44-58. Arch. Julius Klaus-stift. 20, Erganzungsb.: 142-152. Granhall, I.,1954.Spontaneous and induced bud mutations in Ljunger, A., 1959. Al- och alfOradling. Skogen 5: 115-117. fruit trees. Acta Agr. Scand. 4(3): 594-600. Mason, S. C., 1930. A sectorial mutation of a deglet noor date Gröber,K.,1959.Mutationsversuche an Kulturpflanzen.Xi. palm. Journ. of Hered. 21: 157-163. Die Erzeugung von somatischen Mutationen mittels Röntgen- Mehra, P. N. and T. N. Khoshoo, 1956a. Cytology of conifers. strahlers beim Obst. Die Kulturpfl. 7: 37-54. I. Journ. of Gen. 54: 165-180. Gustafsson, A., 1940. The mutation system of the chlorophyll 1956b.Cytology of conifers. II.Journ. of Gen. apparatus. Lunds Univ. Arsskr. N.F. Avd. 2. 36(11;): 1-40. 54: 181-185. 1947. Apomixis in higher plants. III. Biotype and Mergen, F., 1958. Natural polyploidy in slash pine. Forest Sci. species formation. Lunds Univ. Arsskr. N.F. Avd. 2. 43(12): 4(4): 283-295. 183-370. 1959. Colchicine-inducedpolyploidyinpines. 1948.Polyploidy, life-form and vegetative repro- Journ. of Forestry 57(3): 180-193. duction. Hereditas 34: 1-22. Meurman, 0., 1933. Chromosome morphology, somatic doubling 1953. Statensskogsforskningsinstitut1902-1952. and secondary association in Acer platanoides L. Hereditas Genetiska avdelningen: skoglig växtforadling. Medd. fr. Stat. 18(1-2): 145-173. skogsforskn. inst. 42(1);: 247-270. Morettini, A., 1955. Bud mutations in the olive and their utiliza- 1960.Chemical mutagenesis in higher plants. (In tion in improving the crop.Ital. Agr. 92: 197-204. press.) Muller, H. J., 1927. Artificial transmutation of the gene. Science Gustafsson, A. and A. Nygren, 1956. Fortpflanzung und Verer- 66: 84-87. bung. Die Fortpflanzung und Vermehrung der höheren Pflanzen. Muntzing, A.,1936.The chromosomes of a giant Populus Handb. Pflanzenzüchtg. 2. Aufi. I: 54-85. tremula. Hereditas 21: 383-393. Gustafsson, A. and M. Simak, 1958. Effect of X- and y-rays on 1953.Polyploidernas ekologi.Kgl. Lantbr. akad. conifer seed. Medd. fr. Stat. skogsforskn. inst. 48(5): 1-20. Tidskr. Arg. 92: 119-130. Newcomer,E.H.,1954. The karyotype and possiblesex Heslot,H.,R.Ferrary, R.Levy,and Ch. Monard,1959. chromosomes of Ginkgo biloba.Amer. Journ. of Bot. 41: Génétique végétale.Recherches sur les substances mutagènes 542-545. (halogéno-2 ethyl) amines, dérivés oxygénés du sulfure de bis- Nikitin, I.,1934.Influence of X-rays on seeds and pollen of (chloro-2 éthyle), esters sulfo;niques Ct sulfuriques.Comptes trees and shrubs. USSR Centr. Forestry Res. Inst.Bull. I: rendus des seances de l'Académie des Sciences, 248: 729-732, 103-104.(Breeding and introduction of rapidly growing tree séance du 2 février 1959. plants.) Hesselman, H., 1906. Material for studiet av skogstradens raser. Nilsson, N. H., 1941.Eine segregate From von Salix caprea, 1-3. Medd. fr. Stat. skogsförsoksanst. 3: 65-84. die durch Stecklinge vermehrt werden kann.Hereditas 27: 1907. Material for studiet av skogstradens raser. 9. 309-312. BestAndsbildande ormgran.Medd. fr.Stat.skogsforsoksanst. Nilsson-Ehle, H.,1936.Uber eine in der Natur gefundene 5, 1908: 195-228. Gigasform von Populus tremula.Hereditas 21: 379-382. Holmgren, A., 1959.Nkgra anmärkningsvarda tall- och gran- 1938. Jätteaspen. Den moderna svenska skogstrads- former. Sv. Skogsvârdsforen. Tidskr. 1: 9-42. föradlingens upptakt.Nord. Fam. boks Man. krönika. Arg. Johnsson, H., 1942. Die Chromosomenzahl von Carpinus betulus 1(2):1-4. L. Hereditas 28: 228-230. Nishina, Y. and K. Sato, 1943.Effects of fast neutrons upon 1944.Triploidy in Betula alba L. Bot. Not. 1: foresttree seeds.I.Nippon Ringaku Kaishi 25:313-322. 85-96. (In Japanese). 1946.Chromosome numbers of twin plants of Nybom, N., 1956. Some further experiments on cronic gamma- Quercus robur and Fagus sylvatica. Hereditas 32: 469-472. irradiation of plants. Bot. Not. 109(1): 1-11. 1953. Hybridaspens ungdomsutveckling ochett Osborn, A., 1941. An interesting hybrid conifer: Cupressocyparis försok till framtidsprognos.Sv. Skogvârdsforen. Tidskr. leylandii. Journ. Royal Hort. Soc. 66: 54-55. 1959.FOreningen fOr VäxtfOrädling av skogsträd Petri, L., 1930.Pathologische ;Wirkungen der Uranstrahlen auf 1936-1958. Norrt. Tidn. Boktr. AB. Oleaeuropaea.Phytopathol.Zschr.1930:45-48. Colchicinbehandling sorn Plym Forshell, Chr., 1953.Kottens och fröets utbildning efter Johnsson, H. and C. Eklundh, 1940. självoch korsbefruktning hos tall (Pinus sylvestris L.).The metod vid växtfOrädling av lOvträd.Sv. Papperstidn. 19-20: development of cones and seeds in the case of self-and cross- 1-11. pollination in (Pinus sylvestris L.). Medd. fr. Stat. skogsforskn. Kanezawa, R.,1948.Haploid and tetraploid in locust trees inst. 43(10): 1-42. (Robinia pseudoacacia L.).Bull. Tokyo Univ. Forests 36: Pomeroy, C. S.,1921. Bud variation in Elaeagnus.Journ. of 11-18. Hered. 12(5): 227-230. 1949.Polyploids appeared in twin seedlings of Pratassenja, G. D., 1939. Cited after Kanezawa, 1948. forest trees.Journ. Jap. Forestry Soc. 31: 22-24. Cited after Raunkiaer, C.,1937.Plant life forms.Transl. by H. Gilbert- Mergen, 1958. Carter. Clarendon Press, Oxford. 1951.InducedtetraploidyinJapanese cypress Rehder, A., 1947. Manual of cultivated trees and shrubs. 2nd (Chamaecyparis obtusa Endl.).Bull. Tokyo Univ. Forests ed. Macmillan Comp. New York. 39: 21-30. Sato, K and N. Yoshio, 1951.Effects of fast neutrons upon Kiellander, C. L., 1950.Polyploidy in Picea abies.Hereditas foresttreeseeds.II.Relations between theintensitiesof 36: 513-516. irradiations and the germinations of seeds,the growth of Langner, W., 1953. Eine Mendelspaltung bei Aurea-Formen von seedlings of Pinus densiflora.Sci. Bull. Fac. Agr. Kyushu Picea abies (L.) Karst. als Mittel zur Klarung der Befrucht- Univ. 13: 238-242. ungsver-haltnisse im Walde.Zschr. Forstgen. & Forstpflan- Sax, H. J., 1932. Chromosome pairing in Larix species.Journ. zenzuchtg. 2(3): 49-51. of Arnold Arboretum 13: 363-367. 1954. RückmutationbeiZwergflchte. Zschr Sax, K.,1933a.Chromosome numbers in Ulmus and related Forstgen. & Forstpflanzenztichtg. 3(6): 138-139. genera.Journ. of Arnold Arboretum 14: 82-84. 1959. Selbstfertilität und Inzucht bei Picea oinorika l933b.Species hybrids in Platanus and Campsis. (Pancic) Purkyne. Silvae Genetica 8(3): 84-93. Journ. of Arnold Arboretum 14: 274-27 8.

804 Fifth World Forestry Congress Proceedings and H. J. Sax, 1933.Chromosome number and RESUMES morphology in the conifers.Journ. of Arnold Arboretum 14: 356-375. Polyploldieetmutagenèse enmatièredegénélique Scholz, E., 1957. Röntgenmutationen bei der Birke. Der Zuchter foreIière 27(I): 54-60. Ainsi que lefaitressortirle present rapport,la selection Schwanitz, F., 1953. Uber somatische RUckmutationen bei einer ordinaire et l'hybridation seront pendant longtemps encore les schmalblättrigenPflanzevon hexaquifoliumL.Zschr. méthodes utiliséesle plus couramment pour les travaux de Forstgen. u. Forstpflanzenzuchtg. 2(6): 117-118. génétique forestière.Quoi qu'il en soit, la polyploldie, qu'elle Shamel, A. D., 1917. A bud variation of Evonymus. Journ. of soit spontanée ou provoquée, a déjà pris de l'importance pour Hered. 8: 218-220. certains feuillus, par exemple pour ceux du genre Populus et 1930. A bud variation in the deglet noor date palm. Alnus, qu'il s'agisse d'essences pures ou d'hybrides.Bien que Journ. of Hered. 21: 164-166. présentant un intérét énorme pour les plantes agricoles et les Shamel, A. D. and C.S. Pomeroy, 1932.Bud variation in arbres fruitiers, les mutations provoquées ont jusqu'à present été apples. A study of the role of bud mutation in deciduous d'une application pratique réduite, mais elles peuvent en fin de fruit improvement. Journ. of Hered. 23: 173-180, 213-221. compte produire de nouvelles variétés de valeur en ce qui concerne 1936. Bud mutations in horticultural crops. Journ. les arbustes employés pour l'ornementation et les arbres resultant of Hered. 27: 486-494. de multiplication végétative.Ii convient de tenir compte des Simak, M. and A. Gustafsson, 1953.X-ray photography and mutations spontanées pour l'analyse de la structure d'une popula- sensitivity in forest tree species.Hereditas 39: 458-468. tion. Smith, B. Cli., 1941. Chromosome behavior in Catalpa hybrida Du point de vue phytogénétique, il convient de mentionner que Spaeth. Journ. of Arnold Arboretum 22: 219-221. nombre de genres de feuillus ont pour origine des hybrides qui and Ch. Nichols,Jr.,1941.Species hybrids in ont par la suite double, ou même accru dans de plus grandes pro- forest trees.Journ. of Arnold Arboretum 22: 443-454. portions, le nombre de leurs chromosomes. Un grand nombre Sparrow, A. H. and B. Christensen, 1953. Tolerance of certain d'entre eux possédent des chromosomes de trés petite taille. Sans higher plants to chronic exposure to gamma radiation from êtrecomplètement absente,lapolyploidieest rare chezles cobalt-60. Science 118: 697-698. PBA 24: 1587. gymnospermes, et leurs chromosomes sont en général assez gros. Stadler, L. J., 1928. Mutations in barley induced by X-rays and Le Sequoia sempervirens constitue un cas remarquable de poly- radium. Science 68: 186-187. ploIdie. L'analyse du karyotype indique souvent un remaniement Stebbins, G. L., Jr., 1938.Cytological characteristics associated profond de la structure des chromosomes de genre a genre. with the different growth habits in the dicotyledons. Amer. L'hybridation des espècesetdes genres et le doublement Journ. of Bot. 25(3): 189-198. concertédeleurschromosomespermettraientcertainement 1948. The chromosomes andrelationshipsof d'acquérir des renseignements de valeur théorique considerable Metasequoia and Sequoia.Science 108(2796): 95-98. et de se faire une idée des possibilités d'application pratique de 1950. Variation and evolution in plants. Columbia ces méthodes pour les travaux de génétiqueforestiêre.Les Univ. Press. New York. diversaspectsdeladendrocytologieontététerriblement Stiff, M. L., 1951. A naturally occurring triploid juniper. Vir- négligés au cours des dernières décennies. En fait, la plupart ginia Journ. of Sci. N.S. 2: 317. des méthodes mises au point et des résultats acquis remontent Sugihara, Y.,1940.On the multipartite chromosome-ring in aux premieres etudes effectuées par K. et H. Sax au cours des Cephalotaxus drupacea Sieb. et Zucc.Sci. Rep, of Tôhoku années 1930.Les travaux de cytologie doivent être poursuivis Imp. Univ. Sendai 4(15): 13-18. sur un plan trés vaste en faisant usage des techniques modernes. Sylvén, N.,1907.Material for studiet av skogsträdens raser. 4-8. Medd. fr. Stat. skogsfOrsoksanst. 5, 1908: 169-193. Poliplodia y mutagénesis en el cultivo de árboles forestales 1909.Studier over granens formrikedom, särskilt Medd. fr. Como seseflala en este trabajo, los métodos de selecci6n dess fOrgreningstyper och deras skogliga värde. ordinaria y de hibridación serán los más comunes para la crIa Stat. skogsforsoksanst. 6: 57-117. de árboles forestales por muchos años más.Sin embargo, la 195 1'.Skogstradens mängformighet. Sv. Vaxtforädl. poliplodia, tanto espontánea cornoartificial, ha adquirido ya II: 413-452. importancia entre los géneros de hoja ancha, esto es, Populus SOderberg, E.,1917. En knoppvariation hos Alnus glutinosus. y Alnus, en las especies puras y también en las hIbridas.Aunque Sv. Bot. Tidskr. 11: 401-402. de profundo interés en el caso de plantas agrIcolas y árboles Toyama, 5., 1954. Studies on breeding of forest trees.(Breeding frutales,las mutaciones inducidas hasta ahora han resultado of forest trees and its fundamental studies. Rep. 24).Bull. de poco uso práctico, pero quizás a la larga produzcan nuevas Governm. Forest Experim. Station 66:1-269. Tokyo. y valiosas variedades en arbustos de adorno y en árboles Tralau, H., 1957. Uber eine haploide Form von Populus tremula reproducidos vegetativamente.En elanálisis de la estructura aus Uppland. Bot. Not. 110(4): 48 1-483. delaproblaci6n han de tenerse en cuenta las mutaciones Traub, H. P. and H. J. Muller, 1934. X-ray dosage in relation to espontáneas. germination of pecan nuts. Bot. Gaz. 95: 702-706. Biol. Abstr. Desde un punto de vista filogenético es digno de mencionarse 9: 9048. que muchos de los géneros de hoja ancha tienen su origen en Wettstein, D. von, 1959. Proceedings of the Scandinavian electron hIbridos que más tarde han aumentado en ci doble o más el microscope society. (5) The effect of genetic factors on the nitmero de sus cromosonas.Muchos poseen cromosonas de submicroscopic structures of the chloroplast. Journ. Ultrastruc- tamaño reducido. Aunque no faltan enteramente los casos, Ia ture Res. 3: 234-350. poliplodia es rara en las especies gimnospermas. Generahnente, A. Gustafsson, and L. Ehrenberg, 1959. Mutations- las cromosonas son más bien grandes. Un caso notable de forschung und Zuchtung. Arb. Gemeinsch. f. Forschung des poliplodiaeselobservado en el Sequoia sempervirens.El Landes Nordrhein-Westf. 73: 7-48.Engl. summary 59-60. análisis cariotIpico acusa a menudo una profunda reconstruc- Wettstein, W. von, 1937. Forstpflanzliche Zuchtungsversuche-be- ción de la estructura de las cromosomas de un género a otro. sonders mit Populus. Bot. Not.: 272-284. La hibridación de las especies y gCneros y la dupiicación Wittrock, V. B., 1914. Meddelanden om granen, särskilt hennes revista del nilmero de cromosomas, ciertamente suministrarlan svenska former, i bild och skrift. I. Acta Horti Bergiani 5(I): datos de considerable valor todrico y darIan indicaciones uitiles 1-91. sobre la aplicación práctica de estos métodos en la crIa futura Zinnai, I., 1952.Tetraploid plants of Japanese red pine (Pinus de árboles. Algunos aspectos de la citologIa arbórea han caldo densiflora) Sieb. et Zucc. discovered in transplant beds. Journ. muy en olvido durante las dltimas décadas.En realidad, la of Jap. For. Soc. 34(6): 185-187. mayorIa de los métodos y resultados son de Ia época de los and S. Chiba, 1951.Tetraploids of Sugi (Crypto- primeros estudios de K. y H. Sax, realizados a mediados de Ia meria japonica D. Don) discovered at forest nursery. burn. década del 1930. DeberIan hacerse estudios citológicos en gran Japanes of Breeding 1: 43-46. escala, valiéndose de los métodos técnicos modernos.

Genetics and Tree Improvement 805 SPECIAL PAPERS Quelques observations sur la selection des peupliers de la section Leuce en Italie

MICHELE SEKAWIN Ente Nazionale per Ia Cellulosa e per la Carta, Istituto di Sperimentazione per la Pioppicoltura, Casale Mon/errato, italie

Lors du VIe Congrès International du Peuplier, MM. n'était pas très répandue. Les inconvénients de leur cul- P. Bouvarel et M. Lemoine (1) * ont présenté un rapport ture sont la lenteur de l'accroissement et la propagation sur la selection des peupliers de la section Leuce en difficile, tandis que leurs mérites sont la bonne qualité France. La situation francaise présente beaucoup d'ana- du bois,l'adaptation au climat froid et aux terrains logies avec les conditions italiennes. En effet, en France pauvres, et une certaine résistance a l'ombrage. et en Italie, la populiculture industrielle est fondée es- Les peupliers blancs, Populus alba L., poussent soit sentiellementsurleshybridesdepeupliersnoirs dans la plaine, soit sur les collines et les montagnes. us euraméricains, tandis que les peupliers indigènes, Populus sont fort répandus surtout dans l'Italie Centrale. nigra L., P. alba L. et P. tremula L. sont de plus en plus Les caractéristiques les plus importantes du point de refoulés vers les stations moms fertiles, les marais, les vue de la selection sont l'accroissement assez rapide, graviers, les terrains sales, les montagnes. l'adaptation a des terrains très varies, même andes ou Ce procès est tout a fait justiflC par la croissance plus sales,la bonne aptitude au bouturage,la coloration rapide et par les meilleures propriétés technologiques du rougeâtre du duramen, a cause de laquelle son bois est bois des hybrides euraméricains.Mais cela ne signifie peu appréciC par les principales industries du bois. pas que les peupliers de la section Leuce doivent être Le but que vise notre travail d'amélioration, c'est de abandonnés. Même dans des stations moms favorables réussir a combiner les bonnes qualités des deux espèces, on peut obtenir des rendements satisfaisants a condition c'est-à-dire de créer des hybrides faciles a propager, ayant qu'on trouve les types de peuplier et les méthodes de un accroissement rapide, une bonne adaptabilitC au milieu, propagation et de culture les plus appropriés. Cette étude un beau port, une grande résistance aux maladies et de a été entreprise par les deux stations de recherche de bonnes qualités technologiques. Pour sa réalisation, on se l'Ente Nazionale per la Cellulosa e per la Carta, celui de sert non seulement des espèces indigènes, mais on effectue Casale pour l'Italie du Nord et celui de Rome pour aussi des croisements avec les trembles américains, Pop- l'Italie centrale et méridionale, avec une collaboration qui ulus tremuloides Michaux et P. grandidentata Michaux. est destinée a devenir de plus en plus étroite. L'améiioration est basée sur deux méthodes: Trois communications ont été déjà publiées par le Récolte de graines issues de la fécondation naturelle; Centre experimental agricole et forestier de Rome (2, 3, Hybridation artificielle. 4) sur les trembles de l'Italie méridionale. Le travail Pour obtenir des hybrides naturels, on récolte des entrepris a Casale depuis plusieurs années s'est tout de graines sur des arbres bien formés et sains dans des suite concentré sur la selection d'hybrides améliorés, sans regions différentes et on les sème directement sur des approfondir du point de vue botanique l'étude des peuple- plates-bandes. ments existants. Les croisements artificiels sont exécutés dans une serre, L'existence d'innombrables formes interrnédiaires entre soit sur des branches coupées placées dans l'eau, soit sur les espèces Pop ulus tremula et P. alba, sans entrer dans des branches greffées avec Ia méthode du "bottle-graft". la question concernant l'identité botanique du P. canes- Le pollen provient en partie de peupliers indigènes, en cens,rendextrêmementdiffidiletouteclassification partie de l'étranger, surtout des Etats-Unis et du Canada precise. On se borne a distinguer lestrois groupes: (Prof. S. S. Pauley, Harvard Forest, Petersham, Mass.; trembles, peupliers blancs et formes intermédiaires. Dr. C. Heimburger, Southern Research Station, Maple, Les trembles, Populus tremula L., se trouvent en Italie Ont.), grace a l'aimable collaboration des stations de presque exclusivernent a la montagne et présentent le type recherches étrangères. de Ia "race de montagne", c'est-à-dire füts droits, écorce Les hybridesartificiels sont semés dans des petites verdâtre ou jaunâtre, lisse,feuilles glabres.Dans les caisses dans la serre et ensuite repiqués dans une plate- peuplements qu'on a pu examiner, la pourriture du coeur bande. Qu'il s'agisse d'hybrides naturels ou artificiels, après une *Les chiffres entre parentheses indiquent les références notées année de végétation on effectue une selection parmi les a la fin du present article, semis et les meilleurs sont repiqués dans une pépinière en 806 Fifth World Forestry Congress Proceedings les recépant. Les boutures tirées de la tige sont plantées aussi dans la forme de la tige et de Ia couronne et dans a côté des racines et permettent de juger de l'aptitude au les autres caractères morphologiques. bouturage de l'hybride en question. Comme les auteurs En ce qui concerne les propriétés technologiques, on n'a francais cites plus haut, nous sommes de l'avis qu'une pas encore de données sur la qualité du bois, mais la méthode de propagation facileet économique est in- coloration orange du duramen est souvent déjà visible dispensable pour qu'un clone puisse trouver un large dans les plants de deux ans. Les clones qui présentent emploi dans la pratique. cette coloration sont éliminés, puisqu'on vise a obtenir Dans la pépinière, on effectue une deuxième selection du bois blanc. pendant la premiere année et une troisième pendant la Les observations sont poursuivies dans les peuplements seconde année, puis les plants sont mis en place dans les de selection et comparatifs. Actuellement on a dans les plantations expérimentales. plantations de Ia ferme expérimentale 164 clones de Depuis 1943 on a observe dans les pépinières le ma- peupliers de la section Leuce: tend suivant provenant de semis: Nr. de clones Nr. de plantes- Hybrides naturels 70 mères ou de Nr. de crosements plants a/ba x alba 47 a/ba x tremuloides 34 Hybrides naturels 49 988 a/ba x grandidentata 6 Hybrides artificiels: alba x tremula 4 alba x alba 10 510 trein u/a x tremuloides 2 alba x tremula 7 46 trem u/a x tremula alba x tremuloides 14 586 alba x grandidentata 11 93 tremula x tremula 1 6 Mais le milieu qui offre les possibilités les plus amples tremula x alba 4 a la culture de peupliers de la section Leuce, c'est la tremula x tremuloides 5 20 montagne. C'est pourquoi on est en train de développer tremula x grandidenrata 2 7 un programme d'expérimentation dansleszones de montagne.Des pépinièresetdes plantations expéri- mentales ont déjà été établies a Sauce d'Oulx (Torino), La propagation a été faite toujours par boutures de tige a Armeno (Novara), a Trento et a Borgo Val Sugana pour les raisons expliquées plus haut. C'est pourquoi les (Trento). Mais II n'y a pas encore de plantations com- exemplaires qui ne se propagent pas par ce moyen ont paratives qui puissent fournir des résultats sürs. Dans les Cté éliminés. Les autres ont formé des clones qui sont ann'es a venir, de telles plantations seront établies. encore sous observation ou ont étd abandonnés pour On espère que les résultats de ces etudes pourront d'autres raisons. Sans compter les semis de 1959, on a contribuer a rernédier aux conditions diffidiles des regions encore en pépinière: montagneuses et des zones moms fertiles de la plaine, en crdant de nouveaux hybrides correspondant aux ndces- dont propagés sites de la culture et de l'utiisation industrielle. clones ultérieurement Nr. Nr. Références Hybrides naturels 87 8 Bouvarel, P. et Lemoine, M. Selection et amelioration des a/ba x alba 213 35 peupliers de la section Leuce en France. 9' Sess. de la Comm. a/ba x tremuloides 66 18 mt. du Peuplier, Avril, 1957. alba x grandidentata 29 9 Messeri, A.Preliminary notes on a stand of Populus tremulaL.at Sila(Calabnia).I Auxometric analysis.9' Session de la Comm. mt. du Peuplier, Paris, 1957. On voit bien que beaucoup d'hybrides de Populus alba Scaramuzzi, G. Idem. II Histological data of the wood. 9 avec P. tremuloides et P. grandidentata se bouturent facile- S. de la Comm. mt. du Peuplier, Paris, 1957. Giordano, E., Avanzo, E. et Gramuglio, G. Observations ment, tandis que les hybrides de trembles divers ont été sur le P. tremula en Italie méridionale.100 Session de la éliminés Comm. Intern. du Peuplier, Venise-Turin, 1959. Quant aux autres caractères, on obtient de nombreuses Sekawin, M.Prime impressionisui nuoviincrocifatti combinaisons diverses.Les résultatsdes croisements nel 1953.Actes du Congrès National du Peuplier, Rovigo, changent selon le choix des parents.En 1953 on a Novembre 1953. exposé (5) queiques observations sur des croisements RESUMES entre Populus alba indigène d'une part et P. tremuloides et P. grandidentata provenant des Etats-Unis d'autre part. Some Observations on the Selection of Poplars of the On avait observe que les types morphologiquement plus Section Leuce in Italy proches des trembles étaient plus résistants a la rouille, For cultivation in less fertile land efforts are made to obtain tandis que les hybrides plus proches du type alba étaient hybrid poplars of the section Leuce which combine the good propagation(bycuttings)and growth characteristics of the plus développés en hauteur.Toutefois,II y avait des Populus a/ba L. with the technological qualities of the trembling individus qui unissaient a la résistance a la rouille un bon poplars, P. tremula L., P. tremuloides Michaux, and P. grandi- accroissement. Des differences marquees se manifestaient dentata Michaux. Genetics and Tree Improvement 807 Observaciones sobre la Selección de Alanos de la Sección obtener hIbridos de álamos de la secci6n Leuce que reunan las Leuce en Italia buenaspropiedadesdereproducck5n y decrecimientodel Populus alba L. con las cualidades tecnológicas de los temblones, P.tremulaL.,P.tremuloides Michaux y P. grandident ala Para el cultivo en los terrenosmenos fértiles,se trata de Michaux.

Improvement Rates Through Clonal and Seedling Seed Orchards

JONATHAN W. WRIGHT Professor, Department of Forestry, Michigan State University, East Lansing, Michigan, U.S.A.

In the past few years there have been enough studies Presumably, the planting will start to produce seed a few which showed the presence of genetic variation among years after establishment. individual trees to justify the belief that individual-tree The value of such a clonal planting as a producer of selection and breeding should be considered as an im- information on inheritance is very limited. At the worst portant part of any tree improvement program. There (no replication, clones of widely different provenances or are still many unknowns about selective breeding, how- species, insufficient attention paid to the elimination of ever. topophytic effects), the performance of the various clones In this paper I shall confine my attention to one aspect gives false information about genetic variation within a of the methodology of selective breedingthe use of population. At best, a well-designed clonal test gives in- colonal propagation. I chose this particular aspect because formation about the total amount of genetic variation the need has been assumed rather than proven.In ex- but gives no information about the transmission of that amining this need for grafting and cutting work I shall variation by seed. Hence, estimates of heritability based limit the discussion to those genera (pine, spruce, larch, only on clonal tests are practically valueless when com- eucalypt, etc.) in which clonal propagation is relatively ex- puting genetic gains from breeding systems involving pensive. In those genera a living ramet costs from 10 to seed propagation. 100 times as much to produce as does a living seedling, If the characteristic for which the plus trees were and clones are useful only as test material or seed pro- chosen is heritable, the clonal planting yields superior ducers rather than as actual planting stock in commercial seed. This superiority is due to mass selection for addi- plantations. tive-effect genes and is the same as the gain expected when collecting seed from selected mother trees pollinated Useful Aspects of Vegetative Propagation by superior pollen parents, and is termedG (= mass- There are three ways in which clonal propagation is so selection gain). obviously useful that little discussion is needed.First, When the clonal planting approaches maturity it may scionwood taken from high in the crowns of fruiting trees be thinned to leave only the best clones. Providing that the usually continues to fruit when grafted on small trees close planting was designed to provide statisticallyreliable to the ground. This makes controlled pollination an easy information on genetic differences among clones,this matter. Second, if selected trees are chosen from a wide thinning is a refinement of the original mass selection and geographic area, their germ plasm can be moved into a will cause thinned planting to produce seed which is conveniently located, small breeding arboretum by means slightly more thanG superior to average. of grafts or rooted cuttings.The advisability of using vegetative propagation to facilitate controlled pollination Half-Sib Progeny Tests and Seed Orchards work is a matter of economics which must be worked out The second case to be considered is a half-sib (= open- separately for each species from known costs for con- pollinated) progeny test and seed orchard. It is established trolled pollination and grafting.Third, a properly exe- by collecting open-pollinated seed from selected plus trees, cuted clonal test can show the total genetic variation planting the seedlings in a carefully designed progeny within a single tree progeny. test, and thinning at the proper time to leave the best individual trees of the best progenies. This is primarily The Limitations of Clonal Tests Unsupported by a research planting to give data on inheritance and to Seedling Progeny Tests provide material for another generation of work. How- The first case to be considered is a clonal planting ever, with proper attention to plot size,spacing, and unsupported by a seedling progeny test.It is established thinning, it serves well as a seed orchard while fulfilling by making grafts or rooted cuttings of phenotypically its primary research function. superiortrees,planting the ramets under conditions In difficult-to-root species the cost of such a planting favorable to seed production, and thinning the planting is minor when compared with the cost of establishing a to leave the best clones when they are several years old. clonal test.I expect that in most pines a 100,000-seed- 808 Fifth World Forestry Congress Proceedings ling progeny test could be established with as little effort 20, it starts to produce seed which is 2G-superior, as as could a 1 ,000-ramet clonal planting. compared with (1 +) i-superior seed from clonal seed The half-sib progeny test is much superior to a clonal orchards or 1½G-superior seed from half-sib progeny test as a producer of information about tree inheritance. tests. The progenies yield data on the additive genetic variance The above estimate ofG for the per-generation gain in the parental population and on the degree to which from combined mass-full-sib-family selection is minimal. superior parents transmit their superiority to seedling The gain is more likely to be at least 2 G per generation. offspring.The information on heritability permits esti- Therefore, it is reasonable to use a figure of 3 G super- mates of future genetic gain if selection is continued in iority for seed produced by the progeny test after it is future generations. thinned at age 20. The selected parents of half-sib progenies are G superior to average, just as the clones in a clonal test. Combined Clonal Tests and Progeny Tests However, they were pollinated by average parents and The fourth and fifth cases to be considered are clonal therefore produce F1 seedlings which are only ½ G seed orchards combined with half-sib or full-sib progeny superior to average. Because this is a mass-selection gain tests, respectively. The clonal and seedling plantings are due to additive genetic variance it is transmissible from established at the same time.The seedling plantings parent to progeny.Therefore, the F1 seedlings in the will be evaluated and thinned to leave the best trees in progeny test can be considered as a seed orchard produc- the best progenies. The clonal plantings will be thinned ing seed of ½A G superiority. The thinning to the best to leave the clones with the best proven combining ability trees in the best progenies constitutes another generation (= ability to produce good progenies). of selection and adds a furtherG of genetic gain. There- The gains registered before progeny evaluation need not fore, after thinning, the progeny test will produce seed of be considered because they are the same as those given 1½ G superiority, as compared with G + for a above (zG for cional and full-sib progeny tests, ½ z G thinned clonal seed orchard. for half-sib progeny tests). Once half-sib progeny tests have been evaluated and The gains registered by the progeny tests after progeny thinned they are clearly preferable to clonal seed orchards evaluation and thinning are also the same as given pre- in all respects. The only justification for using clones in viously (1½G-superior seed produced by half-sib preference to open-pollinated progenies is the temporary progeny tests,3zG-superior seed produced by full-sib initial advantage in quality of seed produced before evalu- progeny tests). The seed produced by clones will gen- ation (x G-superior seed from clones vs. ½ G-superior erally be of lower quality than that produced by the seed from seedlings). The decision as to whether or not accompanying progeny test for two reasons.First, the to use clones to obtain this temporary genetic advantage clones will be of parental generation and will produce should be based on a careful consideration of costs. For F1 seed; the seedlings will be of F1 generation and will example, it would probably be better to accept the ½ G produce F2 seed.Thus, seed from the clonal plantings gain in five species than the G gain in one species if will include only the 1-generation, family-selection gain five seedling progeny tests could be established as easily as whereas seed from the progeny tests will include a 1-gen- one clonal planting. eration, mass-selection gain and a 1-generation, family- plus-mass-selection gain.Second, if the clonal planting Full-Sib Progeny Tests and Seed Orchards is thinned to the several clones with best (general or The third case to be considered is a full-sib (= con- specific) combining ability, pollination is among several trol-pollinated) progeny test and seed orchard.Itis clones and the seed has only a general-combining-ability established by selecting plus trees, crossing these with gain. The clonal test must be thinned to the two clones selected males, planting a well-replicated progeny test in with best specific combining ability if it is to produce F1 which the identity of the seedlings is maintained with seedlings equal in quality to the best family in the 2-parent regard to both male and female parents, and thinning to progeny test.Such a thinning to two clones raises the the best individual trees of the best progenies at the proper cost of a clonal seed orchard to an almost prohibitive time. figure, because it means that a 1,000-ramet planting (10 A full-sib progeny test is the best producer of informa- ramets of each of 100 clones) would be reduced to a mere tion.It yields estimates of the additive and non-additive 20-tree seed orchard. components of genetic variance. Such estimates are es- The genetic gains ofG, 2G, 3z G, etc., quoted thus sential in planning a rational, many-generation, improve- far are approximate. In Table 1, which compares gains ment program.In most coniferousgenera,full-sib (after thinning) from seedling progeny tests and their progenies are much cheaper to produce than similar-sized accompanying clonal tests, I used more precise estimates clonal plantings. based upon calculations in which heritability and exact In ability to produce high quality seed, this type of breeding method were taken into account. These more planting is always equal or superior to a clonal test. The precise estimates agree with the approximations in showing progenies originate from selected X selected matings and that the quality of seed produced by a seedling progeny therefore have an average superiority of zG. Because test is higher than the quality of seed produced by a thisis a mass selection gain due to additive genetic specially designed clonal seed orchard. variance, most ofitis transmissible from parent to Table 1. Quality of seed produced by seedling progeny progeny. Hence, the first seed produced by the progeny tests and their accompanying clonal seed orchards after test is G-superior, the same as from a clonal seed the plantings have been thinned to the best trees of the orchard.If the test can be evaluated and thinned at age best progenies or to the clones with best combining ability.

Genetics and Tree Improvement 809 The estimates are more precise than the approximations est toujours d'une qualitésupérieure aux semences produites found in the text, and are based upon calculation methods par les plants cultivés a partir de l'arbre-parent. Une série de contrôlesdedescendance d'unparent ou dedeuxparents outlined in Lerner(1958)and Wright(1959)*. produirait done non seulement des renseignements et un materiel de reproduction utiles, mais pourrait aussi servir de meilleurs General quality of seed produced in terms of percent of jardins de porte-graines provisoires que les jardins de porte- phenotypic range in parental population by strength graines issus de clones, spécialement affectés a cet effet. of heritability Ce serait une erreur que de vouloir considérer la propagation par clones comme la partie principale d'un programme de sélec- Seed produced by 10% 20% 30% tion.Son utilisation devrait plutôt se limiter a atteindre l'un des trois objectifs suivants: (1) Fournir des renseignements sur Half-sib progeny tests accompanying les variations génétiques totales entre arbres-parents; (2) Faciliter clonal tests la pollinisation contrôlée en rapprochant les fleurs des arbres Seedlings 20.8 36.0 49.1 du sol; et (3) Produire un jardin de porte-graines qui produira Clones des semences d'une supériorité de l'ordre de G (G étant égal 13.8 21.0 46.7 au gain de la selection de masse) dans des essences dont les Full-sib progeny tests with accom- jeunes plants ne donnent pas de fruits pendant des anndes. Dans le panyingclonalteststhinnedto cas de plusieurs essences,la propagation par clones n'a pas several clones with best general permis d'atteindre le troisième objectif, car un jardin de porte- combining ability graines issus de clones a pris tant d'années a Ctre cornplété que Seedlings 30.8 42.4 56.4 les plants pourraient porter des fruits avant que la dernière greffe Clones 13.8 21.0 26.7 ne soit faite. Full-sib progeny tests with accom- panyingclonalteststhinnedto Mejoramiento mediante semilleros clonales y de posturas two clones with best specific com- La propagación clonal reproduce árboles exactamente iguales a bining ability sus padres.Esto, más bien que ventaja es desventaja en el Seedlings 30.8 42.4 56.4 mejoramiento de Ia calidad de los árboles porque los que se Clones 20.6 30.4 37.6 han escogido como superiores en 1960, no son tan buenos como por ser propagados indefinidamente.Los verdaderos mejora- mientos los conseguiremos por medio de la selección en pobla- RESUMES ciones de posturas variables. Con pocas excepciones,los proyectos de crianzaselectiva Taux d'amélioration avec des jardins de porte-graines están basados en la suposicion de que existe una correlación de issus de clones et de semis importancia entre los padres y la progenie. Tal correlación se debe principalmente a la variación genética aditiva. Con esta La propagation par clones reproduit des arbres exactement variaei6n aditiva la ealidad de la simiente producida por los identiques auxarbresd'origine.Ceci comporte plus de dé- mejores posturas en las mejores familias de una prueba progenie, savantages que d'avantages dans l'amélioration des arbres, car es siempre más alta que la de la simiente producida por los ceux qui ont été choisis comme les specimens d'élite en 1960 clones paternales.Por consiguiente, una serie de pruebas de ne sont pas assez bons pour que leurs caractéristiques soient progenie de padre 1 o padre 2 no solaniente nos darian informa- propagées indéfiniment.Ii ne sera possible d'obtenir des améliora- ción fltil y material de cria sino que nos servirIan mejor de tions réelles qu'en pratiquant une selection parmi des populations huertos para semilleros provisionales que los clonales especial- variables de plants issus de graines. mente preparados, por excellentes que sean. Sauf quelques exceptions,les programmes de reproduction Es un error considerar la propagación clonal como la parte selective a l'intérieur de Ia même espèce sont bases sur la sup- principal del programa de selección. Al contrario, su uso debe position qu'il y a une correlation importante entre parent et estar limitado al logro de uno de los tres objetivos siguientes: descendance. Une telle correlation est due le plus souvent a (1) suministrar datos sobre la variacion genética total en des- des variations génétiques additionnelles. Avec de telles variations cendientes plenamente afines; (2) facilitar la polenización con- additionnelles,la qualité des semences produites par les meil- trolada al acercar al suelo las fibres del árbol; y (3) producir leurs sujets des meilleures familles d'un contrôle de descendance un semillero fioreciente que dé semillas de superioridad G (AG: ganancia de selección en masa) de especies cuyas posturas no fructifiquen por muchos afios.El uso de la propagación clonal *Lerner,I.M.,1958.The genetic basis of selection.298 no ha logrado el tercer objetivo en el caso de varias especies pp., Wiley, New York. Wright, J. W., 1959. The role of selec- porque un semillero clonal ileva tantos años en completarse tion in forest tree bresding.Lake States Forest Tree Improve- que las posturas pueden estar ya fructificando antes de hacerse el ment Conference Proceedings 4: In press. ilitimo injerto.

810 Fifth World Forestry Congress Proceedings Recent Work on Populus deltoides in Italy

ERVEDO GIORDANO Centro di Sperimentazione Agricola e Forestale, Rome, Italy

Introduction from a mixed stand of Populus deltoides and Salix nigra In recent years the extension of poplar culture in Cen- grown up on recent deposits at Yancopin at the confluence tral and Southern Italy has become of ever-increasing of the Arkansas River with the Mississippi. importance as a result of the profound transformation First Results brought about in many areas by land reclamation schemes. In view of the desultory nature of previous experiments In April 1958, 226 seedlings of Populus deltoides col- in poplar culture in these regions, the Centro di Speri- lected in Illinois, and 214 from the Mississippi Delta, were mentazione Agricola e Forestale has worked out a pro- planted out.Success of those from thefirstsource gramme of co-ordirated research. reached 95%, while those from the second barely One feature of this programme envisages a series of achieved 40%, as a result of damage suffered in transit crosses between spontaneous poplars selected from Cen- to Italy. Growth was, on the whole, satisfactory: at the tral and Southern Italy and various forms of Populus end of the growing season the average height of the Mis- deltoides originating from the United States.For this sissippi seedlings was 2.8 metres, with a maximum of 3.10 purpose the present writer carried out a research mission m., while that of the Illinois seedlings was 2.40 m., with to the United States in 1958, in order to study P. deltoides a maximum of 2.95 m. on the ground and to collect seeds and cuttings from which Vegetative propagation was carried out from this to build up a first nucleus for selection and observation. material in February 1959; a total of over 2,000 cuttings This paper summarises the results of the first two years was obtained, of which 689 were from Mississippi ortets of experimental research. and 1,452 from Illinois. The cuttings were treated, with a 0.2% solution of indolylbutyric acid for 17 hours, Material Collected before planting out at a spacing of 0.30 x 1.25 metres. Collections were made mainly in Illinois and in the Success was, in general, very satisfactory, and proved Mississippi Delta, from sites lying between the 38th and to be slightly higher in the case of Illinois provenances 31st parallels, where the climatic conditions, though not (86%) asagainst those from the Mississippi Delta entirely similar to those obtaining in Central and South- (83%). ern Italy, show marked resemblances as regards length A preliminary selection was carried out at the end of of the growing period and seasonal temperatures.* the first year, using as a basis of comparison the growth In order to obtain the greatest possible enrichment of of a certain number of cuttings of Populus x eurameri- the genetic range of Populus deltoides available for selec- cana "I 214," which, on account of its high growth rate, tion in Italy, preference was given to the collection of is one of the most widely spread clones in Italy. The seeds and seedlings rather than of cuttings. average height growth of P. deltoides, though on the whole Several hundred one-year-old seedlings were collected well maintained, proved less than that of clone "I 214." in Illinois from near Ware (Carbondale), an area under- The average height of plants produced from Illinois going intense natural regeneration and which includes cuttings was 2.80 m., with a maximum of 3.95 m., and stands of P. deltoides particularly notable for their habit that of Mississippi types was 2.60 m., with a maximum and speed of growth. of 3.50 m. In the Mississippi Delta, seeds and cuttings were col- Taking into account also percentage success, form, and lected from theStoneville experimentalforest,from resistance to adverse conditions, it has been possible to Indian Point, along Lake Beulah, and in the area of King pick out 75 types of the Illinois plants, and 15 of those at the foot of the Vicksburg Hills. from the Mississippi Delta, which are clearly above One-year-old seedlings, on the other hand, were taken average and deserve to be followed with attention. Itisobvious that a final assessment can only be *For purposes of comparison, material was also collected from Vermont and Iowa.In this last-named area, apart from the arrived at by comparative plantings, which will be car- collection of Populus deltoides,particular attention was also ried out with the material in course of propagation. paid to the spontaneous hybrids between P. alba and P. grandi- dentata, belonging to the section Leuce. These poplars, in fact, The seeds sent from the United States in the spring show good morphological characteristics and a high degree of of 1958 produced 3,688 seedlings, which were grown in adaptation todifficultenvironmental conditions analogous to pots and planted out in the open at a spacing of 0.30 x those in the mountain areas of Central and Southern Italy. 1.25 rn. at the end of August of the same year. The A special collection was made of cuttings and root suckers of P. shimek and P. crandon from certain stands in the area of growth of the seedlings was very rapid, and at the end of Farmington, Iowa. the 1959 season their average height was as follows:

Genetics and Tree Improvement 811 Average height de boutures de P. deltoides ont été recueillies en 1958 dans de Provenance nombreux sites forestiers du Vermont, de l'Illinois, de 1'Iowa et (metres) du delta du Mississippi, et envoyées en Italie. Stoneville 1 3.51 La présente note resume les premiers résultats obtenus. Vicksburg 1 A la fin de la premiere saison végétative, les jeunes brins en 3.34 provenance du Mississippi avaient atteint en moyenne une hauteur Vicksburg 2 3.28 de 2,80 m. avec un maximum de 3,10 m, tandis que ceux en Vicksburg 3 3.18 provenance de l'Illinois atteignaient en moyenne 2,40 m. et un Vermont Neg 1490 2.29 maximum de 2,95 m. En ce qui concerne les boutures, celles venant de l'Illinois ont réussi dans une proportion de 86 pour cent, contre 83 pour cent It is interesting to note that the plants from each single pour celles en provenance du Mississippi. La croissance en hauteur des plantes obtenues en partant de provenance proved to be fairly homogeneous, while there boutures en provenance de l'Illinois a été en moyenne de 2,80 m. is a clearcut difference in habit between those of different (avec un maximum de 3,95 m.), tandis que celles en provenance origins. du Mississippi ont atteint une moyenne de 2,60 m. (avec un In general, the seedlings from the Mississippi Delta maximum de 3,50 m.). Tenant compte de facteurs tels que: réussite, forme et résistance have a growing period about 20 days longer than the aux conditions défavorables, il a été possible de sélectionner 75 Vermont plants, and a faster growth rate. The maximum types parmi lesplantes obtenues en partant de boutures en growth height achieved (4.80 m.) was, in fact, bya provenance de l'Illinois, et 15 types de celles venant du Mississippi, seedling from Stoneville. lesquels sont très nettement au-dessus de la moyenne et méritent d'être suivis avec attention. Propagation of all the seedlings by means of cuttings On a obtenu a l'aide de semences en provenance des Etats- is now under way, in order to effect comparison with Unis 3.699 brins présentant un taux de croissance très élevé. A la homogeneous material. fin de la premiere saison végétative, tous les plants, excepté ceux issus de graines en provenance du Vermont, avaient dépassé 3 Conclusions metres de hauteur. La multiplication des plants de Populus deltoides a été effectuée The material collected has, on the whole, given satis- a notre Centre au cours de cette année, et l'on dispose maintenant factory results.The plants developed no pathological de 3 5.000 boutures qui seront plantées aux fins de comparaison conditions and showed a notable resistance to rust, from avec les clones plus répandus en Italie de P. x euramericana. which they may be considered practically immune. There was, however, a notable susceptibility to the Estudios Recientes sobre Populus deltoides en Italia attacks of Paranthrene asiliformis Schif, which made their Los experimentos en el cultivo del alamo realizados en el Centro y Sur de Italia han sido hasta la fecha de carácter poco appearance from the month of June on. The larvae of metódico. Para rectificar esta situación el Centro de Experimenta- this insect tunnel into the stem and give rise to very ción AgrIcola y Forestal ha iniciado un programa de estudios de noticeable nodular hypertrophies.Gaseous insecticides investigación que planea, entre otras cosas, una serie de cruces were introduced into the boreholes in order to combat de álamos nativos del Centro y Sur de Italia con varias formas del Poptdus deltoides, y también la cultivación directa de estos these larvae. The attacks of Melasoma and other defolia- tiltimos. Con este propósito, se recogió en 1958 usia gran canti- tors were on a small scale and caused no appreciable dad de material (semillas, semillones y tallos de plantar) del P. damage. deltoides procedente de diferentes lugares de Vermont, Illinois, At the end of the second year's propagation over Iowa y del delta del Misisipi, que fué lievado a Italia. El presente trabajo resume los resultados obtenidos. 35,000 cutings of Populus deltoides are now available Al final de la primera estación de crecimiento el alto de los from the various provenances, and these wifi be employed semillones de Misisipi eran de 2,80 m., con un máximo de 3,10 in direct culture. The abundance of this material enables m., mientras que el de los semillones de Illinois resultó ser de us to adopt highly selective standards in planting for 2,40 m., con un máximo de 2,95 m. El buen éxito de los tallos de plantar fue un poco mayor entre purposes of comparison with hybrids of P. x eurameri- los provenientes de Illinois, o sea un 86%, que entre los de cana. To complete these researches it will be necessary Misisipi, 0 Un 83%. to extend observations to a greater range of provenances, El promedio de crecimiento en altura de las plantas producidas and in pursuit of this aim an ever closer collaboration de los tallos de Illinois fue de 2,80 m. (con un máximo de 3,95 between American and European research workers will m.), mientras que los de Misisipi registraron solo 2,60 m. (con máximo de 3,50 m.). not fail to open up new prospects for the increase of Tomando en consideraciOn el buen éxito, Ia forma y resistencia poplar planting in both continents. a condiciones adversas, ha sido posible seleccionar 75 tipos entre las plantas producidas de los tallos de Illinois y 15 de los RESUMES provenientes de Misisipi que sobrepasan el proniedio y merecen observarse con atenciOn. Essais de culture du Populus deltoides en Italie De las semillas recogidas en los Estados Unidos, se obtuvieron Les essais en matière de plantations de peupliers en Italic 3.688 semillones que acusaron un indice de crecimiento suma- centrale et méridionale ont jusqu'à present été effectués de facon mente elevado.Al finalizarla primera temporada decreci- assez peu méthodique. Ann de rernédier a cet état de choses, le miento, todas las plantas, con excepción de aquellas del estado de Centre d'Expérimentation agricole et forestiêre a mis en oeuvre Vermont, hablan excedido los tres metros de altura. Un programme de recherche qui prévoit, entre autres projets, une Durante el año en curso Se ha llevado a cabo en este Centro série de croisements entre des peupliers croissant spontanément la propagación del material Populus deltoides y se cuenta en dans le centre et dans le sud de l'Italie et diverses formes de Ia actualidad con 35.000 estacas que se plantarán con fines de Populus deltoides, ainsi que la culture de cette dernière essence. comparación con los clones más difundidos en Italia del P. x A ces fins, de grandes quantités de semences, de jeunes brins et euramericana.

812 Fifth World Forestry Congress Proceedings Some Observations of the Morphology and Classification Of Populus tremula L. in Italy

G. GRAMUGLIO Centro de Sperimentazione Agricola e Forestale, Rome, Italy

The silvicultural researches on Populus tremula L., In Sicily, only the Etna region has been explored, and which this Centre has been carrying out for some years, the only population worthy of note is that at Randazzo, have been accompanied by studies on the morphology which contains the forms with oval and expanded leaves. and classification of this species. We give here, in antici- Reference to the most important monographs on the pation, some observations on material collected in Central genus Populus shows that the various authors have con- and Southern Italy. siderably subdivided P. tremula. The first results of this research are concerned mainly Thus. Aseherson and Gracbner (1908) recognise, apart with a very fluctuating characteristic of Populus tremula, from the var. typica Kochne, also the var. freynii Hervier that is to say, the morphological variability of its leaves. and the var. vilfosa Lang. However, as the var. freynii is This instability has enabled us to compile a classification based on the character of the "shape of the Ianiina," we of the leaf patterns; only one pattern is normally found do not consider it a sufficient basis for recognition, all the on the single tree or, more rarely, different patterns. more soas its distribution is not clearly delimited (Ascher- The classification has been based on the shape of the son andGraebner only give it for Central FranCe, Central brachyblast leaves, without taking into consideration other Europe,and Western and Eastern Asia) and it would be such characteristics as denticulation of the margin, tip, more exact to consider it as the form freyn.ii(Hervier) etc.Only very rarely did we encounter an individual C. K. Schneider. presenting more than one leaf pattern.Lastly, we have This form, together with the var. villosa Lang (which not taken into account the turion leaves, since the shape is recognised by almost all the authorities on account of of these is extremely variable even on the same individual, its quite distinctive characteristics and is held by some due, in our opinion, to the position of the growing shoot to be a geographical race), has been found by us in or even their position on the shoot itself. Calabria.At Ferdinandes we have the form freynü, We have distinguished five patterns of leaf (Fig. 1): and in Piedmont and Abruzzo the var. villosa. rhomboid or subrhomboid, Another taxon Populus australi.c Ten., which is con- oval, sidered by Asherson and Graebner as synonymous with orbicular or suborbicular, P. trernula,is, on the contrary, held to be distinct from expanded, the species by some authors on account of its having the flabelliform. twice or three times as long as the lamina (Tenore, The most commonly distributed of the patterns we have who first classified it as a species, Fiori and Allegri, who distinguished is the orbicular type, which was found in considereditas a veriety, etc.).However, the length 29 of the 69 localities from which samples were taken. of the petiole does not seem to be of notable importance, The oval and expanded types are also fairly frequent, at least judging by the material collected. The study of followed by the rhomboid and flabelliform types(this our samples led us to conclude that P. australtc Ten, does latter being extremely rare), which represent the extremes not exist, since on the same individual the petiole may in variation of the patterns considered. prove either shorter or longer than the lamina. Their distribution proves to be very heterogeneous, in The authors we have consulted attribute to the leaf of the sense that none of the individual forms is localised in Populustremula a shape ranging from the orbicular, any particular area, but is present in numerous localities, which isthe most typical and most common, to the oval; where, moreover, it may be the single representative in but notone of them refers to leaves withrhomboid, an isolated stand or coexist with other patterns in stands expanded or fiabellate form, as shown in Figure1., interspersed over the same locality. which are clearly distinguishable from the others. On In Campania and Lucania, Populus tremula is very the same principle by which some authors have subdivided scantily distributed, the orbicular pattern being prevalent, the species into so many minor taxa, basing these on the while in Calabria, itis concentrated in the two main shape of the leaf or leaf size or the denticulation of the groups of La Sila and Le Serre, where the expanded leaf margin, we, too, could give a systematic value to these type is very common. three leaf types, recognising the individuals bearing them In Aspromonte, Populus tremula is of cultivated origin as forms, that is to say, as groups of individualsbelonging and iscentered mainly on Mt. Basiicô and on the to a biotype which has arisen within a specks andis Aspromonte plateau, where the populations are made up recognisable from related biotypes existing in the same of individuals with expanded leaves. species in virtue of clearly defined characteristics, though Genetics and Tree Improvement 813 Variability of leaf morphology in P. tremula L.:I =rhomboidal leaf, 2=oval, 3=orbicular, 4expanded, 5=flabelliform. not constituting a locally or regionally distinct facies (Du L'auteur fait un exposé des recherches accomplies dans le Rietz). centre et dans le sud de l'Italie sur la morphologie et la classifica- Possible correlations between the morphological char- tion du peuplier tremble (Populus tremula). acteristics of the leaves of these biotypes and such other Ces recherches ont permis de reconnaltre pour cette méme biological details as tree habit, character of the wood essence cinq formes distinctes de feuilles, dont trois doivent être (sound or rotten heart), resistance to disease and pest, etc., considérées comme le caractère distinctif des différentes formes. are being studied. In the present state of affairs it seems Algunas Observaciones sobre la Morfologia y la Classi- that the technological and cultural characteristics are ficación de Populus tremula L. en Italia independent of any morphological structure. El autor de este trabajo rinde informe sobre las observaciones realizadas acerca de la morfologIa y clasificación del Populus RESUMES tremula, (alamo temblón) en Centro y Sur de Italia. Quelques remarques sur Ia morphologie et la classification Se han observado cinco formas de hoja diferentes, de las cuales du Populus tremula L. en Italie tres pueden considerarse como distintamente caracterIsticas.

814 Fifth World Forestry Congress Proceedings Evolving New Forms of Oak by Hybridization

SERGEY SERGEYEVICH PIATNITSKY The Ukrainian Scientific Research institute of Forestry and Agro forest Reclamation; Dean, Forestry Faculty, Kharkov Agricultural Institute, Kharkov, U.S.S.R.

The problem of speeding up the growth of timber-tree About two months after the pollinations the majority species holds an important place in scientific and practical of the types of oak will fertilize.After the ovule is forestry.Its solution is very important to such valuable fertilized the embryo begins to develop. At this time the timber species as the oak, which is noted for its slow acorns start to develop and their tips appear fromthe growth. That is why there is an urgent need to evolve a stem. The developing acorns can be the subjects of an variety of oak that will grow faster than the existing attack by acorn weevils (Curculio glandium and Carpo- species. capsa splendana). To protect the acorns from suchharm, From the times of Kölreuter and Kletsch, hybridiza- the branches of the tree must be enclosed in gauze. tion has been considered as a reliable way of achieving Only by timely pollination of the female stigma of the heterosis in trees. In the last ten years, in many countries, blossom with viable pollen and protectingitsovary numerous efforts have been started in that direction with from harmful insects it is possible to obtain a sufficient a number of species and types of timber trees. amount of hybridized acorns. We started hybridization work between various types In our work, we made about 200,000 hybridizations in of oak in 1937 in the Ukrainian Scientific Research In- this manner in 47 different combinations. Not all the stitute of Forestry and Agroforest Reclamation and at results were good, but in some cases a very high per- the Kharkov Agricultural Institute. centage of acorns set and ripened, 50 to 60 percent of Original forms used in hybridization were: Quercus the pollinated flowers. During natural "inbreeding" pol- suber L., Quercus macranthera F. et M., Quercus robur lination, usually only 1 to 5 percent of the number of L.,Quercus petraea Liebl., Quercus fastigiata Lam., female flowers get set. Quercus macrocarpa Michx., Quercus alba L., Quercus Especially good results were observed when the female montana Willd., and Quercus borealis maxima (Marsh.) stigmas of the following types were pollinated: Quercus Ashe. suber L., Q. macranthera F. et M., and Q. robur L. The ordinary method of cross-pollination was used, The Quercus borealis maxima (Marsh.)Ashe was namely, pollinating the previously isolated (by oilpaper) It is quite female blossoms with pollen of a different type. Numerous almost completely negative to foreign pollen. experiments in the twenty years of work have shown that possible that this is connected with the peculiarities of good results can be achieved by cross-pollination, if the flowering and fruiting of this type. As is known, its acorns following main rules are observed: the female flowers develop for two seasons, and fertilization occurs 11 to 13 must be pollinated at a time when the stigma is most months after pollination. receptive to the pollen. At this time most of the pollen As a result of experiments, altogether over 15,000 grains that have gotten on the stigma germinate and form hybridized acorns were obtained from 27 combinations of pollen tubes which descend into the seed bud (egg cham- cross-pollination, and a significant number of hybridized ber). This moment arrives for the majority of the flowers plants have been grown from them. At present, the fol- on the given tree approximately 3 to 5 days from the lowing hybrids have been preserved and are being raised: beginning of pollination by the male flowers. Q uercus robur x alba, Q. robur X macranthera, Q.robur The pollen to be used for hybridization must be fresh x macrocarpa, Q. robur X montana, Q. robur Xfastigi- and viable.It is best to take it just before the artificial ata, Q. robur X suber, Q. robur X borealis maxima, Q. pollination.Sometimes it happens that the flowering of macrocarpa X robur, Q. macrocarpa X macranthera, Q. the plants being hybridized does not coincide, or the macrocarpa )< borealis maxima, Q. macranthera Xrobur, pollen has to be delivered from some other geographical Q. macrant hera X macrocarpa, Q. macranthera Xalba, location. In such cases, it must be preserved in an en- Q. macranthera X borealis maxima, Q.macranthera X vironment in which it will not lose its viability. The oak suber, Q. montana X robur, Q. fastigiata X macrantlwra, pollen is best preserved at a temperature of around 0°C. Q. fastigiata )( borealis maxima, Q. suber Xrobur, Q. and at a relative humidity of about 60%. Prior to pollina- suber X macranthera, Q. suber x macrocarpa, Q. suber tion it is necessary to check the viability of the pollen by X montana, Q. suber X alba, and Q. suber Xborealis germinating it in vitro. Good results can be achieved by maxima. pollen which gives not less than 50% of pollen tubes. The majority of the hybrids obtained and grown are The pollinated female blossoms must remain enclosed characterized by features which have an intermediate in oilpaper until the flowering of the given tree is com- character between the features of the parent original pletely over, after which the oilpaper is removed. types.Sometimes the features of the parent types are

Genetics and Tree Improvement 815 somewhat mixed in the hybrid. In some cases the hybrids tion, Q. macranthera F. et M. () X Q. robur L. (ci'), have newly formed features. in the majority of cases have a mixed character. The experimentally obtained hybrids of oaks very Hybrids from the reciprocal cross-pollination between oftenhavegreatleaningsindevelopmentfeatures, Quercus macranthera F. et M. and Q. macrocarpa Michx. predominantly of the mother type. This inclination can- differ in exactly the same way. The hybrids of these not be observed in spontaneous hybrids, because the combinations of cross-pollination predominantly show features of any besides the mother's form are usually features of the type which is used as the pollen, in both added to the clear type.It has been noticed in experi- direct and reverse cross-pollination. mental hybrids, whose organization is well known, that The hybrid plants that we obtained from our experi- very often there is an inclination in the development ments began to flower and bear fruit from the age of 6 to towards the side of one of the original types. 8. At present, we receive a large number of acorns every In our work such cases were often noticed, especially year from the old hybrids which we obtained in 1937- if one of the parent forms was a type that was very well 1940. From them we grow the second generation of adapted to the local conditions in which the hybrid was hybrids. grown. For instance, the hybrids between a lOcal type of The second generation of hybrids is morphologically oak, Quercus robur L. (mother), and others, originating very varied.First of all, there is difference between the in other districts,in their development almost wholly plants grown from the seeds from the same mother tree, incline towards the mother type. This type of oak, as the depending on the method of pollination. In compulsory best adapted to local environments, very strongly passes pollination of the same hybrid form or with its own on its features to the hybrids, even if it is used in the pollen, the plant obtained preserves the general features cross-pollination as the pollen. of the parent forms, although it does vary in some features. During cross-pollination of types originating from other From free, uncontrolled pollination, some hybrid forms districts,hybrids are formed which have, to a lesser give various results. For instance, the descendants of the extent, the clear features of the originating forms.In such cases the hybrids develop intermediate features and hybrid Quercus macrant hera X robur have strong signs are something like the parent types, and at the same time, of developing features of Q. robur L. This fact can be different from them.In this regard, interesting are the explained either by the natural-law-governed splitting in results obtained from cross-pollination between Quercus the second hybrid generation or by the possible polli- macranthera F. et M. (a type indigenous to the high nation of the flowers of the hybrid by the pollen of Q. mountain areas of the Caucasus and Asia Minor) and such robur L. In the latter case we are dealing with a double a type as the American Q. alba L., Q. macrocarpa Michx., hybrid type (Q. macranthera X robur) X Q. robur, Q. borealis maxima (Marsh.) Ashe, and the Mediter- where the influence of the latter type must be especially ranean Q. suber L. strong. Inclinations to develop features of Quercus robur L. are Among the plants of the first hybrid generation (F1) also ascertained in the hybrid Q. macranthera X alba. belonging to the same combination of cross-pollination, a In this case the observed phenomena cannot be called great morphological dissimilarity is often seen. It includes natural splitting, because Q. robur L. did not participate not only the known variability of the number of features, in the formation of the given hybrid form. In such a case but also such differences between some of the plants that dehybridization undoubtedly appears, and Q. robur L., create quite new special features. as the species most adapted to the local conditions, domi- The features of the hybrid oaks change greatly with nates in these double hybrids. the years.In this regard, the materials we have fully In the descendants of the hybrid Quercus macranthera confirm the instructions of E. V. Michurin which say that x macrocarpa other natural signs are observed. A signifi- the biology and morphology of hybrid plants change so cant number of the plants resulting from free, uncon- greatly in various stages of their lives, that sometimes it trolled pollination preserve the features and character of is hard to believe that before you are the same seedlings development of that hybrid form of the first generation. of last year. The heterosis inherent to the hybrid form is also pre- These changes are especially notable on features having served. In the other plants of that generation, a certain a broad variability, for instance, on such a feature as the nearness is noticed to the features of the original types form of the leaf. Two types of changes in the signs of (Q. macranthera F. et M. and Q. macrocarpa Michx.), time can be established: the first is connected with the but not one plant has an inclination to develop the age changes, which the hybrid seedling goes through in its features of the local type, Q. robur L. development; the second is connected with the change in To many of the spontaneous and experimental hybrids environment, mainly the change in meteorological con- of the oak, heterosis is inherent. Back in the 18th cen- ditions. tury, the powerful development of Quercus heterophylla Direct and reverse cross-pollination of the same types Michx. was noticed. Heterosis was also noted in Q. cerris give different results, and the hybrids from such cross- X suber.Its first example was singled out at a plant pollination are different in their character and greatly nursery from among other seedlings by itspowerful vary from each other. For instance, the hybrid from the growth. Kletsch also reported the heterosis of his hybrids cross-pollination of Quercus robur L. () X Q. macran- in the Quercus growth. When 8 years old they were thera F. et M. () in the majority of features reminds higher by one-third than all the same-aged seedlings of one of Q. robur L. and has only insignificant similarity original types. with the male type. Hybrids from reverse cross-pollina- Heterosis is vividly manifested in many of the hybrids 816 Fifth World Forestry Congress Proceedings which we have obtained in our work. In hybrid oaks the in the second generation. Gigantic leaves ana compietely heterosis is seen in the general power of the shoots, their straight shoots are characteristic of it. thickness, their exclusive straightness, and size and den- The third interesting form of hybrid is Q. macranthera sity of leaves. One-year-old shoots in some hybrids reach X alba. This is the most moisture-demandingform. It is a length of 1 meter and more. Notable is their thickness, interesting from the decorative point of view: in spring large leaves, and big buds. its leaves acquire a dark-red color.The hybrid form In the hybrid Quercus macranthera X Q. macrocarpa, received the name )< Q. komarovii. heterosis is manifested in the size of the fruit. They are Very interesting and promising are the hybrids between bigger than the fruit of the original types, and reach a the leafshedding and evergreen cork oaks.They are weight of 10 to 12 grams. quite winter resistant under Ukrainian conditions, and The character of growth of many hybrids can also be when seven years old many begin to form cork.This regarded as a manifestation of heterosis.It greatly varies gives reason to consider that by hybridization of the cork from the character of the growth of non-hybrid oaks. The oak with other types it will be possible to significantly latter are characterized by so-called "bushing out," when move the cultivation of the cork oak tothe north, beyond for several years the plant does not grow upwards but the subtropical region. "bushes out." Many of the hybrids, from the very first The method of different-type hybridization of the oak years, start to grow energetically upwards, forming a shoot turned out to be very active. With the aid of hybridization from the top bud and producing 2 to 3 following sprouts we can obtain valuable new formsof oak. in the same vegetation period. RESUMES The so-called "newly formed" features which we men- tioned above would also be considered as a manifestation Le développement de nouvelles formes de chêne par of heterosis of the hybrid oaks. The heterosis of intertype hybridation hybrids of the oak are manifested in the great intensity Ce rapport resume les résultats des travaux exécutés a l'Institut of all life processes, which significantly surpass the inten- ukrainien derecherchesforestièresetd'aménagement agro- forestier et a l'Institut agricole de Kharkov. Les formes originales sity of these processes in non-hybrid plants. This mainly utilisëes pour l'hybridation Ctaient: Quercus suber L., Q. macran- concerns the photosynthesis capabilities of the hybrids. thera F. et M., Q. robur L., Q. petraea Liebl., Q. fastigiata The intensity of photosynthesis of the hybrids Quercus Lam., Q. macrocarpa Michx., Q. alba L., Q. montana Wilid., et macrant hera X robur and Q. macranthera X macrocarpa Q. borealis maxima (Marsh.) Ashe. A peu prés 200.000 hybridations ont été effectuées en 47dif- is more than double the intensity of photosynthesis in the férentes combinaisons. Dans certains cas, entre 50 et 60 pour original types. cent des fleurs pollinisées ont produit des glands mbris.Des Under good water-supply conditions the hybrids mani- résultats particulièrement encourageants ont été observes lorsque lesstigmates femelles des typessuivantsont étépollinisés: fest a great transpiration ability. The intensified expendi- Quercus suber L., Q. macranthera F. et M., et Q. robur L. ture of water for transpiration is ensured by the intense Plus de 15.000 glands hybrides ont éte recueillis ainsi de 27 activity of the root system, due to which the plant has no combinaisons de pollinisation croisde.Des résultats d'un intérêt trouble in acquiring moisture.In times of aridity, the tout particulier ont été obtenus par le croisement entre Quercus hybrids Quercus macran thera X robur sharply reduce the macranthera () et Q. robur () qui ont ëté dénommds xQ. vyssotzkyi; entre Q. macranthera () et Q. macrocarpa (.) transpirational expenditure of moisture, thanks to which qui ont été dénommés xQ. timiryasevii; et entre Q. macranthera they avoid the harmful effects of drought:plants of () et Q. alba () qui été dénommés xQ. komarovii. original types of Q. robur L. continue their strong trans- Des hybrides ont été aussi obtenus en croisant des chênesa piration at such a time, and the leaves lose firmness and feuilles caduques avec des chênes-lièges a feuilles persistantes. us sont assezrésistants a l'hiver en Ukraine et commencent a droop. former du liege a l'âge de sept ails. Among the hybrid forms obtained by us, some are of La plupart des plants hybrides ont commence a porter des great practical interest because of their peculiarities and fruits a l'âge de six ou sept ans. A partir de ces plants, nous produisons la seconde génération d'hybrides.Dans la plupart properties.First among them are Quercus macranthera des hybrides on peut observer de l'hétérose et autres caractéristi- X robur, which was called the oak of Vyssotzky. This ques nouvelles. Les hybrides sont aussiremarquables par une très hybrid form is notable for its good growth and great forte intensité de tous les processus physiologiques, particulière- drought-resistance. By its physiological properties it is ment en ce qui concerne leur capacité de photosynthèse. veryadaptable:itsintensivetranspiration, whichis Ainsi, avec l'aide de l'hybridation, il est possible d'obtenir de inherent to it with good water supply, changes over to nouvelles formes intéressantes de chêne d'une utilité pratique. very economic expenditures of moisture in periods of Desarrollo de Nuevas Formas de Roble Mediante la intense drought.It is also characterized by great photo- Hibridación synthetic capabilities. By its properties the hybrid oak X En este informe se da un sumario de los resultados del trabajo Q. vyssotzkyi answers to the demands of growth in the ilevado a cabo en el Instituto de Investigación Ucraniano de arid steppes. This will be a new type in steppe-forestry Silvicultura y Reclamación Agro-Forestal y en el Instituto de breeding, one which must take the place of the slow- Agricultura de Kharkov. Las especies usadas originalmente en growing local oak in protecting fields. la hibridación fueron: Quercus macranthera F. et M., Q. robur L., Q. petraea Liebl., Q. fastigiata Lam., Q. macrocarpa Michx., Also of great interest is the hybrid form derived from Q. alba L., Q. montana Willd., Q. borealis maxima(Marsh.) the cross-pollination of the Caucasian high-mountain and Ashe. xerophil oak, Quercus macranthera F. et M., with the Se han hecho unas 200.000 hibridaciones en 47 combinaciones large-fruit Q. macrocarpa Michx., a tree pioneer of the diferentes. En algunos casos de 50 a 60 por ciento de las fibres fecundades dieron bellotas que se formaron y maduraron.Se American plains.It received the name of X Q. timir- observaronbuenosresultadosespecialmentecuandofueron yasevii. This form isalso notable for great drought- polenizadoslosestigmas femeninos delossiguientestipos: resistance, a gigantic growth, big fruit, and stable features Quercus suber L., Q. macranthera F. et M., y Q. robur L.

Genetics and Tree Improvement 817 De 27 combinaciones de polenizaci6n cruzadase obtuvieron La mayorIa de las plantas hibridas comenzaron a fructificar a más de15.000 bellotas hIbridas.Son de especial interés los resultados la edad de 6 6 7 ahos. De ellos se sacó Ia segunda generación obtenidosdepolinizacióncruzadaentreQuercus de hIbridos. loshIbridos se observaron macranthera () y Q. robur () que fué ilamada xQ. vyssotzkyi, En Ia mayorIa de entre Q. macranthera () y Q. macrocarpa (s), que fué heterosis y nuevas indicaciones caracterIsticas.Los hIbridos se ilamada xQ. timiryasevii, y entre Q. macranthera ()y Q. caracterizan por511alta intensidad en todos los procesos fisio- alba (s), a la que se le llamó xQ. komarovii. lógicos.Esto,especialmente,conrespectoasucapacidad Se obtuvieron hIbridos también entre alcornoques que cambian fotosint&ica. las hojas y siempre verdes, que pueden resistir el invierno de Con la ayuda de la hibridación se pueden obtener nuevas tjcrania, y que a los siete años comienzan a dar corcho. formas de roble de valor práctico.

The Analysis ofa Diallel Cross in Larch

J. D. MATTHEWS, A. F. MITCHELL, AND R. HOWELL Forestry Commission of Great Britain, London, England

Introduction cross. In anticipation of a much reduced yield of viable In Britain, selection and breeding of the larcheswas seed from inbreeding, fifty female flowers were isolated begun in 1950.Good phenotypes (plus trees) were for each self-poUination but this proved inadequate. Four selected, and during the years 1951 to 1953 a seed hundred and eighty-two female flowers were isolated for orchard for the production of seed of first generation eleven self -pollinations, but the 13,870 seeds obtained hybrid larch (Larix X eurolepis Henry) was established yielded only 249 seedlingsa mean germination of less at Newton Nursery, Morayshire, Scotland. This orchard than two per cent. contains clones of grafted plants derived from three Figures for the number of female flowers pollinated, European and twelve Japanese larches and has been seeds extracted and numbers of one-year-old seedlings described by Mitchell (1959), who also outlined the self- are summarised in Table 2. and cross-pollinations carried out in 1956. The yield of one-year seedlings from pollinated female The Newton seed orchard was planted to produce seed flowers was generally low, the mean for the whole series of an improved cultivar of larch, but the parents are of pollinations being three seedlings per flower (3.4 per merely good phenotypes and, to prove the genotypes, con flower if the selfs are excluded). The highest yields were trolled crosses between the parents and subsequent pro from clones J8 (9.5) and J2 (6.5) and the lowest from geny tests are required. The crossing and testing work clones J20 (0.3), E120 and E141 (both 0.8). must be arranged to permit, first, the identification of The nursery germination of the seed and survival of those parents which combine well with others to produce the seedlings also varied greatly with clones and individ- good progenies(i.e.,possess good general combining ual crosses. The mean yield of one-year seedlings from ability); second, a measure of the genetic gain achieved the seed sown for the whole series of crosses was 12.5 by the selection and cross breeding; third, the further per cent (15 per cent if the selfs are excluded), and improvement of the cultivar produced by the seed orchard. clones J3, J8 and J10 stand out as giving relatively high The object of this paper is to show what has been done nursery germinations and yields; by contrast, clones J20, to satisfy these three requirements. J52 and E141 gave nursery figures of less than ten per cent.Only four crosses yielded seed giving more than The Crossing Programme fifty per cent survival of one-year seedlings. These were J2 X J8, J2 X J40, J8 X E141 and J1O X E141. Table 1 shows the combinations which are possible The variation in these figures and the poor yields of in the Newton seed orchard and the crosses attempted in plants from many crosses is due to many factors of 1956. The clones are tabulated horizontally as female which pollen viability, time of pollination, genetic incom- parents and vertically as male parents. The top left to patibility and ease or otherwise of seed extraction are bottom right diagonal representsself -pollinations, and reciprocal crosses are symmetrically placed each side of the most obvious.Some indication of pollen viability this diagonal. Each cell represents one cross- or self- can be obtained by examining the data for the clones pollination and contains the sowing numbers used to when used as male parents. Clones J2, J8, J10 and J40 identify the various progenies. gave relatively good results when used as fathers, while A minimum of thirty female flowers was isolated for clones J41, J42, J52, E6 and E120 gave relatively poor each cross. results.The pollen of the three European larches was In clone E6' there were sufficient female collected from the parent trees because of a shortage of flowers to permit the isolation of at least fifty for each pollen on the corresponding European larch grafts at Newton. The transport, extraction and storage techniques For brevity, the convention used throughout this paper is: in use in 1956 evidently harmed the pollen and have since E European larch (Larix decidua Mill.) been much improved. J = Japanese larch (Larix leptolepis (Sieb. & Zucc.) Rehd.). Table 2 shows that, in general, the J X J and J X E 818 Fifth World Forestry Congress Proceedings Table 1.The complete crossing pattern and the crosses attempted in1956. Male parents Female E J J J J J J J J J J J J E E parents 52 6 120 141 2 3 8 10 12 20 21 40 41 42 50 2 3 J2 187 4 5 6 - 7 8 9 1 10 11 12 J3 13 188 14 15 16 17 - 18 20 21 J8 22 189 23 24 19 - - 25 26 27 J1O 28 29 30 190 31 - 33 34 J12 35 36 37 38 191 39 40 32 J20 41 -- J21 44 J40 45 46 47 48 49 192 - 42 43 51 52 J41 - 53 54 55 193 50 J42 56 -- 58 59 J50 60 61 62 63 194 57 - 64 J52 - - 75 76 E6 65 66 67 68 69 70 71 72 73 74 195 196 77 E120 78 79 80 81 82 - 83 --- 93 197 E141 85 86 87 88 89 90 91 92 - Notes: (1) J = Japanese larch; E = European larch; - = cross not attempted. (2) The numbers within the cells are sowing numbers used to identify the variousprogenies.

Table 2.Summary of flowers pollinated, seed extracted and seedlings raised. Yield of Yield of Combinations Flowers Seeds Seedlings seedlingsseedlings as a Parentage Possible Attempted pollinated extracted raised per percentage of flower seeds sown J xJ 132 37 664 18,648 4,114 6.2 22.1 ExJ 36 24 876 6,945 916 1.1 13.2 J XE 36 27 1,121 35,544 4,227 3.8 11.9 3.4 EXE 6 4 127 1,179 39 0.3 1.8 Self s. 15 11 482 13,870 249 0.5 Totals 225 103 3,270 76,186 9,545 crosses were superior in both yield of seed and yield of were spaced four inches (10 centimetres) apart.Germi- plants per pollinated female flower to the E x E and nation was rapid and seedling growth exceeded expecta- E x Jcrosses.This may partly be attributed to the tions. The height of the fastest progenies as one-year-old mechanical difficulty of extracting the seeds from the seedlings was 15 inches (38 centimetres); many prog- European larch cones, which were collected rather early. enies produced seedlings nine inches (23 centimetres) These data give valuable indications for future work. tall. In particular, it is now clear that for every 100 plants Two points emerged at this seed-bed stage.First, the required of a given combination of parents at least 50, interspecies combinations E X J and J X E were gener- and more usually 100, female flowers must be isolated ally superior in height growth to J X J and E x E, and and pollinated. Even then failures will occur, and it will all were superior to the inbred progenies. Second,there was an obvious need for a betterexperimental technique almost certainly be necessary to extend the crossing pro- adjacent gramme in a young seed orchard over a period of at least to reduce the variation in competition between three years, during which time the seed of successful plots, which contained different numbers of seedlings. crosses is stored and unsuccessful or poorly represented The one-year-old seedlings were lined out block by block in November 1958 at a spacing of 1 foot x 6 inches crosses are repeated. (30 x 15 centimetres). A randomised block layout was Raising the Progenies and Establishing Field Trials again employed, but the progenies were re-randomised within the blocks. Losses were few, and in 1958 sites were Ripened cones were collected and the seed extracted in selected for the forest trials. September and October 1956; the seed being sown on a In March and April 1959 representatives ofall prog- nursery at the Alice Holt Research Station, Surrey, Eng- enies were planted on one good site in the Forest of land, in late April 1957. A randomised block layout was Dean, Gloucestershire, England.In addition, a total of employed with five replications or fewer, depending on thirty progenies were planted out in four forest trials, one the seed available.Each plot consisted of 100 seeds each in England, Wales, Scotland and NorthernIreland, in sown in a drill 3 feet 6 inches (1.1 metres) long; drills thirty-six plant plots arranged in either triple lattice or

Genetics and Tree Improvement 819 randomised block layouts.The trials in the Forest of empty cells in the two-way table (Table 1) were balanced Dean require further brief description. by the restriction of the number of parents between which Essentially, the progenies are arranged to satisfy the measures of variance and heritability could be obtained. requirements firstly of progeny trials and secondly of Table 1 was divided into four parts, corresponding to the seed orchards.For example, twenty plants of each of species of the parent trees. The J x J section was reduced thirty interspecies hybrid progenies and thirty Japanese to a 7 X 7 table by excluding data from clones J20, J2 1, larch progenies have been planted ina randomised block J4 1, J42 and J52. Selfs were also excluded because of the design consisting of twenty replicates of single tree plots inadequate numbers of plants available.(Also, had they (Wright and Freeland, 1959). The spacing is 15 feet by been included a complication of the mathematical model 7½ feet (4.6 x 2.3 metres), and provision is made fora would have been necessary.) The J x J section, therefore, thinning to remove half the trees, leaving unaltered the took the shape of a modified diallel cross (Griffing, 1956) composition of the trial. The individual treescan be free with ten of the forty-two cells vacant. The E X E section grown for ten to fifteen years, during which time assess- had to be rejected entirely, as being quite useless for the ments of vigour, growth habit, resistance to disease and purpose of the analysis.The two interspecies hybrid insect attack, and wood characteristics can be made. sections (E x J and J X E) were each reduced by the Selection will then become possible, andsome progenies exclusion of data derived from J20, J21 and J52. will be removed on the basis of their performance in the Although the transplants had been set out in random- Forest of Dean and on the other sites.Finally, the trials ised blocks of varying size, a preliminary study of the will contain a number of phenotypically selected seed data suggested that the blocking was not very effective. trees which, because of their free growth, begin to flower The analysis was therefore simplified by ignoring the when quite young, and so form seed orchards producing blocks. For a few progenies comparatively large numbers first or second generation hybrid larch, or the backcrosses of plants were available, and in such cases the data from H X E and H X J, according to their composition. whole plots were excluded at random to reduce the labour of calculation, and Table 3 summarises the number of An Estimate of Combining Ability and plots from which data were used. (Appendix I gives the Heritability of Height and numbers of plants by plots.) Diameter Growth in Larch Transplants It is possible, by using the assessments madeon the The Mathematical Model progenies at the end of the second growing season, to get The equation for the individual observations in the some indication of the general combining abilities of the mathematical model used was: parent clones in respect of height and diameter growth, and of the heritabilities of these two characteristics in the = /h + m, + f + P!3k + e1k1, nursery stages of growth.The concept of combining whereis the measure common to all transplants, ability has already been referred to; that of heritability m1 is the relative general combining ability of the ith needs brief explanation. parent tree as a mother (m, = Heritability is defined as that portion of the observed variance which is due to hereditary factors andmay be fis the relative general combining ability of the jth interpreted in a narrow or broad sense. Narrowsense parent tree as a father (f = heritability refers only to that part of the total variance due to additive genetic factors, while broad sense heritabil- P)k is the contribution of the kth plot in the cross ity refers to all genetic factors, i.e., additive effects, domi- (m, x f) (.P!k = o), and nance and epistasis2. The estimation of heritability enables the breeder to determine the intensity of selection which eIk1 is the contribution of the lth transplant in the must be practised to obtain cultivars with the desired kth plot of the cross (m, xf). characteristics and also to estimate the probable genetic gain for each generation of selection.Estimates have The corresponding variances are o, u, u and o, re- been made for forest trees by Toda (1958), Toda et al. spectively. (1959) and Bingham et al. (1959). Heritability can be Two features of this model should be noted. First, it is determined in three principal ways (Hayes et al., 1955). additive as the occurrence of vacant cells precluded the The method used here is that of estimating the com- use of a simple model with a term for specific combining ponents of variance from an analysis of variance. ability. Second, it is assumed that the parameters are not correlated with each other.This feature of the model The Preliminary Handling of the Assessment Data makes it strictly inapplicable to the J x J crosses because Only data for the two-year-old transplants have been in these crosses the pairs of parameters m1, f, are cer- analysed, and the analysis presented here is regarded as tainly correlated. The effect of this error in the model on a preliminary one. It is based on a selection from the total the estimates of variance is difficult to judge, but as the data. The data from the most poorly represented parent estimates for the J X J crosses agree reasonably well with trees were discarded.The process of discarding data those for the interspecific crosses E X J and J X E (see was continued untilit Table 7), the bias may not be serious. appeared that the advantages For simplicity, the analysis of variance was carried out gained by reducing the proportion of empty or nearly in two stages.The mean square within plots was first 'Epistasis: Dominance of one factor over another, the two not calculated to estimate o. Then ignoring the differences in being at the same locus. the number of plants per plot, the variation between plot 820 Fifth World Forestry Congress Proceedings Table 3.Numbers of replications of the progenies included in the analysis. (Compare with Table 1). Male parents Female J J J J J J J J J E E E parents 141 2 3 8 10 12 40 41 42 50 6 120 J2 o 4 3 3 0 3 0 0 4 4 4 3 J3 2 0 3 .3 3 3 0 0 1 4 3 3 J8 3 0 0 3 0 3 0 0 0 4 3 3 3 3 J10 3 1 3 0 0 3 0 0 0 2 J12 4 3 3 3 0 2 0 0 1 1 4 4 J40 0 2 3 3 1 0 0 0 0 1 4 4 3 J4 1 0 0 0 0 0 0 0 0 0 4 4 J42 0 0 0 0 0 0 0 0 0 4 0 0 J50 3 0 3 0 3 4 0 0 0 4 4 4 0 E6 1 2 3 4 4 3 2 1 3 0 0 0 El 20 2 1 2 1 1 0 0 4 0 0 0 0 E141 2 3 3 4 1 1 0 4 0 0 0 means was analysed as a two-way classification with the The Estimates of General Combining Ability numbers of observations per cell equal to the number of Tables 4 and 5 give the unweighted means of the plot plots of each progeny, by fitting constants (Kempthorne, heights and diameters for each progeny, and Table 6 gives 1952). For the interspecific crosses the following mean the estimated general combining abilities of the parents squares from which the means expected on the additive model can be calculated. No significant evidence was found of spe-. cific (as against general) combining abilities, so Table 6 can be taken as an adequate summaryof progeny means Between E ignoring J, to estimate - + o+ k2 oY + k02 for the interspecific crosses at least. k0 The Estimates of Heritability Table 7 gives the estimates of the variance components Between J adjusted for E, to estimate - +ap2 +kioj' derived from the mean squares and also the estimated k0 heritability defined as 2(z 2 Individual plot deviations from the additive Um + Ut Oe 2 2 2 genetic model, to estimate +rp2 Oin'2 + iff + U + Ue k0 Plainly the male parent plays little part,if any, in determining the size of its progeny at two years of age. Where k0 k1 k2 k3 are constants calculated from the Discussion of the Results number ofplants.shown in Appendix I and from the num- bers of parents. This discussion is confined to two points. These are the

Table 4. Mean Heights (centimetres) of the progenies as 1 + 1 transplants. Male parents Female E J J J J J J J J J E E parents 6 120 141 2 3 8 10 12 40 41 42 50 61 J2 42 48 57 45 - 50 57 63 - 45 60 J3 41 46 45 55 42 - 52 70 61 69 J8 54 57 46 --- 64 48 46 JIM 54 54 54 45 - 64 - 73 73 J 12 58 60 68 67 52 - 68 87 70 J40 54 49 54 64 --- 86 57 67 75 J4 I ---- 71 J42 - -- 69 -- 63 66 81 J50 55 61 55 54 --- E6 62 68 68 64 62 75 62 85 82 - E120 56 56 60 44 72 -- 59 --- E141 74 52 68 82 72 57 - 80 - --

Genetics and Tree Improvement 821 Table 5. Mean root collar diameters (millimetres) of the progeniesas 1 + 1 transplants. Male parents Female parents J J J J J J J E E E 2 3 8 10 12 40 41 42 50 6 120 141 J2 - 7.5 7.4 8.6 7.8 8.4 9.3 9.9 9.7 J3 - -- 7.1 - 7.6 7.5 8.1 7.4 - 9.7 10.3 8.4 8.9 J8 8.1 - 7.8 - 7.5 - 8.6 9.5 9.3 J10 8.6 - 7.7 7.7 -- 7.9 -- 10.0 8.6 7.8 J12 8.7 - 8.7 8.9 9.1 8.3 -- 9.9 11.9 10.7 10.0 J40 - - 9.0 7.5 9.0 10.0 --- 12.0 10.6 10.4 J41 - - 97 10.3 9.9 J42 - - 9.4 J50 8.6 - -- 8.0 8.6 8.1 - 9.7 10.6 11.8 E6 9.4 11.0 9.4 9.0 8.7 10.0 9.4 10.3 11.2 E120 10.6 10.4 8.6 8.0 10.9 - 9.9 E141 11.8 8.2 10.1 11.6 10.7 9.3 10.9

Table 6.General combining abilities for the chosen parents (heights and diameters of 1+ 1 transplants). Height (cm.) Diameter (mm.) Parent JxJ EXJandJXE ExJandJxE EXJandJxE As As As As As As As As father mother father mother father mother father mother J2 51 48 65 60 8.3 8.0 10.8 9.6 J3 50 46 55 59 8.0 7.7 9.3 9.3 J8 54 54 65 64 7.8 7.9 9.4 9.1 J10 57 54 67 52 8.5 8.4 9.9 8.6 J12 58 63 64 75 8.7 9.0 9.5 10.5 J40 47 52 67 67 7.9 8.8 9.9 10.7 J41 - 59 71 9.6 10.0 J42 - - - - 72 67 10.3 9.3 J50 - - 57 57 79 70 9.1 8.5 11.5 10.7 Adjusted means 54 66 65 8.3 10.0 9.8 E6 67 69 - 9.8 9.7 E120 60 57 9.8 9.8 E141 - - 67 72 - 9.7 10.6 Adjusted means 65 66 - - 9.8 10.0 J12, J50 and E141 are seen to have good general combining abilities in size of the E x J and J x E progenies compared with the J both intra-specific and interspecific crosses and the greater from Table 6 alone. x J (i.e., Japanese larches) can also be seen from Tables 4 and 5, or

Table 7. Components of variance and heritability.

2 2 2 a Heritability 0p Of %

J x E (heights) 205 210 25 5.9 14 (diameters) 4.44 1.75 0.34 0 10 E x J (heights) 209 288 23 0 8 (diameters) 3.80 2.53 0.033 0 1 J x J (heights) 155 150 24.6 0 14 (diameters) 2.99 0.99 0.163 0.023 0.8

822 Fifth World Forestry Congress Proceedings Wright, J. W. and Freeland, F. D., Jr., 1959. Plot size in forest effectiveness of the original selection of parent trees and genetic research. Papers of the Michigan Academy of Science, the additional work required to complete the estimate of Arts and Letters, 44, (1958 meetings) 177-182. heritability. Data are available to permit assessment of the pheno- RESUMES typic superiority of the selected plus trees in relation, Analyse d'un croisement diallèle de mélèze first, to neighbouring dominants in the same stand; second, Neuf clones de mlèze japonais (J) et trois clones de mélèze to dominant trees on broadly comparable sites; and third, européen (E) ont dté croisés en autant de combinaisons que to other plus trees. Using these three criteria, plus trees possible.Les descendants ont été dvalués en tant que sujets J12, J50 and E141 are the most outstanding in height and transplantés1 + 1.Les capacités de combinaison des clones parents, et les possibilités de transmission des caractéristiques de diameter growth; in the Newton seed orchard, clones J12, croissance en hauteur et en diamètre ont dté estimées par analyse J50 and E141 all show good combining ability for height de la variation. and diameter growth. By contrast, plus trees J2, J3, J8 Pour les cent plants nécessaires a un contrôle de descendance, and JlO are relatively less outstanding, and the corre- il faut isoler et polliniser au moms cinquante, et plus générale- sponding clones at Newton have shown lower general com- ment 100 fleurs femelles. L'auto-fdcondation est gdnéralement réduite, et on peut observer bining ability. This relationship between the performance une forte depression endogamique chez la plupartdes clones of the parents and their progenies provides evidence that parents. the careful and intensive selection of good phenotypes in Trois clones parents ont manifesté un taux élevé de capacité a the forest can yield positive results in respect of two-year- lacombinaison. Lesarbresparentsavaient égalementété, old progenies. On the other hand, the low figures for lorsqu'on les avait choisis dans la forêt, d'excellents phenotypes. heritability of height and diameter growth mean that La supériorité des croisements entre espèces E x J et J x E, par rapport aux combinaisons J x J, est frappante. adequate progeny testing is essential. The diallel cross La possibilité de transmission, dans un sens limité, c'est-à-dire method strongly commends itself but will have to be celle due a une variation génétique supplémentaire, est réduite en modified to suit the requirements of tree breeding. ce qui concerne la croissance en hauteur et endiamètre chez The analysis presented in this paper is a preliminary one les plants de deux ans.Ccci souligne la nécessitd des contrôles and must be regarded as an essential trial of technique. de descendance satisfaisants. No estimate has been made of the effects of dominance Ii semble que le parent male n'influe pratiquement pas sur la and epistasis. In the mathematical model used, dominance taille de ses descendants a l'âge de deux ans. is included in the figure for between-plot variance (of,), A nálisis de un Cruce Intersectado en A lerce and further work may permit an estimate of the size and effect of this component of genetic variance.Similarly, Nueve clones de alerce japonés (J) y tres de alerce europeo (E)secruzaron en todaslas combinaciones posibles.Los we shall later proceed to an estimate of the genetic gain descendientes se han designado como trasplantes1 + 1.La obtained by selection and crossbreeding in larch. capacidad de hibridación de los clones patronos y de trasmitir desarrollo en altura y diámetro se ha calculado por medio de análisis de variantes. References Por cada cien plantas que se requieren para pruebas de pro- Bingham, R. T.,Squillace, A. E. and Wright,J. W., 1959. genie, se deben aislar y polinizar por lo menos 50 fibres hembra Heritability of resistance in progenies from blister-rust resistant y más comünmente 100. Pin us monticola selections. Paper read in the symposium "Prob- La autofertilizacidn fue generalmente baja y hayindicios de lems of Forest Tree Breeding," at Ninth International Botanical una gran debilidad de producción en IamayorIa de los clones Congress, Montreal. originales. Griffing, B., 1956. A generalized treatment of the use of diallel Tres clones patronos mostraron gran capacidad generalde crosses in quantitative inheritance. Heredity FO, 1, 31-50. combinación.Los árbolesde dondesesacaronlosclones, Hayes, H. K., Immer, F. R. and Smith, D. C., 1955. Methods of escogidos en el bosque, han sido tambidn fenotipos excelentes. plant breeding, 2nd edition. McGraw-Hill Publishing Company, Fué admirable la superioridad de los cruces entre distintas Ltd. London. especies en las combinaciones E y J y J y E sobre los realizados Kempthorne,0.,1952.Design and analysis of experiments. entre la misma especie J y J. Wiley. La herencia en el sentido limitado (en la que parte dela Mitchell, A. F., 1959.Establishment of a seed orchard for the variante obedece a factores genéticos agregados) fue débil en lo production of hybrid larch seed. Report on Forest Research que respecta a desarrollo en altura y diámetrode transplantes de for the Year ended March 1958, 138-147. London, H.M.S.O. la Toda, R., 1958.Variation and heritability of some quantitative dos años. Esto recalca la necesidad de pruebas adecuadas de characters in cryptomeria. Silvae Genetica 7, 3, 87-93. progenie. Nakamura, K. and Satoo, T., 1959. The heritability Parece que la cepa macho generadora influye muy poco, o nada, of tree height and stem girth in cryptomeria through sexual en la determinación del tamaño de suprogenie a los dos años reproduction. Silvae genetica, 8, 2, 37-68. de edad.

Genetics and Tree improvement 823 Appendix I. Numbers of 1 + 1 transplants by plots and parentage

Female Male parents parents J2 J3 J8 J10 J12 J40 J41 J42 J50 E6 E120 E141 J2 12 61 30 44 20 10 20 39 16 53 30 20 26 21 12 33 28 46 46 27 13 13 12 24 6 22 16 22 J3 36 27 42 20 35 10 3 25 23 30 55 29 29 35 5 27 41 25 11 6 39 10 16 17 7 J8 37 37 47 15 26 52 49 26 34 20 21 69 29 53 55 16 19 61 14

J10 28 9 32 33 15 35 43 22 33 24 10 26 25 9 10 10 14 28 J12 23 10 24 20 15 10 14 5 9 25 21 20 24 22 7 9 16 7 19 13 4 14 11 5 10

J40 17 42 16 3 9 9 14 15 59 5 11 11 65 5 10 8 3 9 J41 17 4 31 11 20 19 21 29 25 16 13 J42 18 15 14 15 J50 31 77 32 33 6 31 6 21 46 32 16 4 11 13 21 44 27 22 8 33 8 16 4 20 12 E6 20 25 11 14 10 10 11 7 22 18 12 14 24 26 12 25 10 6 26 26 14 13 13 E120 14 5 27 20 17 9 4 10 10 9 6 E141 3 5 24 4 S 16 9 6 8 18 4 S 6 7 4 7 3 5

824 Fifth World Forestry Congress Proceedings Recherches sur les hybridations sexuées aux espèces du genre Quercus,Fraxinus et Pinus, effectuées dans la R. P. R.

VASILE BENEA Roumanie

Par les travaux sur le croisement sexué on a cherché a borealis) ou plus souvent 100 cm. (cx. Q. robur x Q. obtenir l'acroissement de l'amplitude écologique, l'accé- stellata, Q. pedunculiflora x Q. robur etc.). lération de la croissance et l'augmentation de la résistance Des dimensions maxima en hauteur et en diamètre ont contre les ennemis biotiques et abiotiques, l'amélioration été constatées chez les descendants issus de croisements des qualités technologiques de la masse ligneuse. Q. cerris x Q. borealis, Q. pedunculiflora x Q. stellata La base expérimentale pour les travaux d'hybridation (hauteur 4-5 m., grosseur au collet 5-11 cm. a l'âge de 7 sexuée est la station I.C.F.-Snagov, de l'Institut de recher- ans). ches forestières, située a une altitude de 90-100 m. dans De multiples greffes ont été effectuées en vue de la la province climatique Dfax. La station dispose d'un réalisationd'unecollectiond'espècesnécessairesaux Arboretum riche en espèces indigènes et exotiques, et travaux de pollinisation artificielle et des fructifications d'une superficie d'environ 5 ha destinée au travaux d'hy- précoces, en utilisant comme porte-greffe et greffe, des bridation sexuée. espèces d'âges différents et ayant atteint différents stades Dans les dix demières années on a effectué un grand de développement. Au cours de la Verne année après Ia nombre de croisements sexués, proches ou éloignés, tant greffe (les unes même des la Ième année) ces exemplaires du point de vue phylogénétique que géographique. Parmi ont fleuri et fructiflé; a partir de Ia 9ème année, la florai- les résultats obtenus, on peut mentionner: son et la fructification (a de rares exceptions près) est a. Genre Quercus. Les descendants obtenus et encore annuelle et abondante. existantssont dérivésdes combinaisons qui suivent: Des combinaisons intéressantes et fécondes ont résulté Quercus robur L. (Snagov) x Q. robur L. (Mihãesti), Q. aprés le greffage de Q. robur avec Q. borealis, de Q. robur robur L. x Q. pedunculiflora C. Koch., Q. robur L. x avec Q. macrocarpa Michx., Q. robur avec Q. macran- Q. stellata Wangh., Q. robur L. x Q. corcyrensis A. thera F. et M., Q. cerris avec Q. suber, Q. robun avec Q. Camus Mon., Q. robur L. x Q. borealis Michx., Q. robur pedunculiflora, Q. borealis avec Q. imbricania etc. Les L. x Q. frainetto Ten., Q. pedunculiflora C. Koch., x Q. glands obtenus d'une pollinisation naturelle ont donné des stellata Wangh., Q. pedunculiflora C. Koch. x Q. man- descendants qui ressemblent exciusivement al'espèce landica Munch., et Q. cerris L. x Q. borealis Michx. utiisée comme greffe et très peu a celle utilisée comme porte-greffe. Les plants obtenus (ages de 7 ans) présentent des b. Genre Fraxinus. Dans le genre Fraxinus des des- differences tant morphologiques que physiologiques ayant cendants ont été obtenus après des pollinisations effec- des ressemblances avec les deux composantes parentales. tuées entre: Fraxinus pennsylvanica Marsh. x F. excel- La domination est réciproque. La génération F1 mani- sior L., F. pennsylvanica Marsh. x F. holotricha Kohne feste une grande variétë. si F. pennsylvanica var. lanceolata Sarg. x F. excelsior L. Q. robur x Q. stellata: la proportion est favorable a la La génération F1,et F2 un peu moinsprésente une composante paternelle et non pas a celle maternelle, la majorité des feuilles étant tomenteuse; les feuilles jeunes variété bien marquee des individus inclines vers les deux sont rougeâtres, caractère spécifique de la composante composantes parentales. paterneile. En 1949, au debut des travaux sur les pollinisations artificielles, la grande majorité inclinait vers Ia composante Q. cerris x Q. borealis: la ressemblance des feuilles a maternelle, mais ultérieurement (dans les travaux les plus celles de la plante-rnère a été évidente et totale jusqu'à la récents) vers celle paternelle. 6ème année de végétation quand sont apparues des feuil- les semblables a celles du chéne rouge; cet aspect s'est Les hybrides, particulièrement ceux des combinaisons encore plus accentué dans l'année suivante. récentes (1953-1954) ont une grande supériorité sur les témoins. Les differences se manifestent dans la croissance Q. pedunculiflora x Q. robur: la majorité des descen- en hauteur et en grosseur ainsi que dans la phénophase dants (circa 70%) ont les feuiles a pubescence, semblable (décalage même de 30 jours en cc qui concerne Ia colora- a composante maternelle. tion et la chute des feuilles). Ii est a remarquer encore En general,lesdescendantssontsupérieursaux l'apparition de la fructification régulière tout les 4 a 6 ans témoins; us croissent en hauteur d'une manière vertigi- ainsi que l'apparition de plants hybrides en majorité dans neuse qui dépasse parfois 200 cm. (ex. Q. cernis x Q. la premiere année après l'ensemencement. La rapidité de

Genetics and Tree Improvement 825 Ia croissance en hauteur est évidente (excepté les corn- certain combinations the maternal characters predominate, while in others the paternal characters dominate. binaisons de la F. holotricha Kohne), la croissance an- In the genus Fraxinus, the following combinations have given nuelle en hauteur atteint 200 cm. Des la 7ème année les good results: F. pennsylvanica x F. excelsior and F. pennsylvanica dimensions maxima sont de 12 cm. au collet et de 7 m. var. lanceolata x F. excelsior (up to a height of 7 meters in seven en hauteur(lescombinaisons avec F.holotricha ne years).The morphological characters are just as variable.In the beginning of the hybridization work, the maternal characters dépassent guerre 4,50 m. en hauteur.) predominate; later, the paternal characters. Tout comme pour les espèces de chênes, et dans le Numerous grafting operations have been carried out with these même but on a pratiqué des greffes sur certaines espèces two genera to obtain specimens that bear fruit more quickly. de frênes.L'opération du greff age n'a présenté aucune In the genus Quercus, certain grafts bore fruit in the second year, and all bore fruit annually and abundantly beginning with difficulté; certains procédés ont donné des réussites de the ninth year. 100%. The same results were obtained with the genus Fraxinus be- Par les greffes on a réalisé des croissances rinitiales de ginning with the second or third year. 2-3 m. par an et des fructifications tout les 2-3 ails. Le Numerous sexual hybridization combinations were obtained greffage a été appliqué aussi avec succès au développe- with the genus Pinus. These are too recent to give any conclu- ment des plants hybrides, par la méthode du mentor. sions. At present, the plants are slow-growing. c. Genre Pinus. Les travaux de l'hybridation sexuée Investigaciones sobre Hibridaciones Sexuadas Realizadas pour ce genre n'en sont qu'à leurs debuts. Jusqu'à present en Especies de los Géneros Quercus, Fraxinus y les combinaisons suivantes ont été réalisées: Pinus en la Repéblica Popular Rumana Pinus nigra Arnold x P. montana Mill., P. murrayana Entre lashibridaciones sexuadas realizadas con elgénero Ball. x P.contorta Loud., P.contorta Loud. x P. Quercus, los mejores resultados en cuanto a crecimiento que se sylvestris L., qui ont donné des plants viables. han obtenido, han sido a base de la combinación del Q. cerris con Pinus nigra Arnold x P. sylvestris L., P. montana Mill. el Q. borealis, asI como del Q. robur con el Q. stellata y del Q. pedunculiflora con el Q. robur, (en el séptimo año de creci- x P. sylvestris L., P. nigra Arnold x P. banksiana Lamb., miento la altura alcanzada ha sido de 4 a 5 metros). P. murrayana Balf. x P. banksiana Lamb., P. contorta Las caracterIsticas morfológicas de las plantas son variables, Loud. x P. murrayana Balf., ont donné des plants qui ont predominando las caracterIsticas maternas en ciertas combina- pen a cause de la fusariose. ciones. En otros casos las paternas resultan predominantes. Las siguientes combinaciones dentro del género Fraxinus han Pinus strobus L. x P. excelsa Wall. P. excelsa Wall. dado buenos resultados:F. pennsylvanica con F. excelsior y x P. strobus L. et P. excelsa Wall. x P. ponderosa F. pennsylvanica var. lanceolata con F. excelsior (hasta 7 metros Dougl. Les semences obtenues restentviables (-1959). de altura en 7 afios).Las caracteristicas morfológicas también Les plants croissent lentement. son variables: al principio de los trabajos de hibridación predomi- nan las maternas y posteriormente las paternas. RESUMES Se han hecho muchos injertos a base de los dos géneros ya mencionados con el fin de obtener ejemplares que den frutos Research on Sexual Hybridization of Species ofthe más rápidamente. Genera Quercus, Fraxinus, and Pinus Conducted in Dentro del género Quercus, ciertos injertos han dado fruto a the Rumanian People's Republic partir del segundo año y todos ellos han dado frutos anualmente y en gran abundancia a partir del noveno año. Among thesexualhybridizations producedinthegenus Dentro del género Fraxinus se han obtenido los mismos resulta- Quercus, the best results with respect to growth were obtained by dos a partir del segundo o tercer año. a combination of Q. cerris x Q. Borealis, then Q. robus x Q. Dentro del género Pin us se han realizado numerosas combina- stellata, and Q. pedunculiflora x Q. robur (in the seventh year, ciones de hibridación sexuada,sin embargo, son demasiado a height of 4 to 5 meters was obtained). recientes para que se llegue a conclusiones concretas sobre las The morphological characters of the plants are variable.In mismas. Por el momento las plantas crecen lentamente.

Hybridization and Introgression Between Pinus radiata And P. attenuata JosE M. DE LA PUENTE E. Prof esor, Colegio de Post Graduados, Escuela Nacional de Agricultura, Chapingo, Mexico

Although the existence of the natural hybrid between Anatomical Foliar Features the Monterey and knobcone pines has been mentioned Samples of leaf fascicles were taken from five of the (Stockwell, 1946; Stebbins, 1950), littleis known in collections existing in the Herbarium of the University regard to its actual occurrence in terms of experimental of California and marked as follows: data. Pinus radiata. Monterey County. October 1934. Pinus radiata. San Luis Obispo (Cambria). The writer has had a little opportunity to make obser- November 1934. vations and measurements on thesubject, which are Pinus attenuata. Santa Cruz County. described below. November 1934. 826 Fifth World Forestry Congress Proceedings Pinus attenuata. Orange County. December 1934. hill of calcareous soil, about 15 miles northeast of Colfax, Pinus attenuata.South Fork of the American over U. S. Highway No. 40. Approximately 3,200 feet River. March 1944. elevation. The leaves were kept separate in bottles containing an In the classification of the genus Pinus, Shaw (1914) alcohol-base preparation to cause them to regain their used the evolutionary cone and seed characters as the most turgescence and to prepare them for analysis. Then, with inportant bases for his work. In an attempt to elucidate the aid of the freezing-microtome,several transverse the existence of hybridization or introgression at Año sections, 50 micra thick, were obtained of each sample. Nuevo Point, where the ranges of Monterey and knobcone These sections were later analyzed under the 100 magni- pines overlap, measurements of length, width, and the fication power of the microscope. Of each group, one ratio length/width were made for one representative cone section was chosen as representative, and a comparison of of each sample of the four populations. However, since anatomical features was made; also, an attempt was made population No. 1, the last one collected, had only 13 to draw the outlines of the main internal cellular organi- samples, estimations of characters of apophyses, spines, zations. and general appearance were made in only 13 randomized The most distinct types appeared to be (1) Pinus samples of each population to avoid error due to un- radiata from Monterey County, and (2) Pinus attenuata evenness of sample sizes. These measurements are given from the South Fork of the American River, whose char- in Tables 2, 3, 4, and 5, according to indices of variation acteristics are compared below: shown in Table 1 (procedure followed one example on Iris by Riley, 1938). Leaf cross section P. radiata P. attenuata The means of length, width, and the ratio length/width Shape carinate triangular were also obtained and are shown in Table 6. Endodermal cell thick thin(less thick) walls Table 1.Characters and index values for the cones of Pinus Endodermal cells large, roundlike smaller, elliptical radiata (Monterey) and Pinus attenuata (Colfax). Leaf-bud scales Index Index Edges striated very striated P. radiata Value P. attenuata Value Needle length Approximate 9 cm. 14 cm. Length 0 3 average Apophyses broad; when Apophyses narrow, mar- not flattened, dull mar- ginsalwayssharp;if Basal sheath gins and semi-spherical not flattened, pyramidal length shape. 0 shape. 4 Approximate 11 mm. 5 mm Spine,directedtoward Spines,directed toward average the base 0 the apex 3 General appearance 0 2 Type 2, Pinus radiata from San Luis Obispo, and type 3, P. attenuata from Santa Cruz County, seem to be Total Index Values 0 12 intermediates. Reliability on the above information is, of course, very restricted; nevertheless,itgives suggestions asto the Several observations can be made from the above data. occurrence of intermediate types. First of all, the length/width ratio cannot be taken as an index of variability, because even though these characters Cone Characteristics are quite different in each species in their natural habitat (Monterey and Colfax), the ratio indicates great similar- In order to detect the suspected occurrence of natural ity (1.6 and 1.7); therefore, its use would be misleading. hybridity between the species to which we are now refer- On the other hand, it can easily be seen that length and ring, population samples were collected in several locali- width are quite distinct characters in the typical species. ties. It is interesting to note that these characters, far from Population No. 1.Pinus radiata, 13 samples. Mon- being intermediate in the overlapping populations, are terey, California. Collections were made in a pure stand much larger than those of either parent. This is probably over a seaward hill to the east of State Highway No. 1. due to a twofold effect:heterosis, and natural larger Deep organic soil. High relative humidity. Approximately dimensions due to peculiarities of the habitat. Neverthe- 400 feet elevation. less, one of the characters, length, was chosen as a feature Population No. 2. Pinus radiata, 30 samples.Santa in the determination of variability indices because of its Cruz, California. Collections were made in a stand ocas- distinctness,in both the typical and the overlapping sionally mixed with Sequoia sempervirens and Pseudot- populations. suga taxifolia on seaward slopes at Año Nuevo Point. From Table 1, frequency diagrams were drawn to show Approximately 150 and more feet elevation. graphically the position of the individuals belonging to Population No. 3, Pinus attenuata, 30 samples. Santa populations 2 and 3 at Año Nuevo Point on what might Cruz, California.Collections were made in a stand with be called the "introgression line." The typical population understory of chaparral on ridgetops in back of Año samples serve, of course, only as a matter of comparison. Nuevo Point.Serpentine soil.Approximately 600 and We may conclude that on the basis of cone character more feet elevation. a moderate degree of hybridization and introgression has Population No. 4. Pinus attenuata, 30 samples. Colfax, taken place at Año Nuevo Point where Pinus radiata and California.Collections were made in a pure stand on a Pinus attenuata overlap their ranges. Genetics and Tree Improvement 827 Table 2. Collection No. 1. Pinus radiata, Monterey; December 25, 1953. Variation indices Specimen Length Width L/W Length Apophysis Spine General Hybrid number (mm.) (mm.) appearance index

1 96 58 1.6 0 0 0 0 0 2 112 60 1.8 0 0 0 0 0 3 82 52 1.5 0 0 0 0 0 4 80 48 1.6 0 0 0 0 0 5 56 34 1.6 0 0 0 0 0 6 108 62 1.7 0 0 0 0 0 7 96 52 1.8 0 0 1 0 1 8 72 46 1.5 0 0 0 0 0 9 76 44 1.7 0 0 0 0 0 10 96 66 1.4 0 0 0 0 0 11 112 62 1.8 0 2 0 1 3 12 84 46 1.8 0 0 0 0 0 13 96 54 1.7 0 0 0 0 0

The diagrams suggested that there is probably a flow of attenuata. Although the average pollen shedding dates are genes from knobcone to Monterey pine stronger than in March 13 for P. radiata and March 29 for P. attenuata the opposite direction. This may be understandable, on (Duffield, 1953), at their typical habitats-Q and 3,000 theoretical grounds, by supposing an earlier or simul- feet, respectively-it can be thought that the latter pos- taneous period of pollen shedding on the part of P. sibly advances its date as a result of altitudinal effect

Table 3.Collection No. 2. Pinus radiata, Año Nuevo Point; November 1, 1953. Variation indices Specimen Length Width L/W Length Apophysis Spine General Hybrid number (mm.) (mm.) appearance index 31 87 66 32 120 67 33 111 76 1.4 3 1 0 1 5 34 157 86 35 141 68 36 83 33 37 116 63 1.8 1 3 0 1 5 38 112 71 39 114 64 40 120 72 41 127 68 42 104 56 43 127 66 1.9 0 2 1 1 4 44 80 51 45 98 58 46 120 78 1.5 0 0 0 0 0 47 146 62 7.3 2 o 2 4 48 110 62 1.7 3 3 1 2 9 49 112 70 1.6 3 0 1 0 4 50 96 69 1.3 3 1 0 0 4 51 136 77 52 124 72 1.7 0 2 0 0 2 53 144 71 54 129 72 55 99 64 56 119 71 1.6 0 0 0 1 57 122 63 1.9 0 3 0 2 5 58 139 72 1.9 0 1 0 0 1 59 126 56 2.2 0 3 0 1 4 60 92 67

828 Fifth World Forestry Congress Proceedings on natural ranges, such as is known to happen in the case On a également Pu établir, an moyen de diagrammes de fréquences, que le courant de genes est plus important du Pinus of the distribution of Pinus ponderosa in California. In attenuata vers le P. radiata que dans le sens inverse. the event of introgression, this beliefisfurther sub- stantiated by the fact that the artificial hybrid has shown Hibridación e Introgresiónentre Pinus radiata y P. intermediacy in flowering time (Stockwell, 1946). attenuata El alto grado de variabilidad existente dentro del género Pinus Acknowledgment y la relativa dificultad para clasificar ciertas variedades, especles y The author wishes to express his appreciation for the ecotipos, constituyen una indicación de la posible ocurrencia de hibridación e introgreskSn naturales en este importante grupo de guidance of Dr. L. Stebbins, Professor of Genetics at the plantas. University of California. En Un intento de elucidar la existencia de estos fenómenos biológicos en Point Año Nuevo, California, donde se traslapan RESUMES las zonas de ocurrencia de Pinus radiata y P. attenuata, se hizo un estudio del follaje, conillos y conos de estas especies, a fin de Hybridation et introgression entre le Pinus radiata et le comparar los conceptos de longitud, anchura, relación longitud- P. attenuata anchura, forma de apófisis, espinas, etc., con los de poblaciones tIpicas. Le haut degré de variabilité existant a l'intérieur de l'espèce De esta manera se determinó que existe un grado moderado Pinus et Ladifficulté relative que présente la classification de de hibridación e introgresiOn entre las especies citadas. certaines variétés, espIces et écotypes indiquent la presence pos- Por medio de diagramas de frecuencias, también se logró sible d'hybridation et d'introgression naturelles dans cet important determinar que la corriente de genes es más acentuada del Pinus groupe. attenuata hacia el P. radiata que en el caso contrarlo. Pour verifier l'existence de tels phénomInes biologiques, on a procédé, aPoint Año Nuevo (Californie),oà leszones de Pinus radiata et P. attenuata se chevauchent, a une étude des Comments feuillages et des cones de ces espèces, pour en comparer les facteurs longueur, largeur, rapport longueur-largeur, forme des Ernst J. Schreiner (U.S.A.): apophyses, aiguilles avec ceux de peuplements purs. De cette manière on a établi qu'il existait en effet un degré I have a brief comment on the subject of clonal seed moyen d'hybridation et d'introgression entre les espices a l'étude. orchards.In conversation with forest geneticists during

Table 4.Collection No. 3. Pinus attenuata, Año Nuevo Point; November 1, 1953. Variation indices Specimen Length Width L/W Length Apophysis Spine General Hybrid Number (mm.) (mm.) appearance index

1 103 38 2 119 46 2.5 3 94 42 3 4 3 2 12 4 119 47 5 128 59 2.3 0 4 3 2 9 6 80 30 7 108 46 8 96 48 2.0 3 4 3 2 12 9 104 46 2.2 3 4 3 2 12 10 138 53 11 102 46 12 114 44 13 128 46 2.7 0 3 3 2 8 14 116 54 15 110 48 16 116 44 2.6 4 3 2 10 17 100 41 18 94 40 2.3 3 3 2 11 19 126 44 20 110 42 2.6 3 4 3 2 12 21 104 52 22 84 42 2.0 3 4 3 2 12 23 112 32 24 136 50 2.7 0 4 3 2 9 25 118 54 2.1 1 4 3 2 10 26 114 42 2.7 2 4 3 2 11 27 124 50 2.4 0 4 3 2 9 28 29 110 34 30 106 38

Genetics and Tree Improvement 829 Table 5.Collection No. 4. Pinus attenuata, Colfax; November 8, 1953.

Variation indices Specimen Length Width L/W Length Apophysis Spine General Hybrid Number (mm.) (mm.) appearance index 61 78 40 62 62 34 63 66 34 64 64 40 65 68 38 66 72 38 67 75 48 68 103 40 69 86 52 70 84 46 71 64 36 72 68 38 73 74 42 74 69 40 75 88 41 76 78 54 1.4 4 3 2 12 77 58 26 2.2 3 4 3 2 12 78 66 44 1.5 3 4 3 1 11 79 90 38 2.3 3 4 3 2 12 80 102 50 81 70 40 1.7 3 4 2 12 82 78 43 1.8 3 4 3 2 12 83 68 44 1.5 3 4 3 2 12 84 66 36 1.8 3 4 3 2 12 85 80 54 1.4 3 4 3 2 12 86 86 46 1.8 3 4 3 2 12 87 94 46 2.0 3 3 3 2 11 88 67 38 1.7 3 3 2 12 89 69 34 90 63 41 1.5 4 3 2 12

Table 6.Collections 1-4. during the 19th Century. This once profitable culture was Means of length, width, and length/width ratio. based on the seed produced in closely controlled seed gardens of progency-tested, high-producing ledger clones Species and Length Width derived from the original seed collected by Ledger in locality (mm.) (mm.) Length/Width South America. Pinus radiata: I bring this early commercial use of clonal seed gardens Monterey 89.6 52.6 1.6 to your attention for two reasons: (1) to point out that Aiio Nuevo Point 120.6 67.6 1.7 the many years of seed orchard culture did maintain the Pinus attenuata: average quinine production of the original ledger stock Año Nuevo Point 111.2 46.1 2.3 (which presumably were from a single provenance, and Colfax 74.1 42.3 1.7 possibly each from a single tree) but apparently did not result in any appreciable improvement; and (2) to call attention tothisearly source of information on the the past few years I have been somewhat surprised that methodology, and the advantages and limitations of com- the concept of clonal seed gardens is so frequently as- mercial clonal seed gardens. sumed to be of rather recent origin. As part of a three-month study of the possibilities of Ervedo Giordano (Italy): Cinchona breeding and culture in Guatemala during the I wish to refer first to Dr. Ernst J. Schreiner's state- summer of 1945, I reviewed the available literature on the ment. I believe that it is very important to underline the selection and culture of quinine in the then Dutch East item concerning the nature of pest resistance. If we want Indies. Unfortunately, my report was mimeographed and real improvement in pest-resistance control a greater available for only limited distribution. effort has to be made to ascertain the nature or mechan- Clonal seed gardens were the basis of the profitable ism, as Dr. Schreiner mentioned, of pest resistance. This quinine culture started in Java by the Dutch horticulturists should be the first step before beginning a programme on

830 Fifth World Forestry Congress Proceedings pest resistance improvement in forest trees; otherwise in such a case the resistance of the parent tree has been it is very easy to have some bad disappointments. only apparent and was not related to its genetical inheri- For example, it has been noticed in Italy that there is tance. A better knowledge of the nature of resistance variation in the resistance of different poplar clones to would probably avoid such failures. the disease called "bacteriosis." This disease, quite com- I want to thank Dr. Helge Johnsson for the promising mon in Northern Italy and also in Central Europe, forms prospects he gave to us for attaining an increase in growth numerous bleeding spots on the barks of susceptible rate through selection, hybridization and polyploidy.I poplars.Under these spots thereiscortical necrosis wish to point out that the main line suggested by Dr. of about 4 inches in diameter, and frequently this necro- Johnsson to achieve genetical improvement of our trees, sis also damages the wood. Causes of "bacteriosis" are first establishing phenotypical seed orchards, then plus not yet determined, but it seems now that its incidence tree orchards, has a dramatically real possibility, particu- has to be related to environmental conditions.Recent larly for the eucalypts. In Italy some eucalyptus species work by Mr. Rambelli has pointed out that root competi- begin to produce seed regularly after only three to five tion is playing a very important role in determining such years, and the evaluation of "second generation" seed a disease. orchards requires a very short time. Unfortunately, only Some years ago, research was carried out in Italy to a little work has been done in this particular field by the find poplar clones resistant to bacteriosis. For this pur- countries that are growing eucalypts, and I think that pose, cuttings were collected from a resistant tree of clone closer international cooperation would overcome some 488 in a heavily damaged plantation. Unfortunately, the difficulties connected with the establishment of eucalyptus progeny of this resistant tree has been regularly damaged seed orchards, as, for instance, the difficulty of vegetative by bacteriosis 7-8 years after transplanting. It is clear that propagation, etc.

Genetics and Tree Improvement 831 Section III Forest Protection

Session A Weather and Climate in Forest Protection L'incidence des conditions atmosphériques et du climat sur la conservation desforéts El Estado del Tiempo y el Clima en Relación con la Protección de Bosques Weather and Fire Control Practices

WILLIAM E. REIFSNYDER Professor, School of Forestry, Yale University, New Haven, Connecticut, U.S.A. Introduction mates; D, cold snow-forest climates; E, polar climates; Fire is the result of a propitious combination of fuel, f, no dry season; s, summer dry season; w, winter dry oxygen and heat.In the forest, the nature of the fuel season; S, steppe; T, tundra; and F, perpetual snow. and the supply of oxygen are directly dependent on cli- The Koeppen classification, or a modification based on mate and weather. Only heatthe ignition source fire-weather considerations, should prove useful in asses- remains to be supplied by man; and even this, on oc- sing the potential wild-land fire hazard on a worldwide casion, can be supplied by lightning. Weather and climate basis.Detailed climatic maps are available for most determine, therefore, whether or not there will be fuels regions of the world. to burn, and whether or not the fuels present at a particu- Climatic variation and fire-weather periodicities. Once lar place and time will burn, once ignited. a forest type is established in a region, it changes but Thus the weather and climate of a place largely de- slowly in response to long-term changes in the climate termine the nature of the problem and circum- (Brooks, 1949).Short-term fluctuations on the order scribe the fire control practices needed to cope with it. of decades or a century will generally not be reflected in In addition, the weather at the time of a wildfire has forest-type or fuel-type changes. However, these fluctua- important implications for the conduct of suppression tions are likely to have a measurable and important effect operations. on the quantity and flammability of the available fuels. Some attempt has been made to correlate periods of Weather Influences on Forest Flammability severe fires with precipitation cycles as determined from The very existence of a forest or grassland which can tree-ring studies (Marshall, 1927). Attempts have also produce cellulosic materials capable of sustaining com- been made to correlate fire hazard with sunspot activity bustion depends largely on the past and present climate. (Wright, 1940; Morris, 1947), but the validity of the But production of these materials is not enough; they sunspot-weather correlation is still in considerable doubt must accumulate in sufficient quantities and in a form (Lands;berg and others, 1959). dry enough to enable a fire to burn. The accumulation of From these and other studies of climatic fluctuation combustible materialssuchasdeadconiferousand in the last millenium (see Brooks, 1954, for example), deciduous leaves, twigs, and branchwood, cured grass it appears that cyclical fluctuations in fire weather are and herbaceous vegetation, and so forth, depends on the essentially aperiodic in nature.It is not possible, there- balance between production and removal by cultural fore,to use such variations for predictive purposes. activities or decay. The flammability of the accumulated Examples of areas in which knowledge of climatic fluctu- materials is dependent on their moisture content, which, ationisimportant include the cumulativeeffectsof in turn, is controlled by meteorological variables. droughts of several years' duration, occurrence of precipi- tation patterns required to prevent or relieve persistent Thus, on the one hand, in order to have wild-land droughts, and ecological analysis of the fire history of an fires we need a climate suitable for vegetative growth but area. not so hot and humid that dead material decays nearly Annual variation: seasonal weather changes. Most im- at once; on the other, we need periods of weather that are portant to the concept of fire season and to the climatic conducive to the drying of the dead fuels to moisture controls of fire suppression practices is the annual march contents that will permit rapid and sustained combustion. of meteorological elements. In particular, the distribution In general, we need not be concerned about the nature of precipitation throughout the year determines the normal of the climate that has produced the existing fuel complex; duration of periods of fire hazard. In Mediterranean (Cs) it is enough to know that wild-land fires can burn in a climates, such as exist on portions of the west coasts of certain area, and that they must be prevented or sup- North and South America and in the circum-Mediter- pressed. ranean region, a long period of summer drought ensures Correlations can be developed between fire occurrence that any continuous accumulation of fuels will burn nearly statistics and climatic classifications such as the commonly any time during the summerIn steppe (BS) climates used Koeppen system (James, 1922). Although to my with relatively little rainfall at any time during the year, knowledge no study of this sort has been published, it is the hazard of fire may be year-long in areas that sustain possible to rank the major Koeppen designations in order vegetative cover sufficiently dense to carry fire.Such of descending fire-weather severity as follows: Cs, Cw, areas are represented by portions of the Great Basin in Cf, Dw, BS, Aw, Af, ET, EF, and BW. In this scheme, the Western United States and sections of Australia. the symbols have the following meanings: A, tropical In climates where precipitation is distributed relatively rainy climates; B, dry climates; C, temperate rainy cli- uniformly throughout the year (Cf and Df, for example),

Forest Protection 835 there may be no distinct fire season. Fires willoccur any ing energy for evaporation: solar radiation and wind. time that a sufficiently long dry spelloccurs; or the fire The relative humidity of the air in contact with a fuel season may be dependent on vegetational factors (such as particle determines the moisture content toward which leaf fall) or on the persistence of wintersnow. An ex- the particle tends; the amount and duration of solar ample of the former is the southeast coastal region of radiation and wind determine how fast the equilibrium the United States (Cf). The latter is typical of northern point is approached. For very fine fuels, the approach is temperate forests (Df). rapid; heavier fuels respond more slowly. As used in the United States, the term "fire season" Synoptic-scale weather patterns provide the milieu for applies to that portion of the year when fires will burn drying and indicate how rapidly fuels will dry and what and do damage and require organized effort for their levels of moisture content they will approach. Generally, suppression (U.S. Forest Service, 1956). In this sense, so-called "air-mass" weather provides the conditions con- the term implies more than merely theappropriate ducive to rapid drying of fuels to low moisture contents. weather conditions to permit combustion; the concept of Long periods of sunny skies, light winds, and low relative damage is also involved. Vegetation factors, suchas the humidities result in fuels with low moisture content and life cycle of herbs and grasses, thatare only indirectly high flammability.Meteorological studies can show the dependent on variable meteorological phenomena also synoptic weather patterns producing these conditions play a part in determining the fireseason. (Schroeder, 1950; Foley, 1947). The nature of the "normal" fire season, and its periodic Other large- and middle-scale weather changes can have annual recurrence, has implications for the type of fire a major effect on fuel flammability.Large-scale sub- control organization established.Areas with short but sidence and downslope currents (such as the Santa Ana "dependable" fire seasons may require small year-round and chinook in the United States, the foehn in central organizations with expansion to larger organizations with Europe, and the pusash in India) produce extremely low full-time employees during the fire season. Areas with relative humidities, usually associated with high tempera- highly variable fire seasons will require provisions for tures and clear skies, which accelerate the fuel-drying rapid expansion and contraction of the suppressionor- process and produce severe burning conditions (Krumm, ganization, and may have to rely largely on part-time help 1959: 154; Thams, 1953). Monsoons, and the smaller- for the actual firefighting job.Studies of the climatic scale land and sea breezes, produce marked changes in probabilities of the various types of fire weather would be humidity conditions that are also reflected in fuel mois- most useful in the planning of fire control organizations ture. in areas with little or no previous organized fire control. Diurnal changes. In dry weather, the diurnal cycle of Many of the analytical techniques are available (Court, net incoming and net outgoing solar radiation isthe 1952; Conrad and Pollak, 1950; Thom, 1958); a few primary control of fuel moistures (Byram and Jemison, pioneering studies such as Lowry's (1959b) studyon 1943). Evaporation is an energy-consuming process, and frequency, persistence, and sequence of low humidity the sun is the ultimate and yet most immediate source of spells in Oregon have been made. this energy.Closely related to this energy cycle is the Synoptic-scale weather changes. In a particular vegeta- diurnal cycle of relative humidity, which controls the tion and climate type, the meteorological conditionspro- equilibrium moisture content of hygroscopic materials. ducing flammable conditions in natural wild land fuels are The finest fuels, such as grass and leaves, respond quickly associated with either the existence and movement of high to drying influences and so exhibit periodic fluctuations of and low pressure systems, or the diurnal cycle of weather moisture during drying periods. Heavier fuels, such as elements. sticks, twigs, and logs, however, respond more slowly. In order for dead fuels to be dry enough to ignite Although the surfaces of such materials may become readily and burn vigorously, their moisture content must alternately dry and moist during day and night, the deeper be below about 20 percent of the dry weight (Brown and portions may become progressively drier or wetter, de- Folweiler, 1953: 46). Although the moisture content of pending on the trend in the meteorological variables. live foliage fluctuates in response to meteorological fac- Although little effort has been directed to the analytical tors, it is usually above 100 percent, and therefore has treatment of these moisture changes under the influence little effect on the inception of fires (although moisture of periodic boundary conditions, the mathematical tools content of the live foliage does affect the subsequent are available. behavior). The meteorological problem, therefore, is to In addition to the time variation in flammability, there reduce the moisture content of vegetation from the high are significant space variations associated with variations values in living material to the low values necessary to in the microclimate. Whereas fuel flammability may be permit ignition and sustained combustion. The physio- quite uniform over extensive flat areas of uniform vegeta- logical prerequisite is death of the vegetation; the sub- tive type, wide variations may be experienced in areas of sequent physical process is that of evaporation, and the varied topography. Differences in fuel moisture as much as five percentage points can be expected to occur simul- important principle is the relationship between the relative taneously in locations less than a mile apart (Byram and humidity of the air and the equilibrium moisture content Jemison, 1943). The important implications of this for of the dead cellulosic material (Baker, 1956). fire control activities are that fire behavior and, therefore, The moisture content of dead fuels in the natural suppression techniqueswill vary asfuel flammability environment at any particular time will be the result of varies, and that estimates and predictions of fuel flam- the recent meteorological history, especially with regard mability must be adjusted for time and space variations to precipitation, relative humidity, and the factors supply- in microclimate.

836 Fifth World Forestry Congress Proceedings Weather Influences on Fire Behavior More than just windspeed, however, is involvedin the effect of wind on fire behavior. The variabilityof the Discussion to this point has centered on the meteoro- wind in direction and speed plays a large part inde- logical influences on the predisposition of fuels to burn, termining how a fire will spread and what control meas- primarily through the mechanisms of evaporation and ures are indicated.Although partly a meteorological hygroscopicity. Once fuels have been ignited and a wild- phenomenon dependent on turbulence and thermalstrati- firestarted,however, the problem shiftsto one of fication, wind variability is also stronglyinfluenced by determining the influence of the atmosphere on fire be- topography. havior. The resulting fire behavior, together with such As an aid to planning a control organization,studies factors as fuel type, soil type, topography, accessibility, can be made of wind direction,force, and variability dur- and so forth, will determine the nature of the suppression ing periods of high fire hazard (Gisborne,1941). Special effort and the organizational structure required to ensure consideration should be given to abrupt changes inthe optimum efficiency. wind associated with frontal passages, sea breezes,and In this connection, the flammability of the fuel as in- large-scale local winds. dicated by its moisture content is important. In addition, In mountainous terrain, the problemof determining however, many other weather variables must be con- the nature of the wind is much more complicatedthan it sidered: winds and wind structure; air temperature and is on level ground. Abstractions of thelocal wind pattern, thermal structure; atmospheric moisture; and lightning. such as proposed by Defant (1951), provide abasis on Lightning.Although lightning does not influence the which to assess the departures from the pattern; itis behavior of a going fire,itis an important source of unfortunate that the departures are more commonthan ignition in many wild-land areas of the world. The most the pattern. Even in such terrain, however,studies of serious hazard occurs in regions where lightning storms local winds are helpful, even necessary, in theplanning of are frequently not accompanied by heavy rainfall, such fire control activities (Countryman andCoison, 1958). as the interior forests of the Western United States, where Such studies have also proved useful in thecontrolled ninety percent of the fires are lightning-caused (Barrows, use of fire for vegetationmanipulation (Schroeder and 1951). Even in more humid regions, lightning may cause Countryman, 1957). five or ten percent of wild-land fires; although in tropical One of the biggest problems imposed bywind variabil- regions, the proportion is usually much less (U.S. Econ. ity is that of insuring the safety ofsuppression forces. Coop. Admin, 1952). Many of the recent tragedies in the UnitedStates are The implications for fire control practices are tremen- attributable to unexpected vagaries in the windflow that dous. Lightning fires generally start in areas remote from resulted in sudden drastic changes in the direction andrate habitations and transportation facilities.Great emphasis of fire spread. Also, topography and windflow may con- must he placed on detection of fires and rapid transport spire to produce violent fire whirlwinds (Graham,1957). of men and materiel in inaccessible areas. In the United Until more is learned of windflow patterns inrugged states, early fire control organizations in regions subject topography and of the meteorological conditionsproduc- to numerous lightning fires embarked on extensive pro- ing these patterns, fire control organizationswill have to grams of trail and road building. An extremely dense be extremely conservative in the deploymentof men in network of lookout towers was established, frequently such areas (McArdle, 1957). with the idea that the observer, having spotted a lightning Wind profile. The variation of the verticalprofile of fire, could walk to it quickly and extinguish it while it was wind speed and direction can also have aprofound effect still small. on firebehavior.Many largefiresspread primarily Widespread use and availability of fixed-wing aircraft through spottingsuccessive ignitions produced byfire- and, more recently, rotary-wing aircraft have permitted brands carried through the air and dropped outsidethe radical changes in the type of organization developed to fire perimeter. Spotting is partly a matter ofthe dryness combat lightning fires. Since about 1940, the U.S. Forest of the fuels and partly a matter of the characteristicsof Service has parachuted firefighters to fires in remote por- the wind field and the vertical convectioncaused by the tions of the western forests. More recently, helicopters fire. When humidities are low, frequent spotting canbe have been used to transport men and equipment to expected and special aerial and ground watchesshould previously prepared landing spots or to spots constructed be established on large fires. hastily by men parachuted nearby. Recent work indicates that the development oftall Wild-land fires started by human activities are generally and vigorous convection columns above going fires may more accessible by road and trail. This reduces the need depend on the wind profile (Byram, 1959). Manyof for rapid air transportation; organizations in such areas the most disastrous and erratic fires in recent yearshave find that they can rely on motorized road and trail trans- been associated with convection columns extending to port. twenty thousand feet or more. On-the-spotmeasurements Surface wind. The surface wind is, in many ways, the or estimates of the wind profile mayalert fire control most obvious and important of all the meteorological personnel to the possible imminence of blowup conditions. elements in influencingfire behavior.The supply of Observations of the smoke column above a fire may yield oxygen directly affects the rate of combustion of free- estimates of the wind profile (Keetch, 1956). burning fuels; the kinetic energy of the wind influences Thermal structure of the atmosphere. There is some the direction of fire spread both directly through directing evidence to indicate a relationship between thevertical heat transfer from burning to unburned fuels, and indi- temperature distribution in the atmosphere andthe be- rectly by carrying burning brands through the air. havior of forest fires (Byram and Nelson, 1951;Reif-

Forest Protection 837 snyder, 1954). The primary effect of thermal structure the sun (Blum, 1954), or from a fire, place an additional and the consequent state of atmospheric stability, how- burden on the body and may reduce the tolerance limits ever, is in the relationship between it and the wind pattern. indicated by Herrington. And because of the intimate relationship between wind Climatic stress on the working firefighter may also come pattern and fire behavior, adequate planning of suppres- from a reduced oxygen content of the air at high eleva- sion strategy depends on detailed knowledge of existing tions.At 8,000 feet elevation, the oxygen pressure is and predicted wind and temperature distributions. about 75 percent of the sea-level value.Although the During typical fire weather, there is a strong diurnal fully acclimatized man develops compensatory reactions fluctuation in the vertical temperature gradient that is which balance the hypoxic stress, a newcomer from a low reflected in surface wind structure. During midday hours, elevation may exhibit symptoms of mountain sickness for unstable superadiabatic lapse rates prevail, with surface several days (Monge, 1954). winds coupled closely with the wind at gradient level. In extreme examples of the foregoing types of climatic Surface speeds are high, winds are gusty and normally stress, the individual may be completely incapacitated. In blow in a direction that is 30-40 degrees counterclock- less extreme cases, however, clinical symptoms may be wise from the upper winds (over level ground in the nearly or completely absent. The only manifestation may northern hemisphere). At night, stable lapse rates isolate be a reduced working efficiency or lowering of the powers the surface wind from the upper flow; air motion is of judgment of the individual. Brown (1937) suggested relatively nonturbulent and dependent more on density that salt pills might be used by firefighters to maintain flow than on large-scale pressure distributions. their stamina when working under conditions of great In mountainous terrain, the same considerations apply, heat and exertion. Although there is an extensive litera- though considerably complicated by the irregularities of ture on the physiological effects of high temperatures the surface. Winds are more subject to local topographic (Bass, 1953; Lemaire, 1957), the information has been influences, although the normal daytime coupling between put to very little use by fire control organizations.In surface and upper winds is prevalent to a degree. Both some regions, these effects may point strongly in the di- daytime and nighttime winds, however, depend strongly rection of increased use of mechanized firefighting; in on local pressure and density differences produced by others,modification of work schedules or production microclimatic variations in solar radiation and tempera- standards may be indicated. ture, and surface winds are often governed more by such Visibility.Meteorological factors exert a strong in- variations than by the synoptic pressure pattern. fluence on visibility.Stable atmospheric stratifications Periods of changeover between stable and unstable hold smoke and dust close to the ground, reducing hori- temperature stratifications and the displacement of one zontal visibility. Unstable conditions, on the other hand, airmass by another of different stability are critical periods result in the rapid turbulent diffusion of these particles. in the control of wild-land fires. A fire flank can become The diurnal fluctuation ofstability and itseffect on the running head in a matter of a few minutes.Fires visibility can be seen in data gathered by Jemison (1940). may reverse direction almost instantaneously, and a pre- In a Kentucky forest, the distance that a standard smoke sumably safe rear portion of the fire perimeter may sud- could be seen averaged greater at noon than at 9 a.m. denly become the active head (Hayes, 1947). every month of the year, and greater than at 4 p.m. in every month but one.Visibility was best in the fall, Weather Influences on Fire Control Activities undoubtedly the result of frequent invasions of clear, It is obvious that the weather exerts a large influence unstable, polarair.Climatological studies of relating on the conduct of fire control activities through its effect visibility to fire weather are of key significance in the plan- on fire behavior: the previous section indicated some of fling of detection systems. theserelationships.There are numerous other ways, Aircraft operation. The increased use of aircraft for however, in which weather affects the conduct of the fire- detection and suppression activities has required increased suppression job. attention to weather as it affects flight operations. Weather Human physiology and work efficiency.Most wild- is important in two ways: in its effects on aircraft opera- land fires occur during periods of high temperature and tion; and in its effect on certain tasks that are performed high insolation. Many of them occur at high elevations. from aircraft. These factors, together with the heat produced by the Although flying for suppression activitiesis usually fire itself, frequently conspire to produce a severe climatic accomplished under visual flight rules, many hazards are stress upon the men engaged in suppression efforts.In encountered that are not normally associated with good- extreme cases, the climatic stress may result in heat ex- weather flying. Much flying is done at low altitudes with haustion,heatstroke,mountainsickness,orother narrow safetymargins, whereslightchanges inair pathological conditions resulting from hyperthermia or temperature and density may have adverse effects on hypoxia. lift.In mountainous terrain, these variations, together Upper limits of temperature and humidity for the with erratic wind behavior, combine to produce extremely evaporative regulation of human body temperature have hazardousflyingconditions.Helicopteroperationis been established (Herrington, 1954). Raising either the especially subject to weather limitations (Murphy, 1959). temperature or the humidity above these limits will raise Weather forecasters with an intimate knowledge of local the heat load on the body to the point where evaporation winds and microclimate in mountainous terrain are a vital can no longer maintain normal temperature, and the part of the air operations on a large fire. internal temperature will rise with consequent deleterious Wind speed and direction, and turbulence, both at the physiological results.Additional radiant heat loads from surface and at flying level, are important in a number of

838 Fifth World Forestry Congress Proceedings operations performed from aircraft. Among these are the as clothing, sleeping bags, water supply,shelter, and type parachuting of men and supplies and the dropping of fire and quantity of food. Day length, or more particularly, retardants. Although pre-drop checks are often made by night length, will influence the quantity of fuel or bat- dropping streamers on an initial pass over the target area, teries needed for camp and fireline lights. In all of these, information on local conditions prior to the flight would climatology can be important in the planning stages; help in flight planningClimatological studies of the prob- and meteorologythe current weathercan be put to use abilities of suitable and unfavorable conditions would help on existing fire situations. fireplanners in determining the feasibility of aircraft Distribution of control forces. Fire load and transporta- operations on going fires. tion facilities are primary considerations in the determina- Visibilityisanother factor that may affect aircraft tion of optimum location and strength of suppression operations. At times when horizontal visibility may be forces.Fire load may migrate over a protection area, poor, but vertical visibility relatively good, aircraft may however, in response to seasonal vegetation and climatic be needed to supplement lookout towers in fire detection. changes.Pre-fire-season planning should take into ac- If visibility becomes too restricted, air operations may be count these changes; modifications and readjustments severely curtailed or even discontinued (U.S. Forest Serv- during the fire season can be made in response to existing ice, 1958). weather and to long-range weather predictions.In the Fire-suppression strategy and tactics.By influencing United States, 30-day forecasts of trends in temperature fire behavior, weather exerts a major influence on the way and precipitation are issued twice each month.I know a forest fire must be suppressed. Control forces must be of at least one State forest service that has used these matched to the fire situation, which, in turn, is shaped forecastsfor planning purposes.The U.S. Weather by the existing fuels, topography, and weather.It is Bureau recently concluded pilot projects on the use of relatively easy to evaluate fuel and topographic factors 5-day mean forecasts in predicting periods of high fire on a fire, inasmuch as they are relatively fixed, and de- danger on the West Coast (Beers, 1959) and thunder- tailed maps can be prepared in advance. Weather, on the storms in the northern Rocky Mountains (Colson,1959). other hand, is so variable and exerts such a tremendous Beers' conclusion was that further work would yield influence on all phases of fire control that it frequently relationships that "can be applied to the prognostic ma- looms as the most important and troublesome factor to be terial prepared by the Extended Forecast Section to give considered in the planning of fire strategy. extended-period, fire-weather forecasts with worthwhile For example, windspeed affects rate of fire spread and positive skill." so influences such matters as the size of the control force, the speed with which the fire must be attacked, the nature Evaluation of Weather and Climate Influences of the suppression tactics (e.g., whether direct or indirect Fire control personnel are generally very much aware attack), and equipment needs. Duration and variability of the influence of weather on their many and varied of wind also play a large role in determining strategy duties. Much of this awareness comes from long ex- and tactics.Control forces on a fire driven by a foehn- perience with the realities of fire-suppression activities type wind that blows steadily day and night must be and has not been formalized so that it can be readily organized differently from those engaged in suppressing communicated to the novice. The major exception has a fire influenced primarily by local winds displaying a been the development of fire-danger rating systems marked diurnal variation in speed and direction. In the schemes to evaluate the influence of weather on the flam- latter case, the major suppression effort may be mounted mability of wild-land fuels. during the night and morning hours, when winds are light Measurement of fire danger. Ever since the pioneering and the fire quiescent. With the foehn wind, however, efforts of Hoffman and Osborne (1923), foresters have the fire may burn as vigorously at night as during the day, known of the close relationship between relative humidity and the major control effort may be confined to daylight and fuel moisture.Subsequent work, especially by Gis- hours for reasons of safety and efficiency. borne, elucidated the nature of the relationship between There is scarcely an activity connected with the actual significant weather variables and the flammability of suppression of a fire that does not depend directly on the natural fuels. From this came the first formal system to weather.Climatological analyses of these relationships measure and integrate weather variables into a measure should be just as much a part of the fire strategist's of fire danger (Gisborne, 1936). collection of basic data as are his fuel-type and topo- Subsequently, many attempts have been made to de- graphic maps. velop fire-danger rating systems for specific purposes and Fire-suppressionlogistics. Other waysinwhich for specific regions (Jemison, 1944). More recently, the weather affects the operation of a suppression organiza- U.S. Forest Service has undertaken to develop a universal tion include the logistics of service and supply. Many rating system that would be applicable in all regions of a firefighter has wished that a particular fire camp had the United States, and would be adaptable to many pur- been laid out so that eating and sleeping areas were upwind poses (Keetch, 1959). This system should beapplicable of dusty roads. In the location of the camp, consideration with minor modifications to any wild-land region in the should be given not only to the present weather conditions world. and fire location, but also to possible future developments Special climatological techniques. For many purposes, in the meteorological situation that might pose a threat to existing danger-index systemsare not adequate, and the safety or suitability of the camp. special climatological analyses must be made. Some of The comfort and safety of firefighters both in camp and these have been mentioned previously. Recent years have on the fireline may depend on such weather-related items seen rapid advances in the development ofanalytical

Forest Protection 839 techniques (Landsberg and Jacobs, 1951; Lowry, 1959c; Blum, H. F., 1954.Effects of sunlight on man. Meteorological Conrad and Pollak, 1950), and of methods of processing Monographs 2(8): 43-49. Brooks, C.E.P., 1949.Climate through the ages; A study of large quantitiesof numerical weather data (Bellamy, climatic factors and their variations. New York: McGraw- 1952; Landsberg, 1958; U.S. Weather Bureau, 1960). Hill. 2d ed. Fire-weather forecasting. The United States Weather 1954. The climatic changes of the past thousand years.Experientia (Base!) 10(4): 153-158. Bureau has provided specialized forecasts to the various Brown, A. A., 1937. Does salt affect the stamina of the fire forestry services during the fire season since 1913 (Wil- fighters?Fire Control Notes V: 250-254. liams, 1916). At present, there are twelve regional cen- and A. D. Folweiler, 1953. Fire in the forests of ters where fire-weather forecasts are prepared (Altman, the United States.St. Louis: J. S. Swift Co. Byram, George H., 1959. Forest fire behavior. In: Davis, K. P., 1950). In addition to routine forecasts, special forecasts Forest fire: control and use. New York: McGraw-Hill Book are supplied for going fires on request. On large fires, Co. Chapt. 4. mobile weather units may be used to provide continuous and G. M. Jemison,1943.Solar radiation and advisory service. At present, the table of organization of forest fuel moisture. J. Agric. Res. 67(4): 149-176 and Ralph Nelson, 1951. The possible relation of the U.S. Forest Service includes fire-behavior and fire- air turbulence to erratic fire behavior in the Southeast. Fire weather specialists who work with Weather Bureau per- Control Notes 12(3): 1-8. sonnel in evaluating weather effects. Colson, DeVer, 1959. Part II.Forecasting thunderstorms in the northern Rocky Mountains from 5-day mean charts.Proc. Severalforestfirecontrolorganizationsemploy West. For. Fire Res. Council Meeting, Spokane, Wash., Dec. meteorologists in both research and operational capacities. 8, 1959. pp. 18-20. These men have been variously employed in making Conrad, V., and L. W. Pollak, 1950. Methods in climatology. climatological surveys of particular areas to be burned Cambridge: Harvard Univ. Press. Countryman, C. M., and D. Colson, 1958. Local wind patterns under control (Countryman and Schroeder, 1959), in in Wildcat Canyon. Calif. For. Range Exp. Sta. Tech. Paper devising cimatological aids for adapting forecasts to local No. 28. areas (Cramer, 1958; Berg and Lowry, 1959), and in and M. J. Schroeder, 1958.Prescribed burn fire- makingclimatologicalstudiesofminimumrelative climate survey1-57.Fire environment studies.Calif. For. Range Exp. Sta. Tech. Paper No. 29. humidities (Lowry, 1959a). Studies have also been made Court, Arnold, 1952. Some new statistical techniques in geo- of the requirements for fire weather forecasts (Wilson, physics.in: Advances in Geophysics 1: 45-8 5. 1958 Molga, 1950), and of ways of making local fire- Cramer, Owen P., 1958.Using fire-weather forecasts and local weather forecasts (Beau, 1948). weather observations in estimating future burning index for individual fire-danger stations.Pacif. Nwest. For. Range Exp. Though foresters have long recognized the importance Sta. Res. Paper 28. of weather to fire behavior and fire control, they have Defant, Friedrich, 1951.Local winds. In: Compendium of Me- been slow to demand the services of qualified meteorol- teorology. Boston, Amer. Meteor. Soc., 1951, pp. 655-672. Foley, J. C., 1947. A Study of meteorological conditions associ- ogistsandclimatologists. On theotherhand,the ated with bush and grass fires and fire protection strategy in meteorological profession has been primarily concerned Australia. Australia. Bur. Met. Bull. No. 38. with the problems of forecasting and of describing atmos- Gisborne, H. T., 1936. Measuring fire weather and forest inflam- pheric processes on the grand scale, and less interested mability. U. S. Dep. Agric. Circ. 398. 1941. How the wind blows in the forest of northern in the applications of meteorology to agriculture and Idaho. Northern Rocky Mtn. For. Exp. Sta. forestry.Recently, however, there has been an upsurge Graham, HowardE.,1957.Firewhirlwindformationas of interest in fire-weather relationships on the part of favored by topography and upper winds. Fire Control Notes both foresters and meteorologists.This has already re- 18(1): 20-24. Hayes, G. L., 1947.Forest fires and sea breezes. Fire Control sulted in great strides forward in our understanding of Notes 8(2,3): 30-32. these relationships, and in their practical application in Herrington, L. P.,1954.Biophysical adaptions of man under fire control activities. We have seen the beginning of climatic stress.Meteorological Monographs 2(8): 30-42. what I predict will be a long and extremely fruitful Hoffman, J. V., and W. B. Osborne, Jr., 1923. Relative humidity association of fire scientists and weather scientists. and forest fires.U. S. Dep. Agric., For. Serv. Bull. James, Preston E.,1922.Koeppen's classification of climates: References A review. Mon. Weath. Rev. 49(2): 69-72. Jemison, G. M., 1940. The influence of locality, season, time of Altman, H. E., 1950. The Weather Bureau's fire-weather service. day, and year on the visibility of smoke columns.J. For. 38: Weatherwise 3(5): 99-102. 435-437. Baker, William J., 1956. How wood dries. U.S. For. Prod. Lab., 1944.Forestfiredanger indexes.J.For. 42: Madison, Wis., Report No. 1642. 261-263. Barrows, J. S., 1951. Forest fires in the northern Rocky Moun- Keetch, J. J., 1956. Convection column--motion and shape char- tains. Nth. Rocky Mt. For. Range Exp. Sta. Paper No. 28. acteristics as fire behavior indicators, in: Proc. Neast. For. Bass, David E., and others, 1953. Mechanisms of acclimatization Fire Protect. Corn. 8th Training Session, Concord, N.H., Feb. to heat in manQuartermaster Climatic Res. Lab., Environ- 14-17, 1956. mental Protect. Branch. Report No. 214. 1959. Unifying fire danger rating-progress toward Beau, H. W., 1948. Forecasting weather and forest fire hazard a national system. Fire Control Notes 20(3): 87-88. from local observations.Canada. Dom. For. Serv. For. Fire Krumm, W. R., 1959. Fire weather. In: Davis, K. P. Forest Fire: Res. Note No. 10. Control and Use. McGraw-Hill Book Co. Chapt. 5. Beers, Francis D., 1959. Part I. Use of long-range forecast tech- Landsberg, H. E., 1958. Data processing in geophysics, in: Guten- niques for fire-weather forecasting. Proc. West. For. Fire Res. berg Volume. Pergamon Press; pp. 210-227. Council Meeting, Spokane, Wash., Dec. 8, 1959. pp. 13-17. and W. C. Jacobs, 1951. Applied climatology, In: Bellamy,J.,1952.Automatic processing of geophysical data. Compendium of Meteorology. Boston. Amer. Met. Soc., 1951: in: Advances in Geophysics 1: 1-43. pp. 976-992. Berg, Alan B. and William P. Lowry, 1959. Fire weather studies andothers,1959.Power spectrum analysis of on Bald Mountain. Oregon For. Lands Res. Center. Res. Note climatological data for Woodstock College, Maryland. Mon. No. 39. Weath. Rev. 87(8): 283-298. 840 Fifth World Forestry Congress Proceedings Lemaire, R. R., 1957.Influence du climat tropical sur le corn- par consequent, sur les méthodes et moyens nécessaires a employer portement physiologique de l'homme.Tnt.J.Bioclim. and pour lecombattre.Ilest particulièrement important de bien Biomet., Vol. II, Pt. Iv, Sect. A 4. connaitre le caractère local des vents en terrain montagneux, Lowry, William P., 1959a. Frequencies of daily minimum relative afin de pouvoir déployer avec le maximum d'efficacité la stratégie humidity at Portland, Oregon.Ore. For. Lands Res. Center, de la lutte contre l'incendie. Climatological Note No. 17. Le temps agit aussi sur les diverses formes d'activité de l'homme 1959b. Frequency, persistence, and sequence of low dans sa lutte contre le feu. Les conditions climatiques extremes, humidity spellsat Portland, Oregon.Ore. For. Lands Res. comme les hautes temperatures et les grandes altitudes, ont une Center, Climatological Note No. 23. influence défavorable sur les fonctions physiologiques de l'être l959c.Putting weather records to work-an intro- humain; mais on ne sait pas encore mesurer les effets de ces duction to applied climatology for foresters. Ore. For. Lands conditions sur le rendement de la lutte directe contre l'incendie, Res. Center, Climatological Note No. 22. comme sur les autres formes d'activité humaine relatives a cette McArdle, R. E., 1957. Standard fire fighting orders. Fire Control lutte.Les operations adriennes ayant pour but de combattre les Notes 18(4): 151. incendies de foréts sont régies par des conditions favorables de Marshall, Robert,1927.Influence of precipitation cycles on vol, et certaines de ces operations exigent des conditions atmo- forestry. J. For. 25: 415-429. sphériques particulières. La repartition des moyens de contrôle du Molga, M,1950.0 pracach z zakresu meteorologiilesnej. feu dans une region a protéger peut dépendre de la succession (Problems in the field of forest meteorology.) Gazeta Obser- saisonnière des conditions atmosphériques.Ii est utile de tenir watora PIHM (Warsaw) 3(11): 1-51. compte des previsions météorologiques a longue échéance, lors de Monge,G.,1954.Man,climate and changesofaltitude. l'établissement des plans de cette repartition. Meteorological Monographs 2(8): 50-60. Les organisations dédiées a la lutte contre les incendies de Morris, William M., 1947. The forest fire hazard in the sunspot forêts ont recours aux spécialistes dans les questions relatives cycle. Fire Control Notes 8(4): 4-8. aux conditionsatmosphdriquessusceptibles de provoquer des Murphy, James L., 1959. The helicopter and the dead man's curve. incendies; ces spécialistes font des recherches sur les conditions Fire Control Notes 20(1): 1-2. climatiques et sont d'une aide effective lorsque des incendies se Reifsnyder, William E.,1954. Atmospheric stability and forest déclarent.Danscertainspays,lesservicesmétéorologiques fire behavior.Yale School of Forestry.Ph.D. Dissertation. nationaux fournissent des previsions spéciales, relatives aux con- Schroeder, Mark J., 1950. The Hudson Bay high and the spring ditions atmosphériques susceptibles de provoquer des incendies fire season in the Lake States. Bull. Amer. Meteor. Soc. 3 1(4): deforêts.Un grand nombre de procédés techniques pour 111-118. l'analyse climatologique et l'établissement de previsions météoro- and C. M. Countryman, 1957. Fire-weather survey logiques spéciales sont actuellement publiés, et certains d'entre eux can aid prescribed burning. Calif. For. Range Exp. Sta. Tech. sont cites dans le rapport. Paper 21. Thams, J. C., 1953. Zur meteorologie der waldbraende im Tessin. El Estado del Tiempo y las Prácticas de Control de Leben und Umwelt 9(8): 169-173. Thom, H.C.S., 1958. A note on the gamma distribution. Mon. Incendios Weath. Rev. 86(4): 117-122. El estado del tiempo y el clima ejercen una influencia de Li. S. Econ. Coop. Admin., 1952. Report of the forest fire control importancia mayor sobre la composición de un bosque y, por study tour, Sept. 5-Oct. 12, 1951. USDA. ende, sobre los materiales combustibles que pueden quernarse en U. S. Forest Service, 1956. Glossary of terms used in forest fire un incendio forestal.El estado del tiempo determina tarnbién la control. U. S. Dep. Agric., Handbook No. 104. inflamabilidad del combustible al regular el contenido de humedad 1958.Forest Service Handbook.Title 5700-Air de la vegetación muerta. Debido a ello, las variaciones estacio- Operations. nales barométricas determinan la duración de la estaciOn de los Ii.S. Weather Bureau, 1960.The National Weather Records incendios; pero la progresión de esas variaciones y las influencias Center. U. S. Govt. Printing Office. locales y diurnas determinan la inflamabilidad en un mornento Williams, H. E., 1916. Fire-weather warnings. Mon. Weath. Rev. dado. Estos factores a su vez son importantes para determinar la 44(3): 133-135. organización de las fuerzas de extinción. Wilson, G. U., 1958. A capability study of forecasts of maximum Los rayos pueden ser un importante origen de incendios en temperature, relative humidity, dew point, wind and precip- algunas zonas del mundo. Una vez iniciado el incendio, el viento itation in several States with special application to fire-weather y sus corrientes y la estructura térmica de Ia atrnósfera influyen requirements. Australian Met. Mag., Melbourne, 21: 3 1-48. poderosamente para propagar la conflagraciOn y por lo tanto, en Wright, J. G., 1940. Sunspots and forest fires in New Brunswick. el tipo de actividades necesarias para su extinción. De especial For. Chron. 16: 233-238. importancia en los terrenos montañosos es el conocimiento de los movimientos del viento, cuando hay que determinar la estrategia para la extinción. RESUMES El estado del tiempo también afecta el desarrollo de las activi- Le role du temps dans les incendies de forêts et différents dades del hombre en la extinción de incendios.Las tensiones climáticas resultantes de las altas temperaturas y las grandes alti- procédés employés pour les combattre tudes afectan la fisiologIa humana, pero hasta ahora poco se sabe Le temps et le climat ont une influence importante sur Ia de sus efectos cuantitativos en los esfuerzos de extinción y en composition des forêtset,par consequent, sur le genre des otras actividades humanas relacionadas con estos incendios. Las matériaux combustibles qui peuvent s'enflammer dans l'éven- operaciones aéreas contra incendios dependen de las condiciones tualité d'un incendie de forêt. Le degré d'inflammabilité du com- favorables de vuelo y algunas de estas operaciones realizadas por bustible depend également des conditions atmosphériques, du fait losaviones requieren condiciones especIflcasdel tiempo.La qu'elles agissent sur la teneur en humidité du bois mort et d'autre distribuciOn de las fuerzas de extinción en el area protegida puede vdgétation sèche. Ainsi, les variations saisonnières des conditions depender de la progresión estacional de los elementos que cors- atmosphériques déterminent la durée de la période des possibilités tituyeneltiempo.Los pronósticos meteorológicos de largo d'incendie des forêts, mais Ia succession de certaines conditions alcance son iitiles en eI planeamiento de Ia distribucidn de fuerzas. atmosphériques, ainsi que des influences locales et diurnes, peu- Las organizaciones de control de incendios pueden emplear vent occasionner l'inflammabilité du combustible a tout moment. especialistas en meteorologIa para los estudios clirnáticos y para Ii est important de tenir compte de ces facteurs, en procédant a las operaciones de asistencia al dirigirse a los incendios.En l'organisation de la lutte contre les incendies de forêts. algunos palses, los servicios meteorológicos nacionales suminis- Dans certaines regions du monde, les incendies sont souvent tran pronósticos especiales sobre el tiempo y la posibilidad de causes par la foudre. Lorsque le feu s'est déclaré, le vent et son incendios. Muchos de los métodos seguidos en los análisis cli- caractère, de même que les conditions thermiques de l'atmos- matológicos y los pronisticos especializados suelen publicarse phère ont une influence puissante sur l'évolution de l'incendie et, y en este trabajo se citan algunos de ellos.

Forest Protection 841 and Forest Diseases

GEORGE H. HEPTING Chief, Division of Forest Disease Research, Southeastern Forest Experiment Station, Forest Service, U.S. Department of Agriculture, Asheville, North Carolina, U.S.A.

Climatic factors, as we use this expression, constitute the spread of blister rust in Wisconsin is limited princi- weather. We know a good deal about the relation of pally by the lack of sufficient moisture for sporidial forma- weather to certain plant diseases, including those of tion and germination on the pine needle.In addition trees, and I shall try to point out some of the ways in they state that ". .. aprimary requirement for the pro- which weather is known to influence the incidence and duction of fertile teliospores is a period of 2 weeks with severity of forest diseases. However, I intend to discuss no 3 consecutive days over 280 C.,, mainly ways whereby changes in climate, which we may The conditionsnecessaryforsubsequentsporidiai consider long-term weather trends, or fluctuations, can formation and germination have been investigated by influence known diseases or create new disease problems. many workers. l3ega (3) found that sporidia were formed In general, we might consider that our field crops and during the seventh hour after a telial column was placed other annual or short-lived vegetation reflect weather in a saturated atmosphere at 150 C., and peak sporidial changes; whereas trees,soil flora, and other perennial production occurred between the 11th and 30th hours, flora will reflect, in addition, climatic changes.I shall Van Arsdel (15) and his co-workers stated that from 36 divide my presentation into three principal parts:first, to 48 hours were necessary for sporidial formation and the influence of climatic factors on diseases caused by germination. pathogens; second, the influence of climatic factors on I have been told that given any set of requirements for physiogenic diseases; and lastly, how climatic change maximum spore discharge, pathologists now can predict could bring about the recession of certain forest tree the probabilities for future rust waves or epidemic years. species through pathological influences. If one adds to these requirements the microclimatic re- You will notice that through much of this discussion quirements of the other three stages as well as those of I will be alluding to macroclimatic factors; that is, those the host plants, we see why, once the pathogen and host measured by conventional instruments and that represent are brought together, it still takes a special set of climatic thegrosseffectsof the meteorological environment. factors to produce an epidemic. Particularly in dealing with infection by pathogens, I In the Southern United States, one of our most im- will often be alluding to microclimatic factors, which portant forest and nursery diseases is the fusiform rust represent precise effects of meteorological environment that attacks southern pine and has as alternate hosts the immediately surrounding a plant, sometimes for a matter oaks. This fungus, among its weather requirements, needs of just a few hours. Yarwood (20) * has presented a good 18 hours of saturated air, with temperatures between 60 discussion of microlimate and plant infection. and 80° F., in the early spring after pine shoot growth has begun, for an important amount of infection to de- Influence of Climatic Factors on Pathogenic Diseases velop.Thus we have so-called "rust years" only at The main climatic factors that we pathologists are irregular intervals over most of the range of the disease. concerned with are precipitation, temperature, humidity, Although most pathogenic fungi grow well at 90° F., fog and dew, atmospheric pressure, wind, and radiation. inoculations with the oak wilt fungus failed when the If a pathogen is well equipped for reproduction and means surrounding temperature was over 90°. At Asheville, of spread, we find that climatic factors are usually para- North Carolina, we were generally unsuccessful in isolat- mount in determining disease severity. Most of our forest ing this fungus from infected wood when the laboratory diseases are caused by fungi. Weather factors will affect air rose over 90° F. There is also strong field evidence the growth of the fungus, its sporulation, its rate of spread, that the spread of the disease southward is limited by high spore germination, and infection, and the response of the temperature, since there has been little or no southward host to infection.In fact, for most plant diseases a spread reported from Arkansas to North Carolina since rather special concomitance of circumstances is necessary the early 1950's. to produce an epidemic.White pine blister rust is an One of our most serious pine nursery diseases in the example of such a disease.The fungus produces five South is black root rot, caused in part by a Fusarium distinct spore stages, two on pine and three on ribes and Scierotium bataticola, and aggravated by nematodes. leaves. Each stage has an important part in the life cycle Recent unpublished work by Hodges has established of the pathogen, and weather affects markedly the devel- that no serious destruction of roots takes place unless or opment of each stage. Van Arsdel, et al. (15) state that until the soil temperature reaches 90° F.This could explain why such divergent measures as soil fumigation * Numbers in parentheses denote the references listed at the or sawdust mulching checked the disease. Fumigation is end of this paper. effective by killing the fungi. Mulching may be effective

842 Fifth World Forestry Congress Proceedings by preventing the high soil temperatures required for Two of our tree species in the Southern United States severe damage. are quite generally tapped or streaked for the production Surges inthe northeastward spread of Dutch elm of oleoresin. Sometimes these tapped trees will no longer disease through Maine and into New Brunswick followed produce gum and are said to have dry face.This is the paths of a series of hurricanes in the early 1950's. particularly true of trees of low vigor or those that are This spread may well have resulted from the long-distance chipped too deeply and during droughty conditions. The transport of infested elm bark beetles. dry and dead areas of the bark usually extend only a Innumerable cases could be cited of the critical role of few inches above the face. However, during the prolonged climatic factors in plant disease epidemiology.In the periods of unusually warm weather lasting several years in control of diseases of crop plants, meteorological knowl- the 1930's and 1950's, dead areas extending 20 to 30 feet edge is being made use of in forecasting epidemic condi- up the trees developed from dry faces. The newcondi- tions so that growers can take the necessary added control tion was given the name "pitch streak" (7). The only measures.Miller (11), for example, has shown that a two reports of outbreaks of pitch streak coincided with remarkable relation exists between the earliness of ap- the latter years of the hot periods. pearance and severity of tobacco blue mold and mean Toole (14) relates the cause of the widespread sweet- January temperature. High January temperatures were gum blight in the Southeastern United States tocumulative followed consistently by high blue mold severity later. drought factorssince1950.While he conceded the Similar disease forecasting is being successfully used in obvious adverse direct effects of low soil moisture on the case of late blight of potatoes, downy mildew of roots, he brings in also the fact that the resultant demon- lima beans, and some other diseases. strated high imbibitional water value, together with a In considering those of our forest tree diseases that are falling water table, and high contents of potassium and caused by pathogens, we have those that are quite rare sodium in the soil probably still further limit the amount and that are seldom found under normal weather condi- of water available to the roots.High manganese and tions. Then we have what I would term the threshold certain other metal toxicities have been suggested as diseases.The rusts are good examples of these.Ord- contributing to a dramatic decline of oaks in the southern inarily the concomitance of conditions needed for an Appalachian region of the United States following pro- epidemic may occur only about every three to five years longed dry weather. Dry periods can lead to increases in a given locality. A slight but consistent change in in the concentration of metals in the soil solution. temperature, or in days of fog or rain, could make such Prolongedrainscan resultin undue leachingof a disease epidemic almost every year, or if conditions nutrients from sandy soils and from foliage, with con- went the other way, the disease might be epidemic only sequent deficiencies. The toxicity of air-pollutant gases about every 10 or 12 years. In addition to the low-vigor andaerosolsisstronglyinfluenced by temperature, endemic diseases and the threshold diseases, we have the humidity, air drainage, sunlight, and other climatic fac- third type, which is so well equipped to infect and so tors.An extensive literatureisaccumulating on the undemanding with respect to climatic factors that it rolls meteorological aspects of .Recent studies on with its destruction, varying to only a minor degree of air-pollution toxicity to trees and other plants have from year to year until it creates havoc with a species over brought out such climatic influences as the importance a vast range.Such diseases are the chestnut blight, of topography and windspeed on dilution rates, the in- mimosa wilt, and Dutch elm disease. crease in sulfur dioxide injury with increase in atmos- Most of our tree foliage diseases are caused by fungi, pheric humidity, and the formation of toxic ozone from and their epidemiology is controlled mainly by weather. certain stack gases in the presence of sunlight. Such relationships are known for many such diseases. Examples are the needle casts of larch and lodgepole Climate Change and Species Recessions pine,Rhabdocline pseudotsugae on Douglas-fir,and It is now well established that a worldwide warming Keithia thujina on western redcedar. trend has been going on, at least since about 1900, and this trend is expected to continue. Evidence in support Influence of Climatic Factors on Physiogenic Diseases of this position is well presented by Dr. H. E. Ltndsberg, By physiogenic diseases we mean those that are caused Director of the Office of Climatology, U.S. Weather by agents other than living organisms, such as drought, Bureau (9). Baum (2) has presented a thorough review water excess, and toxic gases. The direct effects, over of recent climatic fluctuations with emphasis on the mari- relatively short periods, of meteorological extremes, such time provinces that clearly show this warming trend. as drought, flooding, heat injury, and others, are usually In general, the magnitude of the mean annual tempera- quite obvious and need no elaboration. These events are, ture increase has been abo'ut 2° F. in the North Temper- generally speaking, weather changes. Symptoms in trees, ate Zone and about 5° in the Arctic. Some areas show indicating marked pathology and often mortality, may greater increases. There have been positive trends of sea- occur with less dramatic suddenness following long-time surface water temperatures in the North Atlantic of about changes in climatic values; that is, climate change. the same order of magnitude as the long-term air tempera- The Southeastern United States has experienced pro- ture changes (9). Glaciers have been receding in Alaska; longed periods of unusually warm weather, lasting several the harbor of Spitsbergen is open for twice as long a years in the 1930's and again in the 1950's. I will give period each year as it was around 1912; the tree line in some examples of the possible influence of these climatic Finland has been migrating northward; and there has been changes in inducing unfamiliar maladies of certain forest a northward migration of snowlines, freeze-free seasons. trees. and of animals and plants. The thickness of the Green- Forest Protection 843 land icecap has been greatly reduced, and ocean levels are and the long series of hotter summers and milder winters up a few inches. Analyses by Baker (1) for Minnesota characteristic of much of this century could be extending for the period 1900 to 1958 show increases in mean its damage northward. temperature for summer, winter, and annual, respectively, Let us consider how a mean annual rise of 2 or 3° F. of 1.4, 3.7, and 1.3° F. He mentions that this would be might bring about a species decline of major proportions. equivalent to a rise of mean summer temperatures of We know that any such change would have some in- 6.3° F. per century. However, no one knows how long fluence on trees' normal functions, such as ratesof this warming period will last. photosynthesis, respiration, and mineral absorption, and One possible explanation in attempting to account for on hardiness.If these temperature changes affected only this warming trend is that it is due to an increase in such factors or processes, we might see changes in the carbon dioxide in the atmosphere, probably as a result of behavior of a species only around the extremes of its man's industrialactivities(Landsberg (9)and Plass range. I should like to discuss three other ways in which (12)). a small but consistent rise in temperature over two or I should like to present for your consideration the view three decades could bring about tree declinesof a that some of the major tree species' declines of recent pathological nature over wide areas: 1) through loss in years, which appear to have complex causes or for which soil moisture where water supply was already critical; we are still seeking the cause, may have been set in 2) through upsetting the favorable competition against motion as a result of this warming period.I refer to root parasites by antagonistic soil organisms; and 3) such serious diseases in the United States and Canada through enlarging or changing the range of insect vectors as birch dieback, littleleaf of pine, sweetgum blight, pole of disease organisms. blight, pitch streak of turpentine pines, and a widespread In the case of a hypothetical area receiving 50 inches decline of oaks. Since all of these are dramatic declines of rain per year, a mean annual temperature rise from and do not simply represent migrations northward or 50 to 52° F. might be expected to increase evapotrans- southward along the fringes of the ranges of the species piration about 6 percent in the colder months and 10 concerned, they have claimed the attention of the path- percent during the summer. In the case of a disease such ologist more than the ecologist.It is interesting to note as pole blight of Pinus monticola, additional moisture that all of these problems seem to have their origin loss of such a magnitude might account for the appearance below the ground line. of this disease. In reporting their research on pole blight, The Northeastern Forest Experiment Station, in their Leaphart and Copeland (10) state: "During periods of October 1959 Northeastern Forest Pest Reporter, dis- prolonged moisture deficiencies,... notonly would the cussed the current incidence of many diseases of known moisture requirements not be satisfied, but mineral re- cause. Toward the end, under the heading "Diebacks," quirements would not be supplied.Pole-blighted trees, they mention serious declines of unknown cause of many show sharp, sustained radial growth reduction. species, including sugar maple, ash, black walnut, and, Causes . ..appear to be of below-ground origin, and in some areas, hardwoods in general.In surveying for among the most likely reasons for this are abnormal root sweetgum blight in the South (8), I reported the elms to deterioration and deficient moisture supply." They state be suffering dieback almost as bad as sweetgum in most that their results "indicate an edaphic relationship to the sample areas. pole blight disease." Wellington (18) has studied the behavior of certain Wellington (16) has also suggested a relation of pole forest insects in the light of established climatic changes, blight to climate change, and he points out some interest- mainly in North America. ing ways by which the succession of wet, cool summers Some pathologists have considered the possibility that he reported might contribute to this dease. the declines just mentioned may have been brought about Pitch streak of turpentine pines, which many of us by climatic factors. Each of these investigators has been regard as an exaggerated form of dry face but a lethal concerned with one or two of these diseases, and usually form of a benign disease, has been reported only during in relation to droughts or a series of unusual years. Red- the two very prolonged periods of drought in this century mond (13), working with birch dieback, recognized the in the Southern United States. The persistent drain on the long warming trend in Nova Scotia and New Brunswick water tables of this region, accompanying higher tempera- that raised the mean temperature between 2 and 3° F. tures and often deficient precipitation, is cited by Toole during the 30 years prior to 1950, and he studied its (14) as probably the major factor in the wholesale dying possible effects on the new and spectacular dying of birch of sweetgum over an area of several States. in eastern Canada. One of the most intriguing and complex effects of Woods (19), in 1952, proposed the view that climate changing climate, which in our current era is a warming change could have much to do with the accelerated activi- period, is influence on the often delicate balance between ties of some of our forest tree pathogens, and that the parasites and their antagonists in the soil. The effects of relation of certain species' recessions to a warming climate this hidden battle are often not apparent to us in our was probably, in many cases, through the effects of the annual crop plants, because they may be planted and change on disease organisms. He cited particularly the produce a crop before the effects of this struggle manifest losses of chestnut by the soil fungus Phytophihora cm- themselves. However, perennial vegetation in our forests namomi preceding the blight, and the aggressiveness of has to withstand itssoil enemies for decades or even this same fungus, starting in the 1930's or shortly before, centuries. in bringing about the littleleaf disease of pine. P. cm- Changes inair temperature are soon followed by namomi is largely a tropical and subtropical organism, equivalent changes in upper soil temperatures.When

844 Fifth World Forestry Congress Proceedings Redmond (13) suspected that a small but consistent in- rhizosphere.Whole new disease complexes can result crease in soil temperature might induce birch dieback, from such climatic changes, and in this new field of he placed heating cables under birches in the field and diseases induced by climatic change we often will have found that small temperature increases upset the popula- not simply the direct relation between a single pathogen tion balances of fungi inhabiting the roots and the rhizo- and a host plant but a whole series of interrelated factors sphere and disturbed the development of mycorrhizae. that together produce a disease. Thus, in littleleaf disease, Moreover, he found that a mean increase of only 2° C. symptomsresult from a combinationofattack by after 100 days resulted in an increase from a normal Phytophthora cinnamomi, poor subsoildrainage, low root mortality of about 6 percent to about 60 percent, fertility, and the effects of low soil aeration in preventing and an increase of 7° C. resulted in 100-percent root regeneration of roots to replace those killed by the fungus. mortality. He showed that a species of Cylindrosporium We can expect to find more forest tree diseases caused isolated from dead yellow birch roots inhibited the growth by complexes of organisms interrelated with edaphic and of another fungus isolated from mycorrhizae and dead climatic factors in many of our new and complicated roots, but that the growth rate of the former increased major tree diseases. while that of the latter decreased with temperatures raised In seeking some appropriate remarks with which to above the optimum for rootlet development. The current end this paper, that would urge a greater consideration views of the Canadians on birch dieback, however, as of climatology in forest pathology, I found the message summarized by Clark and Barter (6), lean toward an already provided toward the end of Landsberg's "Trends infectious disease rather than a soil organism imbalance, in Climatology" (9). He says: "The greatest advances of and in particular to a virus as reported by Berbee (4). climatology are destined to lie in the border field of The virus may 51 art the chain of deteriorating events such biology, provided an adequate cooperative research pro- as the insect, disease, and edaphic pressures that char- gram is started.The interactions between the physical acterize birch dieback. changes in the atmosphere and living organisms are too This brings us to an interesting possibility,again great a challenge to scientific curiosity to remain in a strongly involving climate change. If the syndrome known relatively unexplored state." as birch dieback is set in motion by a virus, the manner of spread would most likely be by an insect vector. References Unless this is a new disease, why then would such dev- Baker, Donald G., 1960. Temperature trends in Minnesota. astating spread have taken place just during the last Bul. Amer. Met. Soc. 41: 18-27. Baum, Werner A., and Havens, James M., 1956.Recent 30 years? Wellington (17) has presented much evidence climatic fluctuations in maritime provinces. 21st North Amer. on the relation of climatic factors to insect behavior. He Conf. Trans., p. 436-453. brings out that shifts in storm paths and related phenom- Bega, Robert V., 1959. The capacity and period of maxi- ena have brought about definite climatic changes in North mum production of sporidia in Cronartium ribicola. Phyto- pathology 49: 54-57. America. These storm-path changes can bring about new Berbee, J. G., 1959. Birch dieback: present status and future dispersals of insect populations. He cites the findings of needs.(Abstract.) IX Internatl. Bot. Cong. Proc. 2: 28-29. Pschorn-Walcher(18)that Central Europe hasex- Broadbent, L., 1959. Insect vector behavior and the spread perienced recent outbreaks of insects that had been of plant viruses in the field.In Plant Pathology Problems and Progress 1908-1958, p. 539-547. Univ. of Wis. Press, Madison. destructive only in the southern parts of the Continent, Clark, J., and Barter, G. W., 1958. Growth and climate in and that these changes in distribution are related to the relation to dieback of yellow birch. Forest Science 4: 343-364. recent warm period. Thus, a virus disease could have its Cobb, Fields W., 1957. Pitch streak-a disease of turpentined arena altered or greatly expanded by fluctuations in slash pine. Naval Stores Rev. 67(9): 4, 5. Hepting, George H., 1955. A southwide survey for sweet- climate brought about by changes in the paths of cyclones gum blight. USDA Plant Dis. Rptr. 39: 261-265. and anti-cyclones. Broadbeit (5) stresses the point that Landsberg, H. E., 1958. Trends in climatology. Science 128: viruses spread fastest under conditions optimal for insect 749-758. multiplication and activity. Leaphart, Charles D., and Copeland, Otis L.,Jr.,1957. Root and soilrelationships associated with the pole blight When we consider how small a mean annual change of disease of western white pine.Soil Sci. Soc. of Amer. Proc. 2 or 3° F. seems to be, we must remember that many of 21(5): 551-554. our diseases are on the threshold of developing into Miller, Paul R., 1959. Plant disease forecasting. In Plant serious epidemics and that slightly milder winters, or Pathology Problems and Progress 1908-1958, p. 557-565. Univ. of Wis. Press, Madison. consistently hot summers, or steadily increasing evapo- Plass,GilbertN.,1959.Carbon dioxide and climate. transpiration with a little less precipitation, or a shift Scientific American 201(1): 41-47. in storm paths could tip the balance in favor of a pathogen Redmond, D. R.,1955.Studies in forest pathology. XV. or in favor of the physiogenic factors operating against our Rootlets, mycorrhiza, and soil temperatures in relation to birch dieback. Canadian Jour. Botany 33: 5 95-627. trees.Again, if a 2 or 3° warming of our Temperate Toole, F. Richard, 1959. Sweetgum blight. USDA Forest Zones over a half century seems small, it is well to reflect Pest Leaflet 37. that only about 18° F. separates us from the temperatures Van Arsdel, E. P., Riker, A. J., and Patton, R. F., 1956. of the ice age.I have been informed by Dr. Landsberg The effects of temperature and moisture on the spread of white pine blister rust.Phytopathology 46: 307-3 18. that the North American Continent is now the warmest Wellington, W. G., 1954. Pole blight and climate. Canad. it has been since about 900 A.D. Dept. Agr., Sci. Serv. Forest Biol. Div. Bi-monthly Progress Macro-andmicroclimaticconditionswillusually Rpt. 10(6): 2-4. , 1954.Atmospheric circulation processes and determine the severity of pathogens attacking the aerial insect ecology. Canad. Ent. 86(7): 312-333. parts of trees.Climatic variations will often determine , 1957. The synoptic approach to studies of the complex interactions among the soil organisms of the insects and climate. Ann. Rev. Ent. 2: 143-162. Forest Protection 845 Woods, Frank W., 1952. Disease as a factor in the evolu- Un accroissement de 2° ou 30 F. de Ia moyenne annuelle pour- tion of forest composition. Contrib. Botanical Lab., Univ. of rait determiner le dépérissement d'une essence dans d'énormes Tennessee, N. Ser. 147. proportions, et cela de plusieurs façons: 1) par nne reduction de Yarwood, C.E.,1959.Microclimate and infection.In l'humiditd du sol là oO l'approvisionnement en can était déjà Plant Pathology Problems and Progress 1908-1958,P. 548-556. dangerensement insuffisant; 2) en perturbant Ia lotte favorable Univ. of Wis. Press, Madison. des organismes antagonistes du sol contre les parasites des racines; et3)en étendant ou modifiant l'habitat des insectes porteurs RESUMES d'organismes pathologiques. Les changements climatiques et les maladies jorestières Imaginons le cas dune region hypothétique recevant 50 pouces de plule par an: il faudrait sattenare a cc qu'un accroissement de Le present rapport est divisé en trois parties principales:(1) temperature de 2° F. (moyenne pour l'année),soit de 50 a l'influence des facteurs climatiques sur les maladiescausées par 52° F. y accéière l'évapo-transpiration d'eviron 6 pour cent pen- des agents pathogènes; (2)l'influence des facteurs climatiques dant les mois froids et de 10 pour cent pendant l'été. sur les maladies physiogenes; et (3) comment les changements Bien qu'une telle moyenne annuelle de 2 on 3° F. paraisse a climatiquespourraientdeterminerlaregressiondecertaines premiere vue bien infime, ii ne faut pas oublier que nombre de essences forestières par des influences pathologiques. nos maladies sont au seuil de l'dtat endémique et que des hivers Parmi les maladies forestières causéespar des agents patho- légèrement moms froids, on des étés réguiierement plus chauds, genes, 11y a celles qui se rencontrent trés rarement, meme dans on un accroissement constant de l'évapo-transpiration jointe a une des conditions climatiques normales.Ensuite ily a ce qu'on reduction des précipitations, on encore un changement dans la peut appelerles maladies latantes dont un bon exempleest distribution des orages, pourraient perturber l'équilibre actuel en constitué par les rouilles.Ordinairement, la concomitance des favenr d'un agent pathogène on en faveur des facteurs physio- conditions nécessaires pour une épiphytie peutse produire tous genes défavorabies a nos arbres. Répétons-le, si un accroissement [estrojs a cinq ans seulernent dans une localitédonnée. Un de 2 ou3°F. de nos zones tempérées nous semble mfime au changement léger, mais continu, dans la temperature,ou dans le cours d'un demi-siècle, ii convient de ne pas oublier que seulement nombre de jours de brouillard on de pluie, pourraitrendre une 18° F. environ nous séparent des temperatures de la période gla- telle maladie endémique presque tous les ans,OU si les conditions ciaire,et que la temperature du continent nord-américain est changeaient dans le sens inverse, Ia maladiene prendrait une maintenant plus élevée qu'elle ne l'a été depuis l'an 900. forme épidémique que tons les 10 a 12ans environ. Nous arri- vons maintenant au troisième type de maladies, lesquelles sont si Los Cambios Climáticos y las Enfermedades Forestales bien armées pour se répandre, et sont si pen exigeantesen ce qui concerne les conditions climatiques, qu'elles sèment partout la Este trabajo está dividido en tres partes principales: primero, destruction, avec très pen de changements d'une année al'au- la influencia de los factores ciimáticos en las enfermedades can- tre, jusqu'à la destruction a pen près complete d'uneessence sur sadas por microbios patógenos; segundo, la influencia de los une vaste superficie. De telles maladies sont le chancre du châ- factores climáticos en las enfermedades fisiogenicas; y, finaimente, taignier, la flétrissure (Fusarium) de l'acacia (Albizziajulibrissin) la forma en que un cambio climático podria causar la recesión de et la maladie de l'orme subéreux. ciertasespeciesdeárbolesforestales a través de influencias Par maladies physiogènes, on entend celles qui sont causées patoiógicas. par des agents autres que des organisines vivants, commepar Entre las enfermedades de los árboies forestales causadas por exemple la sécheresse, l'excès d'humidité et lesgaz toxiques. Les los patógenos hay algunas que aparecen pocas veces ann en con- effets directs, an cours de périodes relativement courtes, de cala- diciones normales del tiempo. También hay aquellas enfermeda- mites météorologiques, telles que sécheresse, inondation, dégâts des endémicas que pueden convertirse en epidemias fácilmente. causes par Ia chaleur et autres, sont généralementmanifestes. El añubio es un buen ejemplo de este caso. En general, la con- Ces faits sont en général des changements météorologiques. Les comitancia de condiciones necesarias para ocasionar una epidemia syinptômes que présentent les arbres, et qui indiquentun état suelen presentarse en una misma localidad una vez cada tres o pathologique accentué, penvent apparaItre avec une soudaineté cinco aflos. Un cambio pequeño, pero regular en la temperatura moms frappante a la suite de modifications a long terme dans les o en los dIas de niebla o iluvia podrIa convertir esta enfermedad valeurs climatiques; a savoir, des changements de climat. en epidemia todos los aflos, o si las condiciones fueran exac- tamente opuestas, la epidemia podria ocurrir solo cada diez o C'est un fait maintenant bien établi que notre planètetraverse doce años. También hay un tercer tipo, qne está tan capacitado actuellement une période de réchauffement progressif,an moms para infectar y depende tan poco del clima, que avanza en ola depuis environ 1900, et l'on s'attend a ceque cette tendance destructora, variando solo en grado menor de nn año para otro continne.En général,l'amplitudedel'accroissementdeIa hasta que crea el caos en una especie a lo largo de on vasto temperature annuelle moyenne a été de l'ordre de 2° F. dans la territorio.Enfermedades de esta ciase son las que han atacado zone nord, et de 5° dans la region arctique. On a constaté de al castaflo, Ia mimosa y al olmo. facon positive quelestemperatures de l'eau de surface de l'Atlantiqne nord accusent des tendances de la même amplitude Por enfermedades fisiogénicas se entienden las que se deben que les changements a long terme de la temperature de l'air. En a agentes que no son organismos vivos, tales como la sequIa, ci Alaska, les glaciers reculent; le port de Spitsbergen est maintenant exceso de aguas y los gases tóxicos.Los efectos directos por perIodosrelativamentecortosde fenOmenosmeteoroiOgicos ouvert chaque année pendant nne période deux fois plus longue severos, como las sequias, las inundaciones, los daños causados qu'anx environs de 1912; en Finlande, la ligne limite de lazone por el calor y otros parecidos, son por lo regular bastante obvios. boisée avance vers le nord; et la ligne limite des neiges, les saisons Todos estos se deben, en general, a cambios del tiempo. Ciertos sans gel et, en général, les animaux et les plantes ont tendance sIntomas de los árboles, que indiqnen una marcada patologia, a se déplacer vers le nord. L'épaisseur de la calotte glaciaire du pueden ocurrir en forma menos repentina después de un cambio de Groënland a diminué dans de grandes proportions et le niveau des larga duración en las condiciones climáticas, esto es,cuando oceans s'est élevé de quelques pouces. ocnrren verdaderos cambios de clima. Ii eSt possible que le dépérissement constaté depuis quelques Es un hecho bien conocido que desde ci año 1900, por io années chez certaines des principales essences,et qui semble menos, el mundo tiende a registrar temperaturas más altas y que avoir des causes complexes, et dont nous recherchons toujonrs se espera que esto continue. En general, el grado de aumento l'origine, soit le fait de ce relIvement de la temperature. Men- del promedio de Ia temperatura anual ha sido de dos grados tionnons a ce propos certaines maladies très graves qui régnent Farenheit en la zona templada del forte y como de unos cinco aux Etats-Unjset an Canada, telles que le dépérissement du grados en el Artico. En las aguas superficiales del Norte del bouleau, Ia maladie dite de la "petite fenille" dn pin, Iacane Atlántico se han registrado tendencias positivas en las tempera- du gommier Liquidam bar styraciflua,la cane des perchis, la turas, las cuales concuerdan en graduaciOn con los cambios de maladie dite "pitch streak" (conlée de résine) des pins a téré- largaduración observados enlastemperaturasatmosféricas. benthine, et une regression générale des chênes. Etant donnéqne Los glaciares han retrocedido en Alaska; la bahIa de Spitzbergen tons ces cas représentent une regression très nette et non pas de está abierta ahora durante el año por un perlodo dos veces mayor simples migrations vers le nord on vers le sud le long de Ia quo en 1912; la ilnea de vegetaciOn de Finlandia se ha extendido ligne limite de l'habitat des essences considérées, ils ont retenu en dirección Norte; se ha registrado, también, un cambio hacia l'attention dn phytopathologiste plutôt que celle de l'écologiste. el Norte de las lineas de nieve, de las estaciones libres de hielo y 846 Fifth World Forestry Congress Proceedings de los animales y plantas.El grueso de la capa de hielo en cambiar el campo de acción de insectos que lievan a los organis- Groenlandia ha disminuIdo mucho y los nieveles oceánicos han mos causantes de las enfermedades. subido varios centimetros. En el caso de una region hipotética que recibe 1,270 mm. de El autor expone la teorIa de que la decadencia de algunas lluvia al año, un aumento promedio de la temperatura anual de especles principales de árboles ocurrida en años recientes, que 10° a 11,1° C. se supone que aumente la evapotranspiraci'n en parece obedecer a causas sumamente complejas o que toclavIa cerca de un 6 por ciento durante los meses más frIos y en un10 están por determinarse, bien pudo haberse iniciado durante este por ciento durante el verano. perlodo de aumento de temperatura.En tal sentido, se hace Aunque un cambio de dos o tres grados en el promedio referencia a algunas de las graves enfermedades ocurridas en los anual nos parezca ligero, también debemos tener presente que Estados Unidos y Canada, tales como la del abedul (dieback), muchas de nuestras enfermedades están a punto de convertirse del pino (littleleaf), del liquidámbar (blight), del pino trementino en verdaderas epidemias y que inviernos ligeramentetemplados, (poleblight y pitch streak), asi como la seria decadencia del roble. o veranos de calor constante, 0 Ufl aumento constantede la Debido a que estas enfermedades son simplemente migraciones evapotranspiración con un poco menos de iluvia, o un cambio hacia el Norte o hacia el Sur a lo largo de los lImites de creci- en el curso de las tormentas podrIa inclinar labalanza en favor miento de dichas especies, han despertado la atención del patólogo del patógeno o en favor de los factores fisiogénicos y en per- más bien que la del ecólogo. juicio de nUestros árboles. Repetimos, si Ufl aumento de dos o Hay varias formas en que el aumento medio anual de dos o tres grados en la temperatura de nUestras zonas templadas por tres grados puede causar la decadencia en grandes proporciones un perIodo de medio siglo nos parece ligero, debemos tener en de una especie:(1) mediante la pérdida de la humedad del suelo en lugares en que la escasez de agua de por si ya era cUenta que solona diferencia de 18° F. nos separa de las tern- crItica; (2) al ocurrir un desnivel en la competencia favorable peraturas de la edad glacial y que el continente de laAmerica contra los parásitos que atacan a las raices, causado por organis- del Norte registra ahora las temperatUras más altas que hatenido mos antag6nicos desarrollados en el suelo; (3)al aumentar o desde 900 A.D.

Weather and Insect Epidemics

W. R. HENSON Professor of Forest Entomology, School of Forestry, Yale University, New Haven, Connecticut, U.S.A.

Since the publication of Uvarov's monograph in 1931, of weather and the numbers of insects apparent at any there has been a general increase of interest in the field time is a dangerous one. Two particular dangers are of insect bioclimatology. The extent of Uvarov's review involved. The first is that dramatic changes in the size of suggests that an enormous literature existed prior to 1931 insect populations may be expected when the weather is and extended indeed to the beginnings of the systematic far from modal.It is at such times that the covariant study of insect natural history.It should be noted at the relationships between the components of weather break outset of this contribution that I am making no attempt down.The second danger comes from the fact that to review the literature pertaining to the effects of weather weather is a dynamic process taking place in a system of on insect epidemics.I shall try rather to view the field global extent. There are time lags and geographical dis- from those aspects of the relationship which I take to be placements in chains of causality within weather systems most critical or most deserving of further attention. I have and their dependent biological systems. In short, there are drawn my material from North American sources for the two serious dangers in the assumption of a causalrelation- most part. Those works to which I make reference are ship between a weather factor and its correlated biological chosen simply because they seem to me to offer particu- system.The first danger is that one has measured a larly convenient or powerful examples. covariant, but biologicallytrivial factor which is im- From the earliest times, there has existed a general perfectly related to the causal weather factor. The second body of lore concerning the effects of weather on insect is that one has measured the weather factor at the wrong outbreaks. This information has been accumulated from time or place and thus has formed an incorrect estimation the impressions of generations of acute observers working of the nature of the relationship. During recent years, powerful techniques have been in the forest and very much aware of the year-to-year evolved which avoid the difficulties I outline.Because changes in all aspects of their environments. As the keep- I feel these techniques are of transcendent importance in ing of records became more general, there grew up a the future of insect bioclimatology, I shall proceed with body of information which has made possible a very large this review following the lines which I understand to have number of gross correlations between the numbers of in- led to the present state of the field. sects apparent and some factor or factors of the weather. Since the concern of foresters and entomologists alike Many of these expressions remain very interesting to this with forest insect populations is, in truth, a concern with day but most of them suffer from the tacit assumption of a stochastic expression of individual insects' activities,it causality in the relationship expressed. is efficient to attack the problems of bioclimatology first The various components of the physical processes in from the study of individual insects rather than from the the atmosphere which we call weather are covariant, but initial study of group statistics. The first level of relation- not perfectly so.Thus, the assumption of causality as ship between insects and their environment comes in the applied to a derived gross correlation between a factor relationship between single insects and their microhabitats. Forest Protection 847 It has been recognized for some time that the micro- here that they exist and are a measurable characteristic climatic experience of insects is not thesame as that of insects. implied by ambient weather (1) *The internal environ- One very interesting facet of preferenda is that they ments of the insects are modified directly by radiation and are frequently subject to shift by two sorts of influences. evaporation (2, 35). Probably as important is the modi- The first of these is continued environmental stress which fication of the weather in the immediate vicinity of the shifts the preferendum in the direction of the stress. This insects by the physical characteristics of their habitats. is called "acclimation."It has been shown that the re- Location of the habitats on the tree, their orientation to sponses of insects to temperature (8), humidity (9), and sun and wind, and their color are all important (3). evaporation rate(10) can allbe influenced by the The form of many insectan habitats is species specific. A previous experience of the insects with respect to the number of quite distinct environments may be provided tested stress. The capacity of insects to withstand extreme from the same substrate by virtue of the differing physical stress can also be influenced by an acclimation process. properties of the habitats constructed by various insect This has been shown particularly with respect to tem- species (4). The effects of these special structurescon- perature (8). The mechanism of acclimation is not well structed by many insects may extend beyond the modi- understood, but there is considerable evidence (11) which ficationofthetemperatureand humiditytothe suggests that metabolic compensation takes the form of a modifications of rather fundamental sorts of behavior shift in metabolic pathways, at least in the case of tem- such as feeding patterns (5). perature compensation. It is impossible to discuss the effect of special habitat The physiological state often has a great deal to do with climates without being concerned with thevery close the response of an animal to an environmental stress. integration of behavior patterns and these climates. The As water is lost from the body of an insect, it may seek behavioral mechanisms which result in the construction wetter conditions (12). Food lack may have a similar of special habitats by insects arevery closely linked to effect (13). In this case, the gradient response is appeti- special behavior mechanisms by which the insectsare tive and, like all such behavior, tends to have an isostatic enabled to utilize their substrate.The best illustration effect.In other words, the behavior of a stressed insect of this point is offered by the lightresponses of tent- may be expected to be that which will tend to restore building defoliating caterpillars. Incommon with a very physiological balance. The selective advantage of such large number of insect types(for example, 6), these behavior is a perfectly good explanation of its universality. animals reverse their light orientation as their body tem- A further interesting facet of gradient responses is that peratures change through specific ranges. In Hyphantria the reaction of insects to one stimulus may often be modi- textor (7) the direction and threshold of the heat reversal fied by the level of another stimulus. This phenomenon of lightorientation change during the growth of the larvae. is most frequently observed with respect to light responses This change is such that the insects havea being modified by temperature (14, 6).Similar effects mechanismforescape from damaging temperatures are also known with respect to temperature and humidity throughout their residence in the tent.This mechanism acting in concert to modify light responses (12). A is modified throughout the growth period in sucha way further extension of such mechanisms is found in the way that it meets the changing situation represented bya tent in which factors which can evoke gradient responses can of increasing size, increasing frass accumulation, withcon- influence behavior only partly associated with the insects' sequent increase in absorbtivity, increasing ambient tem- direct response.For instance, atmospheric evaporation peratures, and radiant heating. affects silk-spinning behavior in spruce budworm (10). The mechanisms which are invoked in the positioning Both temperature and evaporation rate affect locomotion, of an insect within its physical environment dependto a feeding, and aggregation in the same insect (15). considerable extent on the existence of gradients within thatenvironment. I cannot hope in a few moments to suggest all the The leveloftemperature,light, ramifications of behavior patterns which are evoked by humidity, and evaporation rate allvary throughout the various factors which we call "weather." I hope, though, space to which each insect has access. Insects move along that I have suggested that insects as individual organisms these gradients and adopt positions where the level of the have a considerable number of rather simple responses to combined physical factors is closest to a "preferendum." physical conditions.Though these individual responses It may be as just to describe thesezones as locations are rather simple, they are subject to modification and which are least intolerable as it is to think of themas facilitation by covariant responses of many sorts. The most tolerable. By this, I mean that insects may adopt a result of this combination of rather simple elements is a given position because it is farthest from a source ofa very complex adjustment of insects to the world in which repelling stimulus or because it is closest toa source of they live. This adjustment is to some extent plastic. The an attracting stimulus. insect's behavior and its physiological capacity to with- Whatever the nature of the process which positions stand stress are both subject to modification.In any insects within a physical gradient, the fact that theseproc- population,therewillbeaconsiderablevarietyof esses take place has given rise to the concept of "Pre- physiological capacity to withstand environmental stress. ferenda" or preferred zones. There are difficulties in the Physiological characteristics vary much the same way as way of defining such preferenda either in terms of directed morphological ones and are subject to much the same response or in terms of insect optima.Suffice it to say sortof limitations.Much the same way as extreme morphological variationis marked by low Darwinian * Numbers in parentheses denote the references listedat the fitness, so is extreme physiological variation marked by end of this paper. failing homeostasis (16). A population has, nevertheless, 848 Fifth World Forestry Congress Proceedings considerable capacity to adapt by selection.Itis im- the more obvious effects of weather on populations of portant for us to hold in mind the possibility that the parasites where differential mortality can affect the bal- populations with which we are dealing are being subjected ance of populations, other, more obscure effects have to strong selective pressures and that rapid physiological been described.It is known, for instance, that the stress evolution is taking place. imposed by weather can affect the resistance of insects It is often very difficult to evaluate the ecological im- to disease and the rate of infection (30). portance of even quite striking events.The tendency These points serve to establish the necessity of starting toward compensationwithincovariantsystems may investigations of the effects of weather on insects with obliterate the effect of the most wide-spread processes. the examination of individual insects.Only on such a It is not uncommon to discover that a population is ap- basis is it possible to assess effects of weather on whole parently unaffected a mere generation following an event populations with the assurance that one is dealing with which killed the majority of the animals present at the a system of known attributes. time.Losses which are constant from generation to In nature, the relation between weather and insect generation are probably not so important in the determi- population levels is much more complicated than that nation of population level as those losses which vary implied by such direct effects as are involved in overt from year to year (17). A very powerful tool for the mortality following an isolated weather displacement. isolation of critical mortality factors in each generation The reasons for this complexity lie in the multiplicity of experience is the construction of life tables (18, 19). In interactions within a natural community (24, 25). We the analysis of mortality experience, it is common to find must therefore consider what means are available for the that two sorts of processes which have to do with weather analyses we wish to conduct. may influence the survival within any generation. The As I have already suggested, the first step is the exami- most obviousoftheseisdirectmortality following nation of individual insects in their catastrophic weather modification.The nature of this and a rigorous description of that environment and its weather event may be extreme winter conditions (20), relationship to ambient conditions (1).Once this has extreme displacement of precipitation (21, 22), phen- been done, the behavior of the insect and its other re- ological upsets of various sorts (23), or a variety of such sponses to a range of conditions which it encounters in disasters (24, 25). An important and similar sort of nature may be described (31, 15, 32). Various specific influence is much less dramatic but still involves direct mechanisms, such as acclimation (33), the selection of mortality attributable to discrete weather events.Re- sites for specific activity by the insects (34), behavioral peated sequences of weather events, each of which cause modification of various physical processes (5, 35), ag- small amounts of direct mortality, may modify populations gregation (36), dispersal (37), and competition (38) extensively (26, 27). will have to be investigated. In addition to the direct mortality which follows some During the course of these investigations, the range of sorts of weather events, there is an important sort of individual variation will become apparent. This range is indirect mortality. An example of this is to be found in an important characteristic of the population.On it the very high dispersive losses suffered by populations of depends the capacity of the population to survive various spruce budworm in the Maritime Provinces of Canada. stresses. The nature of the range determines the potential These losses may be attributed to the weather inasmuch of the population with respect to various selective proc- as the behavior which leads to dispersal is initiated by esses.The implications ofthispoint have occupied discrete events in weather (19, 28). students of evolution for many years and, recently, forest Though large-scale mortality following discrete weather entomologists have been directly concerned (39). As events is rather easy to detect and even to measure, the seasonal weather changes from year to year, the selective most important effects of weather on populations may be pressure under which the population exists will change. of rather a different sort. The size of the habitat may be The capacity of a population to withstand such stress may limited by weather (29). Probably more common is the depend on the distribution of behavioral and physiological mediation of population efficiency by changes in seasonal types (40). The point is most obvious in clonal colonies weather. of gregarious insects but it probably applies to a great When one starts to consider the effects of weather on variety of populations. Certainly the dispersive capacities a population of insects in nature, one must at once face and general population vigor may be affected by the the fact that no population is in ecological isolation. The weather, either by selective processes (40) or by a trig- weather which one observes affects not only the popula- gering of physiological responses by environmental stimuli tion under observation but all of the secondary popula- (41). tions which depend on the primary pest, the plants which There remains a whole area of analytical difficulty in support the pest, and the various mechanisms on which assessing the role of weather and climate in population the interactions of these populations depend. The com- dynamics of insects.The heart of the matter is the plications which arise from this very elaborate interaction bewildering variety of weather encountered by natural would make analysis of weather effects as such almost populations and the crushing accumulations of physical impossible if one depended on simple correlation methods. data which seem to be required for the description of I think it just to suggest that some of the frequent dis- weather sequences. There have been two main lines of appointments which have attended attempts to predict approach to this series of problems. The first and most population response to weather may arise from the tacit obvious technique is to derive some statistical index of assumption that an analysis has applied to a system con- each of a series of weather factors and simply compare sisting only of the pest and the weather. In addition to the expression with population figures either by graphic

Forest Protection 849 or statistical means(42, 43).The advantages of this The line of reasoning and investigation outlined in this approach are mainly didactic.It is rather easy to ap- paper is apparently rather remote from the daily prob- preciate the nature of a relationship from the inspection lems of forest entomology.Its importance springs from of a set of graphs. The disadvantages of the approach the fact that a great deal of the future of forest entomology are those which I outlined in the first part of this con- certainly lies in the hope that prediction of population tribution. changes will become possible.investigations are needed A much more sophisticated analysis may be done on to make possible the assessment of the importance of the basis of ecological studies such as those I have out- climate in overall population change (17). The same lined. From such studies, it frequently becomes apparent researches also lead to those more advanced investigations that certain sorts or periods of weather conditions are on which predictive understanding of bioclimatological critical.It is possible to determine by the methods of relationships must be based. meteorological analysis under which circumstances such There is an area which is apparently untapped at the critical conditions can arise. When this has been done, moment. It goes without saying that all the components field and other investigations can be concentrated on of a biological system respond to their physical environ- periods which offer good examples of those sets of con- ment to some extent. Though it has been possible in a ditions.The approachisdirectlyanalogous tothe number of cases to investigate the effect of climatic con- synoptic approach to the analysis of weather (44). When ditions on two populations of insects in competition (38) the relationships between the weather of type days and and on such systems as an insect and its parasite (48), the activity and response of the insects have been de- it has proved very difficult to investigate whole systems scribed,itispossible to express the effect of entire in the field.Such investigations would have to include sequences of weather by a simple extension. the plants as well as the animals. The well-known re- The application of the synoptic approach to the analy- sistance mechanisms of conifers to bark beetle attack, sis of insect bioclimatology is most conveniently started for example, are certainly mediated by weather. At the by an analysis of the regional weather in terms of synoptic same time, the bark beetle activity is affected by the climatology.The weather sequences over a period of same weather. The interaction between these two sorts time are examined and the origin of thesignificant of effects presents an important field for future investiga- weather is described in terms of its airmass processes tion.Some theoretical basis for such investigations has (45). Type days for field study are selected which offer already been provided (49). The eventual goal of these good examples of these various airmasses and their ecological investigationsis the evolution of techniques interactions.It is not essential to record and analyze which will make possible the understanding of whole long sequences of weather since the relationships between ecological systems. In the long run, we must be prepared overall conditions and insect response will be similar as to direct our attention to the investigation of the forest as long as the overall pattern of the weather is unchanged. a metabolic engine. This engine is driven by the sun as The biological effects of whole sequences of weather the energy source, and its various components act in can be expressed in terms of the frequency and persistence ways which reflect the energy distribution of the whole of weather types (46). Indeed, the biological effects of system.The utilization and transformation of energy such major weather events as changes in circulation pat- takes place in a manner which must be conditioned by terns can be assessed by the use of normal methods of ambient conditions.In the course of time, we should airmass climatology (47). reach the point where we can start to understand this Because the available habitat within any region for relationship and turn it to our advantage. any insect is not uniform, under any given circumstances a considerable degree of physiological variation within a References population is of considerable selective advantage. Again, Wellington, W. G., 1950. Sci. Agric. 30: 209-234. because conditions vary from season to season, genetic Shepherd, R. F., 1958. Can. J. Zool. 36: 779-786. variability which provides for adequate selective response Henson, W. R., and R. F. Shepherd, 1952. Can. J. Zool. 30: 144-153. to seasonal changes is a necessity.It has been possible Henson, W. R., 1958. Can. J. Zool. 36: 463-478. to demonstrate(39)that the constitution of a population Henson, W. R., 1958. Can. J. Zool. 36: 809-818. which can survive unfavorable conditions is quite dif- Perttunen, V., 1959. Ann. Ent. Fenn. 25: 65-71. ferent from that of a population which can respond to Wellington, W. G., C. R. Sullivan, and W. R. Henson, 1954. favorable conditions. An interesting point which emerges Canad. Ent. 86: 529-542. from this study is that the part of the environment within Baldwin, W. F., 1954. Can. i. Zool. 32: 157-171. which a population survives an unfavorable period of Riegert, P. Wm., 1958. Canad. Ent. 90: 680-685. Wellington, W. G., 1950. Trans. Roy. Soc. Can. 44 section weather is probably the least favorable for the species 5 Ser. 3: 89-100. under conditions which permit general increase.The Bullock, T. H., 1955. Bio. Rev. 30: 311-342. whole field of the response of populations as biological Green, G. W., 1954. Canad. Ent. 86: 261-274. entities to the stresses imposed by changing weather from Willis, E. R., and L. M. Roth. Jour. Exp. Zool.115: 561-587. season to season is only now coming under investigation. Perttunen, V., 1958. Ann. Ent. Fenn. 24: 12-18. Certainly, the explanation of many obscure relationships Wellington, W. G., 1949. Sci. Agric. 29: 201-215. between insects and weather must lie in the probability Prosser, C. L., 1955. Biol. Rev. 30: 229-262. that the constitution of the population, as wellas its Morris, R. F. et al, 1958. Proc. Xth mt. Cong. Entom. V. 4: 137-149. numbers, is to a considerable extent determined by the Stark, R. W., 1958. Proc. Xth mt. Cong. Entom. V. 4: physical environment. 15 1-162. 850 Fifth World Forestry Congress Proceedings Morris, R. F. and C. A. Miller, 1954. Can. J. Zoo!. 32: Wellington, W. G., 1952. Can. J. Zoo!. 36: 114-127 28 3-30 1. Wellington, W. G., 1954. Canad. Ent. 86: 312-333. Henson, W. R. et al, 1954. Canad. Ent. 86: 13-19. Burnett, T., 1949. Ecology 30: 113-114. Hall, R. C.,1958. Proc. Xth mt. Cong. Entom. V. 4: Odum, H. T., 1960. Amer Sci. 48: 1-8. 34 1-347. Key, K. H. W., 1957. Austral. Mus. Mag. 12: 209. RESUMES Blais, J. R. et al, 1955. Canad. Ent. 87: 1-8. Solomon, M. E., 1949. J. Anim Ecol. 18: 1-35. Le temps et les invasions d'insectes Glen, R., 1954. J. econ. Ent. 47: 398-405. Pour analyser les effets des conditions météorologiques sur les Davidson, J. and H. G. Andrewartha, 1948. J. Anim. Ecol. populations forestières d'insectes, il convient d'examiner d'abord 17: 193-199. les facteurs qui affectent la vie des sujets isolés. Les caractéristi- Chant, D. A. and J. H. McLeod, 1952. Canad. Ent. 84: ques climatiques de l'habitat, les modes de comportementet la 174-180. mortalité évidente doivent être examines en fonction du temps. Henson, W. R., 1951. Canad. Ent. 83: 240. Ceci fait,il devrait être possible d'établir un rapport entre les Graham, S. A. and D. R. Satterlund, 1959. For. Sci. 5: conclusions de ces travaux et l'expérience de la population, grace 28-36. a l'utilisation des techniques de la climatologie synoptique. Cette Steinhaus, E. H., 1958. Proc. Xth Tnt. Cong. Entom. V. 4.: méthode permet de mesurer les effets du climat dans la mesure 725-7 30. oii ils sont ressentis par l'élément insecte du système écologique Vité, J. P. and J. A. Rudinsky, 1957. For. Sci. 3: 156-167. forestier.Le but final des travaux bioclimatologiques devrait Jacobson, L. A. and P. E. Blakeley, 1957. Canad. Ent. 89: être d'examiner le temps et le climat en fonction de la totalité de 465-469. l'écologie forestière. Baldwin, W. F., 1959. Can. J. Zool. 32: 157-171. Ives, W. G. H., 1955. Canad. Ent. 87: 301-310. El Tiempo y las Epidemias de Insectos en los Bosques Parry, D., 1951. J. exp. Biol. 28: 445-462. Chapman, R. F., 1955. J. exp. Biol. 32: 126-139. Para el estudio de los efectos del tiempo en las poblaciones de Rainey, R. C., 1951. Nature 168: 1057-1060. insectos de los bosques hay que comenzar por un examen de Park, T., 1954. Physiol. Zoo!. 27: 177-238. los factores que afectan a cada insecto de por si.Es necesario Wellington, W. G., 1957. Can. J. Zoo!. 35: 294-323. considerar las caracterIsticas del ambiente, la conducta del insecto Wellington, W. G., 1960. Can. J. Zoo!. 38. (In Press) y la mortalidad evidente en relación con el tiempo.Hecho esto, ha Shull, F. A., 1935. Biol. Bull. 68: 35-50. de ser posible relacionar las conclusiones con lo observado en las Davidson, J. and H. G. Andrewartha, 1948. J. Anim. Ecol. poblaciones empleando técnicas de climatologIa sinóptica.De 17: 200-222. esta manera es posible apreciar los efectos del tiempo en lo que Birch, L. C., 1957. Cold Spring Harbor Symposia 22: 203- respecta al componente de insectos del ecosistema forestal.La 218. mira de las investigaciones bioclimatológicas debe ser el examen Wellington, W. G., 1957. Ann. Rev. Ent. 2: 143-162. del tiempo y clima en su relación con el conjunto de la compleja Henson, W. R., 1959. Jour. Meteorology 16: 585-588. ecologIa del bosque.

Control of Lightning Fires in

J. S. BARROWS Chief, Division of Forest Fire Research, Intermountain Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture, Missoula, Montana, U.S.A.

From the beginning of forestry in America, fire control 39 States. The annual cost of lightning fires is estimated has been a major concern.In vast areas of American to be more than 25 million dollars. As aresult of the forests, the climate and the nature of the vegetative magnitude and importance of this problem, a significant complex is such that a mass of flammable fuel is created. part of American forestry science deals with thecontrol In this environment almost any source of ignition may of lightning fires and methods for reducing their damaging createdamagingfires.Theactivitiesof man,and effects on timber, watershed, recreation, and other values especially hisactivitiesin areas of rapidly expanding of the forest resources. populations, provide ample sources for the ignition of forestfires.But in many American foreststhereis Lightning Fires in the Western United States another potent source of ignition. This source is lightning. While lightning fires occur in many regions of the Fire-setting lightning storms cause great damage to country, the problem is most severe in the WesternUnited forests in the United States (1) *About 7,500 lightning States. In the 13 Western States, including Alaska, more fires occur annually During years when there is a critical than 132,000 lightning fires occurred during the 20-year combination of dry weather and lightning storm activity, period 1939-1958 (Table 1). Forest protection organiza- a much larger number of fires may occur. In 1958, more than 10,000 lightning-caused forest fires were reported in tions in the three Pacific Coast States must combat an annual average of 2,644 lightning fires.In the Rocky Mountain States, 69 percent of all fires are started by * Numbers in parentheses denote the references listed at the end of this paper. lightning. Forest Protection 851 Table 1.Lightning fire occurrence in the Western United States Intermountain Forest and Range Experiment Station of Percent of the U.S. Forest Service organized a long-range research all fires program known as Project Skyfire to investigate some of 20-year Annual caused by the critical features of lightning fire control (3). Project State period average lightning Skyflre, which is being carried out with the assistance of Alaska* 622 33 23.2 several private, State, and Federal agencies, has two Washington 10,547 527 28.8 broad objectives: first, to gain a basic understanding of Oregon 20,340 1,017 52.5 the occurrence and behavior of lightning-caused forest California 21,992 1,100 29.1 fires and the characteristics of the stonns that produce Montana 12,429 621 70.2 these fires; and second, to develop methods for suppres- Idaho 20,383 1,019 68.7 sion of lightning fires, including study of cloud modifica- Wyoming 2,000 100 59.6 tion as a possible means of preventing or reducing the South Dakota 2,130 107 62.0 severity of lightning fires (6). Colorado 3,105 155 35.9 Arizona 25,963 1,298 84.6 Cloud and Lightning Survey New Mexico 10,884 544 79.7 One of the first research jobs of Project Skyfire was to Nevada 613 31 32.5 make a cloud and lightning survey in the northern Rocky Utah 1,794 90 34.2 Mountains. A special network of 22 forest Totals 132,802 stations was established for cloud and lightning observa- 6,642 47.2 tions in Montana, Idaho, northeastern Washington, east- * Alaska data incomplete for 1939-1949 period. ern Oregon, and northwestern Wyoming (14).The observers at these stations were trained to obtain specific Alaska also has a severe lightning fire problem. Dur- information on cumulus cloud development, area and time ing the nine-year period, 1950-1958, lightning started distribution of lightning storms, and number of strikes 549 fires which burned 7,665,727 acres in the new State. per storm. A map was prepared for each lightning storm Although lightning caused only 22 percent of the total showing the general area covered and the direction of number of fires, this ignition source accounted for 76 travel (5). The survey also included the measurement percent of the area burned. In 1957, a siege of lightning of standard meteorological variables such as wet and dry fires was primarily responsible for the burning of nearly bulb temperatures, precipitation, and wind velocity. 5 million acres in the Alaska interior. The results of the cloud and lightning survey have provided information useful to lightning fire control plan- Research in the northern Rockies has shown that the ning and to other aspects of the research program. The greatest number of lightning fires occur near the summit following general characteristics of lightning storms in of forested mountains (1).In studies of more than the northern Rocky Mountains were revealed (11): 13,000 fires in western Montana and northern Idaho, it The number of lightning storm days per national was found that lightning fire occurrence increased in each forest per fire season varied from an average of 1,000-foot elevation zone from the valley bottoms to the 17 in relatively low lightning occurrence areas mountain tops. At elevations of 2,000 to 3,000 feet above to a high of 44 in the more severe lightning sea level, the average annual occurrence was 33 lightning areas. fires per million acres. In the 5,000- to 6,000-foot eleva- Most lightning storms have a relatively short tion zone, the occurrence increased to an annual average life. About one-half of the lightning storms had of 74 lightning fires per million acres.In the national a duration of 30 to 90 minutes. Some 15 percent forest of this region having the greatest number of light- of the storms lasted less than 30 minutes, and ning fires, the range was from 22 fires per million acres only 4 percent lasted longer than 300 minutes. in the lower elevation zone to 177 in the upper zone. One Many storms produced a relatively low number small area aboe 7,000 feet on the same national forest of cloud-to-groundstrikes.Studies of1,027 had an average annual occurrence of 441 lightning fires storm periods showed that about 50 percent had per million acres. 10 or less strikes to ground. The five percent A critical feature of the lightning problem in western of the storms which produced more than 100 forests is the outbreak of a very large number of fires strikes accounted for more than one-third of in a short period of time. During a 10-day period in strike total in the study. July 1940, the national forests in western Montana and A large number of lightning storms produced northern Idaho reported 1,488 lightning fires. During the relatively little precipitation. During a four-year same outbreak, 335 lightning fires occurred in a 24-hour period, some 50 percent of the storms produced period (1). Such an outbreak of fires places a sudden less than 0.1 of an inch of precipitation. Another and very groat task of firefighting on forest protection 20 percent produced from 0.1 to 0.2 of an inch organizations.Ability to cope with this problem often of precipitation.The occurrence of so many determines the degree of success of the fire controlsys- relatively dry storms in this area illustrates one tem. of the reasons for the large number of lightning fires. Research Program Lightning storms studied in a specially instru- The various aspects of the lightning fire problem have mentedareainthemountainsofwestern been the subject of research for many years. In 1953, the Montana had high cloud bases and were rela- 852 Fifth World Forestry Congress Proceedings tively shallow in total height. The average cloud the major effort was from the ground. A special ground- base was approximately 12,000 feet above mean based silver iodide smoke generator was developed for the sea level. The average cloud tops were at 27,000 experimental program (10). This generator is capable feet above m.s.l. of producing a very large number of nuclei and has ahigh efficiency rating.Calibration tests show that this genera- Measurement of Lightning Discharges tor has an output of 2 or 3 x 1 Q'nuclei per second, One of the objectives of the Project Skyfire research effective at _200 C. program is to gain a better understanding of lightning Operation of a network of 30 ground-based generators discharges,including the possible relationship of the spaced one-half mile apart in a western Montana experi- electricalproperties ofstrikesto their potentialfor mental area during 1957 and 1958 provided a good test of ignition of forest fuels.During 1958 and 1959, pre- proposed cloud-modification techniques.These experi- liminary studiesof these characteristics were started. mentsdemonstratedthatsomedegreeofcloud The instrumentation in the study area includes a network modification could be achieved.The results indicated of electric field meters.These instruments permit the that glaciation was produced in seeded clouds and that recording of intra-cloud and cloud-to-ground strikes and growth and structure of some clouds was altered. The the calculation of the electrical moment of the discharges. results also showed that virga, both solid and liquid, oc- The preliminary data from these measurements of curred as a result of seeding some cumulus clouds (6). lightning show that about one-fourth of the discharges Following completion of the 1958 experiments, the are cloud-to-ground strikes. Comparison of the measured Project Skyfire research staff concluded that the most strikes from the recording network with counts made at fruitful approach to modifying lightning storms would be fire lookout stations showed that the observers can visually achieved by the use of airborne silver iodide generators. detect only about 20 to 25 percent of the number of Analysis of the results obtained with the network of cloud-to-ground strikes that actually occur. ground-based generators indicated that insufficient nuclei Research has not progressed far enough at this date were being delivered to the base ofthe clouds selected to determine the possible relationship of lightning strike for treatment.Preliminary experiments with airborne intensity to fire starting potential. In one storm period, generators indicated that this method offered a far greater 129 cloud-to-ground lightning strikes fell within range possibility of delivering a large number of nuclei to the of the electric field meter network.Fires started from clouds. Theoretical studies showed that the goal should be three of these strikes.Analysis of the field meter data to deliver 10,000 nuclei per liter at cloudbase (8). indicated that the strikes causing fires were no more in- As in the case of ground-based generators, theeffective tense than other strikes in the area (11). The information dispersal of cloud-seeding agents from aircraft required presently available is not adequate to draw firm conclu- the development of special equipment for this purpose. sions on the intensity of fire-setting lightning strikes. In 1959, the Project Skyfire staff developed an efficient, These investigations will be continued. high-output silver iodide smoke generator for use on light aircraft (9).This generator, which employs a ramjet Cloud Modification principle in burning silver iodide in an acetone solution, From the time that the initial discoveries were made in has an output about two orders of magnitude greater than the field of weather modification, foresters and meteor- the Project Skyfire ground-based generator. Also, the tests ologists have speculated on the possibility that cloud- of the generator indicate a production efficiency of about seeding methods might be developed for the prevention of 4 x 1 0nuclei per gram of silver iodide. Development of this new airborne geierator accomplishes one ofthe lightning fires (15). This possibility is being thoroughly the investigated by Project Skyfire. essential steps for experiments aimed at determining At the outset of the Project Skyfire research in weather effects of heavy seeding on lightning characteristics. modification, analyses of lightning storm theory and of Concurrent with the development of the airborne gen- the characteristics of cloud-seeding agents indicated that erator, an area on the Deerlodge National Forest in west- efforts to alter the storms required the delivery of large ern Montana was selected as thesite for a series of quantities of nuclei to the cloud system. During prelim- cloud-seeding experiments.This area was identified by inary research, both dry ice and silver iodide were in- the cloud and lightning survey as a zone of intenselight- vestigated as cloud-seeding agents (4). Because of the ning occurrences.In 1959, this area was specially in- relative ease of employment in large quantities, silver strumented for measurement of lightning characteristics. iodide was selected as the agent for an intensive experi- The instrumentation includes a mobile radar unit, a net- mental program.Silver iodide crystalsserve as ice- work of electric field meters connected by land line to a forming nuclei at a theshold temperature of about 4° C. central recorder, standard weather stations, and several The cloud modification mechanism in the experiments time-lapse camera stations. The same area will alsobe used by the Physical Science Laboratory of the U.S. requires the conversion of supercooled water droplets to elec- ice crystals.Furthermore, the theoretical considerations Weather Bureau in basic research on atmospheric of lightning formation indicate that this conversion of tricity and lightning discharges. water droplets to ice crystals should take place on a massive scale. Future Lightning Experiments During a three-year period, a series of cloud-seeding The researchaccomplished todate haslaidthe experiments was conducted in northern Arizona and west- essential foundation for more intensive studies of lightning ern Montana (6). While seeding was performed with both characteristics and the effects of heavy seeding. In 1960, airborne and ground-based silver iodide smoke generators, a two-year program of experimentswill begin at the

Forest Protection 853 Deerlodge National Forest site.This program will be by a lightning storm. While the lightning strikes may not conducted with the assistance of the National Science be detected by the radar, the storm path will be clearly Foundation and the U.S. Weather Bureau. The character- shown.Sferics receivers may indicate which parts of a istics of each lightning storm will be observed, measured, storm system areactually producing cloud-to-ground and analyzed. Through a system of randomization,some lightning strikes.This information can be relayed to of these storms will be seeded by two aircraft employing patrol aircraft so that they may fly to the area involved the new ramjet silver iodide smokegenerator. The results for fire detection operations. As a result, much time and of the seeded and nonseeded storms will be comparedto effort may be saved in detecting lightning fires.This determine the possible. effects of the seedingon lightning method might be especially useful in remote areas such frequency and individual strike characteristics. as Alaska. Searching for lightning fires while they are in One basis for the design of the experimentsnow being their incipient stages in millions of acres of wilderness conducted comes from the results of earlier tests using forests is like searching for needles in a haystack. When both ground seeding and airborne seeding in comparison radar has mapped the storm path only this particular with unseeded situations. A study by Fuquay of 28 area need be searched from patrol aircraft. In areas con- lightning strikes occurring in an experimentalarea for- taining fire lookout stations, radar storm tracking also merly used by Project Skyfire indicated that theaverage may prove useful.Identification of the storm area will electrical moment per lightning strikewas reduced in permit the lookout observers to pay particular attention the heavily seeded cases as compared to the lightly seeded to it and may speed up fire detection. or unseeded cases (8). His data are shown in Table 2. A future part of the Project Skyfire research effort will be aimed at developing techniques for the use of radar Table 2. Electrical moment of lightning strikes during seeded and as an aid in lightning fire control. This research effort nonseeded situations willutilize new radar facilities being developed near Average Missoula, Montana. A mountaintop weather radar station electrical to be erected by the U.S. Weather Bureau on an 8,000- Treatment Estimate of Number moment foot peak will be connected by a microwave relay system nuclei/liter of (coulomb- Standard to radar scopes in the Missoula Fire Weather Forecaster's at cloud base cases kilometers)deviation Office and the new Northern Forest Fire Laboratory. No seed Less than 10 8 232 121 Forest Service research personnel at the laboratory will Ground use this radar system in studies of several possible new seeding 50-3 00 17 92 26 techniques for lightning fire control operations. The in- Aerial vestigations will include the rapid production of lightning seeding Greater than 3 42 6 storm maps from radarscope photographs and area rating 10,000 of fire danger according to precipitation zones indicated by the radar. The number of cases involved in these preliminary Lightning Fire Control Systems experiments is insufficient to warrant any conclusions at present.However, the future experiments should aid The results of research plus the experience of many materially in determining the effect of heavy seedingon years of firefighting have shown that there are several reducing the electrical moment of lightning discharges key requirements in developing adequate systems for the and possibly in making other changes in lightning char- control of lightning fires(1).These include: a fire- acteristics. The results should bring us closer to answering weather forecasting and fire-danger rating system; a detec- the question of whether or not lightning firesmay be tion system for the rapid discovery, location, and reporting prevented or reduced in severity by cloud-modification of fires; and a highly flexible suppression force capable operations. of being moved rapidly to fire areas. use of Radar Fire-Weather Forecasting and Fire-Danger Rating Radar is a useful tool in lightning research andmay Advance warning that a lightning storm may hit a have important future applications in lightning firecon- specific area is fundamental information for a fire control trol.Since 1956, Project Skyfire has operateda mobile organization. For many years the U.S. Weather Bureau radar unit during the various experiments conducted in has been makingforecastsoflightningoccurrence. Arizona and Montana. This unit, assembled from surplus Advances in the science of meteorology, coupled with military lO-centimeter radar, is mounted ina specially experience in the fire-weather forecasting problems of the built house trailer, permitting it to be towedover moun- various forest regions have contributed measurably to the tain roads. Power is supplied by a gasoline engine driving accuracy of the lightning predictions. However, lightning a 3.5 kw. generator. This radar has proved effective in forecasting remains as one of the critical problems in detecting, tracking, and analyzing lightning storms. Time- lightning fire control. This is especially true with respect lapse photography of a slave scope is used to record the to the identification of local areas that may be hit by storm images for future detailed analysis. lightning,the prediction of storm intensities, and the Experience in the use of radar indicates that itmay forecasting of precipitation amounts which may accom- be developed for use as an aid in lightning fire detection pany storms. Detailed analysis of all types of lightning and analysis of the characteristics of lightning storms. storms is one of the essential research undertakings to Observation of a radar scope can show thearea covered advance knowledge in this field (7).

854 Fifth World Forestry Congress Proceedings Development and use of radar facilities will be one of more efficient in detecting firesthat smoke up quickly the important steps in improving the lightning warning afterorigin.However, the combined lookout-aircraft and forecasting system. In addition, the continued devel- method reduces the number of fires which hang overfor opment of methods and equipment for the measurement more than 24 hours before being detected. of local meteorological factors will contribute to advances in both fire-weather forecasting and systems for fire- Suppression of Lightning Fires danger rating. Recent work at the Northern Forest Fire Because large numbers of lightning fires may occur in Laboratory has resulted in the development of improved a short period of time, thefire-suppression force needs instruments and stations for the measurement and record- to be a highly flexible organization capable of being ex- ing of fire-weather information (16, 17, 18, 19, 20). panded rapidly to meet emergency situations.Also, this Also, a simple numerical system has been developed for force needs to be especially mobile so that it can bemoved reporting the various stages of cumulus cloud develop- quickly to the forest areas hit by lightning. ment (12). At one time the method used to achieve fastinitial Another essential part of lightning fire control opera- attack of lightning fires in the Western United States was tions is the employment of a system for the rating of fire to disperse a large number of individualsmokechasers danger. In this activity the various meteorological factors and small crews in the forest areas. This method provided and measurements of the moisture content of fuels are relatively fast initial attack of fires.Studies made in the integrated to provide a single numerical rating of fire northern Rocky Mountains showed that this method per- danger (13).This rating provides the forest manager mitted some 80 percent of all fires to be attacked within with a uniform method for evaluating the possibilities 8 hours after discovery (1). However, this method was for fires to start and spread.During periods when a costly and did not facilitate the strengthening ofinitial large-scale outbreak of lightning firesis imminent or attack on especially dangerous fires, nor did it foster occurring, fire-danger rating is especially important. Such fast and strong reinforcement action. ratings for various forest areas indicate the priorities for The greatly increased use of aircraft in fire control and fire-detection operations and the dispatching of suppres- the employment of has resulted in the sion forces to fires that are reported. development of the highly flexible organization which is so important in the suppressionof lightning fires. Studies Detection of Lightning Fires of action in the northern Rockies show that controlled within From the beginning of intensively organized fire control some 90 percent of the fires attacked are 24 hours. in the Western United States, the fire lookout station Many fires are still attacked and controlled by fire- has been a major means of lightning fire detection. How- fighters who travel on the ground. However, with the ever, experience has shown that it is not economically the forest feasible to attempt to make rapid discoveries of all light- availabilityof an aerialfirefightingforce, ning fires by this means. During the course of a fire manager now has greater freedom toselect the type and season, lightning storms may occur over millions of acres strength of attack which is best suited to each situation. offorestlands.Furthermore,during some seasons storms may be intense over one area while another may Future Developments have little if any lightning.For these reasons, the sole The menace of lightning fires to the achievement of dependence on a fire lookout system for lightning fire necessary and protectionobjectives detection would require hundreds of stations, many of will remain as a critical problem in American forestry which might not be fully and profitably engaged in the for many years to come.Continued research on this discovery of fires. problem and experience in firefighting can be expected to Development of high-performance, light aircraft has further advance man's ability to cope with it.Many provided a very satisfactory answer to the lightning fire promising developments are on the horizon. The use of detection problem.Aircraft patrols following lightning firefighting chemicals dropped from aircraft is in an ad- storms are made over the areas where lightning may have vanced stage of development. Future advances in forest occurred.This method calls for the combined use of fire meteorology, electronics, and knowledge of fire be- lookout stations and aircraft. A few strategically located havior should further the solution of the problem. The lookout stations assist in keeping track of the general goal will continue to be the full development and applica- zones hit by lightning.The lookotitsalso serveas tion of all sciences which can aid in perpetuation of forest meteorology and communication stations.Information resources for the benefit of future generations. reported from these stations is relayed to patrol aircraft. The lookout stations are located in areas where they can References best serve these functions and also can keep critical fire Barrows,J.S.,1951.Forest fires in the northern Rocky areas under constant surveillance. Mountains.U.S. Forest Service, Northern Rocky Mountain Studies of the results of the combined lookout station- Forest and Range Experiment Station.Sta. Paper 28. ,1951.Fire behavior in northern Rocky Moun- aircraft patrol method of fire detection show that it has a tain forests.Sta. Paper 29, Northern Rocky Mountain Forest relatively high degree of efficiency (1). Under both the and Range Experiment Station. old method of using only lookouts and the new method , 1954.Lightning fire research in the Rocky of combined lookout-aircraft detection about 60 percent Mountains. Jour. Forestry 52 (11): 845-847. ,Schaefer, Vincent J., and MacCready, Paul B., of the fires are discovered within 10 hours after origin. 1954.Project Skyfire, a progress report on lightning fire and The combined method provides greater flexibility for atmosphericresearch. ResearchPaper35,Intermountain thorough searches in criticalfireareas.Lookouts are Forest and Range Experiment Station. Forest Protection 855 , 1956. The Skyfire cloud survey. Paper presented RESUMES at l43d national meeting, A. M. S., New York City. , 1958.Project Skyfire.Final report of the Lutte contre les incendies causes par la foudre dans les advisory committee on weather control, Vol. II,Washington, forêts américaines D.C. Les incendies de foréts provoqués par la foudre constituent l'un Colson, DeVer, 1957. Thunderstorm analysis in the north- des plus gros problèmes des forêts américaines. Chaque année, ern Rocky Mountains.Research Paper 49, Intermountain aux Etats-Unis, près de 7.500 incendies de foréts sont provoqués Forest and Range Experiment Station. par Ia foudre. Ces incendies sont particulièrement graves dans Fuquay, D. M., 1959. Some thunderstorm statistics for the l'ouest oui des efforts intensifs doivent étre exercés pour protéger northern Rocky Mountain region. Paper presentedat Skyfire la forêt contre cette menace. conference on thedesign and conduct of experiments in Le present rapport passe en revue le projet "Skyfire": il s'agit weather modification, N.A.S., N.R.C., Shenandoah National d'un programme de recherche sur les incendies düs a la foudre Park, Virginia. entrepris par le Service forestier des Etats-Unis en cooperation ,1959. Generator technology for cloud seeding. avec plusieurs autres organismes. On y trouvera des données Paper presented at joint conference on weather modification, resultant des observations qui ont été effectuées sur les nuages et American Society ofCivilEngineers and American Met. la foudre, ainsi que Ia description d'un programme experimental Society, Denver, Cob. visant a determiner les possihilités de modification des orages , and Wells, H. J., 1957. The Project Skyfire électriques par "cloud seeding" (emission de vapeurs d'iodure cloud seeding generator.Research Paper 48, Intermountain d'argent) dont les résultats préliminaires sont décrits. Le rapport Forest and Range Experiment Station. examine ëgalement l'utilisation de radar dans les recherches sur la foudre et pour les operations de lutte contre les incendies. ,and Baughman, R. G., 1959.Characteristics On trouvera enfin une courte description des systèmes de lutte of Rocky Mountain lightning storms.Paper presentedat contre les incendies de forêts causes par la foudre, ainsi que des annual meeting, Western Forest Fire Research Council, Western renseignements sur l'application, aux problèmes spéciaux de la Forestry and Conservation Association, Spokane, Wash. lutte contre les incendies düs a la foudre, des previsions météoro- Hardy, Charles E., Syverson, Charles E., and Dieterich, logiques relatives aux orages pouvant causer des incendies, de John H., 1955. Fire-weather and fire-danger station handbook. l'estimation du danger d'incendie, de la detection des incendies Misc. Pub. 3, Inter-mountain Forest and Range Experiment et des méthodes de lutte employees. Station. and Brackebusch, Arthur P., 1959. The Inter- Control de Incendios Causados por Rayos en los Bosques mountain fire-danger rating system.Proceedings Society of Norteanjericanos American Foresters Meeting, San Francisco, Calif.pp. 133-137. MacCready, PaulB.,1955.Project Skyfirecloud and Los incendios causados por rayos son un problema de impor- lightning observation handbook.Misc. Pub. 5, Intermountain tancia en los bosques norteamericanos. En los Estados Unidos, Forest and Range Experiment Station. estallan todos los años unos 7.500 incendios causados por rayos. Estos incendios son especialmente severos en el Oeste del pals, Schaefer, Vincent J., 1949. The possibilities of modifying en donde es necesario hacer toda clase de esfuerzos para proteger lightning storms in the northern Rockies.Sta. Paper19, Northern Rocky Mountain Forest and Range Experiment a los bosques contra este peligro. Station. En este trabajo se describe el Proyecto Skyfire, un plan de estudiosdeinvestigacióndirigidoporelServicioForestal U.S. Forest Service, Division of Forest Fire Research, In- de los Estados Unidos, en cooperación con otras agencias. Se termountain Forest and Range Experiment Station,1959. dan datos sobre los resultados de los estudios hechos respecto a Totalizing wind counter for contacting type anemometers. Fire nubes y rayos. También se describen y se presentan los resultados Control Notes 20(1): 7-10. preliminares de un plan experimental para determinar la posi- ,1959. Battery operated fan psychrometer. Fire bilidad de modificar las nubes que causan las tempestades de Control Notes 20 (1): 20-22. rayos con asperciones de ciertas materias.Asimismo, se hace ,1959. Aluminum rain gage and plastic meas- referencia al uso del radar en los estudios de investigación de los uring stick for fire weather stations. Fire Control Notes 20(4): rayos y como medio de control en la extinción de incendios. 111. Se hace un resumen de los sistemas para el control de incendios causados por rayos.Se presentan informes sobre el aprovecha- ,1959.Belt weather kit.Fire Control Notes 20(4): 122-123. miento de pronósticos del tiempo en épocas de peligro de incen- dios, y sobre métodos para clasificar los riesgos de incendios, su ,1959. Aluminum knockdown weather instru- detección y extinción, relacionados con los problemas especiales ment shelter. Fire Control Notes 20(4): 139-140. de las confiagraciones ocasionadas por rayos.

856 Fifth World Forestry Congress Proceedings SPECIAL PAPERS On Certain Factors Influencing Douglas-Fir Beetle Populations

MICHAEL DONALD ATKINS AND L. H. MCMULLEN Forest Biology Laboratory, Victoria, British Columbia, Canada

The Douglas-firbeetle, Dendroctonus pseudotsugae the weather conditions in terms of single factors are (Hopk.), poses a constant threat to Douglas-fir, Pseudot- seldom ideal for the necessary attack flight at that time suga menziesii (Mirb.) Franco, throughout the range of of year.If the air temperature is. below 20° C., as is the insect, but more particularly in the dry interior areas. often the case in May, flight might still occur if the RH Populations of the beetle fluctuate from year to year, and is high and/or if the sun is shining. Sunlight is probably local outbreaks are common. The latter are frequently the most significant stimulus when the temperature is associated with , but not all logging produces suboptimal. epidemics. The insect prefers weakened, recently fallen Weather conditions may supply valuable information in trees,stumps, and slash rather than healthy standing considering the general dispersal of the attacking popu- timber; consequently, when there is an abundance of lation. During a cool, cloudy spring the flight activity may favoured host material the insect's population is more apt be limited, causing the population to attack host material to increase. However, the factors which are responsible in the immediate vicinity, whereas in a warm and/or clear for the general changes in population and the incon- spring the population might disseminate more widely and sistency of the beetle's association with logging are not start new centres of infestation. The latter may be due in fully understood. part to two factors, viz, initially, under ideal conditions This paper illustrates how several factors, namely, the flight would be stronger and uninterrupted, permitting weather, the preference of the insect for certain host a directed flight for several miles; secondly,the flying material, and resulting competition, could affect popula- beetles would be capable of flying beyond the protection tions of the beetle. Although much of the discussion is of the forest canopy and be carried by wind to new areas. based on observations of the insect in the interior of The foregoing may be important in terms of the type British Columbia, the principles should be applicable to of infestation.Although under suboptimal flight condi- other areas. tions the population may be forced to remain in the Weather plays an important and complexly integrated original infestation area, the beetles may have to attack role in the behaviour of the Douglas-fir beetle. In study- and kill standing trees due to a lack of favoured host ing the effect of climatic factors on insect behaviour we material. On the other hand, beetles disseminating more often treat them as separate entities to facilitate less com- widely would have an opportunity to locate new slash plex experiments. However, when considering the effect areas and not attack standing timber. In addition, awide of weather on behaviour under fire conditions we cannot, dispersal of a population would tend to dilute it, lessen- for instance, separate temperature from humidity or tem- ing the chances of an epidemic developing. On the other perature from insolation. hand, the resulting lower attack densities might cause a The insect is critically exposed to weather during its general increase in over-all numbers of the beetle. flight period, which, although of relatively short duration, Although it may appear, from the foregoing discussion, is vital to its success in extending and establishing centres that the flight is staggered or drawn out, this is not the of infestation. The most important feature of weather in case with the bulk of the population. The changes from relation to the flight of the Douglas-fir beetle is tempera- cooler to warm weather in the interior of the province are ture,sinceitdelineates the activity(Atkins,1959). relatively rapid, depending largely on the passing of cold Under shaded conditions and mid-range relative humidi- nights.However, this procedure is not invariable since ties (RH) spontaneous flight will not occur below 19 to spring weather does not follow an inflexible pattern. 20° C., or above 36 to 38°, the optimum being from 22 Throughout the Douglas-fir area of the interior, June is to 32°.However, when exposed to full sunlight the traditionally a wet month. If conditions suitable for flight beetles will fly at 17° C. and will begin to demonstrate a first occur after the middle of May, the flight may be negative phototaxis at 32°, crawling into dark places broken by a period of unsettled weather. This may pro- rather than flying.Similarly, relative humidity changes duce a second major flight following the poor weather or the spontaneous flight-temperature relationship. At 20° C. cause staggered emergence on fine days during the un- flight will occur if the RH is 95 per cent, while at 30° settled period. On the other hand, an open spring with and 95 per cent RH about half of the beetles fail to early warm days and nights may cause a particularly take flight. concentrated flight and attack.This places a maximum These facts are of prime importance when considering stress on the residual timber even when favoured host a spring-flying insect such as the Douglas-fir beetle, since material is present, since a population overflow into living Forest Protection 857 trees is more likely than when the insects have a more same is true, on a smaller scale, with lightning strikes staggered emergence. which may predispose a tree to attack. Where there is a The pattern and distribution of attacks by the Douglas- fairly high population, the overflow of attacking beetles fir beetle is believed to be related to the temperature of may go into living trees adjacent to the lightning strike. the bark at the time of attack. During the early part of Other factors due to weather which could cause weakening the attack period the majority of attacks occur on the oftreesand subsequently attractbeetlesare branch upper and exposed sides of the logs, the highest densities damage by snow and freezing rain, landslides causing occurring on host material exposed to sunlight for part root damage, and drought. Snow covering infested host of the day. Later in the season as the air temperature material acts as insulation to extreme winter tempera- increases, there is a noticeable preference for the under- tures and protection against predators such as wood- sides of logs and host material which is largely shaded. peckers. With regard to the effect of weather on the brood devel- Intraspecific competition and resultant mortality during opment of the Douglas-fir beetle, the only information brood development is a factor that has received relatively available deals withtemperature. Initially, this littleattention.OvercrowdingaffectstheDouglas-fir controls the rate of the boring activity and thus the con- beetle during the entire period of its development under struction of the egg gallery. At 150 C. the insect can bore the bark. At high levels of competition the parent beetles into the bark in five hours, while a.t 25 to 28° it can do remain in their galleries for shorter periods, and, con- so in 40 minutes (Rudinsky and Vité, 1956). Beneath sequently, gallery construction and oviposition arere- the bark activity is minimal at 6.50 C., reaching a rela- duced. Mortality during larval development is higher tively high level at 12° C., then increasing with tempera- under crowded conditions. The result is that the optimum ture.At highertemperatures,excessiveactivityor gallery density for maximum brood production per unit restlessnessisbelieved to hinder the boring activity. area lies between four and eight per square foot of cambial Development of the brood is influenced by temperature surface. Below and above this level the number of brood (Vité and Rudinsky, 1957; Ryan, 1959). The develop- produced decreases.However, the progeny per parent mental time from egg to adult is about 105 days at 14 ratio is highest at the lowest gallery densities and is about to 15° C. and decreases to 33 days at 29 to 30° C. unity at densities of 15 to 17. The fact that the parent Below 8° C. embryonic development ceases, while con- beetles are capable of making a second attack when they stant temperatures above 32 to 34° C. are lethal to eggs leave their initial gallery somewhat offsets the effect of and first instar-larvae. Brood mortality is reported to be competition as represented above. However, when com- higher in slash exposed to the direct rays of the sun than petition is high, the available host material would already in shaded host material (McCowan and Rudinsky, 1954; have been saturated, and the insect would have difficulty Johnson et al., 1959). in locating more. Extreme or unseasonal changes in temperature can be Since the insect tends to have preference for certain lethal to the overwintering population.Sudden severe types of host material, its own behaviour becomes a factor cold temperatures in early November 1955 were as- in its success or failure.In relation to host material, sociated with 60 to 80 per cent mortality of the young when the population is high, competition for available adults that winter (McMullen, 1956), and the general brood space is high, and the insect attacks its preferred population of the Douglas-fir beetle decreased in 1956 host at densities higher than is optimum for progeny (Silver and Ross, 1957).Since then, mortality of the production; conversely, when the population is low the overwintering adults has been in the neighbourhood of attack on the preferred host material is dispersed, and 10 to 20 per cent, and the population has increased, at the population can increase rapidly, conceivably as much least in the Cariboo region of British Columbia where the as ten-fold or more in one generation. Once a population overwintering mortality is being studied. has become static in uniform amounts of host material When exposed to 22° C., the emergence of young from year to year, it should remain so. As soon as the adults was related to the length of cold rest, the peak host relationship is disrupted the population will be af- emergence occurring at two weeks after 50 days of cold fected accordingly, and its manifestation in terms of tree rest and at 6 hours after five months of cold rest (Vité mortality will occur immediately if the preferred host and Rudinsky, 1957). Following a cold winter, many of material has been drastically reduced, or the following the young adults could emerge in a relatively short time year if the host material has been increased. under favourable conditions, only to be caught in the Many of the beetle population problems are associated open by a cold period or even a cold night before they with logging operations and are of prime concern to in- can attack and gain the protection of the bark. It is be- dustry.Logging disturbs theinsect-hostrelationship, lieved that the cold weather in the last half of May 1953, producing host material preferred by the insect, and con- following a short warm period in the first part of the sequently tends to concentrate a population. Moreover, month, may have been a decisive factor in reducing a initially there usually is abundant host material for the beetle population in Oregon (McCowan and Rudinsky, beetle, and it rapidly develops large populations.The 1954). relationship of available preferred host material has been In addition to the direct influence of weather on the previously discussed and applies equally well to logging Douglas-fir beetle there are a number of indirect effects. slash.Changes in the volume of slash or cessation of Wind may cause extensive areas or pockets of blowdown logging may create conditions under which the beetle in the spring of the year when the soil has been loosened attacks the residual stand. The stand on the margin of by frost and rain. These areas are very attractive to the logged-over areas oftenis weakened.The forms of beetle and may act as foci for future infestations. The damage may be a direct result of the logging, such as 858 Fifth World Forestry Congress Proceedings En ce qui concerne les conditions climatiques, la temperature mechanical or fire damage, or may be indirect, such as pendant la période du vol est le facteur le plus important ayant exposure to wind with resulting blowdown. These condi- un effet sur la dissemination de l'insecte, mais leseuil de l'activité tions, by providing host material favourable to the insect, est influence par l'ensoleillement et l'humiditd relative.Etant enhance its chances of becoming a threat to the residual donné que ces ennemis du sapin de Douglas entreprennent leur vol au printemps lorsque la temperature peut être inférieure a stand. la temperature optima, les facteurs qui ont pour effet de réduire The foregoing discussion has been concerned with the Ia temperature liminale revêtent une grande importance.Un effects of weather and favourable host material on the climat favorable a un développement rapide aux premiers stades Douglas-fir beetle.These factors have been treated as de la formation de l'insecte permet l'dtablissement d'une popula- However, they form a complex tion qui émergera simultanément au printemps suivant, au grand though acting alone. dam de l'arbre qui les héberge. Des temperatures extremes pen- relationship with each other and with other environmental dantl'été on l'hiver peuvent causer une mortalité dlevée des conditions, such as predators and parasites, often counter- larves. balancing one another. When conditions are such that L'insecte préfère des arbres tombés ou blesses et des déchets one or more of these agents predominate in their effect, d'abattage plutôt que des arbres sur pied. Quatre a huit attaques par pied carré produisent dans l'hôte choisi lenombre maximum the population of the beetle reacts accordingly. de larves par unite de surface, bien que le nombre d'oeufs par parent soit plus élevé lorsque les attaques sont de plus faible References densité.Lorsqu'il y a abondance de bois a terre, la population Atkins, M. D., 1959. A study of the flight of the Douglas-fir peut s'accroitre très rapidement et devenir une menace pour les beetle, Dendroctonus pseudotsugae Hopk. (Coleoptera: Scoly- arbres sur pied. Lorsqu'au contraire le volume de ces matériaux tidae)I. Flight preparation and response. Can. Ent. 91: 283- se trouve réduit dans des proportions importantes, commelorsque 291. les operations d'abattage ont pris fin, le peuplement est également Johnson, N. E., P. W. Orr, and K. H. Wright, 1959.Beetle menace, étant donné que l'insecte se trouve alors force d'attaquer hazard in wind-thrown Douglas-fir. Weyerhaeuser Timber Co., des arbres sains sur pied. Tacoma, Wash., For. Res. Paper 20. McCowan, V. F. and J. A. Rudinsky, 1954. Biological studies on Observaciones sobre Ciertos Factores que Influyen en el theI)ouglas-firbarkbeetle,Millicoma Forest,Coos Bay, Desarrollo del Escarabajo del Abeto Rojo Oregon.(Prog.Rpt.)Weyerhaeuser Timber Co., Tacoma, Wash,, For. Res. Notes. Las fluctuaciones en nümero del escarabajo del abeto rojo McMullen, L. H., 1956. A note on mortality of the Douglas-fir (Dendroctonus pseudotsugae Hopk.) no han ilegado a compren- beetle in the interior of British Columbia during the winter derse bien todavIa. En este trabajo se trata de los efectos del of 1955-56. Can. Dept. Agr., For. Biol. Div. Bi-monthly Prog. tiempo, la competencia intraespecIfica y el material preferido para Rpt. 12(6): 3-4. desarrollarse, sobre el ndmero y propagación de este insecto. Rudinsky, J. A. and J. P. Vité, 1956. Effects of temperature upon La temperatura durante el perIodo de vuelo es el factor meteo- the activity and the behaviour of the Douglas-fir beetle. For. rológicode más importancia que afectala propagación del Sci. 2: 258-267. escarabajo; pero sobre el comienzo de la actividad inlluyen tam- Ryan, R. B., 1959. Termination of diapause in the Douglas-fir bién la luz del sol y la humedad relativa. Como el escarabajo beetle,DendroctonuspseudotsugaeHopkins (Coleoptera: del abeto rojo vuela en la primavera, cuando las condiciones de Scolytidae), as an aid to continuous laboratory rearing. Can. la temperatura quizás no sean enteramente óptimas, los factores Ent. 91: 520-525. que reducen la temperatura y permiten el comienzode la men- Silver, G. T. and D. A. Ross, 1957. Province of British Columbia cionada actividad adquieren gran importancia. Un tiempo favo- Forest Insect Survey. In Can. Dept. Agr., For. Biol. Div. For. rable alrápidodesarrollodelasfasesinmadurasdel Insect and Dis. Surv. 1956, p. 81. insecto permute un aumento en el ndmero que ha de surgir Ia Vité,J.P. and J. A. Rudinsky, 1957.Contribution toward a próxima primavera, sometiendo al huésped a maxima prueba. Las study of Douglas-fir beetle development. For. Sci. 3: 156-167. temperaturas extremas durante el verano o el inviernopueden causar gran mortandad en la empolladura. RESUMES Este insecto prefiere árboles caIdos o daiiados y la madera populations de cortada a los árboles en pie. En el material huésped preferido, Facteurs ayant une influence sur les entre cuatro y ocho ataques por pie cuadrado producen el máximo coléoptères s'attaquant au sapin de Douglas ndmero de progenie en cada unidad de area, aunque el nimero de Lesfluctuations qui se produisent dans les populations de progenie por insecto es mayor cuando el nilmero de ataques es coléoptèress'attaquantausapinde Douglas(Dendroctonus más bajo.Cuando hay abundancia del material huésped pre- pseudotsugaeHopk.)n'ontpasencoreétécomplètement ferido, el ntimero puede aumentar rápidamente y convertirse en élucidées. Le present rapport examine tour a tour, du point de un peligro para los árboles en pie.Cuando dicho material se vue de leur effet sur Ia population et Ia dissemination de l'insecte, reduce seriamente, por ejemplo, despises de finalizada la corta, certains facteurs tels que conditions climatiques, competition entre losárbolesrestantesestán igualmente en peligro porqueel individus de la méme espèce, et l'hôte qu'ils préfèrent. insecto se ye obligado a atacar a los árboles sanos en pie.

Forest Protection 859 Fire EnvironmentThe Keyto Fire Behavior

CLIVE M. COUNTRYMAN Forester, Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture, Berkeley, California, U.S.A. and MARK H. SCHROEDER Meteorologist, United States Weather Bureau, Washington, D.C., U.S.A.

A casual observer seeing a forest fire for the first time excellent opportunity to study wild-land fire in relation would probably decide there is little rhyme or reason to to its environment, since local patterns of weather and the way the fire burns.Its sudden variations in direction other environmental factors can be determined before the of travel, its quick change from a seemingly mild, slow- burn takes place. The fire behavior can then be observed burning fire to a raging inferno, all seem to add up to in relation to known conditions at any period. erratic behavior without logical explanation. One such study was in the lower foothills of the west Actually a fire behaves in accord with changes in its slope of the Sierra Nevada near Sonora, California'. surroundingsthe character and condition of the burnable Nearly all of the 1,000-acre burn area was on the east- vegetation, the topography, and the meteorological factors f acing slopes on the west side of Don Pedro reservoir. In that affect fuel flammability, fire intensity, and fire this area we set up 5 stations to record windspeed and spread. This complex of environmental factors thatcon- direction continuously. Temperature and humidity were trol the behavior of fire is what we call "fire environment." recorded by hygrothermographs. At another 15 stations, Fire environment is not static.It varies in time, and in measurements with non-recording instruments were made spaceboth horizontally and vertically. Forest fuels not at irregular but frequent intervals.Observations were only vary in kind and amount from place to place, but also started on August 2 and continued through August 10, vary in arrangement and size of fuel particles. The mois- when the area was burned. ture content of forestfuelsiscontinually changing, In the early morning hours before sunrise, the general throughout the day and with the season. Thusa lush, windflow was from the northwest at 1 to 5 miles per hour, green brush field may be virtually fireproof in the spring, and on the east-facing slopes of the' study area, light down- yet literally explode when touched by fire in the fall. canyon and downsiope winds were recorded. Shortly after Probably the most variable factor of all is the weather. sunrise, when these slopes were beginning to be warmed We must consider not only meteorological conditions by the sun, up-canyon and upsiope winds began. Wind close to the ground, but also what is happening throughout direction on the ridges and west slopes continued from the the troposphere. When a fire is small, the environment northwest. The wind-pattern map for 0800 hours (figure affecting the fire is confined to a small horizontalarea 1) is typical of the pattern for the early forenoon hours. and to a layer of air a few feet thick. Buta blowup fire As the day progressed, the west slopes of the Sierra may take in many square miles and be affected by meteor- and of the survey area received more heat. As a result, ological conditions of the air to heights of 25,000, 30,000 the general windflow shifted to the west and southwest or more feet. Thus, we see that fire environment and its and became stronger. By 1000 hours the general wind- relationship to fire behavior is a vast and complex sub- flow predominated (figure 2). Down-canyon and down- ject. Yet an understanding of fire environmenthow and slope winds prevailed on the east-facing slopes except in why it variesis essential to an understanding of fire be- the areas topographically sheltered from the westerly havior and to safe and efficient forest fire control action. winds, such as the steep slope just above the reservoir. Experience and research have taught firefightersa Also, by 1000 hours the local circulation in the area good deal about wild land fire. Its qualitative relationship around Station 4 was being affected by strong heating to weather, fuels, and topography is fairly well known. on the sparsely vegetated ridge to the north.Airflow Quantitative infonnation is far too limited, however, to began to show a definite down-canyon trend in this area. predict the behavior of fire in specific places. Firefighters Around Station 3an eddy circulal ion also began to often do not know how wind, temperature, humidity, and appear.These very localized circulations continued to fuel moisture are affected by topography, water bodies, develop. By 1400 hours they were an important factor in season of the year, and the fire itself. the airflow pattern (figure 3). How closely does fire behavior follow the fire environ- The flow pattern remained much the same until sun- ment pattern? Studies of prescribed burns for wild-land brush removal in California have indicated that behavior is very closely related to this pattern. These prescribed 1Countryman, C. M. and Schroeder, M. J., Prescribed Burn 2-57.Pacific Southwest Forest and Range Experiment Station, burns,conducted by private landowners, providean Technical Paper 31, April 1, 1959. 860 Fifth World Forestry Congress Proceedings down, when any tendency for upsiopeair movement ceased, and the general windflow fromwesterly directions dominated the wind pattern in the survey area. Actual fire behavior when the area wasburned was amazingly close to that indicated likely bythe wind-pat- tern maps.In Survey Canyon numerous spotfires appeared across the fireline around Station4, coalesced into a front, and ran to the top ofNorth Ridge. This fire action took place on the portion ofthe perimeter where the survey revealed persistent windsblowing across the fireline. The fire became well established alongSouth Ridge to the south of Stations 5B and 5C at about1200 hours. It moved along the ridge in aneasterly direction at moderate speed and with a hot front.When the fire reached a point southwest of Station2B (about 1240 hours), a large counterclockwise firewhirl developed. The whirl then moved with the fireeasterly along the ridge, passing over and wreckingStation 3. The whirl Figure I. Wind pattern for 0800 hours, prescribed burn No. 2-57. dissipated before reaching Station 1. The tendency for fire whirls to burn mostreadily on the lee side of ridges has already beenwell documented.2 In this case the whirl developed in thegeneral area where the wind survey had shown the probableexistence of eddy circulations. Although eddy circulationprobably is not a necessary prerequisite for thegenesis of a fire whirl, it can be expected to make thedevelopment of a whirl more likely.Eddy circulations, then, can be awarning of probable fire whirl development,particularly on lee sides of ridges. Another study also gave warning that afire may not burn uphill as is usually expected. Theprescribed burn was in the Coast Rangeabout 150 miles north of San Francisco.3 The 500-acre area was on agenerally east- f acing slope on the west side ofCache Creek valley. Because of dense fuels and steeptopography, all obser- vation sites were selected alongthe perimeter of the proposed burn area.Six recording stations, and eleven nonrecording stations were used.Observations were started August 14 and continued untilAugust 20. Figure 2. Wind pattern for 1000 hours, prescribed burn No. 2-57. Our data showed that the wind patternsin this area deviated in a major way from theclassic pattern of upslope, up-canyon winds during the dayand downslope, down-canyon winds at nightShortly after sunrise there was a general upslope movementof air over the burn area (figure 4). At thehigher and more exposed areas the wind was from a northerly direction.Windspeeds were light, averaging 2 to 3miles per hour. Calm periods were frequent. This same sortof wind pattern continued most of the early forenoon hours. Between 1100 and 1200 hours thewind switched rather quickly to the southwest or west andincreased in speed. By 1200 hours this westerly flow waswell established, and downslope winds prevailed over theentire area (fig- ure 5). The westerly,downslope wind pattern continued throughout the afternoon. Windspeedsalso changed as

Graham, Howard E., Fire Whirlwinds. AmericanMeteorolog- ical Society Bulletin, 36(3): 99-103.March 1955. Countryman, C. M. and Schroeder, M.J., Prescribed Burn Fireclimate Survey 3-57.Pacific Southwest Forest and Range 1959. Figure 3. Wind pattern for 1400 hours, prescribed burn No. 2-57. Experiment Station, Technical Paper No. 34, July 861 Forest Protection to overcome both the usual upslope thermal winds and the normal tendency for the fire to burn uphill. Actual fire behavior was very close to that indicated by the wind- pattern map for 1200 hours. The close tie between fire environment, particularly wind, illustrated by these two prescribed burn studies is fairly obvious. Not so clear, however, are the effects that silvicultural practice and timber harvesting procedures may have on fire environment. Clear cutting of a dense timber stand can cause some drastic changes in the fire environment. Most obvious, of course, is the change in fuels. Although the total amount of fuel on an area is less after timber harvesting, the arrangement of the fuel is much different. No longer is the fuel distributed loosely in great depth; it is now much more compactly arranged, and much of the green fuel soon dies and becomes highly inflammable.Even more important, however,isthe change in the microclimate of the cutover area.It has

been reported4 that surface temperatures of 165° F. can readily occur in the open, compared with 80° in the uncut stand. Fuel moisture of 3 percent in the open compares with 8 percent in the stand. Windspeed in a closed stand seldom exceeds 3 or 4 miles per hour, even with a 25- to 30-mile wind above the crown. In a clearcut area the wind is relatively unobstructed. The highly flammable, compact fuels and the more severe microclimate of a cut area create fire environment

CONTO(m INTEVIL.5o 55 ST*TION$ )f ç MANuAi. OINSRVATION st*iidT_J

Figure 5. Typical wind paftern, 1200 hours, prescribed burn No. 3-57.

the day progressed, increasing from 5 to 6 m.p.h.at 1200 hours to 15 to 18 m.p.h. by 1800 hours. After sundown windspeeds dropped off gradually until at last more normal downslope and down-canyon winds pre- dominated. The plan for this prescribed burn called for firing to begin about 1100 hours on the east or lee side of the area and then proceed clockwise around the perimeter of the burn. This plan was made before thesurvey was started and apparently was based on the assumption that the topography was the dominant environmental factor once the fire would run upslope. Firing began on schedule, but the downslope, westerly winds had already set in. There was littlesuccess in getting the fire to spread uphill. When firing started along the western side, however, the fire took hold immediately and under the influence of the westerly windsran rapidly downslope. The fire crossed the east fire line in several places and continued to spread to the east. More serious, however, were hundreds of spot fires that startedon the inaccessible slopes on the east side of the valley. These fires quickly coalesced into a wide fire front whichran 41 rapidly toward the east and burned several thousand acres outside the original prescribed burn boundaries 1/4 I/S 3/I IU before being brought under control. CONTOUR INTCRVAL.5O FEET 0RECORDING STATIONS The wind pattern, not the topography, turned out to (3MANUAL OBSERVATION STATIONS be the dominant factor controlling the behavior of the fire. The downslope wind componentwas strong enough Figure 4. Early forenoon wind pattern, prescribed burn No. 3-57. 862 Fifth World Forestry Congress Proceedings étre maItrisés dans les endroits que le régime des ventsdésignait conditions that permit fires to start more easily, spread comme des zones dangereuses. Un tourbillonde flammes s'est faster, burn hotter, and become difficult or impossible to développé a ui-i endroit ou le régime des vents indiquait une forte control.It has been estimated4 that a fire in untreated tendance aux revolins. heavy slash may require more than 20 times the control L'expioitation de bois et les pratiques forestières peuvent avoir de très grandes consequences sur le milieu de i'incendie. La coupe, effort needed for fire burning under similar weather con- i'éclaircie et i'émondage du bois créent des ddchets et, en con- ditions in an uncut stand. sequence, sont susceptibles de modifier le facteur combustible Thinning or partial cutting will not cause such drastic dans le milieu de l'incendie.Ces activités, et les coupes plus But they can affect the fire particuiièrement, peuvent provoquer de teis changements dans le changes as clear cutting. microclimat que le comportement de i'incendie et les manières environment enoughthrough rearrangement of fuel and de Ic combattre peuvent subir des modificationsessentielles. change in microclimateto increase materially the num- La prevision precise en matière de comportement del'incendie ber of days when disastrous crown fires can occur. conditionne le succès et l'efficacitd de la lutte contre les incendies de forêts.Les forestiers de plus en plus en arrivent a prendre But silvicultural practices do not necessarily result in conscience du fait qu'il importe au même titre deconnaitre le a worsened fireenvironment.When reproductionis comportement de l'incendie et son milieu. started on an area, and the trees grow and crowns close in, the fire environment moves toward the easier condi- Factores Arnbientales del IncendioModo en que se tions of uncut mature stands. Pruning of young stands, Propaga by changing the arrangement of the fuel, can make it less En ci bosque, un incendio se desarrolia segén los cambios probable that fires will get into the crowns. ambientalestipo y condición delavegetación combustible, Successful and efficient wild-land fire control isde- topografIa y factores meteorológicosque afecteri Ia irtflama- bilidad del combustible, la intensidad del fuego y la expansion pendent upon accurate prediction of fire behavior. More del mismo. Este conjunto de factores ambientaics, que rigen ci and more, foresters are coming to realize that under- comportamiento del incendio, se conoce como "ambiente incen- standing fire behavior goes hand in hand with an under- diario." Un estudio de los incendios controlados recomendados para la standing of fire environment. eliminaciOn de arbustos en California, demuestra, en lo que respecta a los tipos de combustible encontrados, que el desa- RESUMES rrolio del fuego siguió muy de cerca ci rumbo del viento. Algunos Le milieu de l'incendie, facteur-clé du corn porternent de fuegos salieron fuera de control en lugares que el mapa de co- rrientes aéreas seflalaba como zonas de posible peligro. En un l'incendie incendio se formó un torbellino de fuego dentro del area en que, Un incendie de forêts se comporte conformément aux variantes segtmnel mapa de la circuiación de vientos, existIan fuertes de son milieules caractéristiques et l'état de la végdtation com- corrientes arremolinadas de aire. bustible, la topographie et les conditions météorologiquesqui La corta de la madera y las prácticas de la silvicuitura pueden influentsurl'infiammabiiité du combustible,l'intensitéetla ejercer un efecto importante en la propagación de los incendios. propagation de l'incendie. On appelle "milieu de l'incendie" cet La corta, ci aclareo y la poda crean residuos que modifican ci ensemble complexe de facteurs qui régissent le comportement d'un factor de la combustion en ci ambiente incendario. Estas activi- incendie. dades,particularmentelacorta, puede originar cambios tan Les etudes effectuées en Californie sur des incendies presents grandes en ci microclima que ci desarrollo dci incendio y los pour détruire le maquis ont démontré que, étant donné les types métodos de control correspondientes tienen que ser radicalmente de combustibles presents, le comportement de i'incendie suit de alterados. très près le régime des vents.Certains incendies n'ont pas Pu El control de incendios en los bosques, para que tenga éxito, depende del pronóstico exacto de comportamiento del fuego. Cada dIa hay más silvicultores que están convencidos de que ci cono- Countryman, C. M. Old Growth Conversion Also Converts cimiento de las caracteristicas de las conflagraciones marcha a Fireclimate. Proceedings Society of American Foresters Meeting, laparconciconocimientodelosfactoresdelambicnte 1955. incendario.

Forest Protection 863 L'Influence de quelques éléments climatiques sur a variation de la densité des Insectes défoliateurs

DIsEScu GABRIELA Roumanje

On a f alt la constatation que dans la region comprise sivement sec (deux ans excessivement secs, un an très entrelesCarpathes méridionauxetleDanube,le sec et un an sec). phénomènedemultiplicationmassivedesinsectes Ces conditions, extrémement favorables au développe- défoliateurs de la plaine (Lymantria dispar L., Mala- ment du stade de chenille, ont favorisé des multiplications cosoma neustria L., Tortrix viridana L., diverses espêces massives prolongees.On a enregistré dans la region de Géometridae, etc.)se déclanche généralement dans étudiée de fortes attaques de Lymantria dispar en 1947- les années qui succèdent a celles dont le lyeau Vile mois 1949 et en 1953-1956; de Tortrix viridana en 1947-1951 enregistrent des temperatures au-dessus, et des précipita- et en 1951-1952; de Malacosoma neustria en 1951-1952. tions au-dessous du chiffre normal. Après cetteperiodeexcédentaire,ontsuccédétrois On est parvenu a la conclusion que le debut du années moms propices (temperatures plus faibles, mois de phénomène de cettemultiplication massive peut être Mai 1954 pluvieux). On pouvait s'attendre a ce que Ia mis en rapporten premier lieuavec les éléments vague des multiplications en masse commence a diminuer. climatiques concernant les mois d'Avril et de Mai. Une Mais après 1955, les conditions redevenant favorables, on série de multiplications massives des insectes mentionnés a enregistre de nouvelles attaques massives. peut apparaitre avec un retard de 1 a 3 ans, aprèsune Bien que l'attaque des Malacosoma neustria alt diminué période d'au moms trois axis a excédentsmoyens (écarts en 1953, et en 1955 celle des Lymantria dispar, dans positifs) de temperature, de plus de 1-1, 5°Cpar rapport certains foréts M. neustria a fait son apparition des 1956- a la temperature normale de ces mois, et de précipitations 1957, et de nouveau en 1959, et dans d'autres L. dispar au-dessous du chiffre normal, ou tout au plus normales. et M. neustria ont réapparu en 1958-1959. La période des attaques massives peut devenir plus De méme, en général pour tout le pays, i'année 1959 courte, si après l'apparition des premieres multiplications, a été exceptionnellement riche en Géometridae, tout en le ye et le lye mois des années suivantes présentent des enregistrantaussidesmultiplicationsmassivesde deficits de temperature et des précipitations abondantes. Cnidocampa processionea L. Dans ce cas, les sur-multiplications ne comprennent Le rapport entre les éléments climatiques du yje et pas de trop grandes superficies. Comme exemple typique Vile mois, et les multiplications en masse n'estpas si pour cette situation dans la plaine du Danube, nous evident.Malgré tout, la caractéristique constatée pour citons le cas suivant: le lye et ye mois reste en général valable. Dans la période comprise entre 1923-1928, les mois Ii en résulte que les temperatures et le régime des d'Avril et de Mai ont été caractérisespar des excédents précipitations, favorables pendant les années précédentes de temperature (en exceptant les années 1927 et 1928, aux multiplications massives, ont une plus grande im- dont le lye mois a été déficitaire).Généralement ces portance pour le déclanchement du phenomene de sur- mois ont été secs (allant du normal a la sécheresse). multiplication, dans la période oü l'insecte se trouve dans Des multiplications massives de Lyman tria dispar ont le stade de chenille (lye et ye mois). Dans le stade de été signaiées a partir de 1932-1933 (en réalité diesont chrysalide (VP et Vile mois), les temperatures plus commence probabiernent en 1929 ou 1930). Mais les faibles et les pluies au-dessus du niveau normal (sans multiplications massives n'ont pas pris d'extension, a qu'elles soient toutefois excessivement abondantes), ont cause des ye et lYe mois des années 1930, 1931 et une moindre importance, ne pouvant pas empécher 1933, qui ont présenté des temperatures plus faibles l'accumulation en nombre déjà déclanchée. moyennes tout en étant en même temps piuvieuses, ou En cc qui concerne le climat local, on mentionne les tout au plus normales. suivantes constatations: Si après l'apparition des premieres sur-multiplications, Certaines conditions défavorables de temperature et d'humidité atmosphérique peuvent avoir comme con- les périodes favorables se prolongent, on constateune grande extension des attaques dans l'espace et le temps, sequence l'interruption de la multiplication massive d'un la- même forêt pouvant étre exposée C des attaques massives insecte. a de brefs intervaijes. En 1951, pendant la seconde moitié du mois de Mai et le debut du mois de Juin, on a pu constater dans une C'est ce qui arriva durant la période assez prolongée forêt que les papilions des Tortrix viridana, qui voiaient comprise entre les années 1945-1953, quand les deux déjà, ont subi une mortalité massive, étant engourdis par mois étudiés (V et lye) ont éte constamment caract'rjsés le froid, et noyés par les précipitations a ia suite de pluies par des temperatures moyennes plus élevées tandis que le tombées sous forme d'averses, et méme mélangées de régime des précipitations a vane entre normal etexces- neige.

864 Fifth World Forestry Congress Proceedings En 1952, dans cette même forêt on n'a pas eu a aflos consecutivos las temperaturas del aire, especialmente en los meses de abril y mayo sean muy altas y que el regimen de pre- signalerdedéfoliations,bienque pendantl'année cipitación asuma caracteres de sequIa. précedente une forte attaque se soit produite, et par Aun despiés que variasmultiplicaciones cuantiosas hayan consequent on aurait Pu s'attendre a ce que les défoli- comeuzado en losinsectos Lymantria dispar L., Malacosoma ations se répètent l'année suivante. neustria L., Toririx viridana L. y Geometridae, las condiciones desfavorables enlosdos meses indicados pueden reducir y La phdnologie et le pourcentage de parasitation des restringir las multiplicaciones a una superficie muy limitada, pero insectes dependent aussi des conditions microclimatiques, las condiciones favorables durante más tiempo, tienden a pro- propres au lieu de développement. On a constaté ainsi, longar e intensificar la infestación. dans un peuplement de chêne, vieux et très clairsemés, Condiciones microclimáticasdesfavorables pueden disminuir Ia densidad de la población de insectos, pues infiuyen directamente une difference par étages dans le branchage en ce qui sobre los mismos, destruyéndolos o retardando su desarrollo, concerne les deux éléments mentionnés. Vers le falte des exponiéndolos asI por más tiempo a los parásitos y a los animales arbres oü les variations de temperature ont été plus de presa. importantes, et les courants d'air plus forts, le développe- ment des chenilles de Tortrix viridana a été retardé par rapport aux étages inférieurs du branchage, ainsi qu'il Comments ressort des pourcentages suivants: Ralph L. Anderson (U.S.A.): analyse par branches 44% chrysalidés The north-central region of the United States has a au sommet: 28% préchrysalides continental climate typical of the Temperate Zone. The 28% chenilles weather is characterized by wide fluctuations, not only analyse vers le milieu 67% chrysalidés from season to season, but from day to day and year to du branchage: 24% préchrysalides year.Under such circumstances it would seem that 9% chenilles relatively small differences in long-term averages would analyse a la base du 74% chrysalidés have a minimum effect, yet there is considerable evidence branchage: 24% préchrysalides that such differences are important. In Wisconsin, we are studying the influence of micro- 2% chenilles. climate on white pine blister rust infection.Dr. Van En méme temps on a constaté un pourcentage de Arsdel has found that very few pines are infected south parasitation plus élevé chez les exemplaires trouvés vers of the July average-temperature isotherm for 73° F. and le sommet du branchage, c'est-à-dire: that infection is generally common north of the isotherm au sommet 33% parasitation for 700 F., a difference of 30 F.In the zone between au milieu 24% parasitation these isotherms, infection is largely limited to micro- climatically favorable sites. a la base 17% parasitation In Minnesota the prevalence of Hypoxylon pruinatum Les printemps frais, ou les conditions microclimatiques infection on Populus tremuloides near the Canadian défavorables, prolongent la période de développement border is only half as great as it is 100 miles farther des chenilles. Par cela même, la possibilité de parasita- south.No elevation differencesare involved, so the tion s'accroIt, mais en même temps s'accroIt aussi la change in climate is small; yet no other reason for this possibilité de destruction, par les animaux prédateurs. distribution is apparent. Par consequent, les conditions climatiques défavorables During recent years a number of new problems have peuvent conduire dans ce cas aussi a une diminution de developed that are largely of undetermined cause. These la population d'insectes. include diebacks of hardwood species, particularly hard maple, Acer saccharum, localized deterioration of coni- RESUMES fer plantations; and root rots of conifer nursery stock. The Influence of Certain Climatic Factors on Fluctuation These diseases fit the pattern that has been described by in the Density of Population of Defoliators Dr. Hepting, and climate may well be involved. The phenomenon of a very heavy infestation of insect defolia- In my opinion, Dr. Hepting's able presentation poses tors occurs when, for three consecutive years, the temperature, important questions as to what we should and can do in especially in April and May, is excessively high, and there has been a shortage of rainfall. the way of research and applied practices to minimize the Even after a series of massive multiplications of Lyman tria adverse effects of climate change on disease problems. A dispar L., Melacosoma neustriaL.,Tortrix viridanaL., and crucial problem is that of predicting conditions a few Geometridae has begun, unfavorable conditions in the two months decades into the future.Several workers have analyzed mentioned above may shorten thedefoliatorinfestation and pollen from stratified peat bog samples which indicate limit it to a smaller area.Favorable conditions for a longer periodresultinthelengtheningandintensificationof the that climatic fluctuations in postglacial times have been infestation. great enough to cause major changes in forest composi- Unfavorable microclimatic conditions can decrease the density tion. These and other studies, however, have not revealed of the insect population. Such conditions have a direct bearing on the insect, destroying it, or slowing up its development, there- any precise cyclic trends that can be used for sound by exposing it for a longer period to parasites and predators. prediction.If the current warming trend is caused by increasing CO2 content of the atmosphere, as proposed La Influencia de Diversos Elementos Climáticos sobre las by some workers, we do have some basis for assuming a Fluctuaciones en Ia Densidad de los Insectos Desho- continuing warming trend, with the attendant problems. jadores A really sound solution to this phase of the problem must Para que el fenómeno de Ia multiplicación cuantiosa de los await theresultsof future work inthe geophysical insectos deshojadores pueda ocurrir, es necesario que en tres sciences.

Forest Protection 865 I can visualize two major means by which we may be well-known tree-killing bark beetles such as those of the able to minimize the adverse effects of climatic change. genera Dendroctonus and ips, of defoliators, of twig and The first is by intensive study of microclimate and its shoot , and other insects. Epidemics of these insects influence on diseases. Past studies have shown that local are often conveniently, but perhaps understandably, at- variations in topography and vegetational cover cause tributed to drought. While bark beetle outbreaks usually microclimatic differences in temperature and moisture occur in association with drought, beetles may remain that are as great as or greater than the general change in endemic status in drought-affected fores:ts; also, severe in climate that has occurred over the past 50 years. With epidemics may end abruptly during serious drought. Of more knowledge about microclimate we could concentrate interest here is the black turpentine beetle, Dendroctonus regeneration of susceptible species on the most favorable terebrans, which was, for some 50 years, secondary in sites or avoid the most unfavorable, having in mind pos- importance.Since 1948 it has been killing pines on a sible future conditions rather than limiting consideration largescalein the entire Southeastern United States. to present climate. Species of sawifies, virtually unknown in the past, have The second approach is to reevaluate parent materials been epidemic over millions of acres.Outbreaks of the used for regeneration.It is a commonly accepted con- elm spanworm, Ennomos subsignarius, began at the peak cept that the ectotype of a species naturally occupying a of a drought period in 1954 and have since spread over given site is the ectotype best fitted to that environment. 1½ million acres of hardwood timber. Pine tip moths of If the climate is changing appreciably, this may not be the genus Rhyacionia have, in the past 15 years, severely true. With a warming climatic trend it would seem that infested pine plantations, young and old, throughout the the best parent material for a given locality would be South. found in a more southerly location or at a lower eleva- Are these epidemics indeed due to drought? If so, is tion.Locally regenerated stands,therefore, would be the effect solely on the host, as commonly supposed, or is somewhat "exotic" and thus more susceptible to the less it an effect on the biology of the insect or a combination aggressive pathogens. of both? Is this complex further complicated by man's intensive development of land areas, opening of forest R. Joseph Koival (U.S.A.): areas, drainage of wet forest lands, heavy use of water Dr. Henson's presentation on weather and insect supplies, and general lowering of water tables? Or is the epidemics is profound and challenging. My own feeling general warming trend in North America, reported by is that its greatest value lies in his revelation of the Landsberg and mentioned in Hepting's paper, responsible? various avenues of research which will eventually lead Are these broad climatic changes affecting cyclonic storm to a better understanding of this very complex field and patterns and airmass movements as suggested by Welling- permit more precise and scientific predictions of insect ton, and are these responsible for new behavior patterns epidemics. and changes in population levels of insects? I must confess at this point that my knowledge and 1 have posed a few questions to stimulate discussion endeavor in this field are rather superficial, but this is and constructive suggestions from the audience regarding generally true of research in bioclimatology in the field Dr. Henson's thought-provoking paper.I feel that our of forest entomology in North America, excepting of knowledge of insect behavior, population dynamics, and course, the pioneering efforts of such men as Wellington, ultimately chemical, silvicultural, and biological control Henson, Greenbank, Morris, and others in Canada. hinges on an intimate knowledge of the field of bioclimat- During the past 10 to 15 years there has been a series ology. of unusual forest insect outbreaks in the Southeastern United States, with which I am most familiar, in which E. M. Bacon (U.S.A.): climate appears to have played an important, if not the Dr. Reifsnyder has ably discussed the importance of principal part. We have speculated on the problems and weather to the fire control manager. We, in this position, studied the work of leaders in bioclimatology and have use the term fire weather to convey our recognition of this arrived at the usual conclusion that only intensive study importance and to emphasize what we feel is a specialized of climate and its longtime trends, of changing weather field as it relates to the ignition of fires, their rate of patterns, of micro- and macroclimate will provide the spread, and their severity. answers. Two subjects stand out as paramount in these In our work we refer to the big three in fire control: considerations: first, and the one to which Henson gives Weather, fuels, and topography.Weather is properly emphasis, is that we must study the individual insect and stated first and is of primary importance. Even the other its biology in relation to micro- and macroclimate; second, two elements affect or are affected by "weather." we must study the effect of climate on the total environ- Our presuppression fire manning is keyed closely to ment in relation to the insect. Contrary to some opinion, existing and forecasted weather.Firefighters are placed I feel that the tremendous complexity and variability of on standby or used on other work depending on the the environment and the relationships and interrelation- weather.Air tankers and helicopters are placed on ships between insect, host, and environment have dis- standby for immediate use as fire weather worsens. Fire couraged entomologists from more intensive study of seasons are extended as the cumulative and daily effects thisfield.However, advances in the development of of weather change conditions for burning. scientific instrumentation and data-processing equipment To the fire boss and his organization charged with sup- should overcome the limitations of the past. pression of a fire, weather becomes all-important. He The outbreaks which I just mentioned have involved musthavedailygeneralforecasts,specializedand unusual manifestations of the population dynamics of localized fire-weather forecasts, and on-the-spot meteor- 866 Fifth World Forestry Congress Proceedings ological advice to translate these into terms of weather to this.Sector bosses and foremen supervising the fire- effects in individual drainages if his suppression action is fighters received this information by radio and promptly to be soundly conceived. moved men from danger spots when critical weather and Better information on weather patterns andtheir resulting erratic fire behavior were predicted. Here, then, localized effects on fire behavior is an important need. were specialists in action; the forester as fire behavior Thousaids of dollars can be saved when this information expert, and the meteorologist as fire-weatherexpert, and its interpretation reaches a high level of dependability. working together to help the fire manager in a critical Less expensive suppression action could be taken if there forest fire suppression operation. were assurance of favorable fire weather to come. As Reifsnyder points out, fuels respond differently to W. Arthur E. Pepler (Canada): weather variables.The fire manager in the Western In his usual masterly style Mr. Barrows has given you United States knows, for example, that with the fine an outline of the lightning-fire situation in the United fuels such as cheatgrass (Bromus tectorum), relative States and more particularly in the Western States, where humidity above about 25 percent brings an end to rapid lightning fires are of the greatest importance. He has also rate of spread. He knows similarly that with heavy fuels described the research program thatisunderway to such as large down logs and standing dead trees, the determine more effective and economic means of control cumulative drying effect of weather as has occurred this and has discussed the key requirements for the develop- year in the Western United States can mean disastrous ment of adequate systems for control. largefires.He knows, too, probably from bitter ex- The research program isof great interest to us in perience, that a short period of rainfall does little to Canada, and I judge it must be to other forest protection restore the moisture content of these fuels. organizations where lightning is a major cause of forest Fire, as a tool in forest management, is becoming in- fires.It is a comprehensive and well-organized program, creasingly important.In this use, weather is a major boldly conceived and carefully carried out. It has already factor.It may be, as in the Southeastern United States, produced useful results and gives promise of more. that the fire manager wants a steady north wind of stated In Canada, lightning is the most serious single cause of speedorspecified maximum temperaturetoavoid forest fires.In British Columbia the situation parallels terminal bud damage. Or it may be that in the Western that of the Western States as described by Mr. B arrows. United States he wants a measured amount of rainfall and In most other Canadian provinces the situation is only specified humidities and wind direction and velocity to slightly less serious, less so because of greater accessibility accomplish a safe slash disposal and mistletoe eradicating and lower values per acre. job by fire.In either case, here is further evidence, as I think it might be of interest to you to tell you briefly Reifsnyder points out,that the forest manager isin- of a project of major importance being carried out by creasingly conscious of fire weather as the single most our Meteorological Branch inco-operation with the important ingredient in his operations. National Research Council, the Federal Forestry Branch The forester and the meteorologist still have a long way and forest industrial organizations. to go before either will be satisfied with the level of fire- This project is primarily a study of cloud and precipita- weather knowledge and the application of that knowledge tion physics. It includes measurement of nuclei and other by the fire control manager in the United States. Much meteorological data peculiar to storm formations within is known and much has been done, however, and these storm clouds. The measurements are made from an air- presentations and discussions are real opportunities to craft fitted with the necessary instruments to record the focus interest and attention on fire-weather and fire con- data. The position of the aircraft in flight is plotted by trol relationships. radar. As a final example, I would like to point to our ex- Concurrently, an aerial seeding experiment is being car- perience this year on the Snake River Canyon fire on ried out. Random selection of storms passing over two the Payette National Forest in Idaho. This fire occurred 32-mile-square areas is made for seeding, and accurate during mid-July. The final area was 14,000 acres. The records are being kept of weather data on the two areas. elevational difference from the canyon bottom to the The project is now only in its second year and while, as ridgetop where the fire crested was over 5,000 feet. has been the case with Project Skyfire, interim findings Each day, as temperatures increased and up-canyon winds serve a useful purpose in improved techniques and in- strengthened, the heavily timbered north slopes would strumentation, the number of cases involved must be built explode and rolling flames flash from canyon bottom to up over a number of years before results of reasonable ridge summit, there to be met by men and equipment accuracy can be derived. committed to contain the holocaust before it cascaded In the meantime, other companion projects are under over the ridge to adjacent drainages.The fire-weather wayI will mention only three of them. The Pulp and forecaster from Boise, on the scene with a trained forester Paper Research Instituteof Canada has made and as fire behavior specialist, faced this critical problem. published a critical review of the literature on lightning, The strategy became one of sending men down into the lightning fires and research to control lightning fires. side canyons to cut off the fire in the lower canyons There has been set up also a project with the follow- before the "blowup" occurred.In several canyons this ing objectives: (1) To ascertain whether lightning storms was successful.In other cases they did not succeed, and tend to follow reasonably well-defined paths; and (2) to thisteam of meteorologist andfirebehavior expert map these paths as the first step in the selection of areas literally stood between the firefighter and disaster. Hourly for concentrated effort on lightning-fire reduction, making weather advisories were issued, and all action was keyed use of the findings of the various weather research studies.

Forest Protection 867 A questionnaire survey of the physicaleffectsof period of time and usually in the more inaccessible places. lightning when causing fires has been organized by the Almost invariably this imposes on any forest protection Federal Forestry Branch. This survey will supply back- organization a sudden and heavy task which stretches ground material for studies of lightning as a cause of forest their suppression facilities to or beyond their capacity. fires. Therefore, whatever prior advice the forest protection Now where is all this leading us? Quite a lot of money organization can get regarding the path of storms, the has been and is being spent and one might reasonably electrical content, the chances of cloud to ground strikes, ask what we will get from it. Mr. Barrows' paper gives the water content, the chances of precipitation, etc., will us an indication of some of the answers to be expected. enable that organization to do a better job and increase Apart entirely from the weather modification aspects, the efficiency of protection.I believe that the research i.e., the reduction of lightning strikes and the increase of teams that are working on these projects should receive precipitation when conditions are favourable, there are a full measure of support and I look forward to useful many benefits to be derived from the additional knowledge improvement resulting from their work. that these studies are providing. I therefore commend the U.S. Forest Service for their One of the characteristics of lightning-fire occurrence work on Project Skyfire and I congratulate Mr. Barrows is the outbreak of a large number of fires in a very short on his very fine presentation to us today.

Session B Forest Pathology Pathologie forestière PatologIa Forestal

The Inter-Continental Spread of Forest Tree Diseases

T. R. PEACE Chief Research Officer, Forest Research Station, Alice Holt Lodge, Forestry Commission, Wrecciesham, Surrey, England

Relatively few fungi, bacteria and viruses attacking where there is a sea barrier, natural dissemination be- forest trees have a worldwide distribution or even cover comes much less important or even non-existent, and man all the areas where availability of host and suitability of is the chief agent of spre:ad (Orton and Beattie, 1923). climate would permit their development. Many instances Thus inter-continental transmission of disease, except be- are already known, however, where pathogens have tween Europe and Asia, is almost entirely due to man's spread from one continent to another, and there are agency. alarming possibilities of further spread.This paper at- This paper is divided into two main sections.In the tempts to discuss the risk and how its immediate and first and smaller, the risk is considered briefly.In the long-term effects can be lessened. Discussion is limited to second and larger, various actions, which have already diseases caused by fungi, bacteria and viruses, but similar been taken or can be taken in the future, are considered. principles ap1y to insect pests. On land masses where the host tree or trees have a The Problem continuous distribution, spread Of diseases by natural A study of the present-known distributionboth in the means is almost inevitable and extremely hard to stop. positive sense of areas known to be infected and in the But where there are breaks in host distribution, for in- negative one of areas known to be uninfectedmakes it stance, a mountain range or a desert, and particularly clear that many pathogens already known to be dangerous

868 Fifth World Forestry Congress Proceedings are not yet generally present throughout their hosts' indicates the large number of species involved. Complete geographical range. In particular, they may not yet have lists for a limited number of important tree genera are penetrated all the areas where the host species has been now in course of preparation on an internationalbasis planted as an exotic. Bacterial canker of poplar, whether under the auspices of the International Union of Forest it is caused by Pseudomonas syringae or Aplanobacterium Research Organisations. populi, isstill apparently confined to Europe; Phloem Thus we are faced with a large number of diseases necrosis, a virus disease of elm, to North America; the known to be damaging in the countries where they are fungus Monochaetia unicornis, causing canker on cypres- present and therefore presumed to be damaging in other ses, to Africa and New Zealand; Ceratocystis fagacearum, countries to which they might spread. There is the strong the cause of oak wilt, to North America; and so on. The possibility that other diseases, not serious in their present compilation of any list of dangerous pathogens of incom- range, might prove dangerous if transported to other plete distribution indicates clearly that the incompleteness areas, either more favourable to their activities or less rests partly on lack of knowledge. A recent unpublished favourable to their host tree.Finally, there are almost list of forest diseases considered potentially dangerous in certainly parasites, as yet unrecorded, that willattract Britain was based on reasonably certain information that attention only when the countries where they now exist the diseases listed were not present in this country, but are pathologically explored, or when they reach other that they were present in other areas. Most records were countries. Thus, we must consider what immediate steps from North America and Europe, where forest patho- can be taken to prevent or slow up disease spread from logical investigations have been reasonably thorough. The place to place, and what long-term work can be under- table below, based on thislist, shows the number of taken to mitigate the effects of such diseases, should they diseases, absent from Britain but considered potentially eventually reach other countries or other continents. dangerous to British forest trees, recorded from the dif- ferent continents. Phytosanitary Action Phytosanitary action can be taken in a number of ways. Dangerous forest diseases, absent from Britain, and known to General reviews of these have been made by GUssow occur in (1936), McCubbin (1946, 1955) and Soraci (1957). N. America only 40 The means used fall roughly into three categories: (a) Europe only 8 measures taken in the exporting country; (b) measures Asia only 3 taken in the importing country; and (c) embargoes, N. America and Europe 5 whereby carriage of specified plants or parts of plants N. America and Asia 1 from one country to another is completely forbidden. N. America, Asia and Europe 2 As far as trees are concerned, there are three main N. and S. America 2 types of material on which fungi, bacteria and viruses are N. and S. America and Europe I likely to be transported, namely, seed, plants and timber. N. and S. America, Europe and Asia 1 Seed presents the smallest risk. Although a good case can Europe and Asia 1 be made for the routine treatment of many agricultural Africa and New Zealand 1 seeds, there is so little evidence of disease transmission on tree seeds, that no general action can be justified. Only in the case of chestnut blight, Endothia parasitica, The preponderance of North American entries in this on Castanea seed is there a strong case for seed disinfec- list is partly due to the importance of North American tion. conifers in British forestry. The relatively small number Timber is much more dangerous, especially when it is of dangerous European diseases, not present in Britain, unbarked.Ceratocystis ulmi, the cause of elm disease, is partly the result of its proximity to the rest of Europe. was taken from Europe to North America on unbarked The low numbers for other continents are mainly due to timber, and Endothia parasitica may have reached Europe the relatively small importance of their trees in Britain from North America in the same way. There has been a and to the fact that in some cases large areas lie in entirely very general tendency, except in the case of fruits and different climatic zones from Britain.Nevertheless, it is vegetables, to neglect the risk involved in the movement almost certain that the low figures for Asia, where nearly of final products, partly, no doubt, because restrictions all the dangerous diseases listed are from Japanese rec- on them would almost invariably involve serious restric- ords, and for other con'tinents poorly represented in the tions on trade. Yet, transmission of some pathogens, such list are due to lack of knowledge of the pathogens occur- as Endothia parasitica on Castanea and on Quercus, or ring there. Hypoxylon pruinatum on poplar, is much more probable While any list of known dangerous pathogens with on timber than on small plants.Morgan and Byrne incomplete continental distributions is certainly impres- (1957) have recently stressed the dangers inherent in the sive, particularly in the number of species involved, it is uncontrolled movements oftimber from country to certain that more diseases remain to be discovered when country or from continent to continent. pathologically unexplored regions, such as China or most There are, of course, several well-known examples of of the temperate area of South America, are properly the transmission of tree diseases on young plants. The investigated. No complete conspectus of disease distribu- most notable is the importation, on nursery plants, of tion exists, but a recent publication of the fungi occurring Cronartium ribicola, the cause of white pine blister rust, outside North America on American native tree species into North America from Europe. Most of the quarantine isof considerable importance (Spaulding, 1956) and regulations designed to prevent the entry of tree diseases

Forest Protection 869 have referred to living plants, rather than to seed or particular on their potential danger and on their distribu- timber. tion, and to condemn widespread embargoes on the Although embargoes obviously give the best chances of ground that they are based on unreasonable fears of the success, there is rather general objection to their use. unknown. However, we must remember our almost com- Where trade exists, they are bound to be restricted, and plete lack of knowledge of potential tree pathogens in there is always the possibility that they may be applied some of the phytopathologically less-advanced countries. foreconomicratherthanphytosanitarypurposes. It is also necessary to take into account the obvious pos- A complete embargo on seed would obviously impose too sibility that a known pathogen may behave quite differ- severe a restriction on any country which was largely ently when moved to a new environment. The behaviour dependent on exotic trees. A complete embargo on young of Phaeocryptopus gäumanni on Pseudotsuga and Keithia trees and parts of trees would stop the international dis- thujina on Thuja, when moved from North America to tribution of trees such as poplars, which are normally Europe, are frightening examples; though the increased raised as vegetatively propagated clones, and of grafting importance of Keithia is due mainly to its severe attacks material of selected trees for breeding work. A complete on nursery plants of Thu/a in Europe, as compared with embargo on timber would be possible only for a country its behaviour on natural regeneration in North America. that possessed a sufficiency of all kinds of timber for its Even when a fungus is already widespread, there is a own use. Conditions vary in different countries, and so, danger thatit may have regional strains of differing therefore, does the extent to which they are able to apply virulence, the transfer of which could prove damaging. embargoes, undeniably the most effective phytosanitary This may well be the case with Lophodermium pinastri, measures. In practice, embargoes can hardly be made the needlecast of pines. Such considerations may support complete.Limited importation by licences subject to the application of embargoes, where they can be imposed specified precautions must be granted for scientific pur- without damage to the forest economy. poses.In any case, spores may enter on aircraft, and It is outside the scope of this paper to discuss all the passengers may carry diseased material knowingly or quarantine measures which have been imposed by various unknowingly in their baggage (Sherman, 1957). countries against tree diseases. They have been fully sum- Itis generally admitted that inspection of imported marised in an F.A.O. publication by Ling (1952 and material on arrival is a very unreliable way of preventing after).The United States regulations, with a very long the entry of diseases (Gravatt and Parker, 1949; Gram, list of tree genera and species and with some restrictions 1955). In the case of large consignments only a sample applying only to specified regions, represent a pains- can be inspected, and, unless the incidence of disease is taking effort to relate quarantine measures to the existence very high, it may well go undetected. In some cases the and distribution of known diseases. The British regula- disease may be in a stage which is not detectable even by tions, as far as conifers are concerned, provide an example carefulvisualinspection.For instance, Chrysomyxa of the widespread embargo, designed to protect a group rhododendri was imported into the United Statesas of genera from all pathogens, known or unknown, from mycelium in azalea leaves. By the time fructifications all regions. appeared and the disease became detectable, the plants In any case, of course, phytosanitary measures can only had been widely distributed (Gould, Eglitis and Doughty, postpone the more or less inevitable spread of all diseases 1955). In fact, inspection on entry, except for the occa- to all areas where there are susceptible crops for them to sional detection of very badly diseased consignments or attack.Nevertheless, such a postponement may have of material subject to embargo, is valuable mainly in enormous value in giving time for resistant strains to be encouraging better phytosanitary practices in the export- discovered or developed and for control measures to be ing country. elaborated. There is obviously a better chance of achieving satis- The remaining sections of this paper indicate what can factory inspection in the country of origin. If plant inspec- be done during this "period of grace" to ensure that we tion is started in the nursery, it can be extended over a are equipped to meet the forest pathological problems of period of time and carried out with a knowledge of some the future, when transport will be so rapid and so cheap of the possibilities of infection to which the crop is subject. that restrictions on movements of goods will be completely Even then it is impossible to state honestly that plant ma- out of place. terial is entirely free of all disease. There is no doubt, how- ever,that efficient pre-export inspection, especially in Exploratory Action the nursery, can greatly lessen the risk, so that the danger When we consider tropical forests, it is readily apparent of importing from any particular country depends not that the area which is relatively unexplored from the only on the pathogens present there, but also on the disease point of view is very large. For many extensive efficiencyofitsphytopathological inspectionservice. regions, incomplete lists of fungi do exist, but rarely, Every country is therefore in a position to lessen the except in the more highly developed countries, have the chances of disease transmission by improvements in the listed fungi been evaluated phytopathologically. Thus, we scope and skill of its inspection service and by the en- have little idea how much damage they are doing in couragement of phytosanitary practices among its export- their native country, and no information at all on which ing nurserymen. to base estimates of their behaviour if they were moved The principles underlying plant quarantine regulations to other countries or continents.Obviously, therefore, have been discussed by Moore (1952, 1955) and by there is a great need for what might be called "phy- Soraci (1957). There is a strong tendency to base regula- topathological exploration," not only in many tropical tions on our present knowledge of specific diseases, in forests, but also in quite large areas in the temperate

870 Fifth World Forestry Congress Proceedings regions.It is clearly important that such work should care must beexercised,for unequaldistributionof be done thoroughly and critically.Firstly, an important sources of infection may cause unequal distributionof disease may exist outside the forest proper on scattered damage, which thus may have no relation to the inherent trees or in scrub areas, so that surveys cannot be limited susceptibility and resistance of the trees affected.For to areas of utilisable forest.Secondly, diseases may be this reason, information from a large number of exotic of slight importance in their country or origin because plantations, preferably growing under a wide range of the native host trees are either resistant, as was the case infective and climatic conditions, is likely, if intelligently with Endothia parasitica on Castanea in Asia (Beattie and interpreted, to be of more value than that collected from Diler,1954),or of restricted distribution. a limited number of specially designed test plantations. Clearly it is difficult, and in the case of tropical forests None of the methods mentioned above will eliminate impossible, to assess the risk exactly or to consider gen- the effect on diseases of differences in climate and other eral precautionary measures until we have a much more environmental factors between one country and another. widespread knowledge of tree diseases.Unfortunately, For this reason, the disease reactions of a tree species in while short-term visits, such as collecting expeditions, one place cannot be taken as a certain indication of its may provide valuable information on the occurrence of behaviour towards the same pathogen elsewhere. They pathogens, evaluation of these pathogens requires study do, however, give the best information which can be pro- over a period of time and must, therefore, await the cured without actually moving the pathogen, a method development of a forest pathological organisation in the which naturallyiscompletely inadmissible.There is region concerned. danger even in moving cultures of pathogens from one country to another (Wheeler,1957).Transfer of cultures Research Action can be justified only if it serves some useful purposeand Any advance in our knowledge of tree diseases is provided the cultures are carefully guarded. The use of naturally of value, when we come to consider the pos- an exotic pathogen, or even of an exotic strain of a native sibilities and results of their transmission from one area pathogen, for inoculation purposes is a pathological crime to another. The testing of the trees of one country or of grave significance. continent for their resistanceorsusceptibility to the There is also room for research on the means of trans- disease of another, whether by chance exposure, deliberate mission of tree diseases over long distances; though this exposure or inoculation, is particularly valuable. In many is of less permanent value than work on disease behaviour. countries there is so much information already available, Too little is known about the relative importance of dif- but not necessarily collected, from existing plantations ferent means of transmission. In particular, it would be of exotics that it is doubtful if plantings designed merely valuable to have more evidence on the importance or for disease-recording purposes can be justified.They otherwise of seed as a means of transmission. are really useful only when placed in regions where the pathogen population was unexplored.The possibility Evaluative Action of doing this is, of course, limited by the lack of path- Any increase of knowledge of thedistribution of ologists in those regions.Nevertheless, it may therefore diseases and of their behaviour on different hosts in prove easier to observe the development of disease in different climates is of great assistance in evaluating their carefully sited plantations than over the unexplored area importance, both present and potential.If more facts as a whole. In addition, forest plantings of exotics are were available on the actual and potential economic probably lacking in a relatively undeveloped country, losses inflicted by diseases transported from one area so that stands specially formed for pathological study to another, there would be more reasoned support for may provide the only chance of getting data on the expenditure, either on means to prevent their spread susceptibility of non-native trees to the local pathogens. or on the mitigation of damage once they had done so. Provided the limitations imposed by siting in relation In the past there has been a tendency to behave as if to virtually unknown sources of disease and by the limited all damaging diseases were of equal importance, at any number of plantations are taken into consideration, there rate as far as restrictions of spread is concerned. It might be better if our were concentrated on the re- is no doubt that such special plantations could yield striction of a limited number of diseases, leaving others results of very definite international value. to spread more or less unhampered, either because they In pathologically explored regions, plantations designed were easily controlled or avoided, or because there was to test under natural conditions the reactions to specific good evidence that they would not be seriously damaging. diseases and therefore deliberately placed in regions of However, selective action of this kind would be possible high infectivity would be more valuable, and there is only on the basis of much greater knowledge of disease certainly room for their extension.It is also desirable behaviour than we yet possess for most forest pathogens. to extend inoculation tests in one country on tree species It can, therefore, be practised only when much more of importance to another (Gravatt and Parker,1949; work has been done on what might be termed "inter- Riker,1957). national disease behaviour." With any of these methods, care must be used in the interpretation of results. The presence of a disease in a Practical Possibilities plantation is always more significant than its absence; It will be apparent from what has been said above very good evidence is required before the absence of a that the amount of work required to build up a knowledge disease from a tree can be taken by itself as proof of of disease behaviour sufficient to form a basis for inter- immunity or resistance. Even when disease is present, national action is very great indeed. The limitations on Forest Protection 871 this work are primarily those of staff. At first sight, the Morgan, F. D. and Byrne, J.,1957. The desirability of inter- most importantlimitationistheabsenceofforest national quarantine measures for exports and imports of timber and timber products.Br. Comm. For. Conf. pathologists in many countries, but the very small number Orton, W. A. and Beattie, R. K., 1923. The biological basis of in most o'ther countries, particularly in Europe, is equally foreign plant quarantines. Phytopathology, 13, 7, pp. 295-306. serious.In many cases, the workers are so few that Riker, A. J.,1957. The discovery of important diseases before their energies must inevitably largely be devoted to im- they move from one country to another. Phytopathology, 47, 7, pp. 388-389. mediate forest pathological problems. They have little Sherman, R. W., 1957. Co-operation of world tourists sought in time to spare for investigations which are not of im- plant quarantine enforcement. FAO Plant Pro. Bull. 5, 6, pp. mediate practical value or which are designed with long- 89-90. term international, rather than immediate national, ends Soraci, F. A., 1957. Redefinition of the principles of plant quar- antine and their relation to the current problems. Phytopathol- in view. Most governments take the view that forestry, ogy, 47, 7, pp. 381-382. earning as it does low rates of interest, cannot support Spaulding, P.,1956.Diseases of North American forest trees a high expenditure on research. And thus, although this planted abroad. Agric. Handbook 100, U.S. Dept. Agric. argument may not be entirely sound, any substantial Wheeler, W. H., 1957. The movement of plant pathogens. Phy- increases in research expenditure must be clearly linked topathology, 47, 7, pp. 386-388. with resultant economic advantages. Economic appraisals RESUMES of disease losses, and in particular of the relation of re- search costs to the prevention or mitigation of these La propagation intercontinentale des maladies forestières losses, are thus obviously desirable.Only thus can a Bien qu'un grand nombre d'agents pathogènes soient répandus un peu partout dans Ic monde, il y en a beaucoup d'autres quA reasoned case be stated for increased expenditure on sont localisés seulement dans certaines regions et qui ont ainsi pathological research. toujours Ia possibilité d'élargir le champ de leurs ravages. La In the meantime, any schemes for international co- repartition d'un grand nombre d'agents pathogènes n'est pas operation must either take full account of the limitations encore connue complItement et il est probable que certains parmi les plus dangereux, qui existent seulement dans des regions patho- which the pre-occupation of forest pathologists with their logiquement arriérées, restent encore a découvrir. local problems imposes, or else allow money for the La propagationdes maladies, notamment entre continents appointment of specialstaffto carry out the work séparés par des oceans, peut être retardée par des mesures phy- envisaged.In thefield of international co-operation, tosanitaires, a savoir embargo ou restrictions sur les importations, et par des mesures plus constructives prises dans le pays exporta- it is perilously easy to envisage grandiose schemes, the teur, notamment dans les pépiniIres. initiation, let alone the operation, of which is far beyond Si Ia propagation des agents pathogènes peut être retardée de the capacity of any existing organisation. Therefore, the cette manière, on peut mettre a profit le temps ainsi gagn'é pour fullest possible international use should be made of prendre des mesures d'un effet durable. On peut explorer, sur le work already in progress, but even the co-ordination of plan phytopathologique, les pays qui n'ont qu'une connaissance trés limitée des agents pathogènes qu'ils peuvent abriter ou des this involves considerations of time and money which ravages qu'ils causent. On peut intensifier, en les portant sur le cannot be overlooked. plan international, les recherches portant sur la résistance et la Thus, while few would deny the importance of in- predisposition desarbres aux agents pathogènes indigèneset creasing our knowledge of diseases, the damage which exotiques. On peut effectuer une estimation des ravages causes par les maladies, afin de donner une base dconomique plus ferme they are likely to do if they become more widespread a toutes mesures pouvant être prises a leur encontre.Ii convient and of the means by which this damage can be avoided, toutefois de ne pas oublier qu'un travail de ce genre ne peut être it is vital that the international work involved should be effectué sans personnel et fonds suppldmentaires. provided with a sound economic background, thus justify- ing the substantial expenditure involved. La Propagación Intercontinental de las Enfermedades de los Arboles References Aunque gran ndmero de enfermedades se propaga extensa- Beattie, R. K. and Diller, J. D., 1954.Fifty years of chestnut mente, hay muchas otras más que están restringidas y, por lo blight in America. J. For., 52, 5, pp. 323-329. tanto, tienen todavIa potencialidades de propagación mayor y Gould, C. J., Eglitis, M. and Doughty, C. C., 1955. European más daflina.La distribución de muchos de los patógenos se rhododendron rust (Chrysomyxa ledi var. rhododendri) in the conoce solo parcialmente y es probable que algunos de los United States. Plant Dis. Reptr., 39, 10, pp. 781-782. peligros existentes en areas patolOgicamente atrasadas no hayan Gram, E.,1955.Barriers and by-passes in plant trade.Ann. sido descubiertos todavIa. appl. Biol., 42, pp. 76-81. La propagación de las enfermedades, especiahnente en las Gravatt, G. F. and Parker, D. E., 1949. Introduced tree diseases masas terrestres separadas por los mares, puede demorarse por and insects.Yearb. Agric., U.S. Dept. Agric. pp. 446-451. medio de disposiciones fitosanitarias, tales como Ia prohibición o Güssow, H. T., 1936. Plant quarantine legislationa review and restricción de las importaciones, o por medidas más adecuadas a reform. Phytopathology, 26, 5, pp. 465-482. tomadas por el pals exportador, especialmente en sus plantarios Ling, L., 1952 (and subsequent supplements).Digest of plant y almácigas. quarantineregulations.Food & Agric.Organ.of United Si de esta manera logra demorarse la propagaciOn de las Nations, Rome. enfermedades, el tiempo ganado con ello podrá usarse entonces McCubbin, W. A., 1946.Preventing plant disease introduction. en medidas de valor más permanente.Aquellos paises en los Bot. Rev., 12, 2, pp. 101-139. cuales se sabe poco acerca de los patógenes existentes o del daflo 1954.The plant quarantine problem: A general que causan, podrán ser explorados fitopatológicamente. Es con- review of the biological, legal, administrative and public rela- venienteintensificarinternacionalmentelosestudios sobrela tions of plant quarantine with special reference to the United resistencia de los árboles contra las enfermedades nativas y las States situation. Chronica Botanica Co. exOticas y avaluar los dafios causados por las enfermedades para Moore, W. C.,1952.Principles underlying plant import and asI poder dar una base econOmica más firme a cualesquiera export regulations. Plant Pathology, 1,1, pp. 15-17. medidas que se tomen contraellas.Sin embargo, conviene 1955. The development of international co-opera- recordar que una labor de esta especie no puede lievarse a cabo tion in crop protection. Ann. appl. Biol., 42, pp. 67-72. sin personal y fondos adicionales.

872 Fifth World Forestry Congress Proceedings The Significance of Introduced Diseases From the European Point of View M. M. KRSTIC Professor, Forest Faculty, Belgrade, Yugoslavia

It is not always certain which forest diseases have been Italy, Yugoslavia). According to the latest information, introduced into Europe.The development of forest the ink disease is progressing through eastern Europe pathology in the second half of the 19th century and the (13). beginning of the 20th century had as a result that a The ches:tnut blight, caused by Endothia parasitica, is number of forest pathogens was discovered in Europe by far the biggest problem inchestnut stands and earlier than on the other continents. But the growth of orchards in Italy, France, Yugoslavia, and Switzerland. this discipline was also uneven throughout Europe. It is It is very likely that the fungus was introduced from the therefore difficult to state whether the parasitic fungus United States during World War I (5). Its serious spread MicrosphaeraaiphitoidesGruff. etMaubl.spread dates from 1938, when the blight was detected near definitely from France, where it was detected in 1907, or Genoa, Italy. The fungus has invaded as far as the large ifitslater report in eastern and southern European chestnutareasinsoutherncountries,includingthe countries was due to a lack of observation. We can U.S.S.R. The last known situation was as follows: rapid hardly conceive that the fungus Cenangium abietis (Pers.) spread in France, slow spread in Yugoisavia, and station- Rehm. was not present in the Balkan pine stands before ary status in Italy and Switzerland (13). The blight was 1957, when it was first observed, knowing that serious practically eradicated in Spain and was never observed in damages occurred in northern pine plantations before Portugal and Greece. that year. Both diseases have caused economic and social dis- When we discuss introduced parasites, it appears more turbances in the corresponding countries.The general difficult to interpret the running course of minor diseases consequence consists in the permanent reduction of the with less evident symptoms. These diseases should not, chestnut area. Some data give evidence of how destruc- however, be the chief theme of this paper. We should tive was the action of the aforementioned parasites (13). review, firstly, the phenomena representing the biggest In France, for instance, the area of chestnut groves problem for European silviculturists and pathologists diminished during the period from 1882 to 1954 by ap- and, secondly, the most important diseases on the other proximately 215,160 ha., and some authors ascribe this continents, imperiling European wood production. fact to the ink disease (15). The total chestnut area in Spain was almost three times larger in 1870, before the Major Introduced Diseases and Their Importance wide spread of the same disease. In Italy a diminution of Among pathogenic fungi which are supposed to be in- 100,000 ha., in comparison with before World War II, troduced, five of them represent key problems in Europe. has also been noticed. Theseare:Phytophthoracam bivora(Petri)Buis., The data are lacking as to what extent wood production Endothia parasitica (Murr.) P.J. & H.W. And., Ceratosto- was lowered by these two diseases. Nevertheless, one can mella ulmi Buis., Phaeocryptopus gäumanni (Rhode) realize why the annual production of commercial wood Petr., and Rhabdocline pseudotsugae Syd. has diminished by more than 47,000 tons in Portugal, where the ink disease is damaging (12). On the other Chestnut Problem hand, chestnut wood production in Greece, believed to be Two fungi, Phytophthora cambivora and its common free of principal diseases, shows an increasing trend (13). associate P. cinnamomi Rands: are considered as the main Both diseases have undoubtedly influenced the produc- chestnut enemies in the countries free of Endothia. The tion of chestnut wood and bark for the tanning industry, first fungus was intensively studied and is therefore bet- but instructive data are lacking. One should note that the ter known than the other one. According to one opinion, production index for this kind of material in Italy has it originates from eastern Asia (9) * First observed in dropped during the period 1952-1957 from 148.6 to the Azores,itlater spread across the Mediterranean 96, though there is a tendency towards an increased region.Both fungi are the cause of the chestnut ink consumptionofsuchmaterials(13). Diminution disease. orincreaseof consumptionshould bepartiallyat- The damages of this disease are particularly serious in tributed to quarantine regulations and to the intensive Spain and Portugal but have also been heavy in the cutting of infected chestnut trees. The nut production shows an evident decline in some countries where Endothia parasitica is rampant (France, countries. In France, for instance, the total annual output * Numbers in parentheses denote the references listed at the was reduced during the period 1947-1957 by around end of this paper. 29,373 tons, which was ascribed to the ink disease to

Forest Protection 873 some extent (13).According to the same source of tion, the volume of elms does not presently exceed 5 %, information, the nut production index in Italy was 100 as against 35% before 1931. in 1953 and only 68.9 in 1957. The annual production The opinion was prevalent that the primary cause of has dropped by 1,000 tons in Switzerland during the last the Dutch elm disease is the parasitic fungus Ceratosto- few years. mella ulmi, whose vectors are two bark beetles, (Scolytus Though the prophecy of the practical disappearance of scolytus F. and Scolytus multistriatus Marsh.).Accord- European chestnut as a forest species is not likely to ing to recent studies made in Yugoslavia, the essential become reality, the two diseases have provoked in all cause lies in climatic changes over a number of years and countries disturbances which are of an economic, silvicul- consecutively changes in bark beetle gradations, which tural, and phytosanitary nature. have enormously raised the potential of the parasitic fungus (18). The economic consequences have been outlined. These The main problems deriving from the English elm are inseparable from the two following problems. decline consist in: (a) a continual loss of valuable elm The silvicultural aspects of the problem actually con- wood; (b) a structural modification of stands composed sist in:(a) conversion of affected groves to coppice, earlier of elm and other forest species (ash and oak with the aim of stopping the spread of both diseases or particularly) that subsequently died out; and (c) difficul- of obtaining higher yields of forest products, better suited ties for maintaining elm trees as ornamentals.It is thus to the agricultural needs of the country; and (b)soil evident that the elm problem is not only of an economic, conservation by replacing chestnut where it is practically but also of a silvicultural and horticultural character. lost. While the positive examples have been recorded as The solution was seen in the replacement of elms by fast- regards high-growth transformation to coppices (Italy), growing softwoods, but the difficulty remains as regards the problem still remains open in relation to the replace- the horticultural aspect of the problem. Numerous and ment of chestnut by other productive species, particularly costly trials to replace the susceptible European elms conifers.In the realm of nut production, the emphasis by Asiatic species have been made; however, the latter must be on the selection and reproduction of clones more species have proved to be less resistant to frost or of resistant to diseases. inferior aesthetic value. On the other hand, the propaga- The phytosanitary measures have lost much of their tion of resistant Buisman's and other elm selections by significance in the countries with widespread diseases but cuttings is still concerned with the more practical problem are still of interest in the others. One should remember of rooting.Finally, the safeguard of susceptible elms is the long and costly attempts to improve the chestnut efficient only by combating bark beetles. This is practical situation in different southern European states by various only on small areas or on individual trees. In conclusion, physical and chemical methods. The phytosanitary aspect the elm problem in Europe remains unsolved, despite all of the problem is especially connected with finding more efforts, to this day. effective and less costly control techniques. Douglas-Fir Problem Elm Problem The growing of Pseudotsuga douglasii Carr. has become It is believed that the parasitic fungus Ceratostomella seriously compromised in Europe by two presumably ulmi, the cause of Dutch elm disease, was introduced into introduced fungi, Rhabdocline pseudotsugae and Phaeo- Europe from eastern Asia during World War I (3). First cryptopus gäumanni. observed in the Netherlands in 1919, the disease spread The first fungus, the cause of Douglas-fir needle cast, consecutively across the Continent, including the Euro- seems to have been introduced into Scotland in 1914 pean part of the U.S.S.R. Almost all European elm species from North America. The parasite is presently distributed are susceptible to this disease. all over Europe, wherever there are Douglas-fir planta- In comparison with the chestnut blight development, tions.In Boyce's opinion (3), the spread of the fungus the Dutch elm disease had a more chronical course. is "an outstanding example of the danger in the promis- Though it was believed at the beginning that the disease cuous shipment of young trees." would cause the complete disappearance of the English The second parasite represents a still more important elm (Ulmus cam pestris L.), the pessimism was not fully cause of Douglas-fir decline in young plantations.This justified, for we still encounter in Europe abundant young fungus, also, is supposed to have been transferred from growths of this species. Owing to its popularity and its North America.First detected in Switzerland in 1925, technical and ornamental value, afforestation with English it was later found in many plantations in Great Britain, elm was not abandoned in most countries. Germany, Austria, Denmark, France, Italy, and Yugo- The data concerning the extent of elm decline are not slavia. complete or available, but it is obvious that the English The result of the attacks of both parasites, which are elm has been seriously decimated during the last four frequently simultaneous, is the permanent shedding of decades. According to some estimates, 60-70% of the needles and thus the diminution of growth rate of the elm trees have been killed in several districts of Belgium, trees. In young and dense plantations the two fungi cause the Netherlands and northern France (3), and 30-50% in killings.It is therefore a question whether under such Yugoslavia (9). The loss is better expressed by volume. circumstances the green Douglas-fir deserves the designa- During the period from 1920 to 1948 in Croatia (Yugo- tion of fast-growing and productive conifer or, using the slavia), 2,035,324 cubic meters of wood died (18) and term of the enthusiastic silviculturists, "the tree of per- had to be cut. In some mixed stands of northern Serbia spective." Unfortunately, more precise information in this (Yugoslavia), according to the same source of informa- sense is lacking.

874 Fifth World Forestry Congress Proceedings The rather extensive decline of the green species was parasitic fungus Ceratocystis fagacearum (Bretz) Hunt, also ascribed to its propagation outside of its natural the cause of this disease, is presently the biggest pathologi- range (21). While this fir was recognized as being rather cal problem in the United States. In less than 20 years resistant, the blue and gray species are subject to severe (until 1958) the pathogen spread over 18 States (6), attacks.But the green fir also proved to be susceptible where severe attacks and considerable losses have been in someareas(Yugoslavia).These facts have led reported (8). Some foreign oaks and Chinese chestnut foresters to look upon the further propagation of Douglas- are susceptible in America.Realizing how catastrophic fir with more precaution or even to recommend the giving could be the spread of this fungus across Europe, the up of its use (21). Food and Agriculture Organization of the United Nations Both diseases interest primarily the countries where inquired some yearsago ofthe European member one part of silvicultural activity has been devoted to countries as to their concern about the eventual occur- Douglas-fir (Germany, Great Britian, etc.) or where it is rence of the oak wilt. No alarm in this regard has been planned in the near future (Italy). The data regarding expressed thus far, but the possibilities of the entering the extent of damages do not always coincide. In appro- of the parasite stifi remain.All reproductive material priatesoils, no serious attacks have been reported in originating from the affected American localities can be, northern Europe, but important losses by Phaeocryptopus theoretically, designated as dangerous. fungus occurred in central Europe and in some localities The other oak diseases in North America (Strumella inItaly and Yugoslavia.Briefly,regardlessof how coryneoidea Sacc. & Wint., Sphaeropsis quercina Cke. promising results seem to be attained, it comes out clearly & Ell., etc.) have proved to be of minor importance. that both parasitic fungi will or should play a significant The parasitic fungi of the American beech are also role in planning the future use of Douglas-firs as forest common in Europe. The major beech problem in Amer- or ornamental species, particularly in central and south- ica, beech bark disease, caused by Nectria coccinea var. ern Europe. faginata Loh., Wats. & Auers, does not seem equally important as regards the European beech. The fungus has Danger of New Diseases already been observed in northern Europe, but it has not caused remarkable losses (3). The other more or less important introduced diseases The cultivars and clones of the Euro-American poplars have not been conimented upon because of the limited are menaced by Septoria musiva Pk. (7). Not yet re- space of this paper. One should mention, however, the ported in the European plantations, its importation is oak mildew (Microsphaera aiphitoides) which has led to possible, owing to the exchange of cuttings. Having in a practical disappearance of Quercus toza Bosc in south- mind the rapid evolution of Septoria canker on American western France and which actively contributes to the oak species and hybrids, it is quite probable that the fungus, dying back in Yugoslavia (9). under similar ecological conditions, could become more Purely forestry and horticultural reasons require the nocent in Europe than Dothichiza populea Sacc. & Br. exchange or the purchasing of different reproductive The danger of Septoria fungus appears still higher, in material between Europe and overseas countries. Asiatic view of the fact that it has been particularly pernicious to trees are prized mainly for their resistance to diseases or new hosts (2). for their ornamental value, American for their productiv- The fear of Hypoxylon pruinatum (Klotzsch) Cooke is ity or advanced stage of breeding, African for their less than in the preceding case. The aspens are difficult adaptability to dry climatic conditions or for aesthetic to reproduce by cuttings, so the transfer of the parasite purposes. While the phytopathological situation with most through seeds or root cuttings is unlikely. One should tree species is well known in North America, it remains remember that the fungus was detected in the U.S.S.R. enigmatic as regards the other continents.Generally (1), but its presence in western Europe is unknown. speaking, we can consider that all imported reproductive The richness in pine species in North America had as material from different continents, with the exception of a result a more abundant pathogenic flora than in Europe. North America, represents a permanent danger for the For the Scotch and Austrian pine plantations all over the same or similar species or genus in Europe. Knowing European Continentthefollowingorganismsmight better the diseases existing in North America, let us eventually be pernicious: analyze which of them may be important to European Cronartium fusiforme (H. & K.) Hedge. & Hunt, a forestry. cause of high mortality of southern American pines (20). The interest in maintaining natural and artificial stands The possibility of introducing this parasite by seedlings of many autochthonous deciduous or coniferous species exists, although theoretically it can also be transferred on still exists in Europe. The value of their the leaves of southern oaks. wood and the actual development of wood technology Hypoderma lethale Dearn., H. hedgcockii Dearn., require further regeneration of existingforests.One and Scirrhia acicola (Dearn.) Siggers, all attacking pine should mention wide areas of oak and beech stands, nat- needles and sometimes being a problem in nursery stock ural poplar growths, and natural or artificial plantations and in pine plantations (4, 16). Their transfer through of conifers. Another interest is in the fast-growing soft- seedlings or pine needles is possible. woods or, more precisely, different Euro-American and It is a question whether the real possibilities exist for American poplar selections and American conifers.If bringing in Cytospora kunzei Sacc., parasitic to Norway we adopt this priority, let us see which of the pathogens spruce (Picea abies Karst). This fungus might be harm- in North America represent the imminent danger. ful in the European spruce plantations. The oak wilt problem undoubtedly ranks first.The The main parasites of eastern white pine and Douglas-

Forest Protection 87 fir in America are also present in Europe. Some other The safest method of checking the introduced diseases fungi (Caliciopsis pinea Pk., Chondropodium pseudotsu- is based on the utilization of resistant selections. In this gae White, etc.) have been of minor significance so far. field, considerable efforts have been made. The same was The hardwoods and conifers in North America have achieved as regards resistance to native poplar diseases their specific wood-decay and wood-staining fungi. Some (Italy).In spite of that, one feels the need for closer of them could be of interest to European wood produc- international cooperation in this sense.It is not, there- tion. As an example, one should mention Echinodontium fore, astonishing that in some European states the utiliza- tinctorium Eli. & Ev., a problem in fir and Engelmann tion of resistant elm and chestnut selections is not yet spruce plantations of British Columbia (17). Owing to practiced. The conception grows that the production and the relatively limited shipment of American logs and exchange of resistant selections should be assisted by an lumber to Europe, discussion of the transfer of other international organization, with the financial participation fungi will be omitted here. of the corresponding countries. A similar idea for found- Finally, one bacterial (Erwinia nimipressuralis Carter) ing an international "bank," with the aim of stimulating and one virus disease of elms, known as "wetwood" and distribution of resistant poplar selections, was put forth "phloem necrosis", respectively, may also be of interest. by Argentina(14).The establishment of "seed or- Both disturbances have been important in some American chards," recommended for the resistant Douglas-fir selec- localities.The introduction of these two diseasesis tions (19) would be a complementary action in animating possible through infected plants. this international cooperation. Summarizing the preceding, the most dangerous or- Summarizing the preceding, it results that future efforts ganisms deserving special quarantine attention in Europe to prevent the introduction of new parasites or to check should be considered as being: Ceratocystis fagacearum, the existing ones should be oriented in the sense of: Septoria musiva, Cronartium fusiforme, and the virus Firm quarantine inspection in the countries where disease of elms. the disease has not spread widely or is to be expected; Organizationofspecialsurveysforpernicious Necessary Operations and Research parasites; The discussion of these two subjects appears significant Rapid suppression of first infections; for both introduced and expected diseases. We shall Increased production and utilization of resistant review them separately. selections; and Planting out the resistant selections in unaffected Introduced Diseases forests with the aim of obtaining, in a foreseeable time, The introduced diseases do not receive the same atten- natural and resistant hybrids. tionindifferent European countries.The results of Phytopathological research should, as a rule, precede physical and chemical control not always being satis- the adoption of any new control method. One can gen- factory (e.g., of chestnut blight), these methods have erally state that the research work so far has been mainly been relinquished in some locales. On the other hand, directed at finding out more effective physical and chemi- the tendency for improving or applying new techniques of cal techniques. The attempts in this sense were either disease eradication was emphasized (ink disease in Spain failing(chestnut blight), or not very practical(ink and Portugal,chestnut blightinSwitzerland).One disease), or economic (Dutch elm disease). The breeding should add a third, indirect method, involving the rein- of resistant selections was a more promising way to forcement of quarantine inspection and the organization prevent the epiphytotic spread of some parasites.It of permanent surveys of forest stands in order to detect seems, however, that the basis for this breeding was not and tosuppress promptly new infection spots(e.g., equally developed in Europe and that the interest of chestnut blight in Yugoslavia). Generally speaking, the countries was mostly oriented to the introduction of old techniques are still considered necessary in countries foreign selections. One feels a lack of interest in local where a disease begins to spread. The effectiveness of selectionofvarieties,races,orclones,whichare particular measures should be judged by the spread of the ecologically better adapted and which need testing for disease across a country or across the Continent.It is resistance only. Some poor results with selections origi- quite probable, for instance, that the recent outbreak of nating from geographically distant regions (Italian poplar chestnut blight fungus in the U.S.S.R. and in France was clone 1-214 in Germany, or some Chinese chestnut selec- due, at least partially, to inadequate surveys and quaran- tions in Europe, for example) contribute to the belief tine inspection. On the other hand, the practical eradica- that the present status of major introduced diseases would tion of the same parasite in Spain is a result of energetic be improved if the breeding in narrower geographic zones repressive measures. The slow-spreading course of the were more developed. The future will show how long chestnut blight in Yugoslavia was, aside from natural con- the resistant selections may keep this designation, in ditions, attributed to the aforementioned special examina- view of new strains of introduced pathogens that may tion of outlying chestnut localities and to the rapid build up or of other native parasites belonging to the cutting of infected trees.Such a spread has certainly same or another genus. assured the normal productiveness of unaffected forests In all this scope of questions, the biological opportuni- during the past decade.Thus, we must conclude that ties to combat introduced parasites have not attracted the application and improvement of old and new control the necessary attention of scientists. There are plenty of techniques should be maintained where they seem reason- biological means deserving to be studied. We shall men- able. tion two subjects. The first one concerns the application

876 Fifth World Forestry Congress Proceedings ofantagonistic microorganisms and thesecond,the necessary testing plots. Their activity should bestipulated weakening of virulence of pathogens. by international accords. The experiments to keep back introduced diseases by Studies on the other continents of the susceptibility of antagonists are relatively new and, to the author's knowl- European trees to important diseases would, in a large edge, have been conducted in relation with Endothia measure, help silvicultural planning andthe choice of parasitica only (Yugoslavia). The initial results being species and selections. Activity in this sense was initiated promising (11), the expansion of experiments was recom- two years ago by the Working Group on Forest Diseases mended by the International Chestnut Commission (13). of IUFRO. The same Group, with larger international Although the application of biological control is still in support, could be further recognized as the leading board the experimental stage, hopes are rather high that the for the main studies on susceptibility.In this case, the modification of microfiora in effected localities, by arti- Group shouldgivenecessaryassistancetodifferent ficiallypromotingthereproductionofantagonistic countries, particularly in recommending and organizing microorgansims, might reduce infections. This biological research on the other continents. method seems a priori less costly than the others. The experiments to dominate pernicious pathogens by References their low virulent strains which are little harmful to the Anderson, R. L. Hypoxylon canker of aspen. U.S. Dept. Agr., For. Pest Leafi. 6, 1956. host, i.e., without causing killings or major deformations, Bier, J. E. Septoria canker of introduced and native hybrid are unknown. It does not appear theoretically impossible poplars.Canad. Jour. Res., Sect. C, Bot. Sci., 17, pp. 195- to create mutations possessing a stable character of weak 204, 1939. virulence by using radioactive isotopes or some other Boyce, J. S. Forest pathology, New York, 1948. The advantage oflittlevirulentstrainsof Boyce, J. S., Jr. Needle cast of southern pines.U.S. Dept. process. Agr., For. Pest Leafi. 28, 1958. pathogens over the antagonistic microorganism would lie Darpoux, H., Ride, M. et Boudoux, P. Le chancre du Châ- in the fact that former organisms are better adapted to taignier cause par l'Endothia parasitica.Bull. Inform. Ing. the host plant. Serv. Agr., No. 123, 1957. Fowler, M. Oak wilt. U.S. Dept. Agr., For. Pest Leafl. 29, On this basis, the following research program can be 1958. recommended: Gravatt, G. F. Diseases of the chestnut and poplar in a. Selection in narrower geographical zones for the Europe. OEEC, Paris, 1952. Hepting, G. The current status of oak wilt in the United resistance to diseases, including the international exchange States. For. Sci., Vol. 1, No. 2, pp. 95-103, 1955. and testing of selected clones; Josifovic, M. Sumska Fitopatlogija, Beograd, 1952. b Improvement of rooting techniques; Krstic, M. Une nouvelle maladie des forêts en Yougo- slavie.La chutte des aiguilles du sapin de Douglas. Plant. Studies on the effectiveness of antagonistic micro- Prot., No. 5, pp. 73-74, 1951. organisms and on the possibility of their mass-reproduc- Krstic, M., Grente, J. et Solignat, G. Note sur l'Endothia tion in forests; parasitica en Yougoslavie. 4 Sess. Comm. mt. chat.- (Yougoslavie-Grèce), 1958. Applicability of other biological means of control; Rapport de Ia deuxième Session de Ia Commission i. dii and châtaignier (Espagne-Portugal, 1953), FAO, Rome, 1954. Improvement ofphysicaland chemical control Rapports présentes a l'occasion de la quatrième Session de techniclues. la Commission mt. du châtaignier (Yougoslavie-Grèce, 1958). One should realize that the proposed long-term research Rapport dii Groupe de travail sur les maladies, 2° Sess. Comm. indu peuplier, 1959, Rome, FAO/CIP/MAL/ 11. program would require steady efforts, which are justified Schad, C., Grente, J. et Solignat, G. La protection de la from the forestry standpoint. châtaigneraie contre les maladies en France. FAO/CH/ 25-Ab, 1958. Expected Diseases Siggers, P. V. The brown spot needle blight of pine seed- lings. U.S. Dep. Agr., Techn. Bull. 870, 1944. Two main activities, one operative and one scientific, Thomas, G. P. The occurrence of the Indian paint fungus, are of primary interest. The operative subject consists in Echinodontinum tinctortum E. & E., in British Columbia. Can. thereinforcement of quarantineinspection,and the Dep. Agr., For. Biol, Div., 1041, 1958. scientific, in the testing of European tree species and Vajda, Z.Uzroci epidemijskog ugibanja brijestova. (Rea- selections for resistance to major diseases on the other sons of the epidemic dying back of elms). Glas. Sum.Pokuse, Zagreb, 10, pp. 106-197, 1952. continents. Van Vioten, H. Ziekten en plagen.Een bijdrage voor de Since quarantine inspection varies in organization and Douglasdagen 1957.Ned. Bosb. Tijds.,30,5, pp. 145-149, strictness, the possibilities of introducing new parasites 1958. into Europe are not everywhere equal. Thus, there re- Verall, A. F. Fusiform rust of southern pines. U.S. Dept. Agr., For. Pest Leafi. 26, 1958. mains a permanent risk of new diseases.The safest Viennot-Bourgin, G. Les champignons parasites des plantes solution seems to be either the establishment of several cultivées, Paris, 1949. international quarantine centers or the authorization for several existing stations to inspect all kinds of critical RESUMES reproductive material entering the Continent.In both La signification des maladies introduites du point de vue cases, the countriesimporters or exportersshould be obligated to receive or to send the specified material européefl Dans ce document, l'auteur passe en revue les déprédations through these centers only. This is particularly important causées en Europe par cinq champignons parasitesd'origine for poplar and willow cuttings and for all kinds of seed- étrangère;ii examine les parasites étrangers qui présentent un lings.The international centers should be financially danger pour les arbres européens, ainsi que les mesures et les assisted by the European countries and provided with the recherches qui s'imposent.

Forest Protection 877 Principales maladies d'origine éfrangère. culture dans des zones géographiques plus restreintes; Chátaignier. La maladie de l'encre, causée par le Phytophthora amelioration des techniques de bouturage; cambivora etle P. cinnarnomi, et le chancre du châtaignier étude de l'efficacité de certains micro-organismes antagonis- (endothiose)cause par l'Endothiaparasitica,sontlesdeux tes et de la possibilité de les reproduire en quantités mas- principales causes de la disparition progressive du châtaignieren sives dans les forêts; Europe. étude de la possibilité d'utilisation d'autres armes biologi- Le problème a une repercussion économique en raison de la ques; et reduction importante del'habitatduchâtaignier en Europe amelioration des méthodes physiques et chimiques de lutte méridionale et, par suite, de in reduction de la production de bois contre les maladies. et de châtaignes. Mais en dépit de cette regression évidente iine semble pas que le châtaignier européen soit voué a une disparition Maladies risquant d'être introduites.Deux questions ont dté complete. pnssées brièvement en revue: le renforcement de l'inspection de Du point de vue sylviculture, le problème qui se pose actuelle- quarantaine et le test a faire subir aux arbres européens quant a ment consistea convertirleschâtaigneraies touchées par Ia leur resistance aux maladies des autres continents. maladie en taillis producteurs; et a prendre des mesures de con- En ce qui concerne la premiere question, l'auteur propose servation du sol, en remplaçant les chàtaigniers par d'autre essen- d'dtablirplusieurscentres internationaux de quarantaine, an ces a croissance rapide. d'autoriser plusieurs stations de quarantaine existantes a inspecter En ce qui concerne l'aspect phytosanitaire du problème, ii les graines, boutures et brins de semence suspects arrivant en convient de s'assurer de l'efficacité des diverses méthodes de lutte Europe. contre ces maladies et de réduire le coüt de leur application. Etant donné que des etudes sur la predisposition des nrbres Orme. Les ormes européens sont généralement prédisposCs a européens s'imposent d'urgence, le Groupe de Travail de l'IUFRO une maladie causée par le champignon Ceratostomella ulmi. s'occupant des maladies devrait être chargé d'organiser les recher- PartoutenEurope,lesormesdépérissentaunecadence ches essentielles dans les divers continents. L'aide que ce Groupe considerable. recoitdeses pays membres estinsuffisanteetdevraitêtre Ce dépérissement des ormes pose an double problème: d'une augmentée. part, celui de la perte continuelle de bois de bonne valeur et d'essences d'ombres appréciées, et d'autre part, celui de la modifi- Significado de las Enfermedades Introducidas, desde el cation structurale des peuplements composes a l'origine d'ormes Punto de Vista Europeo et d'autres essences feuillues qui ont par Ia suite dépéri. La solu- tion évidente consistait a remplacer les ormes par des résineux En este trabajo se examina y comenta la importancia de cinco ou par des ormes asiatiques et des variétés européennes resistant hongos parásitos que se supone hayan sido introducidos,el a la maladie. Les ormes asiatiques sont moms appréciés comme peligro de nuevos parásitos y lasmedidas e investigaciones arbres d'ornement et résistent moms bien aux gelées. La multipli- necesarias del caso. cation par boutures des variétés européennes resistant a l'infection est fonction d'une amelioration des méthodes de bouturage. La Principales enfermedades introducidas lutte contre les scolytes n'est efficace que sur des surfaces restrein- El problema del castaflo.La enfermedad producida por in tes. On volt ainsi qu'aucune solution n'a été trouvée au problème Phytophthora cambivora y la P. cinnamomi y in ocasionada por du dépérissement des ormes. in Endothia parasitica, son las principales razones que motivan Sapin de Douglas. Deux champignons parasites, le Rhabdo- la decadencia graduai del castaflo en Europa. dine pseudotsugaeetlePhaeocryptopus gäumannisesont El aspesto econ6mico del probiema está relacionado con in répandus dans presque tous les pays oui se trouvent des planta- importante reducción del area donde crece el castafio en ci Sur tions de sapins de Douglas. us provoquent la chute des aiguilles de Europa y consiguientemente con la disminucain de la produc- et in mort des jeunes arbres, notamment en Europe centrale et ción de madera y frutos. Pero a pesar de su declinación, no es méridionale. En plus des variétés bleues et grises, le sapin vert a probable que el castaño europeo desaparezca por completo. étéégalementl'objet,danscertaineslocalitéssérieuses.Le El problema silvIcola consiste, realmente, en convertir los cas- problème pose par in maladie du sapin de Douglas s'avère par- tañares en montes bajos productivos y en conservar el suelo, ticulièrenient important pour les pays dans lesquels de vastes reemplazando los castaflos con otras especies de más rápido plantations ont été entreprises ou projetées.II semble donc qu'il crecimiento. conviendrait de recommander des mesures preventives ou mCme La parte fitosanitaria del problema está relacionada con in l'abandon de la culture de sapins de Douglas. eficacia de los diferentes métodos de regulación y con la manera más económica de aplicarlas. Autres maladies constituant an danger pour i'Europe El problema del olmo. El olmo europeo es susceptible, por lo Exception faite de I'Amérique du Nord, les maladies qui sévis- general, al hongo Ceratostomella u/mi. La enfermedad existe en sent sur les autres continents et qui risquent d'être un danger toda Europa. pour l'Europe n'étant pas suffisamment connues, l'auteur a passé Los principales problemas que origina la mortalidad del olmo en revue les organismes pathogènes les plus pernicieux vivant sur son in pérdida continua de su madera y de árboles de sombra y lesol américain, ainsi que leurs possibilités d'introduction en las modificaciones estructurales de los bosques compuestos de Europe.Sont considérés comme immédiatement dangereux, et olmos y otras especies de hoja ancha que después desaparecen comme teis doivent faire l'objet de mesures de quarantaine en gradualmente. Se aprecia que la solución radica en reemplazarlos Europe,lesorganismessuivants:Ceratocystisfagacearum, con diferentes maderas blandas, especies nsiáticas y olmos euro- menace pour les vastes peupiements de chênes en Europe, Sep- peos que resisten la enfermedad. Los olmos asiáticos han demo- toria musiva, dangereux pour les plantations de peupliers, Cro- strndo ser menos (itiles como árboles de ornato y menos resisten- nartium fusiforme, qui constitute un risque pour les pins euro- tes a in escarcha. La propagación de especies europeas resistentes péens, et Ia nécrose du liber des ormes qui est causée par un virus. por medio de plantones está relacionada con los métodos más prácticos de conseguir el enraizamiento. La defensa contra los Mesures a prendre et recherches a effeetuer coleópteros que atacan in corteza del olmo es posible en super- Maladies d'origine étrangère. Voici quelques-unes des mesures ficies pequefias.Puede decirse, pues, que el problema del olmo devant être prises dans l'avenir: no se ha resuelto por completo todnvIa. inspection rigoureuse et quarantaine; El problema del abeto Douglas. Hay dos hongos parásitos, el enquête spéciale pour les parasites les plus pernicieux; Rhabdoc line pseudotsugae y ci Phaeocryptopus gaumanni, que se suppression rapide des premieres contaminations; han extendido por cnsi todos los palses donde existen planta- accroissement de la production et de l'utilisation de variétés ciones del nbeto Douglas.Estos hongos ocasionan una caIda résistantes; et constante de ins pinochas y acaban con los flrboles jóvenes, culture de variétés résistantes dans des foréts saines en vue especiaimente en in Europa Central y Meridional. En algunas d'obtenirdansunavenirassezprochedeshybrides localidades la enfermedad se ha extendido no solo a las especies naturels et résistants. azul y gris del nbeto, sino tnmbién a in verde. El problema de las enfermedades de estn clase de abeto es de particular impor- Le programme de recherche suivant est recommandé: tancia en nquellos paises en que se han planeado vastas planta- 878 Fifth World Forestry Congress Proceedings ciones de este árbol. Tomando esto en consideración, lo que más por enfermedades, con ci propósito de obtener en un futuro se recomienda es piantar con precaución o aun abstenerse de inmediato hibridas naturaies y resistentes. plantar ci abeto Douglas. Asimismo, se recomiendan los siguientes estudios de investiga- El peligro de nuevas enfermedades ción: En virtud de que el peligro de nuevas enfermedades que existen cuitivos en zonas geográficas más limitadas; en otroscontinentes, con excepción de Norteamérica, no es mejora en los métodos para conseguir ci enraizamiento; suficientementeconocido,sehan examinadosolamentelos estudios sobre la eficacia de microorganismos antagonIsticos patógenos mas perniciosos de la America y la posibilidad de su y la posibilidad de su producción en gran escala enlos introducción en Europa. Los organismos peligrosos que merecen mismo bosques; someterse a una inmediata y especial cuarentena en Europa son: estudios sobre la aplicación de otros métodos biológicos de Ceratocystis fagacearum, que amenaza a los grandes robledales defensa; y europeos; Septoria musiva, peligroso para los álamos; Cronartium mejora de los mdtodos defensivos fIsicos y quimicos. fusiforme, una amenaza para lospinares europeos y ploem Enfermedades probables. Se han examinado brevemente dos necrosis ci virus que ataca a los olmos. temas: ci refuerzo de la inspección de cuarentena y ci ensayo de los árboies europeos para determinar su resistencia a las enfer- Medidas e investigaciones necesarias medades en otros continentes. Enfermedades introducidas.Las medidas futuras se deberán Con respecto ai primer tema se propuso ci estabiecimiento de encaminar a: varios centros internacionales de cuarentena o autorizar a las una rigida inspección de cuarentena; varias estaciones de cuarentena que ya existen para inspeccionar cimaterial reproductivo que ofrezca peligro y que entre en la organización de un estudio especial de los parásitos más Europa. perniciosos; En cuanto a los estudios sobrc ia susceptibilidad, que son una supresión rápida de las primeras infecciones; indispensables, se sugirió que se le dé mayores atribuciones al un aumento en la producción y utilización de las selec- Grupo de Trabajo sobre Enfermedades de la IUFRO para que ciones resistentes; y organice los estudios escnciaies in varios continentcs.El grupo ci cultivo de selecciones resistentes en bosques no afectados necesita más ayuda de parte de los paIses miembros.

Introduced Diseases With Particular Attention to the Threat TheyPose Forest Protection in Asia

ROKUYA IMAZEKI Director, Division of Forest Protection, Government Forest Experiment Station, Meguro, Tokyo, Japan

Introduction but it is difficult to trace back the introduction in detail. Some instances are given below. ChestnutblightdestroyedtheAmericanchestnut Itisfurther noted here that the study in Asiatic (Castanea dentata) of the United States entirely and then countries other than Japan isstifi primitive, and few severely affected the European chestnut (C. saliva).It mainly is said that the causal organism, Endothia parasitica, was reports have been published. Thus, this report is introduced from Asia into North America at the end of related to studies conducted in Japan. the 18th century and then was distributed over the world, Diseases of Coniferous Trees bringing about the terrible disaster of today. According to another report, Ophiostoma ulmi, causing Dutch elm Blight of Cry ptomeria disease, is also said to have originated in Asia. This disease is said to have been discovered in 1903, Instances in which diseases having their origin in Asia and since 1909 it has spread over the country. Seedlings spread to the European and American Continents and of Cryptomeria at one time were infested so severely that inflicted serious damage are well known. On the contrary, total loss was anticipated, and cultivation of seedlings of cases in which diseases have been introduced into Asia this species was abandoned. and damaged forest trees severely in that region are little This disease not only kills seedlings, but when slightly known in overseas countries. infested seedlings are planted in a forest, it brings stem The major factor seems to be attributable to the fact canker and deformation and makes trees worthless.It is that the study of forest pathology in Asia had been little the most important forest disease in Japan. In 1928, it developed until 1940 and that most papers related to the was found in Taiwan and causesheavy damage there study were expressed in the mother languages of their even today. authors. However, as a result of intensive and long years' study Of the diseases threatening the forest productivity of by the staff of the Government Forest Experiment Station Asia today, some are introduced from other countries, of Japan, almost complete control by spraying chemicals

Forest Protection 879 is now established. Although it is now not so prevalent, to this disease, or that the Japanese fungus is a strain that we cannot neglect the past because it retains the position cannot attack the genus Pinus, the morphological char- of the most important forest disease in Asia. acteristicsin the uredospore and teliospore stages of The cultivation of seedlings of Cryptomeria in Japan the fungus are coincident with those of Cronartium is traced back several hundred years, but there isno ribicola in America and Europe. record of infestation of this disease before 1903. Suppose Pinus strobus, which is susceptible to this disease, has this disease had been found in olden times. Seedlings at been planted in a small plot. Consequently, if it is planted the time of the Tokugawa Era, when no chemical spraying on a large scale more infestation is expected, and if a was conducted, might have been entirely destroyed, but no virulent pathogen is imported from other countries, serious damage was recorded in the history of forestry administra- problems will arise, and much concern and strict caution tionat the time of the clan government, when no should necessarily be paid to these problems. knowledge of plant diseases had been developed, and no record of spread of this disease from the forest to the Diseases of Deciduous Trees nursery has been found. Crown Gall In 1916, the causal organism of this disease was named Cercospora cryptomeriae Shirai, as an endemic disease in Crown gall caused by Agrobacterium tumefaciens was Japan. It is hard to understand that the disease appeared found in 1900 in orchards in Kanagawa Prefecture on suddenly about 1900 and was unidentified for many years. stocks of cherry and peach imported from the United The study of Dr. K. Ito revealed that while C. crypt- States. Since then, it has spread to all parts of the country omeriae does not infest Japanese conifers other than and heavily damaged farm crops, fruits, and forest trees. Cryptomeria japonica.strangetosay,itattacks the Tree species which were seriously infected in Japan are Sequoia gigantea of North America and causes symptoms chestnut, pecan, walnut, willow, poplar, and eucalyptus. quite similar to those in Cryptomeria. The morphologic characteristics of Cercospora cry ptomeriae are coincident Leaf Blotch of Poplar with those of Cercospora sequoiae Eli. & Ev., described in This disease was first found in Tokyo in 1956.In North America. 1958, many thousands of poplars were infested in the From the above, Dr. Ito concluded that Cercospora Kyushu and Tohoku districts.Since then, it has spread cryptomeriae, which is the causal fungus of Cryptomeria over the country, and its infestation is serious. Conidial blight, is the same as Cercospora sequoiae, which might and ascigerous stages of the causal fungus were found in have been introduced from North America into Japan Japan, and it was identified as Septotinia populiperda with seedlings of Sequoia gigantea imported in the Meiji (Septotis populiperda). Era, found new host plants in Cryptomeria, and spread Since the Second World War, improved poplars have rapidly over the country. The probability of this conclu- been imported from Europe and North America as im- sion is considered to be rather high, and the disease in portant trees of short rotation, and this fungus is thought Taiwan seems to have been introduced by seedings of to have been introduced together with scions of these Cry ptomeria imported from Japan. poplars. It is well known that this fungus is distributed in the Blister Rust of Pinus strobus United States and part of Europe, but there it does not Cronartium ribicola, the causal fungus of this disease, seem to be so serious. Under the climatic conditions of is said to have come from Asia to Europe, and it might Japan, however, with high temperature and high humidity, have been found in Japan in olden times.But since it spreads rapidly and infests severely and is now one of recent records in Hokkaido tell of the discovery of this the most serious diseases of poplars in Japan. Another, fungus on the cultivated red currant (Ribes rubrum) the larch poplar rust (Melampsora larici-populina), is about 50 years ago, it may be considered that the fungus found on various hybrid poplars andisparticularly was brought from North America. severe on the improved Italian poplars (which were In the Far East, the fungus is found not only in Japan imported with great expectation) and causes the leaves of but also in Korea and Taiwan, but the aeciospore stage is these trees to fall at an early stage.Therefore, the pos- found only on Pinus koraiensis in Korea, and all others sibilityofcultivationofthesepoplarsin Japanis are found only on the genus Ribes. In Japan, the aecio- jeopardized. spore stage of the fungus has not yet been found on Pinus. Brown Spot of Tung Oil Tree Because the plantation of Pinus strobus, although small In 1951, this disease heavily infested Aleurites fordii in area, grows vigorously in Hokkaido (established as a in Wakayama Prefecture, and much attention was paid pilot plantation several decades ago), the planting of this to it.Since then, it has spread to Hyogo, Nagasaki, and species on a large area is now being planned. In view of other prefectures. Not only leaves and stems but also the severe infestation of blister rust on Pinus strobus fruits are damaged, and the ripening of fruits is hampered. in Europe and the United States, after the careful survey This disease is a fatal blow to the cultivation of this in 1958-1959 on the distribution of the fungus, it was species. concluded that this fungus is still found in parts of Hok- Cercospora aleuritidis was found in Hunan Province of kaido. In this survey, the fungus was found only on plants continental China and described as a new species in of the genus Ribes, but not on Pinus. 1908.Since then no report has been made. In recent Although it is not clear that Japanese five-leaved pines, years, a study was initiated by the outbreak of this disease such as Pinus pentaphylla and P. parviflora, are resistant on the plantation of A leurites fordii in Szechwan Province, 880 Fifth World Forestry Congress Proceedings and the ascigerous stage of the causal fungus was found and eventually causes wide spread of such pests. Particu- and named Mycosphaerella aleuritidis. larly, introduced exotic species should stand a severe From the above, there is no doubt that this disease trial under the new environment. Along with the exchange came from China. But we have no means of knowing how of seeds, scions, cuttings, pollen, and seedlings and the it was introduced into Japan and how seriously it has increase of import and export of timber, the danger of infested. Aleurites fordii is now widely planted in Japan, infestation of diseases is expected to increase. While we and as far as its origin is concerned, it was imported in should pay much attention to the danger, pathologists and 1910intoWakayamaPrefecturefromKwangtung foresters of every country should study the damage caused Province of China as seed which grew into mother trees, by diseases on exotic species imported into each country and these propagated in Japan. This fungus was con- and exchange their views in order to prevent further sidered to have lurked in the tissues of the seed imported havoc, and, in this sense, an international cooperative into Japan and spread and caused severe damage. research organization should be expected to become a reality. Diseases Expected To Be Introduced in the Future The serious diseases mentioned below, not found in RESUMES Asia today but expected to be introduced, are considered Maladies introduites et en particulier la menace qu'elles worthy of attention. posent pour la protection des forêts en Asie Most poplars are imported as scions and are likely to Après la Deuxième guerre mondiale, les forêts du Japon et de import exotic parasites.The diseases to which much l'Asie se sont trouvé considérablement appauvries. Leur remise en état est un problème dont la solution est pressante, l'expansion attention should be paid are: bacterial canker, caused by des forêts artificielles, l'encouragement de la culture des essences Pseudomonas syringae f. sp. populea of Europe; Septoria forestières,l'introduction d'essences exotiques,lecontrôle des canker, caused by Septoria musiva of the United States parasites des forêts,l'emploi des engrais en forêt et d'autres and Canada; Dothichiza canker, caused by Dothichiza méthodes modernes, servent a accroItre la productivité des foréts. La mise en oeuvre de ces méthodes conduit a la simplification de populea of Europe and the United States; and Hypoxylon la composition des foréts et diminue la résistance aux maladies canker,caused by Hypoxylon pruinatumofNorth et aux attaques des insectes et a la longue répand ces parasites. America. Les essences exotiques surtout doivent être soumises a des essais The genus Ulmus produced in Asia is said to be re- rigoureux dans leur nouveau milieu; le danger de contamination va probablement augmenter avec l'échange de semences, de gref- sistant to Dutch elm disease, and it is thought that even fons, de boutures, de pollen, de jeunes plants et l'accroissement if Ophiostoma ulmi, the causal fungus of the disease, is des exportations et des importations de bois. Tout en accordant introduced, there would be no serious damage as in the énormément d'attention a ce danger, les pathologues et les syl- case in Europe and North America. However, not all viculteurs de chaque pays devraient étudier les dégâts causées par les maladies apportées par les essences exotiques importées species of the genus Ulmus in Asia are resistant to this dans chaque pays et échanger leurs vues pour éviter de plus disease.Ulmus japonica, U. laciniata, and many others grands dégâts.Ii est souhaitable que l'on agisse dans ce sens au are susceptible, and this disease is also said to infest moyen d'une organisation internationale de cooperation dans la Zelkova serrata, which is one of the most important recherche. broad-leaved trees in Japan, so that this tree species must Parmi les maladies menacant la productivité des forêts au Japon aujourd'hui, certaines, croit-on, proviennent d'autres pays, be considered in the event that the pathogen is introduced bien qtfil soit difficle d'en determiner exactement l'origine. Cer- into Japan. tains exemples sont donnés ci-après: Bacterial blight of walnut trees, caused by Xantho- Maladies des conifères-Rouille dii Cry ptomeria japonica causée monas juglandis, is a significant disease in Europe and par la Cercospora japonica, rouille vésiculeuse du pin etc. the United States but is not found in Asia. Since it is Maladies des essences feuillues:Chancre de la cime, rouille known that this causal organism is disseminated by pollen, de lafeuille du peuplier(Septotinia populiperda), rouille de caution should be taken when importing pollen for cross- l'abrasin, etc. breeding. Maladies contre l'introduction desquelles il faut dans l'avenir prendrelesplusstrictesprecautions:maladiesbactérielles, The most terrible disease likely to be introduced into Septoria, Dothichiza et Hypoxylon chancres du peuplier, maladie Asia is the oak wilt of the United States. According to de l'orme subéreux, flétrissure dii chêne, rouille bactérielle dii the study in the United States, besides Asian oaks, such as foyer, etc. Quercus acutissima and Q. dentata, Chinese chestnut (Castanea mollissima) and Castanopsis kawakamii are Enfermedades Introducidas, con Especial Consideración said to be susceptible, too. The causal fungus, Certatocys- a la Amenaza que Representan para la Protección tis fagacearum, whose source is diseased logs, requires Forestal en Asia. constant attention. Después de la Segunda Guerra Mundial, las existencias fo- restales del Japón y de Asia han sido agotadas en grado sumo. Su repoblación es un problema que requiere urgente solución. Para Conclusion incrementar la productividad forestal se ha estimulado la expan- Since the Second World War, the forests of Japan and sión de los bosques artificiales, el fomento de crIa de árboles forestales, la introducción de especies exóticas, la lucha contra Asia have been severely depleted. Their rehabilitation is plagas forestales, la fertilización forestal y la aplicación de otros an urgent problem to be solved, and the expansion of métodos modernos. No obstante, tales medidas eventualmente artificial forests, encouragement of forest tree breeding, pueden resultar en Ia reducción de Ia estructura forestal y dar introduction of exotic species, control of forest pests, hugar a una menor resistencia a las enfermedades y a los insectos que, con el tiempo, son la causa de la propagación de tales plagas. forest fertilization, and other up-to-date policies are being En particular, las especies exóticas que se introduzcan habrán taken to increase forest productivity. The implementation de someterse a rIgida inspección en el nuevo ambiente, ya que, of such policies leads to the simplification of forest com- con el intercambio de semillas, vástagos, estacas, polen y semi- position and less resistance to diseases and insect attacks llones y el incremento de la importación y de la exportación de

Forest Protection 881 maderas, aumenta considerablemente ci peligro de la propaga- casos más notables son los siguientes: ción de enfermedades.Si bien es verdad que se debe prestar Enfermedades de conlferas:Piaga del Cry ptomeria japónica, mucha atención a este peligro, los patólogos y silvicultores de causada por ci Cercospora japónica, añublo ampoilado de pinos, todos los paIses deben estudiar el daño causado por las enferme- etc. dades de las especies exóticas introducidas a cada pals y canjear Enfermedades de árboles de hojas caedizas: agallas de la copa, ideas para evitar mayores estragos. En este sentido, cabe esperar descoloramiento de las hojas dci alamo (Septotinia populiperda), que se convierta en realidad una organización internacional para manchas pardas dcl árbol que produce ci aceite de tung, etc. las investigaciones cooperativas. Las enfermedades que requieren precauciones estrictas para Dc las enfermedades que en la actualidad amenazan la pro- evitar su introduccidn en ci futuro, son:las causadas por bac- ductividad de los bosques en ci Japón, hay algunas que Se con- terias, Septoria, Dothichiza y Hypoxylon, liagas del alamo, la sidera que han sido introducidas de otros paises, aunque es muy enfermedad del olmo hoiandés, enfermedad hongosa del roblc, dificii precisar en detalle su origen. Entre elias, algunos de los plaga del nogal causada por bacterias, etc..

New Approaches to Forest Disease Control by Chemicals

HAROLD R. OFFORD Chief, Division of Forest Disease Research, Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture, Berkeley, California, U.S.A.

Under the restrictions imposed by the word "new," more than twice as much progress in the first five years where do we begin an appraisal of new approaches to of the nabam-DDT era than in the previous forty-five forest disease control by chemicals? years." Here, indeed, is a challenging record for those Progress would indeed be spectacular if we were to go looking for increased productivity of forest land. back about 3,000 years to the time of Homer and his For a long-term crop such as forest trees we can ill reference to "pest-averting sulfur," or to 60 B.C. and afford to settle for anything less than full vigor of growing Pliny's recommendation for "soaking wheat seed in a wine stock. The forester, unlike the farmer with an annual or mixture to prevent mildew." We could start in 1882 when short-term crop, cannot readily change the location or Millardet ushered in the age of fungicides with his dis- composition of his crop when danger threatens. Well- covery of Bordeaux mixture. To the forester interested in directed silviculture, if served by effective pest control, will protectants that are safe and practical to use, the advent do much to minimize the attritional losses from endemic in 1934 of the dithiocarbamatesthe first of the fully pests. But epidemics of native and exotic diseases must organic fungicidesis surely a significant milestone. Dur- be controlled quickly if serious losses are to be avoided. ing the quarter century that has elapsed since Tisdale and In epidemic situations,sanitation logging may capture Williams obtained their patent on the salts of dithio- values in merchantable-size trees, but it seldom pays in bamic acid we have seen an imposing array of natural and young stands unless there is intensive utilization for pulp, synthetic products setforth for the consideration of fuel wood, and other small-diameter forest products. diseasecontrolspecialists Today,withprotective More and more, control of forest diseases is being aided organic fungicides, translocatable and selective phytocides, through the use of protectant and eradicant chemicals. soil fumigants, antibiotics that act systemically, chemicals Pathologists and disease-control specialists from all parts that inactivate toxins, and improved methods of using of the world are involved in this developmental work. the time-honored fungicides, we have the motive, means, Colleagues from abroad will, I am sure, be indulgent if and opportunity to follow new approaches to forest the material that follows is drawn largely from the United disease control. States. In addition to facilitating my task, such emphasis These prospects are reassuring because foresters in may serve the interests of visitors at this Congress who many parts of the world are just beginning to appreciate will have the opportunity of seeing our forests and what the need for economic disease control in the face of is being done to protect them. high investment costsinintensive management. We My report will be restricted to the role of chemicals in know from the experience of agriculturists the world forest disease control and, like Gaul, will be divided into over that intensive cropping usually means more trouble three parts: nursery problems, chemicals in the managed from disease and other pests unless adequate protection forest, and new approachestheir direction. is given. Few food and fiber crops could be grown suc- cessfully without the direct aid of protectant chemicals Nursery Problems and fertilizers. And the difference in productivity between Major disease problems and disorders in forest nurs- vigorous disease-free plants and sickly ones is vividly eries are of the following types: chlorosis and nutrient seen in agricultural crops.To cite just one of many deficiencies,seed-bornepathogens, preemergence and examples: McNew (in Plant PathologyProblems and postemergence damping off, seedling root rot, stem and Progress, 1959) recently pointed out, "Today the farmers twig rusts, needle casts and blights, nematodes, and weed provide the people of the United States 50 percent more plants. What are foresters doing to cope with these prob- potatoes than at the turn of the century even though lems? they use 46 percent less land for this crop. Better pest Correction of chlorosis, soil pH, and other nutrient control is only one factor in this progress, but there was deficiencies by metal salts,sulfuric acid, and regular 882 Fifth World Forestry Congress Proceedings fertilizers are well known and need not be covered here. gallons per acre of allyl alcohol controlled damping-off Adequate protection of forest tree seed before nursery or organisms and weeds when applied as a preplanting soil field sowing is obtained by following prescriptions for drench. He found an increase in populations of Tricho- agricultural seed. Fungicidal seed treatments may be dry derma for 8 weeks after treatment. or wet.Organic mercurials (Semesan, Panogen), hot water,formaldehyde,chioranil(Spergon),andthe Chemicals in the Managed Forest dithiocarbamates (nabam, zineb) may be used as disin- The timber resource report recently completed by the fectants and protectants of forest treeseed.Leukel United States Forest Service (1958) shows that diseases (1953) has summarized methods and materials for treat- account for 45 percent of the impact (mortality plus ing seeds to control diseases within and outside the seed growth loss)on total national timber growth.Some coat. of these losses take place slowly during the useful life Black root rot resulting from the combined action of of the forest stand; others strike rapidly against one or two fungi, Scierotium bataticola and Fusarium oxysporum, more ofits component species.Since the advent of causes serious losses of slash pine and loblolly pine in organic fungicides in 1934, the phenoxy weedkillers in nurseries of the Southern United States.Soil fumigation 1945, and fungicidal antibiotics in 1949, chemicals have with methyl bromide is recommended. The application been helping the forester do a better job of containing rate is 1 pound per 150 square feet, injected to a depth of these losses. Let me cite a few examples of practices that 6 inches under polyethylene plastic sheets (Foster, 1959). have proved useful in the managed forest. Soil temperature should be above 60° F. Methyl bromide Improvements in the control of white pine blister rust also kills weed seeds, nematodes, and insects and seems to (Cronartium ribicola)over the past 30 years clearly improve vigor of seedlings. The cost is less than $300 per illustrate the changes that are taking place. acre. One fumigation usually establishes control for 3 In 1929, we developed successful methods of killing years. Ethylene dibromide applied at a rate of 15 gallons certain species of Ribes by aqueous sodium chlorate per acre of 85 percent concentrate also kills nematodes spraysappliedbycrewsequippedwithknapsack and may control root rot for one season. Any general sprayers. These methods were much cheaper than digging recommendation for soil fumigation should be confirmed or pulling and, in fact, were the only feasible means of by someone who understands local soil and environmental eradicating some stream-type Ribes. Twenty years later factorsandtheirinfluenceonresidualeffectsand we were able to do with a few ounces per acre of 2,4-D phytotoxicity of the fumigant. and 2,4,5-T the job that required several hundred pounds Workers in the Southern United States have also de- per acre of sodium chlorate. A recent summary of these veloped spray schedules for control of fusiform rust methods and chemicals by Off ord, Quick, and Moss (Cronartium fusiforme) and brown spot needle blight (1958) shows clearly 'the flexibility in field methods and (Scirrhia acicola).Fusiform rust, a serious threat to equipment that can be obtained with toxicants that are nursery production of slash and loblolly pine in nurseries safe to use, effective in low dosages, and easy to formulate of the coastal plain and piedmont of the Southeastern in oil, water, and solid diluents. United States, is controlled by ferbam at the rate of 2 A method of applying dry pellets impregnated with a pounds per 75 gallons of spray per acre used with high- volatile toxicant to the soil about the base of plants or pressure sprayers (Foster, 1959). Repeated treatments crown sprouts is worthy of special mention. This method are needed, the number of such sprays being determined offers a new approach to selectivity in pest control for by local rust hazard and the sequence of weather favorable wildiand areas. The killing action of the 2,4-D methyl- to sporidial production. For brown spot control under ethyl esters in the pellet is dependent on its volatility and field conditions, bordeaux mixture (4-4-50) may be better upon absorption of a small amount of the toxicant by than the ferbam used in nurseries. Two applications of the foliage. The impact on vegetation is directly related bordeaux (May and November) are usually sufficient. to its average height because the heavy volatilized toxicant In commercial nurseries of North Carolina, Hepting is gradually diluted in the air as it spreads from the soil and Toole (1939) showed that a twig blight of hemlock level. Thus in relatively still air it is possible to regulate caused by an autoecious rust (Melampsora farlowii) was dosage so that only highly sensitive and low-growing controlled most efficiently by weekly spraying, starting plants will be affected.Pellets broadcast from aircraft as soon as the buds burst and the new shoots appeared reach the ground without interception by forest trees. (May to early June).Lime-sulfur at 8 pounds to 100 The selective killing of a fungus already established in gallons of water plus suitable spreader-sticker or ferbam host tissue or the immunization of host against infection at 4 pounds per 100 gallons of water is recommended. has been a long-cherished and worldwide dream of path- Three percent of the twigs on sprayed trees were dead ologists. Forest pathologists have looked to chemotherapy compared with 15 percent on unsprayed trees. for help in the control of white pine blister rust, chestnut Snow blight (Phacidium infestans) has caused losses blight, Dutch elm disease, and oak wilt. Within the past innurseriesofthe Northeastern UnitedStates and few years we have seen a major breakthrough in disease Canada. Spruce and balsam are particularly susceptible. control that might be fairly compared to the place of DDT Effective control is obtained by spraying in the late fall in insect control.I refer to the development of antibiotics with dormant strength lime-sulfur. having fungicidal properties and specffically, in the case of Competitive weed plants and weed hosts of diseases forest pathology, to the use of Acti-dione for killing blister that threaten nursery stock are often best controlled by rust cankers in western white pine. Starting with tests in chemicals such as 2,4-D, allyl alcohol, and light, refined 1949, the U. S. Forest Service, in collaboration with petroleum oils.Overman et al. (1956) report that 25 Upjohn Co., has developed a practical method of applying

Forest Protection 883 Acti-dione in light oil solvent for the direct control of method must place the right amount of toxicant, pro- blister rust in western white pine (Moss, 1958). tectant, or anti-metabolite in the critical site or zone of Instructions for field use of Acti-dione on western white infection. pine now stand as follows: Use Acti-dione in No. 1 fuel The spread of disease in local areas or from infection oil (stove oil) at a concentration of 150 parts per mil- sites in trees or stumps can be retarded by fungicides and lion. For trees 12 feet or less in height, spray bark of phytocides. Centers of oak wilt (Ceratocystis fagacear- trunk and branches up to one-third of crown height. For urn) infection have been contained by poisoning healthy trees taller than 12 feet, spray bark of trunk and branches trees in a 50-foot buffer zone around the infected trees. to a height of 5 feet, or eye level. Drake, Kuntz, and Riker (1957)state that sodium Crews applying Acti-dione to western white pine no arsenite injected into the root collar of affected trees pro- longer search individual trees for cankers. Crop trees in vides the necessary root kill on "barrier" trees. Recent natural stands and all trees in plantations are treated. reports from the Southeastern Forest Experiment Station Costs of large-scale work in northern Idaho during 1959 desøribe the epidemic spread of root rot (Fornes annosus) averaged about 8 cents per tree. in slash pine and white pine plantations, particularly Intensive tests are now in progress with Acti-dione, after thinningOn the basis of previous experience in phytoactin, and other translocatable systemic toxicants to Great Britain with this same problem, Boyce (1959) determine their usefulness in controiling several forest recommends the creosoting of stumps immediately after tree diseases and parasitic plants such as the mistletoes. cutting in high value stands.Dimond etal.(1949) So far, these tests have not shown results comparable to showed that a measure of preventive control of Dutch those obtained on blister rust in western white pine. elm disease (Ceratostomella ulmi) could be obtained by Methods and materials that are successful on one host- combiningachemotherapeutantsoilapplicationof parasite association are not necessarily applicable directly 8-quinolinol benzoate with a DDT spray to control vector to another combination. Method of treatment, formula- insects. tion, dosage, seasonal development of host and parasite, Strong (1957) reports control of apple and hawthorne and type of toxicant need careful adjustment to species, rusts(Gymnosporangium juniperi-virginianaeand G. site, and local environment. globosum) by ferbam, 1½ pounds per 100 gallons, and Hepting (1958) describes the cone rust (Cronartium by Acti-diorie, 100 parts per million, in sprays applied strobilinum) that causes serious losses of slash and long- to red cedar galls before telial horns have swelled and leaf pine seed in Florida, south Georgia, and along the gelatinized. coast of the Gulf of Mexico. Spray tests are under way at the Southern and Southeastern Forest Experiment Sta- New ApproachesTheir Direction tions, seeking improved methods of control. Of several In the examples just cited we see that foresters are fungicides tested, ferbam gave the best control of the rust seeking and taking new approaches to disease control in and was least phytotoxic. Also, there appeared to be some nurseries and in the managed forest. Much will be done in beneficial effects on the germination of pine pollen. Spray the future to improve the effectiveness of the time-tested schedules adjusted to weather conditions and periods of protective and eradicative chemicals.But chemothera- high rust hazard gave better results than schedules based peutants and systemic toxicants are the shining goals of solely on the stage of flower development. forward-looking pathologists. Chemotherapy in its broad- Australian researchers have made encouraging progress est sense may be considered as internal medicine. The in chemical control of a leafy mistletoe that attacks chemical, or plant itself, by internal stimulus is induced to eucalyptus. Here, again, host species, soil moisture, and kill or inactivate the pathogen, parasite, bacteria, or virus vigor of the tree influenced the effectiveness of control. The crop host may do this by neutralizing toxins, by Greenham and Brown (1957) reported 70 to 100 percent changing levels of metabolic activity, or by stimulating kill of Amyema pendula on Eucalyptus polyanthemos by the growth of protective biogens. Chemotherapy may find trunk injection with water solutions containing about 10 its most direct application to vascular diseases where their percent amine 2,4-D.For treesaveraging 16 inches action can be quite local. Systemic toxicants, on the other d.b.h., total cost per tree was about 7 cents. These are hand, imply general mobility within the plant and a encouraging results indeed and point the way to similar specific and selective action on the established pest. methods of control for the dwarfmistletoes. Much has been learned about toxicity and chemical Of the many compounds and formulations so far tested structure and how we might tailor compounds that are ondwarfniistletoes,none has lookedveryexciting. fungitoxic and fungistatic (Burchfield, Crowdy, van der Several have shown promise either by killing the aerial Kerk, and Woodcock in Plant PathologyProblems and parts of dwarfmistletoe without damaging the host or by Progress (1959); Horsfall (1945); and in Advances in exhibiting distinctive facets of toxicity and mobility within Pest Control Research, R. L. Metcalf Ed., 1957). Much the host tree. Among these compounds we might note: has been learned about how chemicals get into plants and isopropyl N-(3-chlorophenyl) carbamate (CIPC), disod- how they move to the site of infection or toxic action ium methyl arsonate (Sodar), maleic hydrazide, poly- (Crafts, 1951; Crowdy, 1952; Gray, 1958; Miller, 1959; chlorbenzoics,antibioticssuchasActi-dioneand Yamaguchi and Crafts, 1959). For conifers, Vité and phytoactin, s-triazine compounds (Atrazine and Simazin), Rudinsky (1959) showed by trunk injections of Acid substituted phenoxy weedkillers of the acetic, propionic, Fuchsin dye how water moves upward in the sapwood and and butyric series, trace amounts of boron and the heavy throughoutthecrownofthetree. Physiologists, metals. The effectiveness of a selective toxicant is often pathologists, and botanists are tracing the penetration and determined by the manner in which it is applied. The movement of toxophores by radioisotope, papergram, and 884 Fifth World Forestry Congress Proceedings bio-assay (Chapman, 1951; Crafts, 1956; Kiomparens, chemicalsto overcome theresistanceof established 1951). Kiomparens detected the presence of 0.5 p.p.m. pathogens to direct poisoning action. At cellular level, of cycloheximide by using Poria microspora as a test fungi will, at any one time, absorb or react with more organism. This bio-assay, in combination with papergrarn than one toxophore. Thus, ultimate killing or inactiva- tests, has been used successfully to follow the movement tion may result from synergistic action or by separate of cycloheximide into the branches and foliage of white and combined effects of two or more toxic elements. pine from basal stem treatments. There is ample evidence In developing screening methods for toxophores, more from this work that systemically active toxicants are attention should be given to establishing tolerance levels absorbed by roots, by foliage, and by penetration across for potential toxicants in conifers. Both field and green- cortical tissue, and thereafter move extensively within the house tests might be speeded up by employing sequential plant. and group testing of two or more chemicals. Distinctions We are learning more about antimetabolites and anti- between in vitro and in vivo activity of toxophores should doting of toxins (Davis and Dimond, 1956; Howard, be more clearly established. Histologists and physiologists 1941; and Woolley, 1959). Howard showed that the are helping us to understand the impact ofthe parasite toxic effect of filtrates of liquid media in which Phytoph- on the anatomy and physiology of the host.The sea- thora cactorum had grown was inactivated by the addition sonal pattern of the exchange of water, mineral elements, of 0.5 percent aqueous solution of Helione Orange amino acids, and carbohydrates in host and parasite, and (diaminoazobenzene dihydrochioride). We are learning the role of enzymes and natural auxins, need to be clari- more about the absorption and action of antibiotics and fied, especially with reference to critical phases in the life growth-regulating compounds on auxin levels and their cycle of the parasite.These studies will give direction role in combating plant diseases (Davis and Dimond, to our search for answers to the all-important question 1956; Horsfall and Diniond, 1951; Iyengar and Starkey, of "What is the nature of disease resistance?" 1953; Martin, 1955). Davis and Dimond, for example, In conclusion, let me emphasize the need for foresters pointed out that a compound such as indoleacetic acid, to give more attention to endemic diseases that reduce in itself not fungicidal in vitro, could reduce the severity vigor and quality of forest trees.It is easy to get research of Fusarium wilt in tomatoes when treatment preceded and control action for the spectacular pests that kill inoculation. Beckman (1958) reported on growth inhibi- merchantable trees rapidly. Too little attention is paid to tion as a mechanism in Dutch elm therapy. He found a the small but continuous attritional losses that take such good correlation between chemically caused inhibition of a large toll during the scheduled rotation. Forthese pests, spring wood development and susceptibility to this wilt as well as for epidemic diseases, chemicalsoffer the forest pathogen. manager new approaches in forest protection. We are gaining experience in the use of antibiotics and We stand now at a new frontier in silviculture where phytocides that translocate in the host tree and act to chemical control,biologicalcontrol,and the use of control fungi and plant parasites. I have aheady referred genetically improved planting stock will permit intensive to the use of Acti-dione in killing established blister rust cropping of forest land at minimum levels of disease loss. cankers in western white pine and to the control of true Mazzini, the Italian patriot, might well have been speak- mistletoe in eucalypts by trunk injection of 2,4-D salts. ing toforesters about disease control when he said, Antibiotics that have a wide spectrum of antifungal "Slumber not in the tents of your fathers! The world is activityandmeritfurthertestingare:griseofulvin, advancing. Advance with it!" phytoactin, phytostreptin, and s:treptomycin.Develop- ments in this area of research may well come from a study References of toxins and biogens produced by natural parasites of the Ark, Peter A., and Stanley M. Alcorn, 1956.Antibiotics as pest. Control of damping-off fungi affected by the mold bactericides and fungicides against diseases of plants.Plant fungi Trichoderma and Gliocladium has been attributed Disease Rptr. 40(2): 85-92. Beckman, Carl H., 1958. Growth inhibition as a mechanism in to soil-produced gliotoxin.Of the systemic phytocides, Dutch elm disease therapy. Phytopath. 48: 172-176. thechloro-fluoro-phenoxyacetic compounds, thehalo- Boyce, John S.,Jr.,1959.Root rot in pine plantations.For. genated phenoxy propionic and butyric compounds, and Farmer 19(3): 17-18. the s-triazines have not been adequately tested for control Brown, A. G., 1959. Mistletoe control on a large scale.Journ. Austral. Inst. Agric. Sci. pp. 282-286. of mistletoes. Chapman, Richard A., 1951.Relation of specific chemothera- Weeding in nursery beds of conifers may be made peutants to the infection court. Phytopath. 41: 6-7. simpler and safer by using some of the new preemergence Crafts, A. S.,1951. Movements of assimilates, viruses, growth phytocides in place of allyl alcohol and light petroleum regulators, and chemical indicators in plants. Botan. Rev. 17: 203-284. oils formerly used.Simazin, one of the s-triazine com- Crowdy, S. H., 1952. The chemotherapy of plant disease. Emp. pounds, for example, has a low order of toxicity to J. Exp. Agric. 20: 187-194. conifers when applied to the soil of nursery beds. Davis, D., and A. E. Dimond, 1956.Site of disease resistance We are learning more about the compatibility of mixed induced by plant growth regulators in tomato. Phytopath. 46: 551-552. fungicides, nematocides, phytocides, and insecticides. A Dimond, A. E., G. H. Plumb, B. M. Stoddard, and J. G. Hors- "package" approach to pest control is surely one of the fall, 1949. An evaluation of chemotherapy and vector control intriguing avenues to cheaper and more effective forest by insecticides for combating Dutch elm disease. Conn. Agric. protection. For home and garden use we can now buy Exp. Sta. Bull. 531. Drake, C. R.,J. E. Kuntz, and A. J. Riker, 1957. Chemical mixed fungicides and insecticides.Growth regulating control of oak wilt.Arborist News 22: 63-64. substances and nutrients that influence specific metabolic Foster, A. A., 1959. Nursery diseases of southern pines.USDA processes might be mixed with fungitoxic or fungistatic For. Pest Leaflet 32.

Forest Protection 885 Gray, Reed A., 1958. The downward translocation of antibiotics du cone (Cronartium strobilinum), rouille brune des aiguilles in plants. Phytopath. 48: 71-78. (Scirrhia acicola), rouille de neige (Phacidium infestans) chancre Greenham, C. J., and A. G. Brown, 1957. The control of mistle- suintant de l'érable (Phytophtora cactorum), gui veritable, néma- toebytrunkinjection.Journ.Austral.Inst.Agric.Sci. todes et mauvaises herbes. On parle en particulier du traitement December. pp. 308-318. du tronc inférieur du pin blanc de l'ouest (Pinus inonticola) a Hepting, George H., 1958.Southern cone rust. USDA Forest l'Acti-dione diluée dans de l'huile pour tuer les chancres de Pest Leaflet 27. rouille vésiculaire établis, et de la destruction a bas prix des and E. Richard Toole, 1939.The hemlock rust hôtes Ribes par le 2,4-D et le 2,4,5-T. Les chercheurs australiens caused by Melampsora farlowii. Phytopath. 29(6): 463-473. ont mis au point une méthode couronnde de succès qui consiste a Holton, C. S., G. W. Fischer, R. W. Fulton, and others, 1959. injecter une solution aqueuse de 2,4-D de sels d'amine ou hydra- Plant Pathology-Problems and Progress, 1908-1958.Univ. zine dans le tronc de l'eucalyptiis pour combattre le gui (Amyema of Wisc. Press, Madison, Wisc. pendula). Horsfall, James G., 1945. Fungicides and their action. Chronica Les recherches actuelles sur l'anatomie, la biochimie et Ia phy- Botanica Co., Waltham, Mass. siologie de l'hôte et du parasite et sur l'absorption, le mouvement and A. E. Dimond, 1951. Plant chemotherapy. Ann. et l'action des toxiques a l'intérieur de l'organisme vivant justifle Rev. Microbiol. 5: 209-222. l'optimisme a propos de l'utilité des agents chimiques dans la Howard, F. L., 1941. Antidoting toxin of Phytophthora cactorum lutte contre les maladies.L'avenir verra beaucoup de progrès as a means of plant disease control.Science 94: 345. dansl'amélioration del'efficacitédes fongicides éprouvés de Iyengar, M. R. S., and Robert L. Starkey, 1953. Synergism and longue date, tels que Ia bouillie bordelaise et l'agent chaux-soufre. antagonism Of auxin by antibiotics.Science 118: 357-358. Les ameliorations les plus frappantes proviennent souvent d'une Klomparens, William, 1951.Toxicity of cycloheximide to cer- méthode simplifléed'applicatiori du prodnit toxique ou d'une tain wood rotting fungi and preliminary studies on absorption appreciation plus exacte du milieu ambiant et de la reaction du of the antibiotic by tissues.Phytopath. 41: 22. parasite. Les agents chimiothérapeutiques Ct toxiques systémiques Leukel, R. W., 1953. Treating seeds to prevent diseases. USDA n'en demeurent pas moms le grand objectif pour les pathologues Yearbook, 1953: 134-145. tournés vers l'avenir.Les excellentes perspectives de Ia chimio- Martin, Hubert, 1955. Fungicides-past, present and future. The thérapie sont indiquées par l'antidote (avec l'Hélione Orange) mode of action of fungicides. Plant Disease Rptr. 39: 561-566. contre les toxines produites par le chancre suintant de l'érable et Metcalf, R. L., 1957. Advances in pest control research. Vol. 1. la protection a court terme contre la maladie de l'orme liege Interscience Publishers, N. Y., London. obtenue par l'infection préalable par inoculation au benzoate Miller, Lawrence P.,1959.Factors influencing the uptake and 8-hydroxyquinoline. La destruction des chancres de rouille vési- toxicity of fungicides. N. Y. Acad. Science Trans. 21: 442-445. culaire du pin blanc de l'ouest par l'Acti-dione montre quel peut Moss, Virgil D., 1958. Acti-dione stove oil treatment of blister être l'effet des produits toxiques qui se déplacent a l'intérieur rust cankers on reproduction and pole western white pine. de l'hOte et attaquent plus vigoureusement le parasite que l'hôte. Plant Disease Rptr. 42: 702-706. Offord, H. R., Clarence R. Quick, and Virgil D. Moss, 1958. Le problème chimique du gui-nain pose un problème qui n'a Blister rust control aided by the use of chemicals for killing pas encore été résolu, et qui est d'une importance vitale pour les Ribes. Jour. Forestry 56: 12-18. forestiers de la partie occidentale des Etats-Unis. D'autres ques- Sharvelle, Eric G., 1952.Systemic fungicides in 1951: British tions portant sur la lutte contre les maladies des forêts a l'aide de investigations. Plant Disease Rptr. 36: 35-43. produits chimiques méritent davantage d'attention, ce sont:la Vité, J. P., and J. A. Rudinsky, 1959. The water-conducting sys- compatibilité et la synergie des mélanges de fongicides, phyto- tems in conifers and their importance to the distribution of cides, nématocides et insecticides; le dépistage des agents chimi- trunk-injected chemicals. Contr. Boyce Thompson Inst. 20(1): ques systémiques susceptibles d'être tolérés par les comfères; la 27-38. nutrition de l'hOte par rapport a la susceptibilité a la maladie. Yamaguchi, S., and A. S. Crafts, 1959. Comparative studies with labeled herbicides on woody plants. Hilgardia 29: 171-204. Nuevos MétodosparaContenerlasEnfermedades Forestales con Substancias QuImicas RESUMES Los silvicultores que deben hacer frente a los elevados costos !',Iouvelles méthodes de lutte contre les maladies forestières de una administraci5n intensiva de bosques consideran la aplica- a l'aide de produits chimiques ción de medios nuevos y menos costosos para protegerse contra las pérdidas causadas por las enfermedades forestales y otras Misenpresencedesfraisd'investissementconsidërables plagas. El informe que el Servicio Forestal de los Estados Unidos entralnés par un aménagement intensif, les forestiers cherchent preparó en 1958 sobre los recursos forestales da cuenta de que des moyens inédits et meilleur marché de se prémunir contre les las enfermedades son responsables del 45 por ciento de la merma maladies des forêts et autres parasites. Le rapport de 1958 sur (mortalidad y pérdida de incremento) producida en el total del les ressources en bois du Service forestier des Etats-Unis montre cultivo forestal del pais. que 45% de l'impact (mortalité, plus perte de croissance)stir Las substancias tóxicas protectoras y erradicadoras que tienen l'ensemble de la productionnationale debois,est dü aux amplia aplicacidn en la agricultura, las aprovechan más y más maladies. los silvicultores en los cultivos de viveros, plantaciones y bosques Les produits toxiques de protection et de destruction dont administrados.Las substancias quimicas tales como fungicidas l'utilisation et l'acceptation sont générales dans l'industrie com- orgánicos (ferbam y nabam), fitocidas selectivos (2,4-D y el mencent maintenant a être connus du forestier pour les travaux 2,4,5-T), fumigantes de suelos (bromito de metilo y cloropicrrna), dans les pépinières, les plantations et les forêts aménagées. Les antibióticos de actuación sistémica (como ser el Acti-dione) y fongicides organiques (ferbam et nabam), les phytocides sélec- substancias qulmicas que ofrecen cierta protección contra las tifs(2,4-Det2,4,5-T),lesfumigants dusol(bromure de enfermedades vasculares (Helio Naranja y benzoato de hidroxi- méthyle et chloropicrine), les antibiotiques a action systémique quinolina-8) proporcionan nuevos medios para el control directo (Acti-dione, par exemple) et les produits chimiques qui protègent de las enfermedades forestales. contre les maladies vasculaires (Hélione Orange et benzoate de En este trabajo se hace referencia a las experiencias recientes 8-hydroxi-quinoline) sont autant de nouveaux moyens permettant con pesticidas en los Estados Unidos, para demostrar lo que los de combattre directement les maladies des forêts. silvicultores de este pals están haciendo para contener las siguien- Des experiences récentesréalisées aux Etats-Unis avecles tes plagas y desórdenes que crean serios problemas: clorosis y pesticides sont passées en revue pour montrer ce que les forestiers deficiencias de nutrición; enfermedades de hongos transportados font pour lutter contre les parasites et maladies suivantes, qui por la semilla y de hongos causantes de la podedumbre por el causent de graves dégâts: chlorose et carences nutritives, champi- pie; enfermedad del olmo holandés (Ceratostomella ulmi); en- gnons héréditaires et de moisissure, maladie de l'orme liege (Cer- fermedad fungosa del roble (Cerastocystis fagacearum); pode- atostomella ulmi), flétrissure du chêne (Ceratocystis fagacearum) dumbre delaraiz(Fomes annosus, Sclerotium bataticola y pourriture des racines (Fomes annosus, Scierotium bataticola, Fusariumoxysporum);añubloampolladodelpinoblanco Fusarium oxysporum), rouille vésiculeuse du pin blanc (Cronar- (Cronartiumribicola);añublofusiforme(Cronartiumfusi- tium ribicola), rouille fusiforme (Cronartium fusiforme), rouille forme); aflublo del cono (Cronartium strobilinum); tizOn pardo 886 Fifth World Forestry Congress Proceedings (Scirrhia acicola); tizón de nieve (Phacidium infestans); liagas Pero los terapéuticos quImicos y las substancias tóxicas sistémicas gangrenosas del arce (Phytophtora cactorum); mudrdago legItimo, constituyen los objetivos codiciados para el patólogo que mira nemátodos y malezas.También se hace mención especial del hacia el futuro. Las perspectivas para el buen éxito de la terapéu- tratamiento curativo de la base del tallo del pino blanco del tica quImica quedan claramente demostradas por la formacidn de Oeste (Pinus monticola) con Acti-dione en una solución de aceite antIdotos contra las toxinas producidas por la liaga gangrenosa que combate las liagas causadas por el añublo ampoilado, y del del arce (con Heliono Naranja) y por Ia protección de corta tratamiento a bajo costo para la erradicacidn de lasplantas duración contrala enfermedad del olmo holandés, obtenida huéspedes Ribes con el 2,4-D y el 2,4,5-T.Los investigadores mediante la inoculación preinfecciosa con benzoato hidroquino- australianos han encontrado un método eficaz para inyectar una lino-8. La eliminación de las ilagas causadas por el anublo ampo- solución acuosa de amino 2,4-D, o de sales de hidracina en el ilado en el pino blanco del Oeste, por medio de Ia aplicación de troncodeleucalipto paraerradicarelmuérdago (Amyema Acti-dione, demuestra lo que puede conseguirse con las sub- pendula). stancias tóxicas que circulan en la planta huésped y actéan con Las investigaciones actuales sobre la anatomIa, bioquImica y más agresividad en el parásito que en la planta huésped. fisiologIa de las plantas huéspedes y de los parásitos, asI como El control, por medios quImicos, del muérdago enano es un sobre la absorción, circulación y acción de las substancias tóxicas problema provocante que aén requiere solución por ser de im- en las plantas vivas, justifican el optimismo sobre la utilidad de portancia vital para los silvicultores del Oeste de los Estados las substancias quImicas en el control de enfermedades. En el Unidos. Otros problemas que se basan en el control de las en- futuro se trabajará mucho para perfeccionar la eficacia de los fermedades forestales por medio de substancias qulmicas y que fungicidas cuya utilidad ya ha quedado comprobada, como ser el compuesto de "bordeaux" y el sulfuro de cal.Con frecuencia merecen especial atención, son: la compatibilidad y sinergIa de los perfeccionamientos más importantes tienen su origen en un fungicidas mixtos; de los nematocidas, y de los insecticidas; en- método simplificado para la aplicaci5n de las substancias tóxicas, sayos para la determinación de la tolerancia desubstancias quI- o en la determinación más exacta del medio ambiente en que se micas sistémicas fuertes en las conIferas y nutrición de la planta desarrolla Ia plaga y la reaccidn que esta ofrece al tratamiento. huésped en relación con su susceptibilidad a las enfermedades.

Present and Potential Significance of RootRots In Intensive Forest Management

HEINRICH VAN VL0TEN Director, Forest Experimental Station, Wageningen. The Netherlands

Control of root rots caused by Armillaria mellea (Fr.) The complete removal of stumps and roots, especially Quél. and some other fungi in tea plantations in the Congo in the case of dense forests, involves high expenses. Try- has recently been dealt with by Fassi (2) *Complete ing to avoid these, Fassi followed the experience of Leach removal of stumps and roots, after clearing a forest area (6,7) in Nyasaland. Leach proposed a biological control to be planted with tea, is recommended to prevent heavy of Armillaria root rot by ringbarking the trees of the losses. original forest.So, in the Congo, large-scale experiments The author's advice is based on the knowledge that have been carried out by ringbarking the trees before root rot fungi need a certain amount of inoculum-poten- cutting the forest.The author applied mechanical ring- tial for their activity.In 1933, De Jong (5) showed barking and tried a stem-spray with phytohormones experimentally that infection and its extension depends (2,4,5-T).Death of the standing trees occurred after upon the inoculum-potential in the case of Fomeslignosus some nine months. The results of these experiments were Klotzsch on Hevea brasiliensis in Sumatra. Decaying the same as obtained by Leach; the roots and stumps of wood with the fungus in close contact with Hevea roots the ringbarked trees appeared to be occupied by sapro- was needed to obtain infection; but, in addition, acertain phytic fungi, whereas roots and stumps severed from liv- amount of the inoculation material had to be provided for. ing and normally functioning trees were invaded by root If it was small, only a localized infection developed. When rot fungi, mostly Armillaria. By interruption of thebark the resources of wood material were exhausted too soon, tissue, the supply of carbohydrates to the roots is stopped, the rot stopped, and even healing took place in such cases. and the starving roots die off much quicker than those of Death of rubber trees resulted with large quantities of trees cut when functioning normally, and they become decaying wood only, increasing with the size of the tree. subject to invasion by saprophytes. Fassi (bc. cit.) formulates the cycle of root rots in Complementary knowledge of the same kind has been tea plantations, based on changes in the inoculum-poten- gained from experiences described by Hepting and Downs tial. In this cycle, we find an "endemic" phase of root rot (4), dealing with thinning experiments in a Pinus strobus occurring in the natural forest with latent or weak and plantation in Biltmore, N. C. The experiment was started scattered infection.This develops into the "epidemic" in 1916. Unthinned sample plots, with only dead trees phase, when large amounts of inoculum-potential become being removed, have been compared with plots thinned available by cutting the natural forest and leaving fresh repeatedly (1916, 1923, 1926, 1936). Another thinning stumps and roots without taking special precautions. took place in 1942. At that time (the age of the planta- tion being 40-45 years)trees were felled also in the Numbers in parentheses denote the references listed at the hitherto unthinned plots, to enable an assessment of the end of this paper. occurrence of root and butt rot in relation to the different Forest Protection 887 treatments. Rot caused by Fomes annosus (Fr.) Karst., In some other details root rot fungi may differ remark- Polyporus circinatus Fr., and P. schweinitzii Fr. appeared ably. This applies, for instance, to their parasitism and in 75% of the trees felled in plots thinned since 1916. their way of infection. Rhizomorphs, known to be charac- Only 4% of the trees were so infected in the previously teristic of Armillaria mellea, are lacking with Fomes unthinned plots. annosus. Infection of living roots by F. annosus is pos- These results have been confirmed recently by Williams sible only by close contact of healthy and attacked roots (18) in a shortleaf pine (Pinus echinata) plantation. Here, or comparable wood material occupied by the fungus. also, Fomes annosus has been responsible for most of the Rhizomorphs, in contrast, enable Armillaria mellea to mortality on medium and heavily thinned plots. It was not push its way through the soil and to reach and eventually found, or scarcely so, only on lightly thinned or unthinned enter living roots of a host plant; provided their supply plots. Dead trees in these plots, generally small and over- of decaying wood permits, they may traverse fairly long topped, died without parasitic interference.Their dying distances in sandy soils; in heavy clay soil they appear to was natural, due to lack of space and light. Thinning a be hampered, probably mechanically. stand means cutting quite normally growing trees; their One aspect of root and butt rot fungi certainly is fun- remaining, still living stumps and roots are invaded by damental: they are root inhabiting, clearly distinct from Fomes annosus, and they provide the inoculum-potential soil-inhabiting microorganisms. Many of the latter are the fungus needs in order to infect neighboring trees of obligate saprophytes, quite a number of them antagonists the stand. of root parasites, as we know, thanks to the research on Evidently, analogous relations exist as to root rots in Fomes annosus in East Anglia by Rishbeth (13), with natural forests in the Congo and, when left to natural Trichoderma viride as one clear-cut example. It is quite development, in the Biltmore, N. C., plantation of Pinus impossible to isolate F. annosus from litter and the under- strobus, as well as in the case of P. echinata referred to. lying soil, not because the fungus is unable to develop on All three may be included in Fassi's "endemic" phase of soil and litter as such, but due to the presence of soil root rot, changing into a more or less "epidemic" phase inhabiting competitors and antagonists; if the soil has following artificial intervention. been sterilized, in fact, F. annosus does grow on it. This is also true if we consider the occurrence and Garrett (bc. cit.:223)characterized his group of significance of Fomes annosus root and butt rot in natural specialized root-infecting fungi as "likely to have evolved forests of North America. Boyce (1) referred to it at from saprophytes of the soil-inhabiting class, that have our first special meeting on Fomes annosus in 1954. "F. escaped the intensive competition for existence on dead annosus occurs in conifers in natural stands in the United organic material." Survival and existence, indeed, of root- States as a saprophyte on old coniferous stumps and inhabiting fungi depends on their parasitic power and on occasionally causes butt rot in mature and overmature the availability of living host plants. living trees." Here, again, we find a situation correspond- The examples in the Congo and the States mentioned ing with Fassi's "endemic" phase, in clear contrast to that above illustrate that Armillaria mellea and Fomes annosus, also mentioned by Boyce in 1954 in speaking of pure enabled by their parasitic character, build up a sufficient plantations of Pinus resinosa and P. ponderosa on agricul- inoculum-potential by invadingstilllivingrootsand tural, either plowed or pasture land in the Eastern States, stumps soon after these have been severed from the trees, where, during the past 20 years, Fomes annosus has before saprophytes get a chance. It is also evident, after become of some consequence by killing following thinning all, that these saprophytes, in contrast to the parasites, are It is well known, on the other hand, that root and butt able to survive indefinitely as soil-inhabiting organisms rots, by Fomes annosus in particular, long since have (Garrett, bc. cit.:223). been causing great losses in several countries in Europe, Accordingly, Rishbeth(13)could not find any evidence where natural forests are exceptional and more or less of an infection of living trees by way of dead roots in his intensively managed forests prevail. Murray (11) dealt research on Fomes annosus.In this case, saprophytes with F. annosus recently as "the most damaging fungus in did "win the race," so to speak. trees in Great Britain." But in North America, since 1954, The parasitic capacity also is basic when Rishbeth (16, reports in root rot by F. annosus also appear in increasing 17) and, following him, Low and Gladman (9) are using numbers (10). We certainly are up against a problem of inoculation of disks taken from living pine trees, "a highly growing significance in forestry. selective substrate for Fornes," with a spore suspension The examples referred to above show that in our dis- prepared with a series of dilutions from the two traps they cussion we need a review of existing knowledge as to the apply, a square of sterile muslin cloth acting as a screen, biology and ecology of root rot fungi in order to get a and foliage acting as a natural trap for fungal spores. clear picture of the situation and a sensible judgment. To The result of an extended and detailed ground survey understand the relationship of root rots and intensive by Low and Gladman (8) in the United Kingdom is in forest management, it is indispensable. perfect agreement with the experiences already referred Garrett(3)did deal with these problems fully; he to.It also fits in with the characterization of root rot contributed essentially to our understanding of the ecology fungi by Garrett. of soil-borne parasites, which are facing the general soil In Britain, Fomes is invariably absent from first rota- microfiora on their way to the roots of host plants. Forest tion crops until after the first thinning operations, except soil, indeed, is a very complex and varying habitat. Due in a few cases of early cutting of Christmas trees, for to the particular environment, root rots have certain instance. On the other hand, infection through colonized aspects in common; "root rot fungi form a natural ecologi- thinning stumps by airborne spores appeared to occur in cal group" (Garrett, bc. cit.:220). all parts of the country, even in relatively isolated forests,

888 Fifth World Forestry Congress Proceedings attackisincreasing during the second Research for the year ended March 1958. Forestry Commis- and butt rot sion. (69-72). rotation. Peace, T.R.,1957.Approach and perspective in forest Summarizing, just one general conclusion is possible. pathology. Forestry 30 (1) (47-56). Root and butt rots caused by fungi like Fomes annosus Rishbeth,J.,1950-51.Observations on the biology of and Armillaria mellea are diseases closely related with Fomes annosus, with particular reference to East Anglian pine plantations.I. Ann. Bot. London. N.S. 14, 1950 (365-383); management. II. Ann. Bot. London. N.S. 15, 1951 (1-21); III. Ann. Bot. I like to quote Peace (12) here. In his Approach and London. N.S. 15, 1951(221-246). ,1951. Butt rot by Fomes annosus Fr. in East perspective in forest pathology-every forest pathologist Anglian conifer plantations and its relation to tree killing. ought to know in detail this excellent critical review- Forestry 24, (114-120). aiming at our root and butt rot problems he states: "No , 1957. Furtherobservations on Fomus annosus matter how 'natural' our forest, if we are to utilise our Fr. Forestry 30 (1) (69-89). timber we shall produce 'innatural' stump surfaces, suit- , 1959.Dispersal of Fomes annosus Fr. and Peniophora gigantea Fr. Trans. Brit. Mycol. Soc. 42 (2) (243- able for infection by pathogens and their transmission to 260). the remainder of the standing or to the succeeding crop." ,and Meredith, D. 5.,1957.Surface micro- The occurrence, extension, and effect of root and butt flora on pine needles. Nature, 179, (682-683). Williams, R. D. 1959. Growth and yield of a thinned short- rots, restricted to practically no importance in their latent leaf pine plantation. Central States For. Exp. Sta. Columbus, stage in natural forests, change into dangerous diseases Ohio. Tech. Paper No. 169. causing great losses when intensive management is applied. Very briefly, we might qualify them as "management RESUMES diseases," indeed. Signification actuelle et éventuelle de la pourriture des Consequently and unavoidably, we will have to find racines danslesforêts soumises a un système ways and means of protection.In this field, the well- d'aménagement intensif known team of research workers in Great Britain has Le rapport porte sur les recherches effectuées par De Jong made conspicuous and extremely valuable progress. Based (1933) en ce qui concerne le Fomes lignosus qui provoque Ia on the information already obtained,further activities in pourriture des racines de l'Hevea brasiliensis en Sumatra; par Leach (1937, 1939) dans le Nyasaland et Fassi (1959) au Congo, research on manifold aspects will be needed in other ces deux derniers traitant de Ia pourriture desracines causée dans countries; they are, in fact, already on the way, notably in les plantations de the par l'Armillaria mellea. L'auteur mentionne Canada and the United States. The second special con- également les résultats obtenus par Hepting et Downs (1944) et ference on Fomes annosus, recently held in Scotland under Williams (1959) a la suite d'expériences portant sur le Fomes annosus qui provoque la pourriture des racines etdes souches the auspices of Section 24 of the International Union of dans les peuplements de Pinus strobus et de Pinus echinata aux Forest Research Organizations, will, I am sure, contribute Etats-Unis. very much to further development. Il est evident que des relations analogues en ce qui concerne Awaiting more complete results of research, for full la pourriture des racines existent dans les forêts et peuplements naturels qui poussent a l'état naturel, resultant en une phase understanding, however, forest practice ought to apply "endémique" de pourriture des racines (Fassi, 1959), au cours careful stump treatment as soon as possible. de laquelle le pouvoir d'infection est faible ou latent et oii la maladie attaque de facon dispersde.II se produit un changement References complet donnant naissance au stage "épidémique" lorsqu'un fort Boyce, J. S., 1954. Survey of experiences concerning root- potentiel d'inoculum est present par suite de l'abattage de tout le rots in second growth conifer plantations in eastern parts of the peuplement ou d'une partie des arbres, laissant exposées des U.S.A. Special Conference on Root- and Butt-Rots of Forest souchesetdes racines fraichement coupées sans prendre de Trees by Fomes annosus. Wageningen, 1954 (13-14). precautions spéciales. Fassi, B., 1959. La lutte contre les pourridiés du théier au Contrairement aux micro-organismes vivant dans le sol,qui sont les concurrents saprophytiques des champignons croissant Kivu. Bulletin d'Information de L'INEAC 8(5)(317-330). dans la pourriture des racines et qui attaquent en partie ces Garrett, S. D., 1950. Ecology of the root-inhabiting fungi. derniers (Garrett, 1950; Rishbeth, 1950, 1951), ces champignons Biol. Rev. 25. (220-254). vivent dans les racines mêmes. Ils peuvent ainsi tirer parti de Hepting, G. H., and Downs, A. A., 1944. Root and butt rot leur nature parasitique pour échapper a Ia concurrenceacharnée in planted white pine at Biltmore, North Carolina.Jour. of qui se livre pour l'existence sur les matières organiques mortes Forestry 42 (3) (119-123). (Garrett, 1950); en réalité, ils doivent leur existence au faitqu'ils Jong, W. H. De, 1933. The parasitism of Rigidoporus micro- sont des parasites. porus (Swartz) van Overeem, syn. Fomes lignosus Klotzsch, Une étude détaillée des sols en Grande-Bretagne (Low et Glad- on Hevea brasiliensis Archief v. Rubbercultuur, Ned. Indië, man, 1960) a montré que le Fomesn'était jamais present dans 17, (83-104). les récoltes de premiere rotation qu'après les premiers travaux Leach, R., 1937.Observations on the parasitism and con- d'éclaircissage, sauf dans quelques cas rares ohils'agissait de trol of Armillaria mellea.Proc. Roy. Soc. Ser. B 121, (561- coupes prématurées d'arbres de Noel. L'infection pardes spores 573). se trouvant dans l'air, après l'éclaircissagedes troncs, s'est pro- ,1939. Biological control and ecology of Armil- duite dans toutes les regions de la Grande-Bretagne, méme dans lana mellea (Vahl) Fr. Trans. Brit. Mycol. Soc. 23 (4) (320- des forêts relativement isolées.Ii a été constaté que dans toutes 329). les regions considérées, l'attaque de la souche et desracines Low, J. D., and Gladman, R. J., 1960. Fomes annosus in augmentait au cours de la deuxième rotation. Great Britain. An assessment of the situation in 1959. Forestry En se basant sur les résultats obtenus, il est possible d'en tirer Commission: Forest Record No. 41. une conclusion générale. Le problèmedes pourritures des racines , 1960. Spore sampling of Fomes annosus. Ob- est étroitement lie a celui de l'aménagement; on pourraittrés bien servations 1957-1960.Second Special Conference on Fomes considérercesinfections comme des"maladies typiquesde annosus, TUFRO Section 24. l'aménagement". Les pratiques forestières devront par consequent Mook, P. V., and Waters, W. E., 1959. Forest disease and comporter des mesures de protection. L'équipe bien connuedes insect conditions in the Northeast-1958. Northeastern For. chercheurs de la Commission Forestière en Grande-Bretagne, qui Exp. Sta. Sta. Paper No. 120, (6,8-9). étudie le problème du Fomes annosus a déjà obtenu des résultats Murray, J.5., 1959.Forest Pathology. Report on Forest extrêmement importants a ce sujet. D'autres travaux de recherche, Forest Protection 889 comme ceux entrepris également au Canada et aux Etats-Unis, Ia podredumbre de la raIz (Garret, 1950; Rishbeth, 1950, 1951). sont nécessaires pour que l'on puisse comprendre parfaitement Debido a su carácter parasitario escapan a la intensa lucha por ce problème. La deuxième reunion spdciale sur le Fomes tenue la existencia sobre la materia orgánica muerta (Garret, 1950); en Ecosse en en 1960 sous les auspices de l'Union Internationale lo que es más, deben su existencia a la circunstancia de que son des Organisations de Recherche Sylvicole, en vertu de Ia Sec- parásitos. tion 24, contribuera a la solution de ce problème. Análisis detallados de suelos en Gran Bretaña (Low y Glad- Dans l'attente de renseignements complets,iiserait utile de man, 1960)invariablemente han demostrado laausencia de procéderautraitementdessouchesentantquepratique Fomes en cosechas pertenecientes a la primera rotación, hasta forestière. después de las primeras operaciones de entresaca, excepto en algunos casos de corta temprana de árboles de navidad, por Importancia Actual y Potencial de la Podredumbre de la ejemplo.La infección de tocones remanentes de la primera Raiz en la Adminstración Intensiva de Bosques entresaca pr medio de esporas existentes en la atmósfera se extendió a través de toda Gran Bretaña, aun en bosques relativa- Se hace referencia a los trabajos de investigacidn lievadosa mente aislados. En todas partes la podredumbre de cepas aumen- cabo por De Jong (1933) sobre Fomes lignosus que causa la ta durante la segunda rotacidu. podredumbre de la raiz de Ia Hevea brasiliensis en Sumatra; por La información disponible permite llegar a una conclusion de Leach (1937, 1939) en Nyassaland y por Fassi (1959) en el carácter general. La podredumbre de la raiz se vincula estrecha- Congo, ambos relacionados con la podredumbre de la raIz de mente con la administraciOn; puede definirse como una clásica Armillaria mellea, en las plantaciones de té; las experiencias "enfermedad administrativa." recogidas por Hepting y Downs (1944) y Williams (1959) con En consecuencia, será menester respecto al Fomes annosus y a la podredumbre de la cepa en hallar medidas adecuadas para la protección contra esta enfer- plantaciones de Pinits strobus y Pinus echinata en los Estados medad. El bien conocido grupo de investigadores de Ia ComisiOn Uriidos. Forestal de Gran Bretafia, que tiene a su cargo el estudio del En cuanto a Ia podredumbre de la raIz, evidentemente existen problema del Fomes annosus, ya ha podido obtener resultados relacionesanálogas en bosques naturalesy en plantaciones sumamente valiosos.Para liegar a comprender el problema en libradasaldesarrollo natural, que dan por resultado la fase forma más cabal, será necesario realizar un mayor nOmero de "endémica" de la podredumbre de la raiz (Fassi, 1959) con Un trabajos de investigación de la Indole de los que ya se han imciado poder de infección latente o débil y con ataques aislados.El en el Canada y en los Estados Unidos. La segunda reunion cambio completo a la fase "epidémica" se produce cuando se especial sobre Foines annosus, que ha de realizarse durante 1960 halla presente una gran cantidad de material de inoculación, como en Escocia bajo los auspicios de la Sección 24 de la Union Inter- resultado de la corta de todo un bosque o de partes de los nacional de Organizaciones de Investigaciones Forestales, ha de árboles, dejando los tocones y las raIces adn verdes, sin adoptar hacer importantes contribuciones en tal sentido. En tanto que precauciones especiales. no se disponga de información más completa, serIa conveniente No dispuestos a vivir en los suelos, los micro-organismos son que en las prácticas forestales seestudie la conveniencia de competidores saprófitos y en parte enemigos del hongo que causa aplicar algOn tratamiento a los tocones.

SPECIAL PAPERS Internationally Dangerous Tree Diseases A. J. RIKER Professor of Plant Pathology and Forestry, University of Wisconsin, Madison, Wisconsin, U.S.A.

The maintenance of sustained yields in high-quality trees than for comparable agricultural crops. If a field of timber is one of the prime aims of research in forestry. wheat should be destroyed, something else could be Among the enemies of sustained yields are the following: planted the next year. But, if the trees are damaged then fire,insects,animals,inroadsof"civilization,"and 10, 25, or 50 years of the productivity of the land may be diseases. In the disease category, one finds not only the reduced or lost. Furthermore, with some of the root and pathogenic agents that destroy foliage and kill trees but butt rot organisms another danger appears. Such patho- also those that cause root, butt, and trunk rot. According gens may develop in an apparently innocuous way in the to the Timber Resources Review, growth impact (viz, fungi nurseries. Thus, dangerous disease organisms may be dis.- killing trees, inducing decay, or reducing growth) causes tributed with the nursery stock throughout the areas used about 45 percent of the overall damage against which for reforestation. trees need protection. A program has been initiated to investigate (1) what In the United States the invasion of foreign forest tree the chances are that certain internationally dangerous diseases has caused tremendous losses.Examples are diseases might be moved from one country to another, chestnut blight, white pine blister rust, and Dutch elm (2) how this movement could be prevented, or at least disease. The latter is insect borne. The importance of slowed down, (3) how quarantines could be made more injurious insects that might come from abroad also is effective, (4) how eradication might be accomplished if clearly recognized. However, the insects are outside the a foreign disease should appear, (5) how its damaging scope of the present consideration. effects might be avoided or reduced if it appeared and Epidemic diseases are much more serious for forest could not be eradicated, and (6) how research might 890 Fifth World Forestry Congress Proceedings supply badly needed information about the host, the names of some important ones follow: European and pathogen, and disease development. To facilitate such a Mediterranean Plant Protection Organization; Moscow- program, as a member of the working group on Foreign Peking Convention; Plant Protection Committee for the Tree Diseases in Section 24 (Protection) of the Inter- South East Asia and Pacific Region; Inter-Africa Phyto- national Union of Forest Research Organizations, Profes- sanitary Commission; Organismo Internacional Regional sor Riker visited sixteen different countries to consult de Sanidad Agropecuaria (Central America); Plant Quar- with leading foresters, quarantine officials, forest geneti- antine Division, A.R.S., U.S. Department of Agriculture; cists, and pathologists. His trip was encouraged by the and Division of Plant Protection, Canadian Department of U.S. Forest Service and was financed by the University of Agriculture. In addition, there is the Food and Agricul- Wisconsin. ture Organization of the United Nations in Rome. The Numerous suggestions on what to do have come from names and addresses of the quarantine services forabout many competent people. A summary appears below: 85 countries are available from FAO of the UN in Rome. (The present working group is a part of Section 24 on Directory of Critical Tree Diseases Protection, International Union of Forest Research Organ- In order to have available information about the epi- izations.)They and others can and no doubt will give demic diseases and their importance in each country, an increasing service against the spread of dangerous tree annotated list of them has been or is being prepared in a diseases. number of places. From such lists, distribution maps can be made. At the same time, the maps may show the A Symposium on Critical Diseases distribution of reporting pathologists rather than that of In order to assemble, interpret, and make readily avail- the disease. So negative reports may be significant oniy if able widely scattered information, we plan a symposium. a qualified person has made a diligent search. Experts from different parts of the world will come Such lists may not disclose diseases which appear innoc- together and describe for one another the most critical uous in one country but which might be dangerous in forest tree diseases that might be dangerous if they moved others (such as the chestnut blight in east Asia). However, from one country to another. Thus, the delegates would research, as discussed later, may bring these to light. An be informed about potential dangers.Furthermore, a example of such an annotated list is given by Dr. P. publication of the symposium papers would serve as a Spaulding for the United States in the USDA Agriculture useful handbook. Handbook 139, where 33 diseases come under the head- ing "American Forest Diseases Potentially Dangerous to Cooperative International Research Forests of Foreign Countries." (See Appendix A for the For a number of critical problems no one knows the list without the notes.) answers. To secure them, cooperative research is essen- Much can be learned by a study of surviving exotic tial between men in different countries.Obviously, one trees in plantations already made, as Spaulding has done. cannot move either the pathogens or living trees that might carry them from one country to another except with List of Key Men in Each Country extensive precautions. However, disease-free selected or A list is being prepared of men active in forest path- treated seed can go from one country to a suitable place in ology, one or more for each country. These men will another country with relatively little danger. exchange critical information, arrange for research on an Some important topics for research follow: international basis between suitable individuals, and advise Host ranges. The different kinds of trees attacked in case of an outbreak. Local circumstances will deter- by critical pathogens need exploration.In some cases mine whether the communications should be directed to related ornamentals carry tree diseases.Such research such an individual or made through official channels. may best be done in nature at a location wherethe patho- gen is active. Strengthening Quarantines Alternate hosts. Especially with the rusts (e.g., white Plant quarantines are the accepted bulwark against the pine blister rust has one critical stage on currants and entry of dangerous tree diseases. Modern air travel greatly gooseberries) the various plants necessary for the devel- increases the chances for distributing pathogens from one opment of certain stages of the fungus need to be charac- country to another. Many foresters are concerned about terized with precision. Environmental influences.Temperature, moisture, the quarantines, no matter how well they are administered, light, and mineral nutrition have important influences for fear dangerous pathogens may get through. Forest favoring or discouraging epidemics. The study of micro- pathologists have an obligation to clarify for quarantine climate is essential for knowing how the pathogens work officers what to look for and what the symptoms look and how their damage may be prevented. like.At the same time interferences with commerce, Disseminating agents. The potentialities of different travel, and the exchange of scientific materials need to be carriers of pathogens need investigation, especially insect held to a minimum compatible with protection.With vectors. many questions, more research is needed if quarantines are Seemingly innocuous pathogens.Attempts should to achieve maximum dependability. be made to disclose dangerous pathogens that are seem- ingly unimportant intheirnative country.Chestnut Organizations Now Operating blight was considered of no consequence in east Asia. But Various organizations deal in one way or another with when the pathogen reached America, it practically elimi- certain aspects of these foreign tree disease problems. The nated the American chestnuts.Suitable experimental

Forest Protection 891 plantings might disclose such wolves-in-sheep's-clothing. Clitocybe tabescens root rot (The technique for such research might follow the work Coryneum berckmanii Coryneum blight with the world collection of wheat.) Cronartium coleosporioides western pine stem gall rust Improved methods for eradication.If a dangerous Cronartium corn ptoniae sweetgale blister rust disease should appear in a limited area of a country, eradi- Ceratocystis fagacearum oak wilt cation might be tried. Fire and chemicals have been use- Ceratocystis fimbriata platani canker stain ful, but certain other procedures may be valuable. To be Cronartium harknessii western globoid stem gall most effective, the technique for eradication should be Diplodia pinea pine twig blight developed in the country where the disease is active. The Endothia parasitica chestnut blight results should be available for immediate use to countries Eusicladium saliciperdum willow scab where the disease might appear as a new invader. Gloeosporium ulmicolum elm anthracnose Disease resistance.In many countries, native trees Guignardi aesculi Aesculus leaf blotch fail to meet the needs for reforestation or afforestation. Gymnosporangiurn libocedri Libocedrus-Pomaceae rust Trees from other countries have been widely and advan- Gymnosporangium nootkatense Alaska cedar rust tageously used, but sometimes with disastrous results from Melampsora abietis-canadensis hemlock-poplar rust disease. Furthermore,treebreedersarecontinually Melampsora occidentalis Douglas-fir-poplar rust developing improved trees. In both cases tests for resist- Peridermium coloradense spruce witches'-broom rust ance to dangerous diseases are essential.The selection Phomopsis juniperovora cedar blight and development of disease-resistant trees hold great Phyllosticta minima maple leaf spot promise. Phymatotrichum omnivorum root rot Rhizoctonia ramicola silky thread blight For many kinds of research involving pathogens and Scirrhia acicola brown spot needle blight isolation, several locations are needed. An island with a Scierotium bataticola damping-off mountain mightprovide many desirableconditions. Septoria musiva leaf spot, canker Changes in moisture occur from the rainy to the dry side. Thyronectria austro-americana hardwoods canker Changes in temperature appear at higher or lower eleva- Trichoscyphella willkommii larch canker tions. In some mountain valleys the length of day would powdery mildew be shortened. In such isolated places pathogens might be Uncinula flexuosa studied effectively with little danger of spreading the diseases. RESUMES Agents pathogènes présentant un danger du point de vue Relations With Agricultural Research Stations international In many countries the forest pathologist works in rela- Les infections fongueuses causent environ 45 pour cent des tive isolation from men trained and experienced in hand- dommages qui menacent le rendement continu (Timber Resources ling various field, forage, fruit, fiber, and plantation crop Review). On ne connaIt que trop les devastations causées par la cane du châtaignier, la rouille du pin et la maladie de l'orme diseases. Where reforestation and afforestation are con- subéreux, toutes maladies d'origine étrangère. Aucun pays ne cerned, numerous people consider that trees are agricul- peut se permettre de risquer une invasion d'agents pathogènes tural crops. Such men usually have a background of infor- doués d'une telle puissance de destruction. (Nous traitons dans mation and "know-how" as well as equipment that the une étude séparée le problème analogue pose par les insectes). Les dangers d'invasionqui peuvent réduire a néant le système forest pathologist could use to advantage. For the most du rendement continuaugmentent chaque année avec la rapidité part, all this would be available merely for the asking. des transports aériens, et aussi parce que certaines facons sylvicul- Active cooperation between forest pathologists and agri- turalesconstituent une veritable invitation aux épidémies au cultural pathologists deserves not only encouragement but cas oü un agent pathogène viendrait a apparaItre. L'auteur a récemment réuni, sur les mesures qu'il conviendrait also the active removal of any physical and administrative de prendre, un certain nombre d'idées émises avec enthousiasme barriers that prevent their working together. par les autorités les plus qualifiées d'Amérique du Nord, d'Europe, In conclusion, the possibilities are dismaying that inter- d'Asie du Sud-Est et du Pacifique Sud. nationally dangerous tree diseases may move from one Voici les principales mesures qui ont été suggérées: country to another and upset sustained yields. However, Dresser, dans chaque pays, un catalogue des agents patho- genes dangereux.Aux Etats-Unis par exemple, Spaulding a international understanding, cooperation, and research établi une liste de 33 maladies qui sont virtuellement dangereuses can do much to slow down or even to prevent more pour lesautres pays (Manuel N° 139 du Département de catastropheslikethat caused by chestnut blightin l'Agriculture des Etats-Unis). America. Une liste de spécialistes est indispensable; un au moms par pays doit être chargé de rassembler et de distribuer tous renseigne- ments utiles. APPENDIX A Renforcementdesmesuresphyto-sanitaires,enveillant American Forest Tree Diseases Potentially Dangerous to toutefois a faire le moms possible obstacle au commerce inter- Forests of Foreign Countries national. Les organisations existantes sont adéquates et il ne semble Causal agent Disease pas nécessaire d'en créer de nouvelles. On envisage a l'heure actuelle d'organiser une conference Virus Pierce's virus of grape internationale sur lesagents pathogènes dangereux, qui aurait Erwinia wnylovora fire blight pour but de rassembler les informations qui existent sur la ques- tion, de determiner les recherches qui s'imposent et de fournir Erwinia nimipressuralis elm wetwood des plans de travail pour un effort international coordonné. Xanthomonas corylina filbert blight Des recherches sur le plan international sont indispensables Cephalosporium diospyri persimmon wilt pour l'efficacitédes operations.Ces recherches doivent viser Cercospora thujina Thuja leaf spot entre autre:(a) a determiner l'habitat des diverses essences

892 Fifth World Forestry Congress Proceedings auxquelles s'attaquent les champignons dangereux; (b) a étudier Sudoeste de Asia y del Sur del PacIfico, sobre lo que debe hacerse. les végétaux abritant lesrouillesa un certain stade de leur A continuaciOn se dan algunas de las ideas sugeridas: développement;(c)a établir l'importance critique de la tern- Una gula de enfermedades peligrosas, que se necesita en pérature, de l'humidité, de la lumière et de la nutrition minérale cada pals. Por ejemplo, en los Estados Unidos, Spaulding da una pour le microclimat et l'éruption d'une épidémie; (d) a identifier lista de 33 enfermedades potencialmente peligrosas para otros lesagentsporteursd'organismespathogènes, notamment les paises. (USDA Handbook 139). insectes; (e) a révéler le caractère dangereux de certains agents Una lista de peritos es esencial.Por lo menos uno por pathogènes en apparence inoffensifs(par exemple la cane du cada pals deberá reunir y distribuir informaciOn. châtaignier) au moyen de plantations appropriées a l'étranger; Cuarentenas mds estrictas,esto es imperativo.Pero sin (1)a améliorer les procédés d'élimination de ces agents patho- causar nada más que un mlnimo deinconvenientes al comerclo. genes; et (g) a mettre au point des variétés d'élite resistant a ces Las organizaciones existentes, son adecuadas. No parece agents. necesitarse ninguna nueva organizaciOn. 7. L'amélioration de la cooperation entre centres d'expérimenta- Un simposio internacional sobre enfermedades peligrosas, tion agricole et centres de recherches forestières serait mutuelle- que está organizándose con el objeto desuministrar informes, ment avantageuse. decidir sobre las investigaciones que es necesario lievar a cabo y preparar planes de trabajo para un esfuerzointernacionalmente Enfermedades Forestales Internacionaimente Peligrosas coordinado. Los hongos causan un 45 por ciento de todos los daños a los Los estudios de investigación internacionales son esenciales árboles que ponen en peligro el rendimiento sostenido (Timber para la eficacia de las operaciones. Estos deberánincluir: a) una Resources Review). Las pérdidas devastadoras causadas por las lista autorizada de huéspedes de los hongos peligrosos; b) cono- enfermedades importadas, como la plaga que ataca a! castaño, ci cirnientos sobre los huéspedes alternos de los añublos; c)la aflubio que produce ampollas en el pino blanco y la del olmo importancia crItica de la temperatura, la humedad, la luz y de la nutrición mineral para el microclima y los brotes deepidemia; holandes, son harto conocidas. No hay pals que yea con tran- patóge- quilidad la liegada de enfermedades destructivas análogas a las d) la caracterizaciOn de los agentes diseminadores de los mencionadas. (El problema análogo causado por los insectos, es nos, especialmente de los insectos; e) la detección ydescubrirniento objeto de estudio aparte). Los peligros de una invasion capaz de ciertos patOgenos al parecer inofensivos (como por ejemplo, de acabar con los rendimientos sostenidos van cada año en la plaga del castafio) por medio de cultivos adecuados deárboles aumento debido a la rapidez de la aviaciOn y a que ciertas exóticos; f) ci rnejorarniento de los procedimientos de erradica- prácticas forestales invitan a Ia epidemia si por casualidad liegan ciOn; y g) el desarrollo de variedades selectas y resistentes. a aparecer los patógenos. El mejoramiento de la cooperación entrelasestaciones El autor de estetrabajo ha obtenido ideas entusiastas de experimentalesagrIcolasylas de investigaciónforestal,que destacadas autoridades de la America del Norte, Europa, del resultarla mutualmente beneficiosa.

Dwarfmistletoe: Parasite of Western Hemlock

RICHARD T. STERLING Forester, Aloha Lumber Corporation, Aloha, Washington, U.S.A.

The early methods have disappeared in the wake of bat the pest.Secondary attack by fungi results in rot, progress, but residual stands of predominately western breakage, and, in some cases, death. hemlock that have escaped 50 years of windstorm, fire, When severe windstorms further thin out residual insects and disease have become stagnated or slowly stands, the openings quickly restock.Infection spreads decimated by a serious pest, dwarfmistletoe, Arceutho- from scattered trees by gravity, wind, and animal, princi- bium campylopodum forma tsugensis Gill.Other forms pally bird, action. The more vigorous trees survive only of this species attack conifers throughout the Western to be infected in turn. The stocking inthese stands is Three other species and another genus, very low. Figure 1 shows thenumber of trees per acre United States. in infected and uninfected stands near Aloha, Washing- Phoradendron, represent the Loranthaceae in the United index150 from States. Most of the 60 genera of this family are tropical ton,andanormal curveofsite (5).* Barnes (1). parasites; 13 are found in Australasia; Hartigan Primitive logging methods of the late 19th and early The only occurence of Arceuthobium outside of North 20th centuries were very profitable in relation to present- America is in three isolated species in the Himalayas, day technology. Compared with the silviculturalmethods the Caucasus, and the Mediterranean basin. that were dictated by market conditions, modern forest- The parasite is found throughout the range of the host land managers are finding it difficult to find a profitable but is of economic importance in coastal Oregon and silvicultural treatment that will correct abuses made in Washington,British Columbia, Alaska, and partsof many western hemlock stands. northern Idaho. It attacks the tree at any stage in its life In 1890, prime timber stands in the Pacific Northwest and can survive until the tree dies.Little is known about stood uninterrupted from tidewater to timberline. The its vigor, but trees several hundred years old contain active most accessible stands were selectively logged by hand, centers of infection which contaminate young growth horse, oxen, and steam donkey ground-lead for the high- around them. These trees have no effective way to corn- qualityDouglas-fir(Pseudotsugamenziesii(Mirb.) Franco), Sitka spruce (Picea sitchensis (Bong.) Carr.), * Numbers in parentheses denote the references listed at the and western redcedar (Thuja plicata Donn). Except for end of this paper. the best trees,western hemlock (Tsuga heterophylla Forest Protection 893 900 and decussate leaves. The current year's leaves of this slow-growing plant are barely distinguishable and as they mature they became heavily cutinized, appearing as scales

800 at the top of the articulated segments. The shoots emerge from an endophytic bud within the cortex of the host. Two years are required for the development of the

700 dimerous flowers.This characteristic is the key feature in the taxonomy of American species of Arceuthobium; Gill (4). The late-summer-developing flowers are pol-

600 linated the following spring entomophilously.Poffina- tion to maturity requires approximately 14 months. The usually late, dry summer causes the to recurve.

900 As the rainy season begins the viscin cells surrounding the seed within the pericarp absorb water and swell to create pressure. A slight jar severs the fruit and releases the pressure, expelling the viscin-covered seed with some force.Trailing a tail of mucilaginous matter, it attaches a itself to the first object it encounters, animal or vegetable. In the case of birds, the act of feeding on the viscin )00 leaves seeds on the bird which are wiped off on new hosts. When the seed adheres to a host plant the viscin attracts 200 water, promoting emergence of the radicle. This "radicle" isan important phaseintheestablishmentofthe I zCf endophytic system. The obstruction of growth by a leaf 170 base or bud will cause a rapid differentiation into a "hold- fast" or mound of tissue from which, by force plus

20 30 hO O 60 70 90 AVERAGE AGE OF D0'I000T rVEEO * a FigureI.Horizontalscale shows average age of dominant trees. Vertical scale shows number of frees per acre. a (Raf.) Sarg.) was ignored and treated as a worthless object that had to be logged through.Little market existed for the species which now supports many wood- using industries. The infection influences yield by interdicting the trans- location of wood-forming substances to the detriment of height growth. In many cases, most of the increment is accumulated in the butt log or in multi-forked, un- merchantable tops. Because a successful parasite depends on a live host, the dwarfmistletoe has found itself a perfect symbiont. Even the stygian darkness of a heavily infected a stand will permit limited regeneration of parasite and host. The occurence of dwarfmistletoe in even-aged stands which result from natural causes or clear cutting is not of economic significance.The yield of uninfected stands growing in the same area is higher. Site index can readily be determined, whereas it is difficult to find a dominant tree in infected stands which can be trusted to be a true indicator of the potential.Figure 2 compares the yield in cubic feet of infected stands vs. uninfected stands and shows a normal curve of site index 150 (ibid). U010PZCTSD To examine the life history of the parasite, almost any O INFECTED stand of old-growth hemlock will permit a limited inspec- tion. Swellingonlimbs,witches'-brooms,burl-like swellings on the bole, and multi-forked tops are macro- scopic symptoms of infection. lo cc Some limbs atrophy to 60 7Q 80 90 100 weights of 500 pounds or more. The evergreen vegetative AVERAGE AGE070is'TNAYr TRIES parts of the plant range in size from less than 1 inch to Figure2. Horizontal scale shows average age of dominant trees 5 inches or more in length and consis't of a perennial stem Vertical scale shows volume per acre in fhouands of cubic feet. 894 Fifth World Forestry Congress Proceedings possible enzymatic action, a primary haustorium pene- are attracted to dense clusters of shootsand mine out trates the host branch radially to the cambium and, in its branches or entire shoots. The older flower-bearing shoots course, sends out branches through the cortex.This seem most heavily damaged. cortical system is the active point of origin of vegetative Further research is necessary before control can be shoots. The "sinkers" grow into the xylem, primarily the effectively incorporated into silvicultural practice.Eco- meduliary rays. Vascular tissues are formed which make nomic considerations will bring this about as the demand direct contact with the tracheids. The enzymatic action grows for complete management of all availableland to of the cells of the haustorium make possible the trans- yield the maximum amount of wood fiber. The potential location of nutrients from host to parasite. The oleoresins of many valuable sites, which are not effectively producing are left in the medullary cells, while the tissues of dormant this maximum and have not done so for almost an shoots show an abundance of starch. The hyperplasia of economic rotation, will then have been recognized. the meduliary ray cells, in turn, results in adjacent xylem elements forming abnormal, irregular, woody, thickened References cell walls. The parasite continues to grow by means of Barnes, W. Yield tables for even-aged stands of western a meristem at the cambial region of the host. Swellings on hemlock.Unpublished report.Oregon State College. Dowding, Eleanor S.Walirothiella arceuthobii, a parasite limbs at first resemble sweet potatoes or yams. Most in- of jack-pine mistletoe. Canad. Jour, Res. 5:219-230.1931. crement is concentrated below the swelling. Ellis, D. E. Anthracnose of dwarf mistletoe caused by a Since osmotic concentration isgenerally higher on new species of Septogloeum.Elisha Mitchell Sci. Soc. Jour. southerly aspects, these relatively dry sites contain the 62:25-50.1946 (Biological Abstracts 1947). most severely infected stands. The lower sites associated Gill, Lake S. Arceuthobiurn in the United States. Conn. Acad. Arts and Sci., Trans. 32:111-245. 1935. with such exposures are, in effect, reduced to a lower Hartigan, D. The Australian mistletoe. Jour. For. 58:211- capability by theparasite.Eventually, logging, or a 218.1960. catastrophe such as windthrow, or, in rare cases, fire, Korstian, C. H., and Long, W. H. The western yellow pine will produce an even-aged stand with only scattered foci mistletoe. USDA Bull. 1112:1-35. 1922. of new infection.The spread of infection is a slow process and can be arrested by harvesting areas of suf- RESUMES ficient volume or by girdling infected trees. Le gui nain: parasite du sapin-tsuga de l'ouest Contrary to popular belief, no evidence points to the Les abus sylviculturaux commis au cours de la périocle 1890- need for debris-burning to "kill" the parasite in the slash- 1920 dans les peuplements vierges de haute futaie du Pacifique ing, although the heavy limbs and defects which car- nord-ouest étaient dictés par l'absence de marches et certaines considerations d'ordre économique.Les peuplements de sapin- acterize these operationsisan argument in favor of tsuga qui ont survécu sont devenus la proie d'unevariété name burning to reduce the fire hazard. The local experience de gui appelée Arceuthobium campylopodum forma tsugensis Gill. has been to leave the logged-over area to reseed naturally On trouve ce parasite dans les peuplements de premiere généra- from surrounding uninfected stands, but to burn con- tion, mais il ne commencemenacer sérieusement les arbres que lorsqu'unpeuplementd'âge uniformedépérit avec l'âgeou centrations of limbs at the landing. lorsque le peuplement est décimé par une tempête, les insectes, Clear cutting of hemlock is necessary to destroy mistle- les épidémies ou des coupes partielles. toe. Both virgin and residual stands should be treated in L'infection se répand lentement, principalement par la chute des graines des arbres infectés vers le sous-étage d'arbres plus this manner. Chemical treatment has been suggested as a jeunes. On a mesuré l'effet de Ce parasite sur la croissance de means of eradication and has been tried on an experi- l'arbre en comparant entre elles des placettes prises dans des mental basis in Australia; Hartigan (ibid). peuplements contaminés près d'Aloha, Washington. Le rende- Complete clear cutting must be the rule in order to ment des peuplements d'âge uniforme ne se trouve pas réduit establish an even.aged, uninfected stand. In uneven-aged dans des sites comparables. Cetteplantedepetitesdimensions,qui cause enflure des forests the advance reproduction is rapidly infected and branches, balais de sorcière, broussins et cimes fourchues, a son is a source of constant reinfection.Korstian and Long origine a l'intérieur de l'écorce de son hôte et ne se remarque (6) state, "Mistletoe develops rapidly after cutting." pas. La graine, qui est recouverte de viscine,peut régénérer le parasite sur n'importe quel jeune tsuga auquel elle se colle. By far the most promising control may be biological. La coupe rasedes peuplements commerciaux estrecoin- An investigation into the synecology of Arceuthobium mandée, mais le brülage n'est pas nécessaire pour détruire le americanum, Dowding (2), showed that the susceptibility parasite sur les déchets d'abattage.L'aménagement intensif des peuplements peut comprendre des injections ou des pulvérisations of mistletoe to Walirothiella arceuthobii Peck increased de produits chimiques, le cernement des arbres sans valeur mar- with proximity to the moister sites in the sand hills of chande, l'élagage et même la lutte a l'aide de moyens biologiques, Alberta.Its effect on Arceuthobium campylopodum f. comme par exemple l'utilisation deschampignons Wallrothiella tsugensis is not substantiated by any reference, but the arceuthobii Peck ou Septogloeum gillii Ellis qui s'attaquent aux fungus attacks the internal tissues of the pistillate flowers. fleurs femelles. De nouvelles recherches sont nécessaires avant qu'une méthode Since this fungus is restricted to relatively damp habitats efficace de lutte contre ce parasite puisse être incorporée dans les it may show promise in developing a treatment in the méthodes sylviculturales appliquCes a cette essence importante. relatively moist forests of the northwest coast of North America. El Muérdago Enano: Parásito del Abeto del Oeste SeptogloeumgilliiElliscausesan anthracnoseof La falta de mercado y ciertos factores económicos ocasionaron A rceuthobium campylopodum f.tsugensis by infecting los abusos silvicolas de corta de los árboles más valiosos, come- tidos durante el perIodo de 1890 a 1920 en los bosques vIrgenes pistillate flowers and prematurely kills great numbers of de la region Noroeste de la costa del Pacifico.Los bosques shoots; Ellis (3). Although Arceuthobium seems to be residuales de abeto del oeste Tsuga se encuentran seriamente entomophilous,there are certainareas where insects infestadosconelparásito muérdago enano,(Arceuthobiuni attack and kill the shoots.Spittle insects (Cercopidae) campylopodum forma tsugensis Gill.)Este paráslto suele encon-

Forest Protection 895 trarse en bosques de antiguo crecimiento, pero no suele afectar de la corteza del árbol que Ia sostiene y es inconspicua. La seriamente el crecimiento de los árboles hasta que un bosque semilla, cubierta de viscina, germina en cualquier abeto joven al coetáneo comienza a entrar en el perIodo de decadencia o hasta ciial logra adherirse. que cualquier catástrofe, como un huracán, losinsectos,las Lo recomendable es desmontar los bosques que tengan valor enfermedades o una corta parcial, disminuya la densidad del comercial, pero no es necesario quemar para lograr la destruc- arbolado. ción del parásito durante la limpia. En una admimstración inten- La infección Se propaga lentamente y de los árboles infestados siva de los bosques podrian incluirse inyecciones o aspersiones pasa, principalmente por efecto de la gravedad, a los troncos de productos quImicos,elanillado de los árboles que hayan más jóvenes. La forma en que esta enfermedad afecta a!cre- perdido su valor comercial, la poda y hasta el control biológico, cimiento se ha determinado por medio de una comparación de mediante el uso de hongos Wallrothiella arceuthobii Peck or parcelasde muestra en bosques infestados,cerca de Aloha, Septogloeum gillii Ellis que atacan a las fibres pistiladas. Washington. Segün pudo compararse, los rodales coetáneosno Antes de que se liegue a perfeccionar un control eficaz, que disrninuyen su rendimiento. pueda pasar a formar parte de las prácticas silvicultoras reco- La pequefia planta parásita ocasiona hinchaz6n de las ramas, mendadas para esta importante especie, será necesario realizar escobas de bruja, nudos y copas de mtiltiples ramas; crece dentro más investigaciones y estudios.

Organization and Problems of Forest Protection In Czechoslovakia

V. MARTINEK Ministry of Agriculture, Prague, Czechoslovakia

Organization of Forest Protection in Forestry Practice protection, arranges central courses to provide workers The total forest area of Czechoslovakia is approxi- with intensive training in forest protection, secures the mately 4,220,000 hectares, all administered by the State. coordination between ministries, and ensures specialized State-owned foreists are administered by the Ministry of direction and funds for the control of pest outbreaks. Agriculture Forest Administration and by the Ministry of National Defense. Small forest properties of farmers and Forest Protection as a Part of Forest Management farm cooperatives total about 22 percent.State forests Plans are divided into independent units of forest enterprises, As mentioned, the proper direct protection of forests which, in turn, are divided into forest districts and these is carried out by forest enterprises and forest districts. into forest 'sections. But sufficient preventive forest protection has required Apart from common tasks of forest protection, forest concrete bases of a long-term character.It is apparent enterprises are concerned with damage caused by man. that in the old days also forest management plans were Planning and training of practical foresters, organization, concerned with these bases, but only in general, and were and forest fire prevention measures are other tasks. They restricted only on general instructions in the general also plan and carry out preventive protection against description of forest management plans. damaging factors, direct the control of insect pests and In1954, forest management institutes began their forest diseases, and check on these measures. Plansare studies of forest protection. Attention has been particu- made for ordering the reduction of damage caused by larly drawn to the health of forest stands and to the game, including control forms for securing efficient and amount of damage by individual injurious factors. We profitable management.Large protection actionsare know that precise data constitute very important and undertaken according to the instructions of the Ministry perhaps the most essential elements in securing sound of Agriculture Forest Administration, and forest research forests and in successfully controlling pests. institutes.Forest enterprises collaborate on the planning of forest management plans, plans of inner spatial ar- Legislation of Forest Protection in Czechoslovakia rangement, analysis and control of logging, and afforesta- Forest protection in Czechoslovakia is, in the main, tion projects from the standpoint of forest protection. outlined by legal regulations.For instance, Law No. All forest enterprises in one regioncome under the 250/1852 is concerned with forest protection against Regional Forest Administration, which drafts the main man, wind, and harmful insects.Slovakia still has Law lines of the protection work of the region.Regional No. 71/1879, which is similar. Since the passing of these Forest Administrations are placed under the Ministry of laws,other regulationsandsituations have brought Agriculture(inSlovakia, under the Commissioner). further amendments. It is of interest to note that principal Forest protectionisdirected from the standpoint of forest protection laws are completed by a series of various multiple uses of forests, 'such as water and soil conserva- rules which are within the jurisdiction of the Ministry of tion and assistance to agriculture. The Forest Administra- Agriculture. tion of the Ministry of Agriculture coordinatesthe Instructions for forest protection came into force in nationwide protection actions, puts forward proposalsas 1953. Since that date the Board of Standards also has to the instructions and standard's in the field of forest published standards for the field of forest protection. 896 Fifth World Forestry Congress Proceedings These are based on the latest results of research and important method of controlling outbreaks in large areas. science.We now have standards on control of ips We use airplanes with carrying capacities of from 200 to typographus L., Hylobius abietis L., Panolis flammea 1,000 kgs. Helicopters have not been used in forest pro- Sch., Bupalus piniarius L., Tortrix viridana L., Lyman- tection up to now, but tests are to be carried out this year. tria monacha L., Lymantria dispar L., Diprion pini L., The first use of airplanes in the control of forest diseases Pristiphora abietina Christ., Pachynematus sp., Lopho- in large areas was the dusting of Lophodermium pinastri dermiumpinastri(Fr.)Chev.,MerialaricisVuill., (Fr.) Chev. in Slovakia in 1957. Airplane dusting is car- M'elolontha sp.,etc.Apart from the above-mentioned ried out by Soviet-made dusters. Aerosols are spread by standards others on aerial dusting of forest stands (CSN machines of Czechoslovak production. Ground control is 482772) and dusting of forests by land motor dusters carried out by various types of equipment (for instance, (CSN 48771) have come into force. At present, stand- type RAG). ards on control of Trypodendron lineatum 01., Choris- Insecticides used in Czechoslovakia after 1945 are toneura murinana Hb., and seedling damping-off are contact chemicals based on DDT, 5 percent,(trade being prepared. names Gesarol, Dynocid, etc.), andchemicals based on BHC, 8-12 percent (trade names: Hexachloran, Cyklo- Present State and Distribution of Injurious hexan, etc.). Chemicals are used individually or in com- Factors in Czechoslovakia bination, mostly in the ratio of 1: 1. Nursery diseases are controlled or reduced by Bordeaux Reduction of forest growth in Czechoslovakia is caused mixture and other chemicals based on copper (Kuprikol, by factors similar to those in the German Democratic etc.).Also used are sulphur and mercurial chemicals Republic, the Federal Republic of Germany, Austria, and (Sulikol and Agronal).Herbicides against weeds are Poland.Southern Moravia and Slovakia show other chiorates, mainly NaCO3, and various oil derivatives, injurious insects, characteristic of Hungary, Yugoslovia, TCA, Simazine, etc. Chemical protection against browsing and the Soviet Union (mainly of their oak forests). Harm- by game includes effective repellents such as Resiston, ful factors cause injury mainly in the forests of Bohemia RZ 1, etc. and Moravia. This is a result of tree species composition Chemical control methods are also abundantly used for change in the above-mentioned regions in the last 200 killing bark beetles, notably ips typographus L. and Try- years (the ratio of conifers to broad-leaved species is podendron lineatum 01. The use of chemicals supports 85:15). the trap-tree method and protects timber at log dumps. Slovakian forests, being of a more natural character Study and use of systematic insecticides in forestry has (the ratio of conifers to broad-leaved species is 45:50), begun in Czechoslovakia. are more resistant to damage. The annual loss of incre- Biological control.Large-scale biological control of ment and volume in Czechoslovakia amounts to about ½ forest insects by means of parasites, predators, and bac- of annual felling quantity. Apart from that, the volume teria has not been applied in Czechoslovak forestry produced is variously damaged (loss of quality). Losses practice. We are currently chiefly concerned with limiting of quality are calculated at a little less than 3.5 million chemicalaction on sites where control operationis cubic meters. urgently needed. In this way we support, indirectly, the Injurious factors play the most important economic part biological control method.In addition, a suitable time on Norway spruce (Picea excelsa), which covers, in for control operations is selected with a view to the main- Czech regions, 61 percent of the forest area (in Slovakia, tenance of parasites(for instance, Pachynematus sp., 30 percent).The importance of injurious factors on Pristiphora abietina Chr., Cephaleia abietis L., etc.). Scots pine (Pinus sylvestris)is far behind.This tree In recent years, experiments with biological control of species covers only 20 percent of the forest area in Czech insects were begun to use bacterial infection. Control of regions and 5 percent in Slovakia. The injurious factors Tortrix viridana has been carried out by the artificial use in oak forests (Quercus robur) show a certain importance, of Bacillus thuringiensis.The trialoperation against as this species covers about 4.5 percent of the forest area Archips crataegana and Tortrix viridana has been done in Czech regions and about 10.5 percent in Slovakia. Sil- by use of Pseudomonas chioraphis Berg., et al.Prelimi- ver fir damage is also reported, but this tree species covers, nary results from experiments showthat the percentage of in Czech regions, oniy three percent of the forest area (9 control is not as high as desired, and tests are continuing. percent in Slovakia). Factors injurious to larch, ash, and A beginning has been made to finding a use of egg elm are of less importance. A recent survey revealed that parasites, notably Trichogramma embryophagum (Htg.), injurious factors attacking poplars cause severe damage. in biological control.Some laboratory work has been (See paper presented by Kalandra.) done. Methods and characteristics of the genus Tricho- gramma are not satisfactorilysolved, and the bionomics Present State of Forest Pest Control and etiology of the individual species or races are not Protection against pests and other injurious factors clear.No doubt these problems require close inter- influencing the forest is similar to that in other countries national cooperation.It is obvious that certain steps of with developed forestry management. It is natural that progress in these tasks and somediscoveries are necessary the importance to be attached to silvicultural treatments before we can undertake the propagation of the species for preventing damage outbreak be correctly pointed out. Trichogramma embryophagum (Htg.)or T. cacoeciae Chemical control development shows the relationship March. for practical biological control in an economic to the development of machines used on the ground and way. Further fundamental researchwork is in progress. mainly in the air.The use of the airplane is the most Special attention in recent years is drawn to the bird Forest Protection 897 population and their importance in delaying or preventing The scope of the research should be widened by biological the establishment of pests and to the total value for bio- pest-control tests. logical control. The experiments include foods of birds, annual population dynamics, and attractive methods for RESUMES nesting concentration by means of biologically correct Protection des forets en Tchécoslovaquie et problèmes qui use of nest boxes. Research work in this field is being se posent dans ce domaine continued. En Tchécoslovaquie, les forêts sont toutes administrées par Preventive methods play an important part in the pro- l'Etat. Les foréts domaniales sont divisées en unites indépendantes tection of Czechoslovak forests.Silvicultural control is appeldesentreprisesforestières.Les entreprisesforestièresse best suited. Czechoslovak foresters stress mainly the cul- composent de districtsforestiers,et les district forestiers sont tivationofsuitabletreespecies(ecotypes)only on divisés en sections forestières. Les districts forestiers sont charges responsiblesites des travaux de detail dans le domaine de la protection des forêts. (Law 206/1948, paragraph 2).In Les districtssont charges des mesures preventives contre les addition, promising results are obtained by the growing of facteurs nuisibles, signalent Ia presence d'insectes nuisibles, entre- resistant mixed forests, notably at lower elevations, and prennent les premieres operations de protection, protègent les by the cultivation of resistant tree species and late-flushing plantations contre les dégâts causes par le gibier, organisent des tree races. cours pour lesgardes forestiers, établissent des méthodes de lutte,et dirigent les operations de destruction.Les entreprises forestièresrelèvent des Administrations régionales des forêts, Present State of Records and Prognoses of Forest Pests qui veillent a Ia protection des forêts a l'intérieur des regions. The maintenance of adequate records and prognoses of Les administrations régionales relèvent de l'Administration des forêts du Ministère de l'Agriculture. Cette Administration dirige insect pests and diseases is evidence of proper forest le service forestier en ce qui concerne l'usage multiple des forêts, protection.Records and prognoses of forest pests are non seulement du point de vue de la production du bois de con- maintained by the Forest Protection Department of the struction, mais encore de celui de la conservation des eaux et du Forestry and Game Management Research Institute of the sol. Les mesures preventives sont basées sur des etudes détaillées Czechoslovak Academy of Agricultural Sciences. Lists of de Ia protection des forêts, faites au sein même de l'exploitation forest insect pests and diseases are prepared twice a year, du complexe forestier. Tous les essais effectués ont pour objet in spring and winter. de réaliser un aménagement planifldsatisfaisantayant pour Lists of injurious factors are being prepared through résultat des forêts saines. results obtained by individual scientific workers of the En Tchécoslovaquie, la protection des foréts est basée sur une série de lois et règlements.Les normes tchécoslovaques sur Ia Forestry and Game Management ResearchInstitute. protection des forêts sont publiées depuis 1953.Ces normes Prognosisstudiesare based on populationdensities, couvrent les principes de lutte contre les facteurs nuisibles indivi- extent of parasitization, and dates of critical numbers. duels auxquels tous les ouvriers forestiers sont tenus de se con- At the beginning of every year, workers of the Forest former. A l'heure actuelle, les forêts tchécoslovaques sont attaquées par Protection Department of the Forestry and Game Manage- toute une série de facteurs nuisibles, en particulier les insectes. ment Research Institute publish a general review citing Ces insectes s'attaquent particulièrement a l'épicéa, Picea excelsa, possibilities of pests for the following year. The review l'essence la plus commune des foréts tchdcoslovaques. us causent shows occurrences and outbreaks of new pests, actual également des dégâts au Pinus sylvestris, au Quercus robur et a l'Abies alba. D'autres essences moms communes ne soufirent pas control work, approximate areas designated for control autant de dégâts. La perte totale de volume de bois en Tchéco- operations, etc. slovaquie s'élève chaque année a la moitié de la quantité annuelle The Forest Protection Department of the Forestry abattue. Les pertes de qualité sont évaluées a un pen moms de 3.5 and Game Management Research Institute is not only millions de metres cubes. concerned with preparing records and prognoses of pests, La lutte au moyen de produits chimiques est la méthode habituelle utilisée pour la protection des forêts.Les entomolo- but italso outlinessteps required for good forestry gistes luttent contre les insectes a l'aide de l'avion, de l'équipe- practices.In addition,several hundred enquiriesare ment au sol et d'appareils manuels. On n'utilise pas l'hélicoptère. answered each year. Les insecticidesutilisés en Tchécoslovaquie sont des produits chimiques tels que le BHC (8-12%), appellation commerciale: Aspects of Forest Protection in Czechoslovakia Hexachloran, cyklohexan, etc.; le DDT (5%) appellation corn- merciale:Gesarol, Dynocid, etc. Les maladies cryptogamiques As mentioned, damage to forests will be reduced sont combattues avec des fongicides a base de cuivre, (le kupri- mainly by preventive methods through silvicultural con- kol, Ia bonillie bordelaise), et des produits chimiques sulfureux (Sulikol). Les produits chimiques a base de mercure sont utilisés trol, such as suitable establishment of new forest stands pour la protection des semencesAgronal. On fonde beaucoup and cultivation of those available. d'espoir sur les chlorates et dérivés de l'huile pour Ia destruction It is clear that preventive protection against loss of des mauvaises herbes. TCA, Simazine, etc., sont actuellement a wood production should be based upon the exact scientific l'essai. La protection chimique contre la paissance du gibier est assurée an moyen de produits répulsifs, tels que le Resiston, RZ 1, level in the near future. Recently, complex experiments etc. Les méthodes forestières ne font pas actuellement usage des were performed to ascertain the dependence of individual poisons systémiques. injurious factors (pest insects, diseases, browsing by game, Dans les zones plus étendues, on n'a pas encore en recours a and decay) on forest type groups or on more closely Ia lutte biologique. Des experiences sont faites avec l'application artificielledu Pseudomonas chioraphis Berg.contre l'Archips defined forest types.Certain conclusions that can be crataegana.Des recherches fondamentales mais qui permettent drawn from preliminary trials are summarized in the fact tous les espoirs sont actuellement effectuées sur les parasites des that suitable tree species composition prevents damage oeufs, notamment le Trichogramma embryophagum (Htg.). to forests. Une très grande attention est accordde aux méthodes préven- tives.L'effort principal porte sur la creation, dans la mesure du Lastly, attention should be paid to less important pests. possible, de forêts composées d'essences mélangées et d'âges- And notably, in this connection, the use of systemic varies, et la culture d'essences résistantes et a montée de sève poisons merits more attention by the research workers. tardive.

898 Fifth World Forestry Congress Proceedings Nous sommes tout a fait conscients du fait que l'efficacité de la por una serie de factores dañinos, en especial porplagas de protection depend d'une documentation appropriée et d'un bon insectos.Estas dafian especialmente al pino del forte (Picea pronostic sur les insectes nuisibles et les maladies. En Techéco- excelsa), la especie más comOn en los bosques checos.Esta slovaquie,lesinstitutsforestiers de recherches orientent leur plaga es más comtin todavIa en el Pinus sylvestris, Quercus robur activité principale sur le rassemblement de données et l'établisse- y Abies alba. Las otras especies sufren menos y presentan menos ment de pronostics sur lesinsectesnuisibles.Les listes des peligro. La pérdida total de crecimiento y producciOn de madera facteurs nuisibles sont envoyées deux fois par an a toutes les en Checoeslovaquia Ilega anualmente a cerca dela mitad de los entreprises forestières. Ces listes couvrent 'galement les insectes árboles maduros para la corta.Las pérdidas de calidad se cal- nuisibles et maladies qui existent dans les entreprises voisines. culan en poco menos de 3,5 millones de metros ctibicos. De cette manière, on obtient une idée générale des facteurs nuisi- El método de control qulmico es el medio comtin de proteger blesquisévissent dans toutelaregion,etlesouvriers de elbosque.Los entomOlogos combaten las plagas de insectos l'enterprise forestiere sont en mesure de lutter a temps contre especialmente por medio de aviones, maquinaria terrestre y la propagation des insectes et des maladies. De brefs rapports equipos manuales. No se emplean helicópteros. Losinsecticidas sont également envoyés aux administrations régionales des forêts, de contacto usados en Checoeslovaquia son quImicos cornoel ainsi qu'à l'Administration des forêts du Ministère de l'Agriculture. BHC 8 al 12%, Hexachioran, en la marca comercial,Cyklohexan Au debut de chaque année un rapport général est publié sur etc.; DDT al 5%, marca comercial Gesarol,Dynocid, etc. Las l'intensité des attaques d'insectes nuisibles et des dégâts causes enfermedades de hongos se controlan con fungicidas a basede pendant l'année. cobre:Kuprikol, mezclas de "Bordeaux," sustancias quImlcas En résumé, a l'avenir, les forestiers tchécoslovaques se con- sulfurosas(Sulikol).Las sustancias quImicas a base de mer- sacreront surtout aux mesures preventives, destinées a améliorer curio se usan para proteger la semilla (Agronal). Los cloratos Ia sylviculture. On sait que la lutte menée par la Tchécoslovaquie y losderivativos de aceite son buenos contra lasmalezas. contre les insectes de forét a suscité une grande admiration, et Actualmente están ensayándose el TCA y Simazine, etc. La pro- ii est naturel que ce travail se poursuive. La lutte plus directe tección quImica contra el ramoneo de la fauna consiste en el uso de repelentes, por ejemplo, Resiston, RZ 1, etc.Los venenos sera développée avec l'emploi d'insecticides systémiques, et la forestaldela mise au point de méthodes biologiques. sistémicos no estánen uso en lapráctica actualidad. El control biológico de insectos forestales no ha sidopracticado Organización y Problemas de la Protección Forestal en en areas extensas. Se han hecho experimentos conel uso artificial Checoeslovaquia del Psedomonas chioraphis Berg. para combatir el Archips cra- Todos los bosques de Checoeslovaquia son administrados por taegana.La investigaciOn básica pero prometedora sobre los el Estado. Están divididos en unidades independientes, empresas parásitos de huevos está progresando, especialmente sobre Tricho- gramma embryophagum Htg. forestales.Las empresas forestales están formadas por distritos preventivos, forestales.Los distritosforestalesse componen de secciones Se presta considerable atenciOn a los métodos forestales. Los distritos se encargan de los detalles del trabajo particularmente al control silvicultural.El esfuerzo especial ha deprotecciónforestal.Losdistritoscontrolanlosfactores sido para el establecimiento, lo antes posible, de bosques regu- dafiinos, dan parte cuando aparece una plaga, llevan a cabo las lares y mezclados y para el crecimiento de razas deárboles primeras operaciones protectivas, aseguran las plantaciones contra resistentes y de retoflo tardIo. los daflos ocasionados por Ia fauna, dirigen los cursos para Todos sabemos que los registros adecuados y la prognosis guardabosques, determinan los métodos de control preventivo correcta de las plagas de insectos y de las enfermedades sonla y realizan las operaciones de control. Las empresas forestales prueba de que existe una protección adecuada. En Checoeslova- dependen de la Oficina de Administración Forestal de la Region quia el trabajo principal de suministro de registros y deprognosis y ésta dirige las operaciones de protección forestal dentro de de las plagas está a cargo de los Institutos deInvestigaciOn ella.Las Oficinas de AdministraciOn Regional están bajo la Forestal. Dos veces al ano se envIan listas de los elementos Administración ForestaldelMinisterio de Agricultura.Esta daflinos a las empresas forestales.Estas listas también incluyen oflcina principal dirige el servicio forestal en el programa de uso un registro de las plagas y enfermedades queatacan a las empre- multiple de los bosques no solo en cuanto a la producciOn de sas adyacentes. De esta forma, se obtiene uncuadro de factores maderas, sino tanibién a la conservación de suelos y aguas. de toda la region y los funcionarios de la empresa forestalpueden La protecciOn preventiva consiste en la realizaciOn de detalla- impedir a tiempo la propagaciOn de insectos y enfermedadesde dos estudios sobre Ia protección forestal dentro del complejo de las secciones adyacentes. Se envIan resémenes a las Oficinasde la la administraciOn de un bosque. El objeto de todos los trabajos AdministraciOn Forestal de las RegiOnes y a la Oficina de Ad- es Ia obtención de una administración bien planeada que dé ministraciOn Forestal del Ministerio de Agricultura. La intensi- bosques sanos. dad de las plagas y de los daños calculados para el aflo en curso La protección forestal en Checoeslovaquia esta basada en una se publica a principios del misnio. serie de leyes y reglamentos. Desde 1953 Checoeslovaquia ha En resumen, en el futuro se atenderá a laprotección pre- venido publicando normas de protección forestal.Consisten e ventiva,esdecir, a las prácticas correctas de silvicultura.Se incluyen todos los principios para el control de los factores sabe que la silvicultura checoeslovaca ha sido objeto de admira- daninos y todos los funcionarios forestales están obligados a ciOn por sus operaciones de control forestal y es lOgico que este seguir estas normas en su trabajo. trabajo contintie.Se ampliará con el uso de los insecticidas Actualmente, los bosques checoeslovacos están siendo atacados sistemticos y el perfeccionamiento de los métodos biolOgicos.

Forest Protection 899 Diseases of Poplars in Czechoslovakia With Special Respect to Dothichiza populea Sacc. and Briand

A. KALANDRA Ministry of Agriculture, Prague, Czechoslovakia

The rising trend of the need for timber in the present mentioned forest pests and diseases. Special attention is age, and notably in the future, requires fast-growing tree drawn to Dothichiza populea Sacc. et Briand. This fungus species, mainly poplars. Poplars are a rapid compensa- is well known in Czechoslovakia (botanical collections tion for timber not only in countries lacking adequate from 1908). Phytopathologists have studied it since the forests, e.g., France, Italy, the Netherlands, and Hungary, winter of 1955-56 (Kalandra, Leontovic, et al.). but also in countries where timber volume is available but Dothichiza populea is present mainly in the poplar utilization and overcutting are at a rapid rate (central regions of Slovakia (in inundation and lowland forests Europe and Germany). It is logical that commissions for along the Danube River, notably on Zitny ostrov, on the the care of poplars have been created. In our country, lower course of the Váh, Hron, and Ipel Rivers, in the diseases and animal pests injurious to poplars are ex- lowlands of the eastern Slovakian region of Kosice, and tremely dangerous, as in other countries, and the failures on the plains of Medzilaborce, Bodrog, Latorica, and discourage the poplar producers. Uhu). Czech regions provide favorable conditions for the Age. Young poplars in nurseries and plantations, on above-mentioned pest in the poplar regions of Bohemia roadsides, and in forest stands suffer severely. and Moravia in the Elbe watershed, along the lower course Period of damage. Europe, notably central Europe, of the Vltava River, and in the watershed of the Berounka; has experienced severe dieback of poplars, mainly since in the Plzen region, the watersheds of the Ohre and Jisera the hard winter of 1955-56. Rivers, etc. Areas of the Morava, Becva, Svratka, Svitava Extent of damage. In stool bed nurseries, not only the and Dyje Rivers are also favorable grounds for the spread stools but even the shoots they put out are attacked. of D. populea. Actually, there is also evidence of sporadic Cuttings from some localities have spread the infection distribution outside the large poplar areas. Severe stunting into other nurseries and plantations. Greater damage is and dieback connected with the occurrence of Dothichiza recorded on plants in nurseries.Relatively less damage populea has been observed since 1955-56. The above- can be found on one-year-old plants, greater on two-year- mentioned localities have been studied in detail. old plants. Maximal damage is recorded in new planta- Infection spots on shoots of the first vegetation period tions. Not only young but even older stands dry and die occur shortly after the end of growth in autumn, mild back. autumn, mild winter and at the beginning of spring. Wood Damaging factors.It should be emphasized that more older than one year shows symptoms during the whole or less constant damaging factors occur. Unsuitable loca- year, and shows evidence of suffering from the disease. tions and improper silvicultural treatments considerably No immune species or clones are to be found in our reduce the resistance of popiars, notably against the fungus country. Only more or less resistant clones occur. Our diseases. native poplar (Populus nigra) and its pyramidal form are Insects attacking foliage (Melasomae and caterpillars) susceptible, more susceptible than Euro-American and can be more or less easily removed by the application of American poplars, e.g., Populus serotina, Populus man- insecticides.Insects attacking the wood cannot be so landica, and Populus monilif era. easily controlled.Widely distributed species damaging Damage in nurseries is caused by the fact that more poplarsare:CerambycidaeSaperda carchariasL., than ten percent of the plants either do not root or show Soperda populnea L.; SesiidaeSessia apiformis Cl., bad development. Damage in plantations, in combina- Sciapteron tabaniforme Rott.; ColeopteraCryptorrhync- tion with other influences, is 20-30 percent or more, as hus lapathi L. According to observations, the results of observed in 1958. control of the above-mentioned species by means of A similar degree of damage is reported also from other insecticides are not as good as desired. countries, and we want to stress the wide spread of this Epidemic diseases cause the most serious damage. The disease. We want to draw it to the attention of the general most destructive poplar pests are Dothichiza populea Sacc. public of world forestry and . We believe that et Briand and, at present, less important Cytospora chry- the carrying out of research on control measures, notably sosperma (Pers.) Fr., Cytospora nivea Sacc., etc.The chemical treatment, becoming preventive in the case of dangerous spread of brown spot plays an important part larger areas (as is done, e.g., by Tans, Ride, and van in the diseases of poplars; here and there twigs and stems Vloten) could reduce the losses of poplar growing to a die back as a result of Micrococcus populi Del. and can- minimum and could secure the success of this fast-grow- kers. Frost is one of the most dangerous abiotic factors. ing tree species where the urgent necessity for greater Research in Czechoslovakia is directed to the above- wood volume occurs in extensive parts of the world. 900 Fifth World Forestry Congress Proceedings RESUMES Enfermedades de los Alamos en Checoeslovaquia con Les maladies du peuplier en Tchécoslovaquie, et plus Especial Ref erencia al Hongo Dothichiza populea particulièrementlaDothichiza populea Sacc.et Sacc. y Briand Briand. Como en otros paIses donde se cultiva el alamo, también en Comme dans les autres pays oii l'on cultive le peuplier, on Checoeslovaquia (notablemente desde el rudo invierno de 1955- constate en Tchécoslovaquienotamment a la suite des rigueurs 56) se registran las enfermedades que marchitan los copados y de l'hiver 1955-56un rabougrissement des rameaux et un arrêt detienen el crecimiento de los álamos de varias edades, acorn- de Ia croissance chez des peupliers d'âges divers, accompagnés pailadas de una serie de factores dañinos y de plagas. d'une série de facteurs de destruction et de maladies. Los álamos de Checoeslovaquia son atacados severamente por En Tchécoslovaquie, le peuplier est gravement attaquó par des insectos xilófagos tales como el Saperda carcharias L., Saperda insectes xylophages tels que la Saperda carcharias L., la Saperda populnea L., Sessia apiformis Cl., Sciapteron tabaniforme Rott., populnea L., la Sessia apiformis Cl., le Sciapteron tabaniforme todos los cuales atacan al follaje, etc. Más peligroso es el conta- Rott., et par une série d'insectes rongeant le feuillage, etc.Plus gio epidémico de Ia gangrena de la corteza, causada por el hongo dangereuse encore est la propagation épidémique de la nécrose Dothichiza populea Sacc. et Briand, asociado con los Cytospora de l'écorce causée par le champignon Dothichiza populea Sacc. et chrysosperma Pers., Cytospora nivea Sacc. etc. Los álamos más Briand, conjointement avec Ia Cytospora chrysosperma Pers., la jóvenes o más viejos son victimas de la gangrena de la corteza Cytospora nivea Sacc., etc. Les peupliers de tout age sont por- teurs de taches de rouille, nécrose de l'écorce causée par le causada por Micrococcus populi Del. Las heladas son tambidn Micrococcus populi Del. Le gel est également un ennemi de la peligrosos enemigos del crecimiento de los álamos. croissance du peuplier. A partir de los aiios 1955-56, el hogo Dothichiza populea se A partir de l'hiver 1955-56, la Dothichiza populea s'est répandue ha propagado, al igual que en otros paises de Europa, como plaga comme iine épidémie, ainsi que dans les autres pays d'Europe. Le epiddmica. Los hongos presentan un serio problema en los semi- champignon pose un problème sérieux dans les pépinières, les Ileros, plantaciones y masas arbóreas jóvenes o de más edad. Se plantations, les jeunes et voire même les vieux peuplements. On extiende por todos los bosques de las planicies y tierras bajas de le retrouve dans toutes les forêts des plaines et des terres en Checoeslovaquia, notablemente en las tierras bajas del Danubio, contre-bas de Tchécoslovaquie, notamment dans les plaines du Moravia y el Elba. Los daños son aquI de un 20 a un 30% y Danube, de la Moravie et de l'Elbe. Les dégâts par endroits ont más, especialmente en las nuevas plantaciones. La infección se été estimés a 20 ou 30% et plus, surtout dans les jeunes planta- propaga a través de los gajos reproductores y las plantas de los tions.L'infection Se propage par les boutures et les plants des viveros. El alamo nativo Populus nigra es más susceptible que los pépinières. Le Populus nigra indigène est plus prédisposé a la álamos americanos y euroamericanos. maladie que les peupliers américains et euraméricains. Para prevenir el ataque de los hongos se recomienda observar Afin d'empêcher lesattaques du champignon, iiest recom- mandé d'observer les règles de sylviculture, l'hygiène du peuplier, las reglas de la silvicultura, cuidar de la higiene de los álamos y et d'essayer les fungicides, surtout avec application de bouillie ensayar fungicidas, aplicándolos especialmente mediante asper- bordelaise. sión con una mezcla de Burdeos. Les résultats des recherches détaillées qui ont été lancées en Los resultados obtenidos de las minuciosas investigaciones Techdcos]ovaquie en 1956 sur la Dothichiza populea seront publiés realizadas con el hongo Dothichiza populea, comenzadas en dans une autre communication. Checoeslovaquia en 1956, serán divulgados ampliamente.

Causas de la Destruccidn Forestal en Mexico

ROBERTO GARDUNO GARCIA Y ANTONIO SIERRA PINEDA Dirección General de Protección y Repoblación Forestales, Mexico, D.F., Mexico

En Ia mente de todos ustedes está lo que significa el Incendios. bosque en la vida del hombre como elemento multiple de Desmontes agricolas en suelos forestales. bienestar, de abundancia y de riqueza potencial en el Pastoreo no controlado. desarrollo de las industrias y en el futuro de la civilización. Plagas y enfermedades. Bajo esta concepción hemos creIdo interesante dar a Expbotaciones irracionaies. conocer a ustedes en este breve trabajo, las causas que originan la destrucción de los bosques en Mexico y Incendios sucintamente las medidas que hernos tornado para con- Son tres los origenes principales del fuego en las zonas trolarlas, no porque éstas hayan sido totalmente eficientes forestales: o porque contengan nuevas prácticas o métodos en materia La quema del rastrojo o de la maleza de la parcela de protección forestal que podamos enseñar a ustedes, agrIcola, denorninada también "quema de limpia", sin sino porque para poder hacer cualquier planeamiento que por parte del agricultor se tome la másmInima pre- ulterior, es necesario cornenzar por conocer bque está caución para impedir que ci fuego se propague a la vegeta- sucediendo en los bosques y, sobre todo, porque a noso- ción forestal. tros nos corresponde meditar y preveer las consecuencias La quema del pasto seco efectuado por pastores y que originan los desajustes entre el hombre y la naturaleza. ganaderos durante la temporada de secas, con el fin de Consecuentemente con la tesis que se sustenta en el podar las grarnIneas y demás plantas forrajeras, permitien- presente trabajo, consideramos que los principales agentes do asI que el brote nuevo alimente ab ganado. de destrucción forestal en Mexico son, en su orden de Las fogatas prendidas por carboneros, explotadores importancia, los siguientes: de raIz de zacatón, arrieros, peregrinos y excursionistas,

Forest Protection 901 sin impedir que el fuego se propaguea las zonas boscosas. permanente y con mayores beneficios económicos que la Los incendios han sido calificados justamentecomo que pueden obtenerse con su aprovechamiento forestal. el peor enemigo de los bosques. Los dañosque causan son La aplicaciOn de los ordenamientos seflaiados, están incalculables porque destruyen ci renuevo natural, la condicionados a los elementos presupuestales disponibles, semilla,la cubierta herbácea protectora del sueloy, habiéndose logrado solo en parte la observancia de los cuarido son muy intensos, destruyen también todo el mismos, por las necesidades urgentes de nuestra pobla- arbolado o cuando menos lo pejudican ensus crecimien- ciOn rural. tos normales, conducidndolo a un estado de debilidad tal que su destrucción es inevitable. Pastoreo no Controlado Frente a estas causas de exterminio de la vegetación El pastoreo en la mayor parte de los casos se lieva a forestal, estamos lievando a cabo simultáneamente,una cabo mediante ci simple sistema de soltar ganado a que campana de educación popular y de prevención y combate paste libremente dentro de una area indeterminada, sin de incendios forestales, con elfin de lograr la cooperación considerar la capacidad de pastoreo de las praderas, ni de todos los sectores nacionales en la solución de tan las condiciones propias del suelo, originando en conse- grave problema. cuencia que ambos recursos vayan desapareciendo lenta Convencidos como estamos, de que sin lograr con- pero inexorablemente. ciencia forestal en nuestro medio rural, no es posible A nadie escapa la importancia de la ganaderla en flues- erradicar las confiagraciones provocadas por los incendios tro pals, pero pocas personas se han puesto a pensar en forestales; cualquier otro esfuerzo desligado a esta labor los daños enormes que sufren nuestros bosques y praderas de convencimiento serIa estéril, pues mientras la extinción cuando ci pastoreo se ileva a cabo fuera de toda técnica de un incendio puede durar una hora, un dIa0 Ufl mes, y control. la causa original del mismo se presenta en una fracción El pastoreo menor, sobre todo ci de cabras, ha sido mInima de tiempo. ci rnás perjudicial a la vegetaciOn forestal de Mexico, por- que su control es casi imposible, dado el carácter nOmada Desmontes AgrIcolas en Suelos Forestales de este tipo de pastoreo; en cambio se ha ilegado a admitir Originalmente la mayor parte del suelo que forma hoy ci pastoreo de ganado vacuno, como servidumbre com- La Repüblica Mexicana, estuvo cubierta por bosques. patible con el desarrollo de los bosques. Desde que las tribus nómadas se hicieron sedentarias Cuando ci agricultor abandona los suelos forestales que y practicaron la agricultura, el bosque comenzó a signifi- han perdido su fertilidad, la vegetaciOn forestal trata de car un estorbo para su desarrollo. Esta situación ha ido reinstaiarse en dichos sueios, en forma espontánea o bien agravándose a medida que la presión demográfica au- mediante la costosa reforestaciOn artificial, pero se ha menta. Desde que los motores de explosion significaron visto Ia imposibilidad de lograr esta recuperaciOn pre- una faceta más del poder humano, los desmontes agrIcolas cisarnente porque se lo impide ci pastoreo de rebaños de han invadido regiones forestales en otro tiempo inaccesi- cabras y borregos que cada dia aurnenta en casi todo ci bles. pals.Si agregamos a esto la ancestral costumbre de los pastores de quemar ci pasto seco para eiminar las alima- La acción devastadora de los desmontes con fines ñas y para provocar ci brote tierno como alimento de sus agrIcolas no ha cesado. Grandes extensiones de tierras rebaños, concluiremos en que ningün tipo de reforestaciOn desprovistas de su cubierta vegetal y con fuertes pen- se logrará mientras subsista este factor de destrucciOn. dientes, se yen dondequiera enclavadas entre los macizos Las medidas que nuestro pals ha tornado para el forestales.Beltrán (1956): "Casos hay sin nümero ni control de esta servidumbre, a travds de la legislación cuenta, los más lamentables tal vez, en que regiones forestal, son las de confinar a la ganaderia menor a zonas extensas de selvas vIrgenes, pobladas por nuestras más donde solarnente sean posibles los pastizales de Ilanura preciadas y valiosas especies forestales, son abatidas e incendiadas por los indIgenas de las regiones tropicales, asociados con leguminosas. para implantar el cultivo del malz y abandonar los suelos Plagas y Enfermedades Forestales a la postre, cuando la acciOn erosiva de las aguas y los vientos los ha despojado de su potencialidad." Siguiendoeste mismo orden, hemos clasificado en "Si dispusidramos de estadisticas que mostraran en ci- cuarto lugar como factor de destrucción forestal los daños fras ci proceso de regresiOn de nuestros suelos hacia Ia que causan las plagas y enfermedades a los recursos roca primitiva, tendrIamos a la vista el más macabro de forestales de Mexico. los espectáculos que pudiera presentárseie Las piagas de insectos, los organisrnos fitopatOgenos y a! hombre las plantas superiores semi-parásitas (muerdagos) forman conciente." un conjunto numerosisimo y heterogéneo distribuido en La invasion de los suelos forestales por la agricultura los bosques de todo ci pals y a los cuáies merrna con- como consecuencia inmediata de la falta de suelos agrI- siderablemente. colas, nos da elementos suficientes para asentar la afirma- Aunque no contamos con estadisticas exactas acerca ción de que esta práctica conjuntamente con los incendios, de los daños que ocasionan, sus estragos se han hecho son las causas determinantes de Ia destrucciOn de los sentir en las más diversas regiones del territorio nacional bosques, de los suelos y de las fuentes fiuviales. y en algunos casos han Ilegado a destruir totalmente la La Legislación Forestal de nuestro pals proscribe defi- vegetación forestal. nitivamente los desmontes agrIcolas en suelos forestales y Nuestros bosques dan abrigo y aiimento a una fauna sOlo autoriza aquéllos en el que los suelos por su espesor, entornológica nativa sorprendente por su ndrnero. Basta calidad y pendiente, son i'itiles para este fin en fonna citar ci dato de que sOlo de la familia Scolytidae se han 902 Fifth World Forestry Congress Proceedings colectado 47 géneros y 158 especies distintas (Dampf., mediante Ia utilización de equipo adecuado, aunando 1938). a esto, ci estableciiniento de industrias económicamente Una consecuencia directa de este gran nñmero de responsables y de solvencia moral reconocida. especies que habitan nuestros bosques, es que la vegeta- Estos agentes de destrucción forestal son provocados ciónforestalseencuentrasiempre amenazada por generalmente por ci crecimiento acelerado de la población erupciones biológicas más o menos violentas que oca- en palses insuficientemente desarroilados como ci nuestro. sionan la muerte prematura de un gran nümero de árboles. Nosotros ignoramos la cuantla y ci estado en que un factor importante en ci incremento de las plagas es actualmente se encuentran las extensiones boscosas de ci abastecimiento fácil de alimentos. Estos, en el caso de algunos paises, pero si sabemos con seguridad que ci insectos descortezadores y barrenadores, están consiituIdos coeficiente forestal dcl mundo mengua cada dia y, esto por el nümero de árboles decrépitos, heridos o desgarra- debe aftigir a todos, porque no solo deben preocuparnos dos, defoliados, debiitados por incendios, o derribados nuestras propias angustias, sino que debemos enterarnos por vientos y nevadas. de las quc le ocurren al vecino, si bien es cierto que los Con esta basese han divulgadoinstructivos que agentes de dcstrucción forestal en cada uno de vuestros establecen las normas generales para efectuar los estudios palses es diferente, tamblén lo es que los efectos son los fitosanitarios y aplicar las medidas de control más con- mismos; erosion del suelo, pérdida de fertilidad de los venientes. Creemos que esto será muy iiitil para suprimir terrenos, agotaniicnto de manantiales y arroyos, azolve a tiempo los brotes virulentos que se presenten. de presas y canales, inundaciones en los valies, etc., que se traducen en un retraso cconómico y cultural en nuestros Aprovechamientos Irracionales respectivos paises y cuyas consecuencias afectan a Ia Los aprovechaniientos irracionales en los bosques de humanidad en general. nuestro pals son de dos clases:(a) Aprovechamientos Por consiguiente, reclamamos una amplia compren- fraudulentos; y (b) Aprovechamientos mal desarrollados siOn humana para los bosques del mundo quc son fuentc en explotaciones autorizadas. permanente dc vida, riqueza y prosperidad, creando a Los aprovechamientos fraudulentos son ilevados través de este evento un principio de solidaridad mundial a cabo en su mayor parte por personas indigentes que en la protección de nuestros recursos forcstales para que tienen sus nücleos de población enclavados en zonas gobiernos y particulares hagamos un esfuerzo comlin y eminentemente forestales. Por las caracterIsticas anotadas, superemos la etapa transitoria de destrucciOn forestal, esta población rural siempre se ha servido del aprovecha- porque la bondad del recurso no es privativa de las niiento fraudulento del bosque para subsistir. gencraoiones actuales y, por lo tanto, debernos lcgario en Este aprovechamiento en pequena escala es sistemático las mejores condiciones posibles para Ia felicidad de y constante, por lo tanto pernicioso y esquilmante de los nuestros hijos. recursos forestales. Finalmente, deseamos dejar perfectamente aciarado Esto no debe considerarse como un contrabando or- ante ustedes que no nos pronunciamos contra la cxplota- ganizado de productos forestales, silo como un delicado ciOn de los bosques.(Garduflo, 1958): "Porque sobre problema económieo-social, cada dia más grave por la tocias las consideraciones anteriores, existe una verdad presión demográfica y sobre todo porque se constituyen evidcntc, que queremos no olvidc ningén sector social de industrias familiares, base del sustento de la población Mexico. Que los montes como un don de la naturaleza, rural. se han hecho para ser utilizados y que su conservación Los aprovechamientos mal desarrollados en explota-. no se iogra cortando poco o mucho, sino aprovechando ciones autorizadas se derivan principalmente de la falta bien esta riqueza, es decir, cortando lo que sc daba, de interpretación o aplicación de los estudios dasonómicos cortar reproduciendo,aprovcchar conservando,cortar por parte de las empresas concesionarias. mejorando; son nuestras doctrinas, tratese de recursos Este problema puede ser accidental o premeditado, leñosos o hcrbáceos." pero en ambos casos constituye un perjuicio de magnitud considerable para la vegetación forestal y es sancionado RESUMES por nuestra legislación en ia materia. La explotación de los recursos forestales de nuestro The Causes of Forest Destruction in Mexico The causes of destruction of Mexico's forests have become a pals desgraciadamente se inició y continuó por muchos basic problem in the development of the country's economy. In años sin una adecuada administración; se concretaba a order of importance they are: una explotación de tipo extractivo, porque se desconocla Fire: the principal destroyer of forest vegetation. To combat la importancia de factores básicos de la téenica forestal. this agent, a campaign of popular education in preventing and Uno dc los más importantes problemas que padeciamos fighting forest firesis being conducted in order to obtain the cooperation of all national sectors in solving so serious a problem. era la escasa o nula industrialización de los productos Clearing of forest land for agricultural purposes: second in secundarios que se consideraban desperdicios y represen- importance.The of our country stipulates that taban hasta un 40% del volümen total del árbol que era clearing of forest land for cultivation shall be permitted only derribado para su aprovechamiento. when the land is suitable for this purpose and will yield greater and permanent economic benefits. Este desolador panorama reclarnaba una adecuada Uncontrolled grazing: which takes third place in our survey. legislación forestal que previera y sancionara los efectos To control grazing, laws have been enacted restricting the raising y consecuencias de este tipo de explotaciones. of sheep and goats to areas where only open field grazing is possible. Por lo que se refiere a las explotaciones mal desarro- Pests and diseases: fourth in importance among the agents of liadas, la legislación forestal ha previsto sus efectos y ha forest destruction. To control these, phytosanitary studies are logradolaindustrializaciónintegraldclosárboles, being conducted and recommendations are being made. Forest Protection 903 Irrational utilization:(a)Illegalcutting of trees; and (b) forestière do notre pays interdit formellement Ia destruction de unsystematic cutting in authorized logging areas. foréts pour faire place aux cultures agricoles, celies-ci n'étant The former is done on a small but systematic scale, so that it autorisées que sur des sols destinés a cette fin, quand elies peuvent becomes pernicious and exhausting to the forest vegetation. These être une source permanente de plus grands avantages d'ordre are sanctioned by the forestry law of the country. économique. The latter is the result,either accidental or intentional, of Pâturage non reglementé: facteur occupant la troisième place failure to interpret and apply forestry studies. As a remedy, the dans notre étude. En vue de leur réglementation, on a promuiguë forestry law provides, among other things, for the full utilization des lois limitant l'accès du petit bétail aux zones oü souls sont of the trees, the use of adequate equipment, and the establish- possibles les pâturages en plaine. ment of economically sound industriesof recognized moral Fléaux et maladies: quatrième, dans l'ordre d'importance, parmi solvency. les agents do la destruction forestière.Pour les combattre, on In view of the necessity of making thorough studies leading effectue des etudes phito-sanitaires, en appliquant ensuite a cette to knowledge of each phase of the problem, it is always well to lutte les mesures recommandées en consequence do ces etudes. think of the protection of our forest resources and to establish Utilisationsabusives:(a) Utilisationsfrauduleuses;et(b) this as a premise in the matter of forest policy. utilisations défectuouses dans dos exploitations autorisées. The utilizationof forest vegetation must by no means be Los premieres, pratiquéos a une petiteécholle, d'une facon abolished, for we must not deprive the country's economy and systématiqueetconstante,sont,parlà-memo,nuisibloset the well-being of the people of what still is an important source épuisantes pour lavégétationforestière.Solon Ialegislation of wealth; rather, we must exploit our forests in such a way as to forestière du pays, dies sont passiblos do sanctions légalos. obtain the maximum sustained economic benefit without damage Les secondes sont la consequence soit d'une interpretation to their conservation. erronée, soit do la non-application, voulue ou accidontelle, des règles resultant d'études forestières; parmi los moyens destinés a Causes de la destruction forestière au Mexique remédier a cot état do choses, la Loi forestière prévoit l'utilisation complete des arbres, l'ernploi d'un outillage satisfaisant, ainsi quo Voici comment se présentent, dans l'ordre de Jour importance, l'établissement d'industries dont la responsabilité économiquo et los agents de la destruction des ressources forestières du Mexique la soivabilité morale ont été reconnues. qui, pour le développement économique do ce pays, constituent Iiest toujours opportun de songor a la nécessité d'études actuellement un problème primordial: approfondies, conduisant a la connaissance do chaquo phase du Incendies: facteur principal de l'extermination de Ia végétatidn problème, etd'étabiir quo la protection des ressourcos est la forestière.Pour les combattre, et pour obtenir quo toutes los condition préalable de toute politique forestière. couches de la population coopèrent a l'échelle nationale, a la Iino faut,sous aucun prétexte,abolirl'utilisationdola solution d'un aussi grave problème, on a recours simultanément végétation forostière, ce patrimoine, encore important, des peu- aux campagnes destinées a éduquer le public et a celles qui ont pies, ne devant pas être soustrait a leur économie et a lour bion- pour objet do prévenir et combattre los incendios do foréts. être, mais, bien au contraire, exploité, de facon a nous permettre Déboisement en vite de l'Utilisation de sols forestiers pour des d'en tirer, sans prejudice do sa conservation,le maximum de cultures agricoles: deuxième dans l'ordre d'importance. La Loi rendement économique soutenu.

Present-Day Trends in Forest Disease Control in Britain

J. S. MURRAY Forestry Commission of Great Britain, London, England

Compared with many other countries, Britain's forest missing. In Britain, there is a great dearth of information area is small, both as an absolute figure and as a per- on the life cycles of even our most commonpathogens centage of total land area.The figures are just over names which have figured in textbooks and published 4,000,000 acre's and just over 7 per cent, respectively. accounts for many years.Examples could be quoted The climate of the country is maritime, offering great where there has been no accretion of knowledge since contrasts between different areas, and no extremes of Hartig's time. Yet, the essence of control is to appraise climatic conditions prevail over the country as a whole. the various stages in the life cycle of the pathogen and As a result, the number of tree species which can be envisage where a control could be applied. Very often, grown as forest crops is large, both in relation to the size seemingly intractable problems lend themselves tore- of 'the forest area and in comparison with many other markably simple solutions when viewed in this way. A countries. The variety of trees grown has, unfortunately, recent example arose in the case of Lophodermium its corollary in tie number and variety of tree diseases pinastri, the pine needle cast. This causes severe defolia- existing in the country. tion in certain seasons, particularly on two-needled pines. Forest pathology in Britain is therefore concerned with its effects, because of their weakening nature, are more a large number of diseases, which vary greatly in im- serious in the nursery tian in the plantation, but because portance.For some, control appears unnecessary at of the sporadic nature of serious attacks, no' control meas- present; for many, control is desirable; and for a few, ures have been advocated in Britain. During the lastfew control is indispensable. years, however, in which wet summers predominatedand The chances of formulating a successful control for any favoured attacks, nursery losses were so severe that re- diseaseare directly proportional to the investigator's quests for control measures assumed unusual insistence. knowledge of the causal agent. Work on control measures The salient facts known about the disease were: is therefore always preceded or accompanied by work on It is confined to pines. the life cycle of the organism, if the relevant details are The Leptostroma stage is non-infective, so that there

904 Fifth World Forestry Congress Proceedings is no quick-sporing stage in the life cycle. Thus, there is is mature. Tsuga heterophylla is very susceptible to butt- no tendency for infections to build up during the season. rot, and its use is avoided on sites where there is risk of 3. Itsdispersal range islimited,ascospore density Fomes. The spruces, larches and Thuja are susceptible falling off sharply with distance from source (unpublished to heavy butt-rot losses. observations). Fomes appears able to invade crops on the majority of A questionnaire based mainly on the above three facts site types in Britain. The two possible exceptions are the was circulated to all pine-growing nurseries in two large deep peats inhigh-rainfall areas and ground which regions which had experienced severe attack. The results, formerly carried hardwoods. On such sites there have when analysed, were revealing. Without exception, those been frequent observations of stump colonisation not nurseries which had suffered attack were situated in pine apparently followed by invasion of the roots of the stand- plantations, and those which had escaped were remote ing crop. Crops on land once under agricultural use have from pine. This result could have been deducted from been repeatedly shown to be particularly prone to Fomes the existing knowledge of Lophodermium and was, in fact, attack. Information has been gathered also on the rate of anticipated.Its complete confirmation from independent spread of Fomes from stumps into adjacent living roots accounts was none the less satisfactory. A basis for con- and into the standing tree. trol was thereforesuggested, and a recommendation The main conclusion from this work is that Fomes is was made that all pine sowings should be remote from. gradually spreading and increasing in Britain and that pine plantations. measures based on stump protection to prevent invasion If this measure deals adequately with the problem, of new ground and limit extension elsewhere are neces- then it probably represents the ideal type of solution, sary. Already, creosote treatment of stumps is standard since it involves no cost and is achieved by a simple practice in many regions and will probably become change of silvicuitural technique well within the forester's standard for the whole country. There may be some site capacity. It has also the great virtue of being a sensible, or crop exceptions, and work on this aspect is in progress. obvious type of control measure easily appreciated by the The problem of eradication of the fungus from infected forester. This last point is of enormous importance, since sites is much more difficult than that of protection of the ready co-operation of the forester in applying recom- uninfected sites, though, fortunately, the area involved at mended control can make all the difference between suc- present is relatively small. Some preliminary work has cess and failure. been carried out, but the indications are that any success- Logically, there is a relationship between knowledge of ful measure is likely to be laborious and costly.It is the life cycle of a pathogen and its economic importance. difficult to envisage any method otiiier than complete Investigations have nearly always required an economic removal of stumps and roots from the sites.This has spur. In Britain to-day, rot losses, especially those due to been done experimentally on butts up to fourteen inches Fomes annosus, in standing conifers represent the most in diameter and proved less formidable and costly than serious damage caused by pathological agencies. As a was expected.The resulting advantages from ground result, for the past few years investigation of this aspect cultivation and weed suppression may offset the cost to has consumed the greater portion of the resources of the some degree. This is still likely to be considerable, how- pathology section at the Forestry Commission Research ever, and this is why priority has so far been given to the Station.Starting from the foundation of stump infection protection side. in pine elucidated by Rishbeth in the nineteen-forties, Opportunities may arise, however, where changes in this work has led 10 the discovery of important new gen- silvicuiture affect Fomes considerations.In the light of eralisations concerning the spread and development of current conditions, there isless need to keep timber Fomes. These have been stated in detail elsewhere, but reserves on the ground, and this might permit both clear briefly they are: felling of sub-mature crops and the planning of relatively Stump infection occurs generally in Britain on all short rotations.This raises the possibility of using a species susceptible to Fomes. susceptible butt-rot crop, even Tsuga, on badly infected Sites can be protected by stump treatment gen- ground, in preference to a low-yielding but resistant pine, erally in Britain provided a short rotation of, say, forty years is envisaged (1) and (2) together confirm that the basic principles and a check is kept of the progress of the rot in the crop. of Fomes infection and protection hold for the much more Future changesinsilvidultureor management may general and important butt-rot problem in several conifer similarly permit further flexibility in Fomes control. species, as well as for the specialised and relatively local Work on Fomes has involved work on other decay fungi problem of death in pine. on conifers. In particular, this has brought on apprecia- Fomes infection intensity varies over different tion of the importance of honey fungus, Armillaria mel- regions of Britain and is highly correlated with a history lea, as a butt-rot agent. Hitherto, in Britain, this fungus of conifer planting. was known chiefly as a cause of death especially of young Build-up of infection isrelativelyslow, to be planted stock, although there have been several reports of measured in rotations rather than decades, but losses can it from the Continent as a butt-rot.Investigations, how- be serious in the second rotation, though slight in the ever, have shown that many cases of butt-rot, particularly first. of spruce, on ex-hardwood sites, are due to honey fungus. In addition, a great mass of data has been collected The rot is distinctive, typically confined to the bottom concerning the reaction of Fomes to species and site.In twelve or eighteen inches of the butt and therefore less Douglas-fir and the pines,root-rot may be expected; serious in the individual tree than Fomes. It is thought butt-rot seldom occurs, and then mainly when the crop that this form of damage will be increasingly met in Britain

Forest Protection 905 as conifer crops on ex-hardwood ground come into the form of damage have been found in most areas of the productive stages. Armillaria is probably one of the best country, particularly in the east and south. Because of the examples of an oft-quoted fungus with an imperfectly nature of the symptoms, preliminary work was concerned known life cycle. There is very little data, for instance, with needle fungi, but it was fairly soon established that on the importance of the spores in dissemination. For no pathogenic needle or shoot fungus was constantly most of our field data, indeed, we are indebted to the associated with the disease. The most commonly occur- cultivators of such exotic crops as rubber and tea. These ringfungus,Rhizosphaerakalkhoffli,which invaded have at least supplied us with one approach to control needles very early in the onset of the disease, could not be treatment of the standing crop before felling and replant- inoculated successfully onto needles of normal trees. Ex- ing, in order to reduce the invasion of the resulting stumps. amination of many of the cases, however, showed that Some experiments on this aspect have been laid down in the crowns of the trees had suffered suddenly increased Britain, but if future developments appear to warrant it, exposure just prior to the appearance of symptoms. The their scale may have to be increased. most obvious cases were where side shelter, such as an The third decay fungus which has received attention in adjoining plantation or a high hedge, or broadleaved Britain lately is Polyporus schweinitzii.This has been shelterhad been removed. "Top dying" symptoms found to be far more general and to cause greater damage appeared at the exposed edges and for a period of a few than was suspected, though it is still of far less importance years could be found increasingly further into the planta- than Fomes.It is potentially a very dangerous fungus, tion. One case is known where the symptoms can be found since it can cause a much faster decay in the individual seventy yards into one stand, seven years after a broad- tree than Fomes.Itis disappointing that Douglas-fir, leaved shelterbelt was removed. Such cases may arouse resistant to the latter, is very prone to butt-rot by P. little interest, since they are typical of what a forester schweinitzii.Again, it is a fungus, long known in the refers to as "exposure damage" without, perhaps, being literature, but apparently with an imperfectly understood able to define exactly what he means by the term. Even biology. The all-important question of infection method more interesting, however, was the appearance of "top is still unresolved. Recent work in Britain has shown it dying" in plantations following a first thinning. Ample to be capable of infecting wounds, especially of the roots mensurational and observational data were available to and stem bases. Work is in hand to see whether spores show that the symptoms were not present before the can bring about colonisation of stumps.If this isso, thinning and that the start of defoliation and increment then stump treatment against Fomes may control P. reduction coincided with the year of thinning Dead trees schweinitzii also. could be found two years after the thinning, but many One investigation lately finished concerned the disease affected ones recovered.The fundamental reason for popularly referred to as "group dying" of conifers. This the disease is not known, but it seems likely to be asso- affects chiefly Sitka spruce, but also Norway spruce, Scots ciated with increased transpiration and lowering of the pine, Pinus contorta, Pinus nigra and Japanese larch. moisture content of the needles.Further work, chiefly Typically, small groups of dead trees are found in pole- observational, is in progress, but a full explanation would sized plantations. The groups enlarge for a period of years involve work on the physiological reaction of crowns to and then become static.Observational and experimental enhanced exposure. Deaths of larch severely opened out work showed that the cause was the root fungus Rhizina for underplanting and not apparently due to any fungus undulata, which became established on the sites of fires or insect are thought to be due to the same cause. Simi- lit by workers in the plantations when carrying out thin- larly, deaths in ash and other broadleaved trees in mixed flings. The fungus spreads radially outwards from the fire woods from which the conifers have been removed are sites, killing roots as it progresses. Many questions, such thought to be associated with increased transpiration. Such as why the fungus can colonise fire sites, why the activity considerations, particularly when ranged alongside Bier's finally stops, and other interesting points about its biology, recent work, in which he shows that certain canker are unexplained. Preliminary results indicate that control diseases are unable to attack their hosts when the hosts' can be effected by the abolition of fires in plantations, and relative turgidity is above 80%, are being brought to the over much of the areas which suffered losses such fires attention of the pathological worker in Britain.If exces- have been prohibited. This is one of the easiest and cheap- sive transpiration can, in a few special cases, bring on est methods ever found in Britain of controlling a forest death, how many other cases must there be where it pre- disease, and the whole story of "group dying" has been disposes attack by less damaging needle-, shoot- and pos- a complete reversal of the usual course of a pathological sibly root-attacking fungi. This is a point of great import- investigation. That is, the investigation took a relatively ance in forestry, where so many of the cultural practices long time before a fairly simple solution was arrived at, have a profound effect on crop transpiration. Conversely, and immediately this stage was reached, the necessary control of such transpiration diseases would probably be, control measure was obvious and uncomplicated. to some extent, in the forester's hands, through thinning In the plantations also, attention has been directed intensity, canopy manipulation, etc. towards the possibility of changes in the crown environ- In nursery diseases, the aim again is to evolve some ment causing disease in trees. A deterioration in pole- control which can be applied by the forester in his normal sized Norway spruce, popularly referred to as "top dying," practice or by some slight deviation from it.Again, the has been the best example. This disease is characterised ideal is a preventive measure which costs nothing, is easily by loss of needles, reduction in increments, and possibly applied and does not reduce output. Lophodermium has death. Some affected trees have recovered. Affected trees already been mentioned in this context.In addition, a tend to have a scattered distribution, and examples of this rotational scheme for sowing Thuja plicata has been put 906 Fifth World Forestry Congress Proceedings into effect to try to minimise or avoid losses by Keithia Britain, and elms resistant to Ceratostomella ulmi, where thujina, which has been most destructive in the past on much of the work so far has been done in Holland. The nursery stock. The essence of this scheme is to avoid firstexample wholly influences our attitude towards having more than one age of Thu/a in any one nursery canker on poplars; it is certain that the second will greatly at any time. Thus the build-up and maintenance of the influence our attitude towards the control of elm disease. disease by infection of young seedlings from adjacent Already, also, we are benefiting from American work on infected older stock would not occur. The nurseries in Pinus strobus varieties resistant to blister rust.Having the scheme are as remote as possible from Thuja stands formed seed orchards from these, we will soon have seed or individuals. The scheme is intended to serve a large available for testing. Similarly, we shall soon be engaged territorial unit, e.g., Scotland, or one-half of England, and in testing large numbers of Thu/a seedlings raised from all the planting needs for the unit for one particular year seed of individuals selected here as being apparently resist- would be met by the out-turn from one nursery in that ant to Keithia.It is probable that forest pathology gen- year.Implementing the scheme has involved changing erally, as well as in Britain, will be increasingly concerned the whole structure of Thu/a raising, which had hitherto been done independently for much smaller areas. It is a with the development of resistance to disease in species. good example, however, of a disease so damaging that its Selection or breeding for resistance is one other aspect control justified a complete change in current methods of of disease control by avoidance, the desirable end in all management. forms of pathological work. Other nursery diseases, such as Botrytis cinerea, Meria laricis, oak mildew, damping-off, etc., are controlled to RESUMES varying extents by chemical spraying. With oak mildew Tendances actuelles du con trôle des maladies forestieres and Meria, control is effective, and satisfactory schedules en Grande-Bretagne have been known for some time. Of the others, Botrytis Le contrôle ideal des maladies forestières repose sur les mesures cinerea, attacking a wide variety of conifers and some preventives. La prevention de ces maladies est le but de tous les exotic hardwoods, is the most intractable.Spraying ex- travaux de pathologie effectues par la Commission ForestiIre a la station de recherches Alice Holt. L'auteur fournit des exemples periments have shown that many chemicals will protect a de cas ott de tels contrôles ont été découverts ou sont actuelle- bed for a short period or against an attack shortly after ment a l'étude.Ii indique d'autres cas pour lesquels on n'a pas spraying.It has not been possible, however, to protect encore réussi a prévenir méthodiquement une maladie et ott beds of susceptible species throughout a whole growing l'on fait encore appel aux produits chimiques.Ii décrit un grand season. Further work on spraying is proceeding, but it is nombre des maladies forestières les plus importantes actuellement difficult to envisage a preventive control against the fungus a l'étude en Grande-Bretagne. in view of its ubiquity. There is some hope that origin of Tendencias Actuales del Control de Enfermedades Fore- seed may affect susceptibility, but practically no work has stales en Gran Bretaña been done on this aspect. El control ideal de enfermedades forestales estriba en evitar la Mention of origin, however, brings up the question of enfermedad. A esto tiende toda Ia labor patológica de la Estación combating disease by the use of resistant varieties gen- Investigadora de la Comisión Forestal, en Alice Holt. En este erally. Although only limited work has been carried out estudio se ofrecen ejemplos de donde se han puesto en vigencia in Britain, there are signs that this aspect may become o se estan formulando tales medidas de control. Se citan otros extremely important in future work there. So far, we have casos en que no se han empleado métodos deprevención y el controldepende todavIa de métodos qulmicos.También se largely profited from efforts made elsewhere. The two describen muchas de las enfermedades más importantes de los great examples of this are poplars resistant to bacterial árbolesque estánsiendoinvestigadasactualmente en Gran canker, where some of the contributory work was done in Bretaña.

Forest Protection 907 Precautions a prendrepour éviter les pertes causées par les pourridiés dans les cultures ligneuses intensives dans la vallée du P

BRUNO FASSI Istituto Nazionale per Piante da Legno, Turin, Italie

Les pourridiés ou pourriture des racines intéressent toujours été signaiées soit dans le jeune age (I.A.S. Gib- essentiellement les plantes ligneuses.Cette alteration est son; H. H. V. Hord et M. J. Hildebrand), soit dans provoquée par des champignons lignivores dont les plus l'âge môr (Biraghi, S. Domansski). connus sont:Armillaria mellea, Rosellinia spp., Fomes D'autre part, c'est un fait bien connu que certaines annosus et Fomes lignosus. Ces parasites sont endémiques essences sont plus sensibles que d'autres aux pourridiés. des formations ligneuses spontanées, mais leur action Nous avons eu i'occasion de nous préoccuper des pour- parasitaireestsurtoutconnuedanslesplantations ridiés dans la culture intensive des peupliers de Ia vallée du forestières et fruitières. Pô (Italie) a l'Istituto di Sperimentazione per la Pioppi- Des dégâts importants düs aux pourridiés ont été coltura (1953) et ensuite dans des cultures arborescentes signalés le siècle passé en Europe lors de l'établissement tropicales a l'Institut National pour l'Etude agronomique de vignobles et de vergers après défrichement forestier (P. au Congo Beige. En partant des notions déjà acquises Viala). Du debut du siècle a nos jours les pourridiés a ce sujet grace a une documentation abondante (T. posent de sérieux problèmes dans les plantations arbores- Petch; R. Leach; H. E. Thomas; S. D. Garrett; R. A. centesindustrielles(hévéas,théiers,cacaoyers,etc.) Aitson; J. Rishbeth; R. L. Steyaert; R. J. Pichel), nous établies sur terrains déboisés dans les pays tropicaux (T. avons poursuivi des recherches et des observations plu- Petch; W. Nowell; S. D. Garrett; R. L. Steyaert; R. J. riannuelles dans des formations naturelles et artificielles, Pichel). Dans les plantations forestières des pertes ont qui nous ont permis de reconstruire le cycle des pourri-

Table 1. Cycle des pourridlés dans une plantation Peuplement nature! Abattage Expansion des pourridiés Pourridiés a l'état endémique.Latence Rupture de l'endémisme. Par colonisation des souches (Mv) on faible pouvoir infectant, du fait de la Progression ou réalisation de l'infection, presence d'une petite masse radiculaire dueaunepetitemasseradiculaire colonisée (mc) par rapport a colonisée (mc) par rapport a mc mc mc Mv Mc Mv R Mv r une grande masse radiculaire vivante une grande masse radiculaire vivante a partir d'une petite masse radiculaire (Mv) et une grande reaction (R) des (Mv) mais faible reaction a l'infection colonisée(mc), cequi aboutit a une arbres du peuplement a l'infection. (r) des souches des arbres abattus. grande masse radiculaire colonisée (Mc). Plantation adulte Regression des pourridiés Jeune plantation Pourridiés a l'état endémique.Latence Par colonisation de jeunes plantes (my) Sujette aux pourridiés en phase dpidémi- on faible pouvoir infectant, du fait de la que. presence d'une petite masse radiculaire Réalisationdel'infectionparsuitede colonisée (mc) par rapport a l'existence d'une grande masse radiculaire colonisée (Mc) par rapport a mc mc my Mc Mc Mv R Mv R une grande masse radiculairevivante a partir d'une grande masse radiculaire une petite masse radiculaire vivante (my) (Mv) et grande reaction (R) des plantes colonisée (Mc) ce qui aboutit a une bien que grande reaction (R) des plantes a l'infection. petite masse radiculaire colouisée (mc) a l'infection. Note explicative du tableau: * Cette masse colonisée (mc) sera d'autant plus petite que la reaction des plants aura dté grande (R),car ii aura fallu une grande masse radiculaire colonisée (Mc) pour infecter et coloniser iine masse radiculaire vivante (my) relativement petite, mais a grande réac- tion (R). mc Mc: masse radiculaire colonisée; my Mv: masse radiculaire vivante qui établit des contacts avec mc ou Mc; r R: reaction de la plante a l'infection. 908 Fifth World Forestry Congress Proceedings dies selon un schema qui figure a la suite du present pourridiés ne présentent plus de problème dans de tel- exposé. L'étude in extenso avec toutes les données est en les plantations. preparation.Sur la base de ces connaissances, nous Chez les autres essences a croissance rapide, Pinus présenterons quelques propositions pour la lutte contre les strobus, P. excelsa, Pseudotsuga douglasii, Larix leptole- pourridiés dans les plantations forestières intensives. pis et autres, que l'Istituto Nazionale per Piante da legno Ii est désormais bien démontré que les agents de pour- di Torino se préoccupe de répandre, il faudra en venir ridiés existant par foyers disperses et de petite entité aux mêmes méthodes de lutte preventive si l'on veut éviter (petite masse radiculaire colonisée) dans les formations des pertes dans l'avenir. naturelles trouvent dans les racines des arbres, une fois Nous avons déjà eu l'occasion d'observer des dégâts abattus, un substrat nutritif particulièrement favorable a causes par Armillaria mellea sur de jeunes sujets de Pinus leur propagation végétative. Ces racines colonisées par ces excelsa, infectés par des souches de vieux arbres abattus. champignons constituent des nouvaux foyers d'infection Dans le cas de plantations intensives a établir sur les d'autant plus virulents que leur masse est grande et que la lieux d'anciens vergers et vignobles ii sera done indispen- masse radiculaire des jeunes plantes de culture, avec qui sable de procéder a l'extirpation complete de ces arbres ils entrent en contact, est petite (B. Fassi, 1959). et des leurs racines lors des operations de labour. La mortalité chez les plantes de culture atteint ainsi un maximum dans le jeune age, lorque leur système radicu- Références laire est déjà assez étendu pour établir de nombreux con- R. A. Altson, 1953. Rep. Rubb. Res. Inst. Malaya 1949-51. tacts avec les foyers d'infection, et ces derniers ont re- Biraghi, 1949. Ital. Forest. e Montana. joint leur expansion maximum. La reaction des plantes de S. Domansski, 1953. Prace Inst. Badaw. Lesn. 93. B. Fassi, 1953.Pubbl. Ente Nazion. Cellulosa e Carta, Roma. culture aux parasites, bien qu'elle puisse être localement Studi e ricerche sulla Pioppicoltura, pp. 45-94. (au point de contact avec le parasite) très élevée dans les 1959.Bul. Information INEAC. Bruxelles, Vol. sujets juenes et vigoureux, est dans son ensemble limitée Viii, No. 5, pp. 3 17-330. du fait même des dimensions réduites de leur système S. D. Garrett, 1956. p. 293, Cambridge. I. A. S. Gibson, 1957.Rep. For. Dep., Kenya, 1954-55, p. 20. radiculaire vis-à-vis de la grande masse des racines fores- H. H. V. Hord et M. J. Hildebrand, 1956.Bi. m. Prog. Rep., tières colonisées, qui constituent l'inoculum. Div. For. Biol., Dep. Agric., Can. 12, 1, p. 2. A cette phase epidémique, qui peut se prolonger pen- R. Leach, 1939. Trans. Brit. mycol. Soc. 23, pp. 320-329. dant des années, fait suite une lente regression de la W. Noweli, 1923. W. md. Committee, London. T. Petch, 1921. Ed. MacMillan. mortalité chez les plantes cultivées due, d'un côté a R. J. Pichel, 1956. INEAC, Serie Scient. No. 49. l'épuisement des foyers d'infection par la pourriture et la J. Rishbeth, 1950. Ann. Bot. Lond. 14, pp. 365-383. désagrégation de racines forestières colonisées, et d'un 1957. Forestry 30, 1, pp. 69-89. autre côté a l'accroissement du système radiculaire des R. L. Steyaert, 1949. Bull. agric. Congo Beige XL, 2, pp. 165 1- 167 8. plantes, qui devient toujours plus important. Les racines H. E. Thomas, 1934.1. agric. Res. 48, pp. 187-218. des plantes de culture colonisées ne représentent qu'un P. Viala, 1892. Comp. Ren. Ace. des Sciences, Paris. nouveau inoculum plutôt réduit.Les pourridiés entrent dans une nouvelle phase de parasitisme réduit, et méme RESUMES de latence, reprCsentée par quelques foyers disperses et de Precautions To Be Taken To Avert Losses Caused by faible entité, comme dans le cas des peuplements naturels. Root Decay in Intensive Tree Growing in the Po Nous avons représenté ces diverses phases dans le schema Valley ci-joint. The author explains the development of root decay in natural Dans des plantations artificielles se trouvant dans ledit and planted stands and the evolution of the host-parasite rela- état d'equilibre, on peut assister a une nouvelle vague tionship. The relationship involves, for the parasite, the mass of épidémique suite a l'affaiblissment d'un nombre important the inoculum, and for the host, the living root mass and the de sujets. Leur racines deviennent de ce fait réceptives et plant's vital reaction to the parasite's penetration of the tissues les parasites, a partir de petits foyers dipersés, peuvent les and growth therein. At the end of his discussion the author advocates, for intensive envahir et constituer de nouveaux foyers importants. Ces planting of rapid-growth tree strains (Pinus strobus, P. excelsa, derniers pourront être assez étendus pour attaquer et faire Pseudotsuga douglasii, Larix leptolepis, etc.) in the Po Valley, périr des plantes limitrophes saines. Les causes d'affaiblis- the complete removal of the roots of ligneous plants prior to sement peuvent être de nature différente: des attaques tree planting. This method, already tried in connection with the repétées d'insectes ou d'autres parasites, des chablis dfls intensive growing of poplars, has given positive results in forestal- ling losses from root decay. au vent, des coupes d'éclaircissage trop intenses et le Moreover, this practice is in accordance with the program of vieillissement. accelerated tree growing which, as in the case of the poplar in Dans le cas de cultures intensives d'essences ligneuses Italy, provides for the growing of crops (maize, potatoes, etc.) a croissance rapide dans la vallée du Pô II y aura donc a in connection with it during the first years of growth. craindre des pertes resultant de pourridiés chaque fois Precauciones que se Deben Tomar para Evitarlas qu'on établira des plantations après des formations hg- perdidas Ocasionadas por los Criptógamos en las neuses spontanées ou artificielles sans extirpation préa- Races en los Cultivos Intensivos de Arboles en el lable des souches et des racines. Valle del Po Pour la culture intensive du peuplier II est désormais El autor explica la evolución de la enfermedad de la podredum- entré dans la pratique de procéder au nettoyage complet bre de las raices en las poblaciones arbóreas naturales y artifi- du terrain des debris ligneux avant la plantation des jeunes ciales y la evolución de las relaciones entre huésped y parásito, sujets.Les résultats ont été absolument positifs et les en las cuales interviene, por el lado del parásito, la masa del

Forest Protection 909 inoculum, y por el del huésped, la masa radicular viva asi como que anteceden al cultivo.Este método, seguido ya en el cultivo la reacción vital de la planta a la penetración del parásito en los intensivo del alamo, ha surtido resultados positivos en prevenir tejidos. las pérdidas causadas por esta podredumbre. Despuës de exponer los hechos, el autor recomienda para el Por lo demás, el sistema estk de acuerdo con el plan de cultivos valle del Po, plantaciones intensivas de plantas de crecimiento leñosos acelerados que abarcan, como en el caso del alamo en rápido: Pinus strobus, P. excelsa, Pseudotsuga douglassii, Larix Italia,cultivosagrIcolas asociados:maIz, papas,etc., enos leptolepis, etc., la extirpación de las raIces de las plantas lenosas primeros afios de la revolución.

Diseases of Acorns Found in Czechoslovakia BRANISLAV URosEvic Forestry and Game Management Institute, Zbraslav Strnady, Czechoslovakia

The prevention of stunting in planted pure oak stands and some from Slovakia and Yugoslavia (imported acorns requires a high production of good oak plants. For this of Slavonian oaks). reason, Czechoslovakia collects from 200 to 300 wagons Phycomycetes develop mainly on seed coats, notably of acorns yearly. Germination losses average about 20 on acorns damaged by biotic and abiotic factors, such percent, sometimes as much as 50 percent, and this as insects, vertebrates, and unfavorable storing conditions. represents a high financial loss annually.Due to the Afterwards they penetrate more deeply into cotyledons pressure of these losses we have undertaken more in- and reduce germination ability. But their economic im- tensivestudies on acorn diseases and on protection portance is insignificant; for this reason I mention only methods. Mucor Mich., Rhizopus Ehrenb., and rarely A bsidia von Acorns lose germination ability not only because of Tiegh.Ascomycetes are of far more economic impor- unfavorable temperature conditions (frosts, overdrying, tance. Fungi such as Scierotinia (Stromatinia) pseudotub- overheating through moisture) but especially because of erosa Rehm, Scierotinia scierotiorum (Lib.) de Bary, the activity of living organismsbacteria, insects, and Ophiostoma(Ceratocystis)sp.,Diaportheinsularis fungi.Bacterial diseases of acorns caused by the species Nitschke (Phomopsis quercella Died.), Valsa intermedia Erwinia carotovora (Jones) Holl. and Erwinia glandicola Nitschke (Cytospora intermedia Sacc.), and Gnomonia C. Georg et M. Badea occur in frozen, overheated, or quercina Kieb.(Gloeosporium quercinum West.)are otherwise damaged acorns, but are not of considerable among the most important in Czechoslovakia. Of the economic importance. Basidiomycetes, mention must be made of Schizophyllum The main insect pests of mature acorns at present are commune Fries and Stereum hirsutum (Wild)Pers., Balanius glandium Marsh. and two species of seed moths, Which sometimes cause serious damage to stored acorns in Laspeyresia grossana Hv. and Laspeyresia splendana Hb. our country. In 1957, damage due to acorns falling prematurely was The prevailing group of mycoflora consists of Deu- from 17 to 64 percent, an average of 37.1 percent. The teromycetes(Fungi Imperfecti).They are not only harmful effects of Balanius glandium Marsh. are more saprophytes but also parasites, and often a polyphagous important than those of Laspeyresia larvae. This is partly species, easily adapted to various sources of nutrition. due to damage done not only by larvae but also by Eighty species have been identified. I mention only those imagoes. Simultaneously, spores of various fungi attack not hitherto cited in literature, for example, Acrospeira the acorns and penetrate their healthy tissue. The growing mirabilis Berk. et Br.; A crothecium tenebrosum (Preuss.) of mycelium shows more rapid and harmful effects than Sacc,; A iternaria humicola Oud.; A iternaria tenuissima does larvae feediig.It is obvious that insects cause not (Fr.)Wiltshire;Cephalosporium acremonium Corda; only a reduction of fertility but also a reduction of seed Coniosporium aterrimum (Corda) Sacc.; Coniothyrium quality. quercinum (Bonord)Sacc.; Cylindrocarpon radicicola During the ripening, collection, and storage of acorns, Wr.; Epochnium monilioides Link; Fusarium bulbigenum a rich development of mycoflora was shown. Mycofiora Cke. et Mass.; Fusarium heterosporum Nees; Fusarium was investigated in the analysis of acorns by cutting on solani (Mart.) App. et Wr.; Fusarium lateritium Nees; Fusella olivacea(Corda)Sacc.; Gliocladium penicil- the base of characteristic spots on cotyledons; peeled and bides Corda; Gliocladium roseum (Link) Bain.; Glio- unpeeled cotyledons were put into moist chambers, in- cladium verticilloides Pidopl.; Helicosporium pulvinatum vestigated by microscope, and isolated in pure cultures on (Nees) Pers.; Monilia siphila (Mont.) Sacc.; Oidioden- malt agar (malt 8° Baumé, 2 percent agar, acidity 5.2 dron griseum Robak; Ooospora glauca (Preuss.) Sacc.; pH).In addition, the seeds were watered by sterile Paecilomyces varioti Bainier; Papulospora sepedonioides distilled water and the obtained suspension was given on Preuss; Passalora Fries et Mont sp.; Pestabozzia quercina agar in Petri dishes.Experiments were carried out by Guba; Pestalozzia truncata Lév.; Septocylindrium virens means of dilutions, i.e., by three concentrations 1: 1,000, Sacc.; Stemphylium ilicis Tengwall; Stemphylium pin- 1:10,000, and 1:100,000.In this way, 73,400 acorns forme Bonord.; Torula convoluta Harz; Trichosporium from 195 mean samples were tested. Tests were made on olivatrum Sacc.; Verticillium compactiusculum Sacc.; and acorns from various localities in Bohemia and Moravia, Verticillium epimyces Berk.

910 Fifth World Forestry Congress Proceedings Imperfecti forment la partie dominante de la mycoflore. On en a Protection methods against fungi, with the exception étudié 80 espèces. Cette communication ne fait mention que de of those penetrating deeply into cotyledons, showed good 32 espèces observdes pour la premiere lois sur les glands d'aprIs results when mercurial chemicals (phenylmercuribromide) les documents traitant de ce sujet. or organic compounds such as Zn-dimethyldithio-car- baminane and tetramethyithiuranbisuiphide were used. Enfermedades de las Bellotas en Checoeslovaquia Durante el perIodo de maduración, recolección yalmacenaje RESUMES seencontn5 un profuso desarrollo de Ia micofloraen 73.400 beliotas de roble.Se analizaron 195 muestras. LosFicomicetos Maladies des glands en Tchécoslovaquie que se desarrollan en Ia corteza de las semillas son de poca On a découvert le développement d'une mycoflore abondante importancia.Los Ascomicetos encontrados en las bellotas son sur 73.400 glands de chêne pendant Ia maturation, la cueillette los de las enfermedades más importantes, como ser, por ejemplo: et l'entreposage.Des essais ont été faits sur 195 échantillons. Stro,naginia pseudotuherosa Rehm, Scierotinia sclerotiorum (Lib.) Les Phycomycètes qui se développent surtout sur l'arille sont de de Bary, Ceratocvstis sp., Phomopsis quereella Died.. Cytospora peu dimportance. Les Ascomycètes que Von trouve sur les glands iniermedia Sacc..y GloeosporiumquercinumWest.También représentent les maladies les plus importantes. telles que:S:rorna- deben mencionarse elSchizophyllutn communeFries y el Stereum tinia pseudotuherosaRehm. Scierotina scierotiorurn(Lib.)de hirsutum (Wild) Pers. de Basidiomicetos. En Ia micoflora pre- Bary,Ceratocystissp..PIio,nops'isquercella Died., Cytospora valecen los Fungi Imperfecti. Se establecieron 80 especies.Este inter,nediaSacc.,et G1oeosporiun quercinum West. L'on dolt trabajo hace mención de 32 especies encontradas por primera vez ëgalement menlionnerleSchizophyllum commune FriesetIc en lasbellotas. segtn ha podido comprobarse consultando los Sfereunz hirsutum (Wild) Pers. des Basidiomycètes. Les Fungi trabajos sobre Ia materia.

El "Tabaco" del Quebracho Colorado Chaqueno

CELINA L. lAcoNis Doctora en Ciencias Naturales, Administraciôn Nacional de Bosques, SecretarIa de Agricultura y GanaderIa de la Nación, Repdbiica Argentina

El quebracho colorado chaqueno (Schinopsis balansae el ruido a hueco caracterIstico, que se percibe al golpearlo Engi) es una de las especies forestales más valiosas de con el hacha. Ia Repüblica Argentina. Su madera muy dura y compacta, El follaje no es afectado por la enfermedad. de color castaflo rojizo. es utilizath sobre todo en Ia preparación de extracto tánico de renombre mundial. Caracteres Macroscópicos de la Pudrición insustitulbie en algunos procesos de curtidurla. Tarnbién En Ia primera etapa de Ia pudrición, el color castaño por su gran durabilidad, es apreciada en la fabr'icación de rojizo de Ia madera se altera oscureciéndose a castaño durmientes, postes, pilones, etc.. y los deshechos, por su violáceo (Rs, 6°, 2 del Atlas de los Colores de Villalobos, alto poder calórico, son estiinados corno lena de rnuy 1947); en este estado recibe el nombre de quebracho buena calidad. "moro". En ci corte transversal de un rollizo enferrno, se La enfermedad más difundida y perjudicial de esta observan manchasdedistintostamaños yformas, especie es una pudrición castaña, fibiosa del duramen, diseminadas por toda Ia superfioie, las cuales a veces se conocida con el nombre de "tabaco" del quebracho disponen siguiendo Ia curva de los anillos de crecimiento. colorado. A medida que la enfermedad progresa, las nianchas Koutché, V., (1929, 1932, 1933) y varios técnicos de aumentan de tamaño y en su centro la madera cornienza la Administración Nacional de Bosques como: Dabas, a disgregarse en forma de astillas, las que alrestregarlas J.y Buresch entre los dedos. se demenuzan en forma de polvo grueso, E., y Martin, R., (1946); Festenessi, J. de color rnarrón. Esta fase recibe ci nombre de "tabaco" Sagner, 0., (1945 )Ia mencionan en susinformes y algunas (FotoNo. 1). Sutton,C.E.. (1944)muestra fotografIas En condiciones más avanzadas adn, se observa en- tIpicas. tremezclado con las astillas, el micelio ocre amarillento Mezey, E., (1946; p. 40, 44, y 64) hace referencia del hongo y muy pequeñas cavidades, que comienzan a a ella varias veces. formarse como resultado de Ia desintegraciOn completa de aquellas.En susültimasetapasIadescornposición Diagnosis aumenta, las cavidades sonmás nurnerosas y grandes y El árbol enfermo se lo reconoce fádilmente porque terminan por ocupar todoci duramen, quedando sola- presenta su tronco deformado, con una tumefacción mente la albura rodeada porIa corteza; este iltiino estado aproximadamente central, recibiendo por este carácter recibe el nombre de "caiión". en la region, el nombre de "quebracho apanzado". Simul- táneamente con este sIntoma, se observan fructificaciones Caracteres Microscópicos de la Pudrición de un hongo leñoso, perenne: Fomes chaquensis lac. y Pararealizaresteestudio,laspreparacionesmi- Wright, conocido con el nombre de oreja o urupero. croscópicas se hicieron siguiendo la técnica ya descrita Otra forma de reconocer un quebracho enfermo es por en un trabajo anterior. (laconis, 1954)

Forest Protection 911 Fofo No.I.Tortede quebracho coloradocon manchas fipicas defabaco. Dibujo No.I.Hifas de Fomes chaquensis en un vaso leoso. El micelio aparece en los distintos elementos leflosos: vasos, células del parénquima y del radio y en las fibras, representado por hifas algo irregulares en su fonna y trayecto, ramificadas, de color castaño claro a castaño rojizo, generalmente angostas de 1,0 a 2,0 micrones de ancho. Cuando el filamento se presenta como emergiendo de un depósito de tanino suele ser más grueso, hasta 5,2 mi- crones de ancho, corto y de color castaño rojizo. Unicamente en las células radiates. se ha tenido opor- tunidad de observar los filamentos pasando de una a otra através de perforaciones hifales, sin disminuir aparente- mente su diámetro; en los otros elementos leilosos solo se Los ha encontrado esporádicamente, en células aisladas, sin continuidad con las adyacentes (Dibujos Nos. 1 y 2). Etiologla Siempre se encuentran asociadas al quebracho colo- rado atabacado, fructificaciones de Fomes chaquensis lac. y Wright.Este hongo aparece, a veces solitario, pero generalmente gregario, en todo el largo del tronco. Forma agrupaciones de esporóforos de distinta edad; algunos muy jóvenes, como un mamelón con la superficie aterciopelada, castaña y los poros poco desarrollados; otros más evolu- cionados ungulados, con la superficie del contexto rimo- sa y los tubos dispuestos en un nümero variable de capas, Indice de su edad. Dibujo No. 2.Hifas en una célula del parénquima.Dibujos por Ia La profusion del hongo no está en relaciOn con la senora Sara Kahanofi. magnitud de la pudriciOn, porque a veces se advierten que- anterior (laconis y Wright, 1953), por lo cual no se los brachos en pie apanzados, completamente atabacados, incluye aquI, para no incurrir en una repeticiOn. casi al estado de cañOn, con muy escasas fructificaciones. Los cultivos aislados de los esporóforos asI como de la Reproducción de la Enfermedad madera enferma son idénticos. En patologla forestal, para las pudriciones del dura- Las fructificaciones de Fomes c/ia quensis y las carac- men, basta que se cumplan los dos primeros postulados de terIsticas de sus cultivos han sido descritas en un trabajo Koch, estos son: simultaneidad de la enfermedad y del 912 Fifth World Forestry Congress Proceedings agente etiológico y la identidad de los cultivos aislados de una disminución en el rendimiento del extracto tánico. ambos materiales, como ocurre en este caso. Además éste es de inferior calidad, de color más oscuro y Sin embargo, como es norma en el laboratorio, se trató composición cuantitativa diferente. de reproducir la alteración "in vitro", sembrando el hongo En situaciones difIciles del mercado, cuando éste es en probetitas de quebracho colorado sanas teniendo como más exigente, resulta dificultosa su yenta, en consecuencia sustrato: agua de canilla, agar extracto de malta y tierra. las fábricas rechazan la madera enferma creando ver- Si bien el micelio se desarrolla muy bien sobre la pro- daderos problemas a los obrajeros. betita, cubriéndola casi completamente, sobre todo en agar extracto de malta, recién a! año se observa una muy lige- Ref erencias ra alteración del color. Dabas, E., y Martin, R., 1946. Informe del Lote 15, Fracción Esta acción lenta del hongo en medios artificiales, serIa D de Ia Sección I del Chaco. Inédito. similar a la que desarrolla en la naturaleza, ya que el Festenessi, J.J., y Buresch Sagner, 0., 1945. Estudio forestal apanzado en los árboles enfermos es, sin duda, el resultado delaColonia AgrIcola"José Mármol;" Chaco.Informe inédito. de una reacción del cambium ante la prensecia del hongo. laconis, C. L., 1957. Corazón rojo o falso corazón del quebracho La deformación que resulta de esta reacción, por sus blanco. Rev. Invest. Forest. 1(4) :39-45. caracterIsticas, no puede producirse en corto tiempo, sobre y Wright,J.E.,1953.Estudios sobre Basidio- todo si se tiene en cuenta, que el quebracho colorado es mycetes.II.Sistemática y biologIa de tres especies de Fomes. Anales de la Soc. Cient. Arg. 155-156:1-35. un árbol de desarrollo muy lento, pues se calcula su Koutché, V., 1929. Estudio de avaluación de los quebrachales. aumento diametral medio por año de 3 mm. (Tortorelli, Informe irsédito. 1956). 1932. Contribuciónalestudiodelquebracho colorado chaquefio. Tablas de cubicación. Informe inédito. Control de hi Enfermedad 1933. Colonia "Juan Lavalle." Informe inédito. Mezey, E., 1946.El quebracho colorado y su extracto tánico. Esta alteración es exclusiva del duramen, ataca que- ed. Bs. As. brachos de todas las edades. Segün Koutché (1932) el Sutton, C.E.,1946.Sección V, Colonia "Brandsen," Chaco. Informe inédito. promedio de árboles enfermos, entre aquellos que tienen Tortorelli, L. A., 1956. Maderas y bosques argentinos. ed. Acme menos de 60 cm. de diámetro es del 40 at 50% y en Bs. As. ejemplares de diámetros superiores es del 70% y a veces Villalobos Dominguez, C., y Villalobos, J.,1947.Atlas de los del 100%. En términos generales esta apreciación sigue colores. ed. LibrerIa El Ateneo, Bs. As. siendo válida en la actualidad. Evidentemente controlar enfermedades de este tipo es RESUMES antieconómico y difIdil, porque cuando la pudrición es "Tabaco" Rot in Red Quebracho Chaqueno apreciable ya está muy extendida y solo conviene adoptar Thisstudy describesthe most important, widespread, and medidas de prevención. En este caso deben establecerse harmful disease of the red quebracho chaqueflo,(Schinopsis normas comprometiendo a los obrajeros a voltear todos ba!ansae Engi.) caused by the fungus, Fomes chaquensis lac. and Wright. los quebrachos que ya presentan los sIntomas caracterIs- This fungus causes a brown, fibrous rotting of the duramen ticos, aün aquellos de diámetro inferior at establecido por which results in considerable financial loss because it lowers the las reglamentaciones vigentes. Además, obligarlos a eli- quality and yield of the tannicextract, the most important minar, mediante el fuego, toda la madera enferma y tam- product derived from this species. bién todos los esporóforos con el fin de exterminar las esporas que son las verdaderas propagadoras de las Le "tabac" du "quebracho" rouge du Chaco podredumbres leñosas. On trouve dans la présente communication une description de la plus importante, la plus répandue et la plus pernicieuse des Importancia Económica maladies qui attaquent le "quebracho" rouge du Chaco (Schinop- sis balansae Engl.), maladie due a un champignon dénomé Fomes Esta alteración está muy difundida y causa importantes chaquensis lac. et Wright. pérdidas económicas, porque la mayor o menor desinte- Ce champignon produit une pourriture fibreuse, de couleur marron du duramen occasionnant des pertes considérables du gracidn que experimentaelleño de todo quebracho point de vue économique, du fait qu'elle réduit le rendement et la enfermo provoca una disminuciOn apreciable en la canti- qualité de l'extrait tannique qui est le plus important de tous les dad de madera ütil por volumen de rollizo y por to tanto produits provenant de l'exploitation de cette essence.

Forest Protection 913 Intoxicacidn Saunaen Alamo y Sauce Alamo

MANUEL 0. AVELLANEDA Jefe de Forestación, Administración Provincial de Bosques, Mendoza, Repáblica Argentina,

y LEON NIJENSOHN Prof esor Titular de EdafologIa, Facultad de Ciencias Agrarias, Mendoza, Repáblica Argentina

Por razones de sana economIa, vinculadas con las nece- relacionaron los slntomas de las especies existentes con sidades de las industrias frutIcola y vitIcola y con la los análisis edafológicos y Ia absorciOn de minerales por actividad de la construcción, es necesario impulsar en la las plantas. region de Cuyo la plantación de montes forestales artifi- ciales que contribuyan a solucionar el deficit general de Material y Métodos madera que se observa en el pals y que signiliquen inver- La plantaciOn estudiada se encuentra en el lugar sionessólidas,libres de desvalorización por procesos denominado "Campo Espejo," Departamento de Las inflacionarios. Heras, Provincia de Mendoza. Los terrenos forestados Especial interds revisten en este sentido las planta- por la AdministraciOn Provincial de Bosques por acuerdo ciones de esencias de maderas blandas de rápido creci- con Obras Sanitarias de la NaciOn, comprenden una ex- miento. Por razones de clirna y por la variada gama de tension de 180 hectáreas ubicadas dentro del predio de su utilizaciOn local se prestan admirablemente para tal más de 2.000 hectáreas cedidas por la Provincia a Ia fin las salicáceas, proveedoras de madera ideal para cajo- mencionada reparticiOn nacional, para servir de campo de nerla, postes preservados para viña, tiranteria y carpinte- derrame a los liquidos cloacales de la ciudad de Mendoza. rla de obra. El lugar de las plantaciones estudiadas se encuentra en Pero, al ser estas especies exigentes en agua, factor de una depresiOn sin derrame superficial, e influida por las producciOn esencial en esta region de agricultura exclu- lagunas y piletas decantadoras que se encuentran, respec- sivamente bajo riego, deben necesariamente sufrir la corn- tivamente, y a la mayor altura, al Norte y a! Sur del petencia de otros cultivos económicamente más conve- mismo. nientes, ya sea por su mayor margen de utilidad o por ci Los materiales constitutivos del suelo son de naturaleza menor periodo de implantación. aluvional, fluviolacustre y de deposiciOn reciente. Es por eso que son muy escasas las nuevas plantaciones Se excavaron cuatro calicatas correspondientes a las de montes forestales de tipo industrial, limitadas actual- siguientes situaciones: mente a las trincheras perimetrales y a lo largo de los Perfil No. 1: Corresponde a un bosquecillo de álamos cauces de riego. chilenoPopulus nigracv.itálicasempervirens.Los Una posible salida a esta situación serla Ia de reservar árboles, cuya edad era de 6 años, presentaban slntomas de para forestaciOn aquellas tierras donde por la excesiva toxicidad sailna que se describen en parágrafo corres- salinidad y/o altura de napa freática la implantación de pondiente. otros cultivos requerirla inversiones muy onerosas0,tam- bién, donde las ünicas aguas de riego que se dispongan, No. MuestraProf undidadObservaciones de campalia generalmente de origen subterráneo, sean de una calidad 285 0-15 cm. Textura franco-arcillosa; abun- dantes restos y ralces de male- que las haga de uso peligroso para tales cultivos. zas; hümda; color obscuro, casi Esta orientaciOn exige el previo conocimiento del corn- negro. portamiento de las diversas especies forestales de interés 286 15-20 cm. Similar color y textura a la frente a condiciones ecológicas como las aludidas. anterior; menor cantidad de raI- cesde malezas, salvolas de En una reciente monografla, Hayward y Bernstein, "carrizo" (Phragmites maxima); 1958, hacen una revision general de las relaciones de las muy hémeda. plantas cuitivadas con los suelos afectados por salinidad. Un capitulo de la misma está dedicado a forestales y en él Desde los 20 cm. zona con influencia de la napa, casi citan trabajos holandeses y rusos, coincidentes en atribuir, saturada de agua. Se extrajo una muestra con estructura entre los álamos, mayor tolerancia a condiciones de salini- natural de 6 a 16 cm. Esta muestra tenla una humedad dad a los Populus alba y Populus canadensis y reacciones del 36,34%. de sensibilidad a! Populus nigra var. itálica. Perfil No. 2: Corresponde a un punto equidistante entre En esta comunicaciOn damos a conocer los resultados los bosquecillos de alamo chileno y de "alamo blanco" obtenidos y las observaciones efectuadas en una planta- (Populus alba cv. bolleana). Los álamos chilenos mues- ción situada sobre un suelo influido por napa salina. Se tran slntomas avanzados de sufrimiento, niientras que los

914 Fifth World Forestry Congress Proceedings álamos blancos presentan solo escasas manifestaciones de del 1:5; pesos especIficos reales y aparentes; conductivi- tal carácter. dad eléctrica y reacción pH actual e hidrolItica. En las aguas de riego y napa freática so determinaron losaniones No. MuestraProf undidadObservaciones de campaña y cationes corrientes. En el material vegetal soanalizaron 287 0-30 cm. Textura franco-arcillosa; abun- por separado las partes verdes y secas; en el extracto dantes restos y raIces de male- nItrico de las cenizas so determinó Cl, so4, po4, Ca, Mg, zas. Medianamentehtimeda. Na y K, estos dos ültimos por fotometrIa de llama. Color pardo obscuro. 288 30-40 cm. Textura franca;casisaturada SIntomas de Toxicidad de agua. Alamo "Chileno": Las hojas presentan un desecamiento Desde los 35 cm. se nota Ia influencia de la napa freática, centrIpeto, con iniciación apical, precedido por clorosis cuyo nivel se establizO en 80 cm. Se extrajeron dos mues- internerval; manchas necróticas en los tejidos aim verdes. tras con estructura natural, una de 6 a 16 cm. y otra de Los sIntomas comenzaron a manifestarse en el quinto 56 a 66 cm. La primera de estas muestras tenIa 33,13% año; aparecieron aisiadamente en enero para generalizarse y la segunda 33,16% de humedad. y acentuarse a fines do temporada. Presumiblemente la Perfil No. 3: Corresponde al costado Este del monte de iniciación de los sIntomas esté relacionada con la liegada álamos blancos, cerca de una sangrIa. En este lugar los do ralces a la zona iniluida directamente por la napa; álamos presentan agudos sIntomas de sufrimiento. al desarraigar cuidadosamente un árbol se notó quo la maxima concentración radicular está en la capa do 0 a No. MuestraPro fundidadObservaciones de campaña 43 cm., a partir de los 50 cm. ci eje principal toma 289 0-15 cm. Texturafranco-limosa;abun- bruscamente una dirección horizontal. dantes restos y raIces de male- En la corteza del tronco de algunos árboles se observa- zas. Medianamentehümeda. ron manchas huimedas, de color externo rojo vinoso e Color obscuro, casi negro. interno casi negro, las quo no ilegan a efectuar el xilema. 290 15-22 cm. Textura franco-arcillosa. Color algo más claro. Menor propor- Por algunas lenticelas se notaron exudaciones de un ción de raIces y restos vegetales. lIquido obscuro y excrecencias blanquecinas. 291 22-42 cm. Mucho más hiimeda,iguales Alamo "Blanco": Se presentaron dos tipos do sIntomas: caracterIsticas que la anterior. leves (zona de influencia del Perifi No. 2) y severos 292 42-65 cm. Saturada de agua. Arenosa. (idem Perfil No. 3), y con variantes segOn so trato de ramas primarias osecundarias.Sintomasleves: El nivel de la napa se estabilizO en 95 cm. Se extrajeron onhojasde ramas primarias y chupones,puntua- dos muestras con estructura natural de 6 a 16 cm. y 48 cionescioróticasgeneralizadas;en ho/asde ramas a 58 cm. La primera de estas muestras tenIa 33,89% y secundarias, se produce un desecamiento marginal quo La segunda 29,31% de humedad. abarca pocos milImetros del tejido perimetral. SIntomas Perflu No. 4: Corresponde a un bosquecillo de sauce severos: en ho/as de ramas primarias y chupones; la alamo (Salix alba cv. calva), de la misma edad que lo ciorosis puntiforme se haco rnás densa, afectandola demás. Leves sIntomas de toxicidad salina. mayor parte del tojido foliar, en ho/as de ramas secun- darias la desecación en casi total, con comienzo apical y No. MuestraProf undidadObservaciones de campauia avance centrIpoto, Ia zona peduncular os la ültima en 293 0-25 cm. Texturalimo-arcillosa;abun- secarse. dantes restos vegetales y ral- ces de malezas.Color pardo Sauce alamo: Solo se obsorvan sIntomas loves, con- obscuro. sistentos on desecamiento restringido al ápice y a p0- 294 25-55 cm. Franca, muy hümeda.Menor quefias zonas discontInuas del borde foliar. proporción de restos vegetales y DatosAnaliticos:Los resuitadosdelosanálisis raIces. Color pardo. practicados se consignan en las Tablas Nros. 1-4. 295 55-75 cm. Arenosa, casi saturada de agua. El nivel de Ia napa se estabilizó en 95 cm. Se extrajeron Discusión dos muestras con estruetura natural de 0-16 cm. y 56-66 Tierras:Los datos dc conductividad eléctricadel cm. La primera de estas muestras tenIa 39,56% y la extracto a saturación permiten cl'asificar como salinas a segunda 30,95% de humedad. todas las muestras, y como salino-alcalinas a las do los Se extrajeron muestras do las diferentes capas de los Perifies No. 3 y No. 4.Esta éltima condición ostá perfiles estudiados, de las aguas de la napa y de riego, revelada por altas Rolaciones do AbsorciOn do Sodio, esta Oltima consistento en lIquidos cloacales previamente correspondientes a porcentajes de sodio intercambiables decantados. Serocolectaronhojasdelosárboles superiores al 15%. En ci Perfil No. 3 la alcalinizaciOn próximos a cada calicata y que correspondIan a los que es más acentuada y, dentro de ella, la sodificación del presentaban ci promedio de los sIntomas observados. compiojo aumenta en profundidad. Paralelamente y como tostigos para las determinaciones Agua de riego:Por su baja salinidad no puedo analIticas, se extrajeron muestras de hojas do las mismas atribuIrselo relaciOn con los sIntomas especiesforestalesdelugarestotalmentelibresde Aguas de la napa freática:So observan marcadas salinidad e influencia do napa. diferencias en la composición do las muestras extraIdas Determinaciones efectuadas: En las muestras do tierras do los diferentes perfiles, lo quo rovela una circulaciOn se analizaron las sales solubles del extracto a saturaciOn y insuficiente y una difusión entorpecida por las caracterIs- Forest Protection 915 ticas fIsicas del suelo. En todas ellas es elevada la pro- la napa freática salina la responsable de la acumulación porción de sales nocivas y es notable la estrecha relación de jones que se maniifiesta con los sIntomas de toxicidad Ca, Mg, la que es menor que en la generalidad de las descriptos.Los fundamentos son los siguientes: a) no aguas subterráneas, aün las muy salinas, de la region. hay diferencias en la severidad de los sIntomas que presentan los álamos chilenos que crecen en las zonas de Conclusiones los Perfiles No. 1 y No. 2, a pesar de que la salinidad y Manifestaciones de la Acumulación Sauna saturación de sodio de ambas tierras difieren notable- mente; b) es significativo que los sIntomas de sufriniiento La distinta severidad de los sIntomas con relación a comiencen a manifestarse cuando las raIces ilegan a Ia la magnitud de las sustancias absorbidas, indicarIa que zona influida directamente por la napa; y c) la aparición mientras en el alamo bianco predomina el aspecto cuanti- está tativo de la acumulación sauna en el alamo chileno y en desIntomasdeintoxicación en alamo blanco elsauce alamo es más importante la acción tóxica aparentemente más en relación con el impresionante especIfica de ciertos jones. aumento de sales totales, y en especial cloruro de sodio, Los cloruros siempre están en mayor proporción en de la napa freática del Perfil No. 3, con respecto a la No. lashojas enfermas; a igualdad de concentración de 2, que con la salinidad de ambos perifies. Estas observa- cloruros en el medio el alamo blanco, absorbe menos que ciones concuerdan con conclusiones arribadas por Nijen- ci chileno (comparar datos de la zona del Perfil No. 2, sohn en intoxicación de vid por cloruros, en 1959. comün para ambas especies). 2. La elevada proporción de cloruros, sodio y posible- Con respecto al sodio, ocurre lo mismo que con el mente magnesio, en las napas freáticas y en las capas cloro. inferiores de tierra es la caracterIstica determinante de En todas las especies de "Campo Espejo", la pro- la aparición de los sIntomas de intoxicación sauna. porción de fosfatos, sulfatos y magnesio es mayor que en los testigos de sitios sanos. Corn portarniento Diferencial de los Forestales Estudiados Con respecto al contenido de calcio, en el alamo De los análisis y observaciones realizadas surge chileno, éste es inferior a los tes:tigos; en ci alamo blanco una neta superioridad, en cuanto a tolerancia a con- las diferencias no son significativas y en ci sauce alamo diciones de salinidad, del alamo blanco y del sauce alamo los enfermos tienen mayor proporción que los sanos. con respecto al alamo chileno. Este ültimo se manifiesta En las hojas enfermas de alamo chileno y blanco la como muy sensible, por lo menos en las condiciones proporción de potasio es mayor que en las sanas testigo. suelo-napa descriptas. En ci sauce alamo, aunque las partes secas de las hojas La mayor tolerancia del alamo blanco está rela- enfermas contienen más potasio que las partes verdes de cionada con una menor absorción sauna en general y de las mismas hojas, nunca se alcanza el porcentaje elevadI- cloruros de sodjo en particular, a igualdad de condiciones simo que registra uno de los testigos: 97 m.e.% gr. de ecoldgicas (Perfil No. 2). sustancia seca. Queda abierta la incognita en lo referente al corn- portarniento diferencial del alamo blanco con respecto Relaciones: Suelo, Napa, Planta al sauce alamo, lo que debe ser motivo de futuros 1. Consideramos que no es la salinidad dcl suelo sino ensayos, en igualdad de rnedio suelo-napa.

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Ref erencias given. Chemical analyses of healthy leaves from non-saline areas were conducted at the same time. Hayward, H. E., and Bernstein, L., 1958. Plant-growth relation- Among the conclusions reached up to the present, the follow- ships on salt-affected soils.Bot. Review. 24:584-635. ing are emphasized: Nijensohn, L., 1955.Conductividad eléctrica potencial.Boletin The tolerance of Populus alba cv. bolleana and Salix alba Técnico del Inst. de Invest. de la Vjd y el Vino (Gno. Mza.) cv. calva to salinity conditions and high water table appears to Vol. 1, No. 4: 183-200. be similar and superior to Populus nigra cv. italica sempervirens. Kuanghu Cheng and Roger H. Bray, 1951.Determination of In Populus nigra cv. italica sempervirens the symptoms of calcium and magnesiuminsoiland plantmaterial.Soil saline toxicity are correlated with a higher percentage of total Science (72). ash in the three species studied and an abnormal concentration of U. S. Salinity Laboratory Staff, 1954. Diagnosis and improvement chloride, sodium, and magnesium ions. of saline and alkali soils. Agr. Handb. No. 60, USDA. The two species of poplars have in their affected leaves a Nijensohn, L., y Avellaneda, M. 0., 1959.Determinación de lower percentage of calcium than the healthy samples. sodio en aguas y suelos por fotometrIa de llama. (inédito). Salix alba cv. calva has in its affected leaves a lower content Nijensohn, L. Resistencia a Ia salinidad de 9 variedades portain- of potassium, in comparison with the healthy samples.In the jertos de vides americanas.Primer Congreso Antifiloxérico. other two species the absorption of potassium increases along Mendoza. the same lines as the absorption of sodium. Nijensohn, L.,1959.Intoxicación de vides por absorción de The differences in phosphorus contents are not significant. cloruros. (inédito). Therearenotabledifferencesinmineralcomposition between dry and green parts of the same leaves. RESUMES Saline Intoxication of the Poplar and the Willow Poplar Intoxication saline du peuplier et du saule-peuplier This paper is concerned with the study of a forest plantation Les auteurs étudient une plantation de peupliers chiliens (Popu- of Pop ulus nigra cv. italica sempervirens, Pop ulus alba cv. bol- las nigra cv. ittilica sempervirens), de peupliers blancs (Populus leana and Salix alba cv. calva, which is located on a soil with a alba cv. bolleana) et de saules-peupliers (Salix alba cv. calva), high saline water table. The plantation is irrigated with sewage située sur un sol de peu de profondeur subissant l'infiuence de la waters from the City of Mendoza. The symptoms of saline nappe phréatique saline. La plantation est irriguée par les eaux toxicity are described for each one of the species mentioned above, d'dgoât de la ville de Mendoza, préalablement décantées.Ils and the results of the analysis made of various soil profiles, of décriventles symptômes de toxicitésaline dans lesdiverses irrigation and underground water, and of affected leaves are also espèces observées et indiquent les résultats des recherches prati- Forest Protection 917 labia 4

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918 Fifth World Forestry Congress Proceedings Forest Fire Control

VALENTIN GRIGORYEVICH NESTER0V Head, Forestry Chair, Timiryazev's Agricultural Academy, Moscow, U.S.S.R.

In the USSR, great attention is being paid to the study Table 1. Classification scale of forest stands as to their of factors causing forest fires and 10 the elaboration of inflammability and fire danger, adopted in the USSR fire prevention measures. (classes of inflammability and fire danger) The occurrence of forest fires and their spreading are Fire danger determined by the following three factors: Inflammability and burning characteristics of forests The availability of The a highway of nearest The nearest depending upon the tree species in a stand and upon common use insidepopulated populated lo- soil conditions. Category of stand the lire site or atlocalitycality is at a Sources of fire (burning matches, cigarette stubs, according to its fire-a distance of 200is at a dis- distance of catching capacity m.; a populatedtance ofmore than sparks, lightning, etc.), and available means for quick locailty or logging5-10 10 km. extinguishing(vicinity of fire extinguishers, highways, operations site as kin. etc.). near as 5 km. Weather conditions (dry, windy) and temperature Coniferous stands of conditions. dry and fresh tree Mathematical expressions of these factors were estab- types and broad- lished in the forms of tables, equations, and graphs. In leaved stands of dry the USSR, a system of warning, detecting, and extinguish- tree types I-A ing of forest fires has been adopted. The measures carried Coniferous tree stands out in compliance with this system are included in special of wet and marshy plans of fire prevention and fire conservancy. Some of tree types TI-A our papers are concerned with tie elaboration of such Broadleaved stands of fresh, damp, and wet plans and with problems associated with forest manage- tree types 111-A ment and reforestation. The basic prevention measures against forest fires in- clude the breakdown of forest territory into plots with In accordance with the above scale, the type and loca- stands consisting of trees with similar burning char- tion of fire prevention forest plantations are established; acteristics and, consequently, with similar susceptibility special recomendations have been worked out as to wood- to catching fire.Isolation of these plots from each other cutting practice and maintenance, types and distribution is achieved by means of special fireproof barriers, such as of fire prevention isolation cuttings, network of mineral- firebrakes (cuttings), fire-protection bands, fireproof vege- ized strip bands, communication lines, road building, dis- tation, and mineralized strips.Provision is made for a tribution of firetowers, fire-chemical stations, landings for road network, transportation, communication facilities, aircraft, etc. and various types of extinguishers. Designs of fire prevention protective forest strips, fire- "Instructions on working out plans of forest fire preven- breaks(cuttings), mineralizedstrips,and damp-grass tion measures for forestry organizations" was published barriers are based on the method of encircled barriers. in 1940, sponsored by the former "Glavlesookhrana", Using this method, the above-mentioned fire prevention under the Council of Ministers of the USSR. Sub- measures, in conjunction with available rivers, brooks, sequently (in 1949), on the basis of these "Instructions," highways, and nonburning wet strips of wood, should another manual on forest conservancy and forest fire ensure the breakdown of the forestedterritory into control was published as a guide for all organizations isolated plots, or fire blocks. Types and networks of bar- concerned. This manual was later corrected and reedited. riers have been established, taking into account the nature The modern concepts and practice of forest fire preven- of the environment, magnitude of fire danger, and eco- tion in the USSR are based on the following classification nomic significance of the stand. Other problems pertain- scale of forest-tree stands (as to their inflammability and ing to forest fire control, i.e., means of transportation and fire danger) (Table 1.). communication,availablefireextinguishers,etc.,are tackled with due account of the conditions prevailing in of forest conservancy of the USSR. individual fire blocks of the stand. Forest Protection 919 The investments which go to forest conservancy and factor of inflammability of stands should be increased by forest lire prevention will be more effective if they are ¼ of its total value. spent in accordance with previously worked-out plans of On the basis of the overall hydrothermal criterion, a forest fire prevention. scale of forest fire danger has been worked out, which is Of great importance in forest surveillance is the effec-. applied in the USSR along with forestsurveillance tive fire prediction service.Foresters of many foreign measures (Table 2). countries have done considerable research work in this field. In the USSR, following a number of investigations, a complex meteorological method of determining fire- Table 2. Classification scale of fire-danger danger weather has been adopted. In 1940, this method weather and fire prevention measures was recognized officially. The first manual on this method Value of com- approved by the Glavlesookhrana (at the USSR Council plex indices of Ministers) was published in 1949 under the title "In- (txd)- struetions for determining fire-danger weather and in- sum of the flammability of forest trees." Class of fire- products of danger weather temperatures Fire control measures in Numerous investigations have shown that the widely and of and humidity summer; foliage and used classificationscales of forest tree inflammability inflammability deficit values of forest tree at 1:00 p.m. on grass are green based on separate meteorological factors (e. g., air tem- stand all days elapsed perature, himidity deficit, relative humidity, etc.) can after the rain- no longer satisfy practical needs. Inflammability depends fall, including on many meteorological factors, and changes occurring the day of the previously are of importance as well. rainfall Special experiments were carried out; 600 test fires I. Absence ofLess than 300 Partial utilization of the were carried out with simultaneous fixation of meteor- inflamma- watch staff and equipment ological conditions, and more than 20,000 meteorological bility for some otherdutiesis indices were applied. The tests conducted showed that the allowed. No duties on fire- inflammability of forest trees is best defined by the dura- towersarenecessary;no need of ground inspections; tion of the period following the last rainfall and by tem- patrol flights of aircraft are perature and humidity deficit changes occurring during forbidden;forestfirebri- this period. Of some importance als!o are the amount of gades are engaged in repair the last rainfall and wind conditions following it. work and technical training On the basis of the physics of the phenomenon and Small 301-500 Routine watch duties and associated coefficients, a reliable, overall meteorological preparedness to take meas- ures against fire. Duty serv- system of determining forest inflammability was worked ice on firetowers is required out. inthe daytimefor 2-4 Many overall indices wcee investigated, and finally the hours; ground inspection is performed only in the mid- following one was accepted: T =(t x d); where T = dle of the day and in the inflammability of the stand, = sign of sum, t = tem- fire-dangeroussectionsof the stand; patrolling flights perature of the air at 1:00 p.m. of each day after the last of aircraft are made occa- rainfall, d = humidity deficit at 1:00 p.m. of each day sionally,by order of the for the same time interval. firewarden of the division; firebrigades are on duty In other words, the inflammability of forest trees is onlyinthedaytimefor determined by the sum of the products of the values of air 2-4 hours. temperature by the humidity defici't at 1:00 p.m. of all Medium 501-1,000 Increased watchguard and the days elapsing after the last rainfall.In order to readinesstofightagainst fire; outposts on firetowers define the inflammability characteristics of the stand, it is must be on duty for 6-8 also possible to use either the sum of the temperatures or hours in the middle of the the sum of the humidity deficits for the period following day;ground inspectionis carried out in the daytime in the last rainfall, since these values differ only slightly the most dangerous sections from the sum of the products of temperature and humidity ofthestand;patrolling deficits. At the same time, a correction on the last rain- flights of aircraft are made once a day; fire brigades are fall should be taken into account. If precipitation is less on duty for 6-8 hours. than 3 mm., it may be neglected, since it does not reach High 1 ,000-4,000 Veryalertwatchand the soil.If precipitation exceeds 3 mm., then the calcu- readiness tostart fight lation of the factor should be started anew, and in the against fire. Duty service on firetowersfrom dawntill first days differential corrections on the size of the last sunset; ground inspection in rainfall should be inserted. all parts of the stand; air- The role of the wind may also be of importance. Thus, craft make patrolling flights twice a day, fire brigades are if on the day of calculating the fire danger the wind on duty during the whole exceeds 10 meters per second, then the calculated overall day.

920 Fifth World Forestry Congress Proceedings V. Extraordi- above 4,000 Extraordinary fire preven- Considering the measures pertaining directly to forest nary tion measures. Firemen are fire control, it may be assumed that the effectiveness danger on duty on firetowers day and night; ground inspection (success) of these measures depends, to a very great and airborne patrolling non- extent, on early fire warning and expeditious arrival atthe stopfirebrigades are on place of disaster. This may be achieved only by using the duty day and night. meteorological systemofsignalization.This system ensures high watchfulness of fire outposts andfiretowers Designations:=sign of sum; t==temperature of the air in °C. at 1:00 p.m.; d=humidity deficit at 1:00 p.m. (in millibars). along the railroads and highways, and near the forestry Note: In spring and autumn, when there is neither vegetation establishments from aircraft and helicopters, and allows nor overland grass cover, fire prevention measures designed for early detection of fire danger. the 2nd class are used in the 1st class; those designed for the 3rd class are used in the 2nd class; those designed for the 4th class To liquidate forest fires two methods may be used; are used in the 3rd class; and those designed for the 5th class are (1) localization; and (2) extinguishing. Which of the used in the 4th class.The fire prevention measures in class 5 two is more effect'ive?so far, there is no general answer. are used as indicated. Everything depends on the nature of the fire and the available means to fight it.Table 3 shows the compara- tive effectiveness of various fire control measures. The above scale was worked out for regions of the USSR where fresh, not dry, and not boggy types of forest Table 3. Effectiveness of various techniques tree stands prevail, i.e., it is applicable to the major part of localizing and extinguishing forest fires of the forest zone. Indices of relative Requirements For regions where dry types of stands are spread (e.g., rate of localizing Name of applied technique in labor band pine forest in the Altai Territory and in the Kazakh and extinguishing(approximate) SSR) other gradations of the hydrothermal criterion are a fire used:1st class weather indices, less than 150 degree- Digging around the stand on millibars; 2nd class = 15 1-250; 3rd class = 25 1-500; firewith spadesor some 4th class = 501-2,000; and 5th class = over 2,000. other hand tools 1 In regions with a predominance of damp and broad- One-furrow ploughing with a leaved forests, the class gradations of the criterion will be horse-drawn plough 30 Two-furrow ploughing with a considerably higher. horse-drawn plough 15 1/5 In some cases a three-class scale of the fire-danger Ploughing around the fire with criterion is used: 1st class, indices less than 300 degree- a tractor-drawn plough 60 millibars (forest fires are impossible); 2nd class, indices Burning up dry branches with equal to 300-1,000 degree-millibars (low fires are pos- torches 2 sible); 3rd class, indices are above 1,000 degree-millibars Burning up with firegun 10 Vio (top fires are also possible). Extinguishing fires by means of Comprehensive local 'scales are also worthwhile men- chemicalsol using manual tioning since they are based on thorough knowledge of sprayers 12 the peculiarities of small territories, but they cannot justify Setting up chemical protective barriers by manual sprayers 3 rejection of a general scale which can be used for making Setting up chemical protective plans for fire prevention measures for large areas. barriers by tractor-drawn On the basis of the classification 'scale referred to sprayers 45 above, the Central Institute of Forecasts issues daily Extinguishing fire by manual information maps with meteorological data on forest fire water pump 9 Extinguishingfireby tractor danger for the territory of the USSR and makes forecasts 1/3 of forest tree inflammability for three days, for a synoptic water pump 20 Extinguishingfirebymoto- period (about one week), and for a month. pu1-1p - 30 The methods of forecasting forest fires, however, need further consideration and improvement. At present, great attention is paid in the USSR to such problems as im- In the majority of cases, the most effective of the provement of meteorological methods of determining techniques referred 'to above are localization of the burn- forest fire danger, correction of the method of wooden ing stand by tractor-drawn ploughs, by means of chemical cylinders, utilization of the method of wooden hygro- substances using various sprayers, and by using water meters, etc. motopumps. It appears that the probability of forest stands' catching More attention should be paid to the development of fire must be determined basically by a complex meteor- chemical means of forest fire extinguishing, particularly ological method, because only this method allows us to to the utilization of fire-extinguishing gases and vapors. make forecasts for the future. At the same time, in every- The experiments conducted in this field give encouraging day practicesuch simple techniques as weighing of wooden cylinders, recording of changes 'in the position of results. a branch taken with a cut of a trunk, utilization of under- RESUMES laid hygrometers, etc., should not be neglected.In all these cases it will be expedient to work out convenient La lutte contre les incendies de jorêts automatic devices which will be of great help. En U.R.S.S. on se penche très sérieusement sur l'étude des

Forest Protection 921 facteurs qui sont la cause des incendies de forêts et des mesures En 1940 se publicaron, bajo los auspicios de la Glavlesookhrana preventives destinëes a combattre ces incendies. (Dirección General de Protección Forestal) dependiente del Con- La fréquence des incendies de forêtsetleur propagation sejo do Ministros de la U.R.S.S., las "Instrucciones para la pre- dependent des trois facteurs suivants: paraciOn de planes para la aplicación de medidas de prevención L'inflammabilité et la combustibilité des forêts, selon les de incendios forestales por parte de orgarnzaciones forestales." espèces et l'état du so!. Subsiguientemente, en 1949, y sirviendo de base tales instruc- Les éléments qui constituent un risque d'incendie (allumet- ciones, so publioO otto manual sobre protecciOn forestal y lucha tes et cigarettes non éteintes, étincelles, foudre, etc.) et les moyens contra incendios forestales, en calidad de guIa para todas las disponiblespourleséteindrerapidement(emplacement du organizacionesinteresadas.Posteriormente,estemanualfue materiel de lutte contre l'incendie, routes, etc.) sometido a revisiOn, puhlicándose una nueva versiOn del mismo. Les conditions métëorologiques(sécheresse, vents)et Ia La práctica ha establecido que la lucha contra incendios temperature. forestales solainente es eficaz cuando el nOmero de incendios es Ces facteurs sont exprimés mathématiquement par des tableaux, reducido y cuando es posible aplicar en forma inmediata las equations etgraphiques.L'U.R.S.S. a créé un système pour medidas de represiOn. l'avertissement et la detection des incendies de forèts et leur extinc- tion. Les mesures mises en oeuvre en vertu de ce système font partie de plans spéciaux de prevention et de lutte contre les Comments incendies.Certaines de nos communications portent sur la pré- paration de tels plans et sur les problèmes relatifs a l'aménagement James W. Kimmey (U.S.A.) forestier et au reboisement. Mr. Offord has excellently summarized the use to date Les mesures essentielles de Ia prevention des incendies de forêts próvoient la division des regions forestières en zones comprenant of chemicals in forest disease control. Of course, in so des peuplements dont les espèces ont des caractéristiques de com- short a time he could, for some types of diseases, only bustibilité identiques et, par consequent, présentent les memos give examples of a wide variety of chemicals used. This risques d'incenclie; l'isolement de ces zones les unes des autres is particularly true for nursery prob]ems, where many au moyen de coupe-feu, de couverture vdgetale ininfiammable ou de revêtements minéraux; la creation de réseaux routiers, de chemical materials are available from a number of manu- moyens de transport et de communication et Ia mise en place de facturers. divers appareils de lutte contre l'incendie. Extensive use of chemicals in forest nurseries is largely Un ouvrage intitulé "Instructions destinées aux organisations attributable to two circumstances: First, the similarity of forestières pour la preparation de plans prévoyant des mesures preventives contre les incendies de forêts" fut publié en 1940 sous our forest nursery practices and procedures to those in l'égide de l'ancienne Glavlesookhrana, (Administration principale horticulturaland ornamentalnurseries,andtoour de Ia protection des forêts) relevant de la direction du Conseil numerous and highly developed agriculturalusesof des Ministres de l'U.R.S.S. Plus tard, en 1949, sur la base de ces chemicals; and second, the economic feasibility of chemi- instructions, on publia un autre manuel sur la protection des forèts Ct sur la lutte contre les incendies de forêts, destine a cal use in forest nurseries because of the high values touslesservicesintéressés.Ce manuel fut subséquemment involved in small areas. révisé et fit l'objet d'une nouvelle edition. The lack of this economic feasibilitythat is, the high Selon l'opinion exprimée dans le manuel, la lutte contre les incendies de forêts ne peut être efficace que lorsque le nornbre unit cost involvedhas deterred our use of chemicals d'incendies est faible et si les mesures pour combattre le simstre for disease control in managed forests. This is especially peuvent ètre prises rapidement. true where silvicuitural practices may be used effectively as an alternate method of disease control. Our greatest Control de Incendios Forestales use of chemical control in managed forests has been where En Ia U.R.S.S. se presta considerable atención al estudio de silvicultural control is not possible or is not practicable, los factores que causan los incendios forestales, as! como a las and where direct control measures are necessary to medidas que previenen tales incendios. La ocurrencia de incendios forestales y su diseminación se prevent enormous losses. determinan por medio de los tres factores siguientes: When direct control is mandatory, as in the case of Intlamabilidad y caracteristicaS de combustion de los bos- white pine blister rust, the use of chemicals may become ques, factores éstos regidos por las especies de árboles que corn- the more economical and otherwise practical means of ponen el bosque y por las condiciones del suelo. control. The use of antibiotics has not only lowered the Origen del incendio (fósforos y cigarrillos encendidos, chis- pas, relámpagos, etc.) y medios disponibles para su rápida ex- costs of blister rust control, but, because of its practicabil- tincidn (ubicación de los equipos para la lucha contra incendios, ity,has extended control to additional acreages.The caminos, etc.). previous one million acres in the Inland Empire western Condiciones cliniatológicas(falta de humedad, vientos)y white pine blister rust control units have now been temperaturas. extended to two million acres, and as aerial application Las expresiones matemáticas de estos factores se establecen en forina de tablas, ecuaciones y gráficos. En la U.R.S.S. se ha is perfected, this area may be further extended. Use of organizado un sistema de alerta, detección y extinción de incen- antibiotics also makes practicable control on small isolated dios forestales. Las medidas llevadas a cabo de conformidad con areas and on shade and ornamental white pine trees. este sistema forman parte de planes especiales para la prevencidn y la lucha contra incendios. Algunos de los trabajos presentados In general, however, the high cost of direct control, por la delegación de la U.R.S.S. hacen referencia a la preparacidn whether by chemicals or by other means, plus the in- de tales planes y a problemas relacionados con la administración terest on investment over long periods, will cause silvicul- y la repoblación forestales. tural measures to remain the favored method of control Las medidas básicas de prevencidn de incendios forestales corn- prenden la division de una zona forestal en bloques que conten- for many forest diseases. When silvicultural control is gan árbo!es cuyas caracterIsticas de combustion son similares y as practicable as it is for dwarfmistletoes, it is doubtful que, en consecuencia, presentan peligros similares de incendio; whether direct chemical control of dwarfmistletoes will el aislamiento de estos bloques entre Si, por medio de claros ever supplant silvicultural control entirely.If we now especiales, vegetación incombustible o superficies mineralizadas; la creaciOn de redes de caminos, servicios de transportes y had a means of chemical eradication of dwarfmistletoe, comunicaciones y provisiOn de equipos para la lucha contra it would undoubtedly be used only to supplement silvi- incendios. cultural control.

922 Fifth World Forestry Congress Proceedings Although we have made noteworthy advances in the What are the main effects of dwarfmistletoe on forest use of chemicals in forest disease control, we have a long trees? In the preceding paper, reduced stocking, adverse way yet to go. So far, we can afford such luxury only influences on yield, and lowering of site index have been Where values at stake are large.However, costsof mentioned. Our own research has shown marked reduc- chemicals and their application wifi undoubtedly decrease tion in radial increment of Douglas-fir associated with with future development, and forest values are bound to dwarf mistletoeinfections.Similar findings have been increase; so we can predict wider use of chemicals in reported by other workers.In western hemlock, the disease control. We must remember, though, that all this swellings and the stubs of broken brooms provide ideal will take time.Each disease organism in each host infection courts for decay-causing fungi. In all species, species may require a different chemical or separate stem infections at an early age result in deformed and formulation, and various dosages and application tech- stunted growth. The large knots associated with brooms niques must be developed for each. reduce log grades significantly. Much isstill to be learned through fundamental re- Current research (Rediske, J. R., and K. R. Shea, search. We need to find out how and Why certain chemi- 1960.Plant Physiol. 35(Suppl.): 3) has shown that cals effect control. When we know this we can lessen the dwarfmistletoeinfectionsinterferewiththenormal time and expense in screening trials for the numerous translocation of photosynthates produced in the needles chemical materials, as we will have a basis for recogniz- distaltoinfection. Inmostinstances,premature ing and for synthesizing suitable chemicals. Our progress decadence and increased mortality have been noted in in chemical control of forest diseases, then, will depend severelyinfectedforeststands.Probably,infeci ions largely upon the amount and quality of research. Mr. predispose trees to the adverse influences of drought and Off ord has indicated the direction this research should other biotic agencies. take and certain types of studies needed. Anything that The limitations on productivity imposed by dwarf- any of you can do to stimulate such research will result mistletoes now is generally recognized. The U.S. Forest in improved forest disease control. Service presently is preparing an economic study of con- siderable extent on this parasite in ponderosa pine to Keith R. Shea (U.S.A.) provide basis for establishment of control procedures. In recent years, the dwarfmistletoes of western conifers Once the loss is defined in dollars and cents, the amounts have received increasing attention by State and Federal which can be spent on control can be resolved. Mean- agencies and by private industry. This has resulted from time, there is a continuing need for basic research such the requirement that every acre of forest land produce as host-parasite relations and physiology.Experimental the maximum potential yield at a minimum cost in the applications of present knowledge on pilot scale basis shortest economic rotation possible. Attention has been focused on the individual tree and the effects of factors and extension to include all commercial conifers attacked influencing growth adversely.Thus, insidious parasites by dwarfmistletoes should be intensified. The long-term suchasthedwarf mistletoeshavereceived growing goals should include development of reliable means for recognition as factors limiting the productivity of forest appraisal of damage and for effecting control in a manner trees. consistent with sound economic principles.

Forest Protection 923 Session C Forest Entomology Entomologie des foréts Entomologi'a Forestal .

Forest Aerial Spraying Dosage Concepts and Avoidance of Hazard to Fish and Wildlife

JAMES J. FETTES Head, Chemical Control Section, Forest Biology Division, Research Branch, Canada Department of Agriculture, Ottawa, Ontario, Canada

Introduction were successfully treated. The spruce budworm had long Prior to 1945 the competition between man and insects been a serious pest of the spruce-balsam forests of Eastern for the produce of some of our forest types was dis- Canada and Northeastern United States, where many couragingly one-sided.Insect outbreaks, particularly of thousands of square miles of merchantable timber had defoliating insects, were frequent and widespread. The fallen to this insect. The forests of the Province of New forest industry could do little but watch the destruction Brunswick, Canada, were seriously threatened in 1951. and try to salvage what it could of the affected forest. The The economy of New Brunswick being largely dependent constant threat of insects and fire to the security of forest on its forest produce, the threat was too great to be borne investment weighed heavily on fiscal policy and, in turn, without some attempt at protection. In 1952, the largest hindered sound conservation. The threat of fire could be forest spray operation in the world was initiated, and, to minimized by improved detection and combat techniques, the present time, about 18,000,000 acres have been but the insect threat was an incalculable risk. The dis- treated, and 2,250,000 acres are scheduled for treatment covery of the insecticidal properties of DDT and the in 1960 (Webb, 1959). Much of this acreage represents improvements in aircraft during the war years combined repeated spraying in different years, but the net acreage to provide the first real hope that some insect outbreaks of infested forest that has been protected totals about 10 might be held in check artificially. Several years of active million acres. Most of the sprayed forest has survived. experimentation in Europe, the United States and Canada Much of it would undoubtedly have succumbed without (Balch, et al., 1956)1 showed aerial spraying of forests treatment. for the control of defoliating insects to be practicable and At the outset, biologists were keenly aware of the economically feasible. Numerous experiments the world dangers of broadcasting poison over vast areas of land and over were judged successful in controlling a great variety water, as evidenced in the numerous studies of wildlife of leaf-eating insects, although the early projects were and aquatic fauna which paralleled the forest spray relatively small. The accumulation of experience paved experiments (Hoffman and Surber, 1945; Anonymous, the way for attempts to control some of the vast infesta- 1949; Rudd and Genelly, l956).2 Many of the studies tions of the spruce budworm (Choristoneura fumiferana were part of the same programs, integrated with and com- Clem.) in the coniferous forests of North America. plementary to the insect control projects. The co-opera- The first program of large proportions was undertaken tion between wildlife,fisheries and forest entomology in the States of Oregon, Washington and Idaho, U.S.A., research teams is even more close today. in the years 1949 to 1957, where several million acres The earlyexploratorystudiesshowed clearlythe hazards to certain populations in the forest biome, partic-

1A review paper on aircraftinforestry,including many references. Exhaustive review of effects of pesticides on fish and wildlife.

924 Fifth World Forestry Congress Proceedings ularly in the aquatic environment. Early in the develop- forested areas causes serious or lasting effects. The acute ment, maximum safedosages weresuggested. The problem appears, therefore, to be the influence on the common safe dosage was set at one pound of DDT in one aquatic environment. gallon of solution per acre. This dosage was considered Since forestry and fisheries are intermingled in coastal the lowest which would control insect infestations and and inland streams, a philosophy of uncompromising seemed to cause no serious harm to fish, fish-food organ- competition for these natural resources may not be un- isms, or wildlife.Actually, the accepted one-pound-per- expected. Uncompromising as the philosophy has seemed acre dosage seems to have evolved empirically rather than in some circles, it should be assumed that forest protection to have been determined scientifically, since there appears and fish conservation are compatible objectives, and it to be no early report of a decision on this dosage. The remainstosolvethe problems associated withthe forester felt this to be the minimum effective dose, and the existence of high hazard to either one of them.Early fish and wildlife biologist felt that a greater amount would acceptance of "one pound of DDT per acre" as a mini- be unacceptable. In fact, reports by several early investi- mum dose, and adherence to this dosage without further gators showed that this dosage could be highly dangerous critical experimentation, were undoubtedly faulty con- to aquatic fauna (Cottam and Higgins, 1946; Hoffman cepts.Primarily, the requirement was for the control of and Surber, 1945). Since no great damage was apparent defoliators, and this goal was achieved. Gradual realiza- except in isolated cases, or because field observation was tion that there have been serious undesirable side-effects inadequate, this dosage became solidly established for suggests the need for re-evaluation of the techniques and forest spraying. Later, in New Brunswick, the logistics of specifications of aerial spraying for the control of forest large-scale operations and a relaxation of the criteria for insect pests. adequate budworm control led to the acceptance of one- half pound per acre (Flieger, 1953). If we ignored the Biological Considerations in a Spray Program earlier biological studies, or if they failed to reveal the real dangers of indiscriminate application of poison on the The decision to spray should be made after a careful forest,it was because most of them occurred in the balancing of the various resource values at stake and after earliest phases of a new era. No long-term observations consideration of all the factors which would help keep could have confirmed or disproved the experimental con- the hazard to associated fauna to a minimum. Treatment clusions; time had not permitted the development of of forests with insecticide should be considered as an improved experimental techniques. A report on the emergency measure and not as a substitute for other earliest work in the United States in 1944 anticipated the methods of protection or management. The history of results of intensive studies repeated in Canada in 1958. insect control in orchards and agricultural lands has pro- Quoting from Craighead and Brown, 1945, "It has been vided an object lesson in the futility of becoming entirely determined that DDT in low dosages is a very effective dependent upon chemical control for the assurance of a insecticideforthecontrol of many forest insects harvest. The elimination of insect pests and all of their gov- probably ½ to ¼ pound (per acre) being sufficient for erning parasites and predators results in a condition which satisfactory control of many forms when the material is fosters even more severe infestations, which, in turn, must effectively applied." be controlled.Repeated treatments increase natural re- sistance so that more intensive control measures must be More recently, the more serious aspects of the hazards taken or new insecticides must be developed, which, in to other fauna, particularly aquatic, have emerged. Long- turn, may become ineffective.Treatment ofspecific and short-term observations on Atlantic salmon popula- forested areas has not been repeated frequently enough tions in the streams of New Brunswick have caused to reveal resistance, but it is conceivable that this could serious concern (Kerswill, 1957).The fry and parr occur if chemical control were to become a prime protec- populations declined greatly in years of spraying, leading tion tool. The forest industry is dealing with a crop re- to forecasts of greatly reduced runs of adult salmon from quiring many decades to mature. The economic drain of the affected generation (Kerswill, 1958b). A relatively frequent chemical treatment may well become intolerable. small spray program against the black-headed budworm There are several criteria which should be considered (Acleris variana (Fern.)) in British Columbia, Canada before a decision to spray is made. (Brown, et al. 1958), sprayed at one pound of DDT in Localizedinfestationwhichthreatenstogain one gallon (U.S.) per acre, resulted in almost complete momentum and endanger large areas.If this situation is eradication of coho salmon fry (Crouter and Vernon, clearly recognizable on biological grounds, the approach 1957) in two streams. Three years later the effect was may well be one of an attempted annihilation, with due dramatically demonstrated when about 5 per cent of the consideration to the forest values at stake and the proba- normal population returned as adults to spawn. It would ble effect on associated land and water fauna.It may be difficult to estimate the period of time needed to be preferable to sterilize a relatively small area of forest restore these populations, even if no further spraying in preventive action than to suffer the risk of a widespread occurred.The literature contains many references to undesirable effects on populations of birds, and a few to infestation which would be destructive to both forest and mammals (Rudd and Genelly, 1956), but none so drastic wildlife values. as those experienced with aquatic fauna. Some insect Large areas already infested and valuable stands populations were entirely absent from streams following seriously threatened. In such areas, widespread spraying spraying (Ide, 1956). Some reports imply serious dam- may be necessary, but it may not be practicable to strive age to avian and mammalian life for DDT spraying at for a high degree of control. A substantial reduction of least, but it is not likely that the infrequent treatment of the insect population would increase the probability of Forest Protection 925 survival of the trees, and chemical treatment may be a more useful criterion.Experiments with various con- sound procedure. centrations of DDT showed that some lesser concentra- 3. Valuable stands engulfed by a widespread, advanced tions were as effective as the customary 12½ per cent infestation. If such stands are to be kept alive for harvest- (Fettes, 1960). It has also been shown (Flieger, 1953) ing in the near future or to preserve aesthetic values, that ½ gallon of 12½ per cent DDT formulation per repeated spraying could be advocated. acre, properly distributed, results in acceptable control. These criteria assume a sound understanding of the Re-examination of earlier data from Hurtig, et al. (1953), dynamics of the insect population under consideration and and Davis, et al. (1956), shows that effectiveness dimin- knowledge of the tolerance limits of the tree species sub- ishes as average drop size decreases. Thus, the concept jectedtorepeateddefoliation.Infestationsofforest of effective contamination involves the interplay of the defoliators are not well understood or predictably regular, effects of droplet deposit density, insecticide concentra- but the periods of great abundance are usually of definite tion, and droplet size. duration, varying, for example, from 2 to 3 years in the A model of these relationships is presented in Figure 1. forest tentcaterpillar (Malacosoma disstria Hbn.)to The shape of bands is derived from the calculated curve about 8 to 10 years in the spruce budworm. During the of Hurtig, et al. (1953). Their width and position are periodof populationincrease, the reproduction and determined by values obtained from a re-working of the survival potential is so great that only an extremely high data from Hurtig, et al. (1953), transformation of data degree of control would subdue the outbreak, and then from Davis, et al. (1956), and data from Fettes (1960). only if the entire area of infestation were treated.If The shaded area on the left includes all dosages from all effective population control is not feasible during the sources (12½, 10, 6¼, 3½% DDT3) and the medium stages of increasing abundance, treatment should be de- and coarse categories from Davis, et al. The Suffield line layed until later in the cycle, but before the trees have from Hurtig, et al., is used as the model because it is been weakened beyond the likelihood of recovery. Treat- based on a large mass of data. The heavier shading cor- ment toward the latter phase of the abundance cycle adds responds to the heavier concentrations (12½, 10, and the burden of the insecticide to the already weakening 6¼ % DDT), and the lighter shading corresponds to the population, hastens its ultimate decline, and gives the lighterconcentration (3½ % DDT).Only drop-size trees a season or two of respite from defoliation while the frequencydistributionswith mass median diameters outbreak runs its course (Fettes, 1952). (MMD4) of 150 microns () or greater are included. Solution of the problems of forest spraying lies, of The conclusions which may be drawn are: (1) the lower course, in a greater understanding of the biological com- the concentration of DDT, the more drops per unit area plex and in improvements in the techniques of spraying. are required for similar degrees of insect control; and Both phases are under continuing study, and some fresh (2)thecriticalconcentrationisapparently between thought may be presented.Any modified insecticide 6¼ % and 3½ % DDT, since there is no significant dif- formulation that would give satisfactory insect control ference between concentrations of 12½ %, 10%, and while lessening the danger to associated fauna would, of 6¼%. course, be welcomed. Furthermore, any improvement of Comparison of the shaded areas at left and right in techniques that would increase the efficiency of application Figure 1 illustrates the effect of drop size on spray effec- and permit reduced dosage would be advantageous. tiveness. Most of the values determining the shaded area The severity of damage to salmon populations in eas- at the right are derived from a transformation of data tern and western coastal streams of Canada (Kerswffl, from Davis, et al. (1956), wherein are reported the re- 1957; Crouter and Vernon, 1957) created sufficient con- cern for the organization of an inter-departmental commit- sults of a series of tests comprising three concentrations tee on forest spraying operations within the Canadian of DDT (12½, 6¼ ard 3½ %), and three degrees of Government (Prebble, 1960). The function of the com- atomization, fine (80 p. MMD), medium (150 p. MMD), mittee is to inform the various govermnental departments and coarse (300 p. MMD). The shaded area at the of proposed spray programs and to suggest investigations right also includes several points from re-worked data designed to develop methods of increased compatibility from Hurtig, et al.(1953), and from Fettes (1960). between forest insect control and fish and wildlife con- The drop size distributions in this area are all of less than servation. 100 p. MMD. The conclusions which may be drawn are similar to those from the shaded band at the left, but the The Concept of Dosage Control and Effectiveness entire array lies significantly to the right, the important The concept of insecticide dosage evolved from earlier difference being the lesser MMD values. The distribution work is an aggregate of conflicting evidence. The resultant within the band demonstrates the relationship between specifications are empirically drawn. More recent ex- deposit density, concentration and effectiveness; the dis- perimental results lead to a re-appraisal of the criteria tribution between bands, that of deposit density, drop size constituting effective application. and effectiveness.If additional data were available it is Atomization, Insecticide Concentration and Deposit likely that the areas would overlap to some degree. The usual criterion for measuring effective contamina- '12½%, 6¼%, and 3½% DDT atI U.S. gallon per acre tion from a given emitted dose has been volume deposited represents 1, ½, and ¼ pound DDT per acre, respectively. 10% per unit area. Hurtig, et al. (1953), and Fettes (1958) DDT is equivalent to 1 pound DDT in 1 imperial gallon. found that the number of droplets per unit area was a 4MMD=50% point in cumulative drop mass distribution.

926 Fifth World Forestry Congress Proceedings /00 Meteorological Effects on Deposit The success or failure of a spray operation depends to a large extent on the meteorological conditions at spray 00 time. Much of the variability and discrepancy experienced in aerial spray research and control programs can be laid

80 to the vagaries of weather. Comparisons of dosages or THE EFFECT OF insecticides may be more a measure of the degree of DDT CONCENTRATION, DROP temperature inversion (stable air)or lapse (turbulent SIZE & DEPO5IT DENSITY 70 ON MORTAUTY o air) than an actual comparison with the prime factors SPRUCE BUDWORM set up for measurement. A low concentration may yield Drop Sie better results in a strong temperature inversion with a Leff8o,d MMD 00 RighiBond MMD bolOw I0O, light crosswind than would a higher concentration in a weak temperature lapse with mildy established thermal Coroj4_1zYo__ - currents. Swath width depends on the buoyancy of the air and the crosswind component. The swath width over open terrain under sunny skies with a 3-miles-per-hour cross- I I i I I Opops PER 100 SQ CM. /000 wind might be three to ten times the wing span of the aircraft.In the forest, where inversions persist longer, Rgure I. the swath width may be a fraction of that expected.If the crosswind component is low, as with upwind or Evaporation downwind flight lines, the effective swath width may be The influence of evaporation on concentration, and reduced to little more than the wingspan of the plane. Failure to consider the wind component and the tempera- therefore on effectiveness, was purposely omitted from the ture gradient places the success of an operation in explanation of Figure 1 in the interest of clarity. Evapora- jeopardy. It is well understood that wind and tempera- tion is an additional important factor in the dosage effec- ture gradient measurements are additional complications tiveness complex. The deposited droplets, in all cases, in the logistics of an operation, but they must be con- contain a greater concentration of DDT than the original sidered in order to avoid over- and under-dosing of formulation. Oil formulations contain fractions of various alternate strips of forest, and to avoid reduced control degrees of volatility. In the common formulations, where through failure of a large portion of the spray cloud to the diluent is a light cut of petroleum such as fuel or settle into the target area. The necessity for improved diesel oil, the half-volume life of a 120droplet is about control over spraying conditions and flight patterns will three minutes, while that of a 200k droplet is about eight be greatly increased if we are to take advantage of mini- minutes. The initial evaporation is rapid, and the rate mum effectiveconcentrations now being determined. decreases as the more highly volatile fractions are lost Factors governing coverage were less important when (Hopewell, 1959). Thus, there is a differential net in- over-dosing was the rule. crease in DDT concentration during the period of descent Droplet Size Spectrum Control from the aircraft.The smaller droplets become more The key to insect control with minimum hazard to fish concentrated because of the higher ratio of surface to and wildlife is the most efficient use of a minimum volume. The deposited spray is therefore more concen- quantity of insecticide formulation.Having considered trated than indicated by the initial formulation, and the insecticide concentration, the required degree of con- concentration at deposition varies inversely with droplet tamination in terms of droplets deposited per unit area, size.The effect of evaporation probably accounts for and the proper control of meteorological factors, the some of the discrepancies between laboratory and field final criterion of efficient application is that of spray tests.Laboratory tests with DDT showed 10 per cent atomization. Accepting the thesis that the prime criterion for effective deposit is the number of droplets per unit concentrations to be unsatisfactory against the later stages area, it is reasonable to apply the spray as droplets no of spruce budworm (Hurtig and Rayner, 1953), whereas larger than necessary. Generally, the drops should be of aerial spray trials indicated good control in the field at sizes large enough to fall within the expected swath similar concentrations and deposit intensities. Secrest and width, but not so large as to be wasteful of material and Thornton (1959) found 3½ % DDT effective in labora- endanger desirable forms of life. A droplet size spectrum tory tests which included younger larvae. Recent aerial of MIVID 225 p. to 275p.has proven effective. In most spray tests (Fettes, 1960) have shown that DDT con- drop size distributions from spray planes the larger drop- centrations of 6¼ % DDT give excellent results.Con- lets have been 500p.to 1000 p., causing over-dosing di- centrations as low as 3½ %, in general, give results at or rectly under the aircraft. As shown in Figure 1, droplet below the lower range of effectiveness of 12½ % DDT. spectra below 100p.MMD become inefficient because The obvious conclusion from the above results is, "the a large number of drops per unit area are required for customary 12½ % DDT concentration is much greater control.It is not desirable to- obtain uniformity of drop- than is required for acceptable control of the spruce bud- let sizes since uniformity would lessen the differential in worm and, by implication, of many other defoliators as drift distances and so narrow the effective swath width. well." The aim should be to adjust atomization to eliminate the Forest Protection 927 large droplets.The smaller droplets represent a minor tect the forest; and (2) those who are against forest spray- portion of the volume, and it is not important that they be ing on principle. Forest sprayers are held up as despoilers eliminated except where drift contamination isto be of nature, while the wildlife conservationists are posed as avoided.Thus, a narrowing of dropletsizespectra, crusaders for the preservation of nature. Although the particularly by eliminatingthe largedroplets, would undesirable effects of spraying are often exaggerated or increase spray efficiency and would result in better con- the facts are misrepresented, there is some justification for trol with less insecticide. Atomization may be modified by the objections.It is apparent that some insecticide ap- changes in spray nozzles, pressure in the spray system, plications have been indiscriminate, but this is no justifica- or attitude of the nozzles in the air stream. Efficiency tion for the existence of opposing camps. A spirit of may be enhanced by reducing the MMD, but the increased understanding and co-operation can gain more than buoyancy of the spray cloud would necessitate closer antagonism.The evidence shows that much headway attentionto permissible meteorological limits for the toward mutual co-existence has been made, and con- spray operation. tinuing research should resolve the objections which re- main. The Effects of Dose Level on Aquatic Fauna It is universally accepted that the spraying of forests References with poisons endangers populations of a wide variety of Anonymous, 1949.Forest spraying and some effects of DOT. natural fauna. The concept that forests must be protected Dept. Lands and Forests, Ontario, Canada, Div. Res. Biol. against potential devastation through insect outbreak is Bull. No. 2. recognized. The simple rule should be that the former Anonymous, 1959.Effects of an aerial application of DDT on fish and aquatic insects in Montana. Final Report. Montana be minimized by making certain that no more poison is Fish and Game Dept. and U. S. Forest Service. used than is necessary to achieve the latter. An integral Angus, T. A., 1956. The reaction of certain lepidopterous and part of the experimental program in New Brunswick in hymenopterous larvae to Bacillus sotto toxin. Canad. Ent. 88: 1958 and 1959 was the study of aquatic fauna in streams 280-283. Baich, R. E., F. E. Webb, and J. J. Fettes, 1955-56. The use of wholly within the spray areas (Kerswill, 1958 and 1959). aircraft in forest insect control.For. Abstr. 16(4) 1955; 17 These studies indicated no measurable effect on aquatic (1) (2) 1956. insects or young salmon at 1 gallon of 31/8% and ½ Bird, F. T., 1953. The use of a virus disease in the biological gallon of 6¼ % DDT per acre (both doses equivalent to controlof the European pinesawfly, Neodiprionsertifer (Geoff.) Canad. Ent. 85: 437-446. ¼ pound per acre), but corresponding higher concentra- Brown, G. S., A. P. Randall, R. R. Lejeune, and G. T. Silver, tions and volumes had a definite depressing effect. Similar 1958.Black-headed budworm spraying experiments on Van- studies in Montana, U.S.A., using one pound of DDT couver Island, British Columbia. For. Chron. 34: 299-306. Cottam, C., and E. Higgins, 1946. DOT: its effects on fish and in one gallon per acre showed serious hazard to aquatic wildlife. U. S. Fish and Wildlife Service, Circ. 11. fauna (Anon., 1959). Craighead, F. C., and R. C. Brown, 1945. Summary of tests It may then be concluded that the spruce budworm can with DDT in 1944 for control of forest insects.U. S. Bur. be treated successfully with DDT at deposit levels com- Ent. and Plant Quar. E-649. Crouter, R. A., and E. H. Vernon, 1957. Effects of black-headed patible with the conservation of aquatic fauna.Since budworm control on salmon and trout in British Columbia. the aquatic fauna are the most susceptible of forest Dept. Fisheries Canada. animals,itis reasonable to assume that the terrestrial Davis, J. M., W. E. Waters, D. A. Isler, R. Martineau, and fauna, other than some insects, would not be seriously J. W. Marsh, 1956. Experimental airplane spraying for spruce budworm control.J. Econ. Ent. 49 (3): 33 8-341. affected by such treatment. Fettes, J. J., 1952. Recent developments in the biological assess- ment of insecticide effectiveness as applied to forest insect Direction of Future Development infestations.Proc. Ent. Soc. Man. Can., 1952: 44-56. 1958. Problems of forest aerial spray dispersal and The search for a substitute for DDT which would assessment.Proc. X Inter. Congr. Ent. 1956. 4: 28 1-289. present lesser hazard to fish and wildlife has not met with 1960.Control of the spruce budworm by aircraft spraying and the hazard to aquatic fauna.Bi-Mon. Progr. success among chemical insecticides, but encouragement Rept. Div. For. Bio. Agric. Can. 16(1): 1-2. may be drawn from recent developments in the field of Flieger, B. W., 1953. Spruce budworm spraying in New Bruns- insect diseases and toxins. Virus diseases have been suc- wick, 1953. Bi-Mon. Progr. Rept. For. Bio. Div. Dept. Agr. cessfully used against several insects, notably sawfiies Can. 9(5): 1-2. Hoffmann, C. H., and E. W. Surber, 1945. Effects of an aerial (Bird, 1953), and further tests are scheduled in 1960. application of wettable DDT on fish and fish-food organisms Through selection,Smirnoff has developed a highly in Back Creek, West Virginia.Trans. Amer. Fish. Soc. 75: virulent strain of a virus of the jack pine sawfly, Neodi- 48-58. prion swainei Midd.(personal communication).The Hopewell, W. W., 1959. Evaporation rates of small drops of two spectacular success of Bacillus thuringiensis preparations DDT solutions. Can. J. P1. Sci. 39: 204-209. Hurtig, H., J.J.Fettes, A. P. Randall, and W. W. Hopewell, (Angus, 1956) offers a possible solution to the problems 1953. A field investigation of the relation between the amount posed by the broadcast use of poisons. The toxins have of DDT spray deposited, the physical properties of the spray shown toxicity to a narrow range of related insects and and its toxicity to larvae of the spruce budworm. Can. Def. Res. Board, Suffield Rept. No. 176. little or no toxic effects on other fauna. Such toxins may Hurtig, H., and A. C. Rayner, 1953. The effect of pyrethrum prove to be the ultimate in insecticides-that is, highly synergists on the toxicity of DDT to sixth instar spruce bud- effective and highly specific. worm larvae. Can. Def. Res. Bd. Suffield Tech. Papr. No. 28. Kerswill, C. J.,1957.Effects of DDT spraying on Miramichi A survey of the literature gives the impression that salmon. In "Trade News," Dept. of Fish., Can. June 1957. those concerned with chemical control of forest insects 1958 a. Interim summary of effects of forest spray- are divided into two camps: (1) those who wish to pro- ing with DOT and DDD insecticides on fishes and aquatic

928 Fifth World Forestry Congress Proceedings insects in the Richibucto area. N. B. 1958. Unpubi. Tnt. Rept. météorologiques et de l'atomisation sur l'efficacité de l'opdration Fish. Res. Board Can. St. Andrews N. B. Bio. Sta. de pulvérisation peut être avantageusement exploitée et diminuer 1958 b. Effects of DDT spraying in New Brunswick les dangers de destruction de la faune forestière. on future runs of adult salmon. The Atlantic Advocate 48(8): La mise au point de maladies d'insectes et de toxines permet 65-68. de grands espoirs pour la lutte contre les insectes au moyen 1959. Preliminary report on observations on young d'agents hautement spéciflques.L'étude se limite avant tout a salmon and trout subjected to forest spraying with DDT and l'expérience acquise sur le continent amdricain au cours des Malathion in the vicinity of the Mactaquac River, N.B., 1959. programmes de lutte contre la tordeuse des bourgeons de l'épicéa. Unpubi. Rept.Fish Res. Board, Can. St. Andrews Bio. Sta. Cette communication ne pretend pas passer en revue les techni- N.B. ques et principes de Ia pulvdrisation, mais s'efforce au contraire Prebble, M. L.,1960.Interdepartmental committee on forest de mettre en evidence un certain nombre de considerations spraying operations. Bi-Mon. Progr. Rept. For. Bio. Div. Can. importantes relatives au problème de la pulvérisation des forêts. Agr. 16(1): 1. Rudd, R. L., and R. E. Genelly, 1956. Pesticides: Their use and Aspersion Aérea de BosquesDosificación y Manera de toxicity in relation to wildlife.Cal. State Dept. Fish and Evitar los Peligros para los Peces y los Animales Game. Game Bull. No. 7. Secrest, J. P., and Dorothy G. Thornton, 1959. A comparison Silvestres of the toxicity of various insecticides to the spruce budworm. El uso del avión para Ia aspersion de insecticidas destinados a J. Econ. Ent. 52: 212-214. controlar las plagas del bosque se ha convertido en un valioso Stewart, K. E., 1949. Application of DDT sprays by aircraft in instrumento de protección forestal. Muchos millones de hectáreas Canada for the control of the spruce budworm. In Dept. of de bosques infectados han podido salvarse gracias a la aspersion. Lands and Forests, Ont. Canada. Div. of Res. Biol. Bull. No. Desde el principio se reconoció el peligro que Ia aspersiOn de 2: 93-140. estas sustancias veneosas representaba para los peces y el resto Webb, F. E., 1959. Aerial forest spraying in Canada. Agr. Chem. de la fauna silvestre y se realizaron estudios para evaluar los 14(11): 63-64, 110-113. riesgos. En las primeras fases los métodos de aspersiOn y evalua- ción no estaban perfeccionados y por tal motivo la cantidad RESUMES correcta de la dosis y sus efectos no se conocIan con exactitud. Los trabajos de aspersiOn deben planearse tomando en considera- Pulvérisation aérienne des forêtsDosage et elimination ción todo el complejo biolOgico del bosque, con el propósito de des dangers pour les poissons et la faune crear sOlo un mInimo peligro a las criaturas vivientes, excepto a L'application aérienne des insecticides utilisés pour la destruc- aquéllas que constituyen la plaga que trata de erradicarse. La tion des insectes de forét joue un role essentiel pour la protection decision para las asperiones debe tornarse teniendo en cuenta los desforêts.Des millions d'acres de forêtsinfestées ont été peligros que presenta para el bosque y ciertas consideraciones épargnées grace a la technique de Ia pulvérisation. Les dangers económicas. La aplicación eflciente del insecticida es la dave que représentent pour lespoissonsetla faune l'application para el control de los insectos dañinos, asI como la dosisminima étendue de substances toxiques ont été reconnus des les debuts de lo es para la conservación de los peces y de la fauna terrestre. El la mise au point des techniques de pulvérisation aérienne, et de cuadro que ilustra la relaciOn entre la concentración del insec- nombreuses etudes en ont évalué les dangers. A l'origine, les ticida,la densidad de depósito de cada gotita y su tamaño techniques de pulvérisation et d'évaluation étaient primitives, si demuestra que la larva Choristoneura fumijerana Clem. del abeto bien que la mesure des doses et les effets sur les poissons et la puede controlarse con concentraciones de DDT al 3½ % corno faune étaient mal définis.Les programmes de pulvérisation mInimo, siempre que las condiciones para la aspersiOn permitan devraient être concus tout en tenant compte du complexe biologi- el depósito de un nfimero adecuado de gotitas de tamaño ade- que de la forêt. Le but a atteindre devrait être de réduire au cuado por unidad superficial. Las dosis eficaces más bajas pere- minimum les dangers menacant toute la faune, sauf les insectes cen ofrecer poco peligro para la fauna. La forma en quela indésirables.La decision de pulvériser devrait être prise en evaporaciOn, las condiciones meteorolOgicas y la pulverizaciOn fonction des dangers qui en résulteraient pour Ia forét, et de influyen en la eficacia de los trabajos de aspersiOn pueden usarse certaines considerations économiques. L'application d'insecticides ventaiosamente y reducir los riesgos para la fauna del bosque. efficaces est la clef de la lutte contre les insectes, et un dosage El perfeccionamiento del empleo de las enfermedades y toxinas minimum efficace, Ia clef de la conservation des poissons et de promete cierto éxito en el control de los insectos con agents la faune. Un graphique montrant le rapport entre Ia concentration controldores sumamente especIflcos.Estetrabajolimitasus de l'insecticide, la densité de dépôt d'une gouttelette, et la gros- comentarios principalmente a la experiencia obtenida con los seur de la gouttelette, indique que des concentrations de DDT programas para controlar la larva que infesta las yemasdel abeto aussi faibles que 3½ % peuvent détruire la tordeuse des bourgeons (Choristoneura fumijerana Clem.) en el continente Norteameri- de l'épicéa, pourvu que les conditions de pulvérisation permettent principios y métodos le dépôt d'un nombre suffisant de gouttelettes d'une grosseur cano. No se hace un exámen crItico de los convenable pour chaque unite de surface.Les dosages les plus de aspersiOn, sino que Se trata de presentar cierto nOmero de faibles semblent ne presenter qu'un danger minime pour les consideraciones de importancia relacionadas con los problemas poissons et la faune. L'influence de l'évaporation, des conditions de la aspersiOn de los bosques.

Forest Protection 929 Chemical Control of Forest Insects: New Approaches, Including Systemics

JULIUS A. RUDINSKY Professor, Entomology Department, Oregon State College Corvallis, Oregon, U. S. A.

Itis generally accepted among foresters and forest mechanical methods used in bark beetle control, made entomologists that the use of insecticides in the forest is, possible the protection of valuable stands and logs by their for several good reasons, not the most desirable way to prolonged residual effect, and provided effective control control destructive insects. An important reason is the of many insects which previously could not be economi- adverse effect the insecticide may have on the various cally controlled. biotic factors upon whose activity depends the equilibrium of the complex forest community. Prevention of insect Control of Bark Beetles outbreaks by silvicultural and management practices as A very important group of forest insectsin some developed in Europe is still the classical approach. Sani- regions actually the primary groupis the bark beetles tation-salvage cuts practiced now in western America to (Scolytidae). Most destructive of this group is the genus prevent outbreaks of the western pine beetle (Dendroc- Dendroctonus. The western pine beetle (D. brevicomis) tonus brevicomis) can be cited as one example of this killed over 18 billion board feet of timber from 1921 to effort. 1937 in Oregon and California; the mountain pine beetle Yet, we know from the past that, in spite of good man- (D. monticolae), 15 billion board feet from 1911 to 1935 agement, insect population's will build up because of in Idaho and Montana; the Engelmann spruce beetle (D. natural calamities (windthrow, fire, climate, etc.) beyond engelmanni), five billion board feet from 1940 to 1951 in the control of foresters.Insecticides, in such instances, Colorado; and the Douglas-fir beetle (D. pseudotsugae), become a very useful tool to prevent or suppress outbreaks almost the same amount in Oregon and Washington from of such insects as bark beetles, wood borers, sap-sucking 1950 to 1953. Many other devastating outbreaks have insects, soil and other insects besides defoliators. occurred in America and other countries during the last The development of insecticidal chlorinated hydrocar- half-century. During a recent outbreak in Europe, the ips bons represents a great advance in the control of many beetle (Ips typographus) killed over five billion board feet destructive forest insects, and even though the results are of spruce from 1946 to 1950. Most of these outbreaks not so spectacular as in the case of aerial spraying of DDT were initiated by natural calamities(fire, drought, and against defoliators, substantial progress has been made in windthrow). control or protection against bark beetles, sap-sucking Itis only natural that foresters were searching for insects, root-damaging larvae, and others. More effective effective methods of controlling bark beetles.The old insecticides in more economical formulations are now practice of felling, debarking, and burning infested trees, being developed. The hazard to biotic factors, particularly although effective, was expensive, very time consuming, insect parasites and predators, remains, of course, and may and usually wasteful of lumber. Also, too often, in large even be increased by the convenience and success of the areas, many beetles emerged and attacked new trees new hydrocarbons. To achieve ideal control, the need before all of the infested trees could be treated. becomes even more apparent for insecticides with specific Experiments with insecticides begun in California in toxicity to given destructive insects. 1932 led to the development of a control method using Therefore, probably the most significant event of the orthodichlorobenzene, paradichlorobenzene, and naphtha- past decade isthe development of selective systemic lene dissolved in oil, which, when sprayed on the 'trunk of insecticides, because they are entirely compatible with the infested trees, would penetrate the bark and kill the brood agents of biotic control. For the first time, at least for beneath. Later, a formulation of orthodichlorobenzene in certain insects, forest protection appears to have reached fuel oil was developed for control of the mountain pine the threshold of a new harmony in control, in which biotic beetle and was also used successfully against many other and chemical control can be made complementary. species of bark beetles (3)Although the oil solutions of fumigant insecticides represented a great advance over old Residual Insecticides and Fumigants methods of control, they still had the disadvantage of The fumigants developed shortly before DDT, and being disagreeable to use and expensive,sincelarge especially the residual insecticides such as DDT, lindane, volumes had to be transported into remote areas. Then a chlordane, and other chlorinated hydrocarbons, brought new possibilities in forest protection apart from aerial Numbers in parentheses denote the references listed at the spraying. They largely replaced the slow and expensive end of this paper. 930 Fifth World Forestry Congress Proceedings water emulsion of ethylene dibromide (at the rate of 2 Another method of control is the prompt destruction of pounds in oil to make 1 gallon and mixed with 4 gallons their breeding places, such as recently felled elms and of water) was found very effective (8). When water is disease-killed trees, and for this purpose one percent DDT available in the area, as is frequently the case, only 20 in oil solution may be used (19). Other individual orna- percent of the volume needed must be transported over mental or forest trees of high value may be protected from long distances. During the 1949-52 outbreak of the Engel- their insect enemies by these or other residual insecticides. mann spruce beetle in Colorado, 1,219,300 trees were As mentioned before,windthrown,fire-killed,and treated by the U.S. Forest Service with this water emulsion freshly cut trees or slash are favorable breeding material of ethylene dibromide (20). for many destructive bark beetles. Here they can develop These insecticides are fumigants and reach the beetle in tremendous numbers and subsequently infest adjacent brood by penetration through thin bark or through the standing trees. If such infested material cannot be removed entrance and ventilation holes made by the boring beetles. from the forest or otherwise disposed of before the beetles Their effectiveness is of short duration. They are applied emerge, chemical treatment may become necessary. by hand-operated pumps from the ground and can reach Chlorinated hydrocarbons, notably DDT and lindane, to a height of about 30 feet. They can thus be used on with penetrating oils, have been used successfully in vari- tree species with thin bark (spruces, lodgepole pine, etc.) ous parts of the world (6, 7, 14). Yet,the use of pene- and against bark beetles, whose habit is to concentrate on tratingoilsprays under forest conditionsislimited, the lower bole. When the entire bole is infested, or trees because great quantities of spray are needed, particularly with thick bark are to be treated, the trees must be cut when large and not easily accessible trees are treated. prior to treatment. Recent investigations have shown that other formula- With the development of DDT and other chlorinated tions can be equally effectiveif applied as protective hydrocarbons, it became possible to control other bark spraysthat is, before insect infestation. This aspect is beetles. The long-lasting or residual effect of certain of considered important, particularly where high-grade lum- the new insecticides offered an opportunity for both ber is involved. It has been shown that bark andambrosia preventive and direct control of bark beetles, weevils, beetles, long-horned beetles, flat-headed borers, and other wood borers, and others. Prevention against bark beetles wood borers may degrade "Select" lumber to "No. 5 Com- was particularly desired on high-value treesand ornamen- mon" (industrial), causing a loss of 150 dollars per Mbf. tals, in plantations of exotic species, in naval stores stands (2). Lindane (0.4% gamma) in emulsion or aswettable weakened by oleoresin production, and in similar places. powder in suspension applied to logs before insect infesta- The black turpentine beetle (Dendroctonus terebrans), tion in the spring gave complete protection duringthe for instance, is a constant threat to the naval stores stands whole summer Various formulations of other insecticides, and is especially dangerous during the drought periods including the newer ones such as Thiodan, endrin, hep- when the pine resistance is decreased. They infest the tachior, and Sevin, in suspension, solution, and emulsion, pines at the base, often without killing the tree. Spraying have also been tested and found satisfactory. Certainof with benzene hexachloride solution in oil (1% gamma) thse formulations penetrate into the bark deeper and not only kills the existing brood but also, because ofits faster than others, a fact that may prolong their effective- residue, prevents subsequent infestation. This method is ness under adverse weathering conditions(13). specially suited for such stands where trees are under The fieldof researchisopen: other solvents and constant attention and a spray program can be easily promising new insecticides have to be tested, andtheir integratedwiththeregular woods operations(15). residual life and toxicity to beneficial insects must be Another Dendroctonus beetle of similar habitisthe studied. Even though the ground application on logs or European species, D. micans, which became a serious standing trees is confined locally and does not present enemy of the introduced Sitka spruce in WesternEurope such danger to fish and wildlife as when sprayedfrom in addition to being the enemy of the native spruces. airplanes, the toxic effect on beneficial insectsisstill Growing under somewhat adverse edaphic and climatic important. The beetle predators and parasites crawling on conditions, the Sitka spruce is infested by Dendroctonus the treated logs come in contact with theinsecticide at a comparatively early age, about 40 yearsold. The trees residue and may be killed. There is almost completelack are not killed outright in one season, sosubsequent infesta- of information on this aspect. The study byRUhm (14) tion can take place for several years. Spraying the trees may serve as a warning. Hefound, while controlling the from the ground with a technical BHC in emulsion not spruce beetle (Dendroctonus micans)with technical BHC only kills the brood established by initial infestation but emulsion, that 90 percent of the hymenopterousparasites also offers protection against subsequent attacks for one in cocoons were also killed.It may be that a search for season (14). selective insecticides, to kill only a particulardestructive Effective prevention of the Dutch elm disease, which beetle species but not harm beneficial insects, iswarranted. killsboth the European and American elm species, Among the systemics, schradan is one suchexample. became possible through control of its carrier bark beetles Of the many problems in the development of preventive by DDT.In the United States, two species of bark or control sprays againstbark beetles, one more can be beetles carry the fungus to elm trees; one is the smaller mentioned. Often, the treated logs are floated to the mill European elm bark beetle (Scolytus multistriatus) and The rate of leaching of the insecticides in variousformula- the other, the native elm bark beetle(Hylurgopinus tions into the river water, the increase of the concentration rufipes). Timely application of DDT emulsion to healthy in storage ponds or lakes, and the effect onfish must be elms can prevent the beetles from feeding on them. investigated.

Forest Protection 931 Control of Root-damaging Insects better quality of seed and with the establishment of seed Root damaging insectswhite grubs, wireworms,wee- orchards, the protection of cone crops from insects be- vils, and symphylidshave been at times very destructive comes urgent.Before the development of residual in- in nurseries and plantations in various regions of the secticides, there was little hope of effective control of world. In Russ.ia, for instance, this group of insects has cone and seed insects. been a major problem in forest protection. Many promis- Experiments conducted in California in 1954 to prevent ing attempts to establish new forests ended in failure damage by the sugar-pine cone beetle by applying DDT because of depredation by soil-inhabiting insects. Before inoilsolution from a helicopter showed encouraging the use of chlorinated hydrocarbons, not much could be results. Only eight percent of the cones were destroyed on done in plantations. In seed beds, frequent cultivation of treated trees, whereas on untreated trees 84 percent of the the soil was of some help. The situation was radically cones were destroyed.In other experiments in Wash- changed after the development of DDT and other hydro- ington, where DDT and Sevin were applied from the carbons.Various methods of insecticide application to ground on younger Douglas-firs for protection against the soil are now in use. cone moths, chalcids, and other cone insects, the results In Russia, to protect the transplanted seedlings against were also encouraging. It appears that insecticides in the white grubs(Scarabaeidae), DDT (5.5% dust) and control of this group of insects have a promising future. BHC (12% dust), either alone or in combination, are used effectively. The insecticide can be applied by pow- Systemic Insecticides dering the roots at the time of transplantation, by sub- The recent discovery that various organic fluorine and mersion in suspensions, or by powdering the planting phosphorus compounds with insecticidal properties are holes. The insecticide used, the amount, and the method absorbed and translocated within a plant opened a very of application depend on the soil type, moisture condi- promising field in plant protection.In fact, Reynolds tion, and the developmental stage of the grubs. In nur- (11) states that the development of systemic insecticides series the BHC dust is applied on the soil and rototilled represents a turning point in plant protection comparable to a depth of from 4 to 6 inches (52 to 70 pounds per to the use of DDT. The ability to control sucking insects acre). The dust may also be introduced by a sowing by applications of systemics to the trunk or roots was an machine (1). especially attractive aspect, and a great deal of progress In the United States, to protect coniferous seedlings, has been made in the last dozen years on the inner therapy chlordane dust (10 pounds actual per acre) worked into of agricultural plants. the seed beds has given excellent protection against white Although research in systemics to protect forest trees grubs for a period of several years.Spraying the roots from destructive insects has not yet progressed thus and the planting holes with emulsion (0.5%) of aidrin, intensively, the development of systemic insecticides opens dieldrin, or heptachior is effective for transplants. a number of promising approaches hitherto unknown in Soil treatment with modern insecticides replaced the forest protection. These include seed treatment and soil old inefficient bait method used against root weevils applications for the protection of seedlings during their (Curculionidae), the larvae of which feed on larger roots, first season, trunk and root applications for younger and root collars, and stems of nursery stock and in plantations. mature trees, complete treatment of trees with limited Aldrin, chiordane, dieldrin, and heptachlor can be used spray coverage, and selective control of destructive forest either as sprays or dusts, or in granulated form(1/4 insects with consequent preservation of theirnatural pound actual/1,000 square feet), and worked into the enemies (12). soil to a depth of six inches. Symphylids have been a serious nursery problem in Selective Toxicity of Systemics various regions and are difficult to control because they The fact that certain systemic insecticides can kill a can move deeply into the soil. Intensive research on their destructive insect without harming its insect enemies is control isin progress.Parathion, a useful but highly probably ofgreatestinteresttoforestersand forest toxic insecticide, is registered by the U.S. Department of entomologists.Insect predators and parasites are recog- Agriculture for symphylid control. Although it is short- nized as the most effective factor in keeping a destructive lived in the soil and will protect seedlings for less than species to a safe level in the forest community. Their three months, often this time is sufficient for seedlings to activity is usually inconspicuous, but its value becomes establish good root systems.More recently, Vapam, very evident if stopped by adverse climate or insecticide, ethylene dibromide, and other soil fumigants, when prop- because their hosts then increase to their fullest biotic erly timed and applied to the soil, have given satisfactory potential. control.Although they do not have residual properties, Examples of haphazard applications of persistent in- one application has reduced and held symphylid popula- secticides in agriculture, with subsequent elimination of tions to a low level for three or more years (10). beneficial insects, are manyWhen this happens, the destructive species usually becomes persistently epidemic, Control of Cone and Seed Insects and repeated applications are often necessary to maintain Several species of cone moths(), flies control.Similar effects can be expected from large-scale (Diptera), cone beetles (Coleoptera), and seed chalcids insecticide application for forest protection, and recently, (Hymenoptera) at times destroy cone crops, thus not the sudden outbreak of the spruce spider mite (Oligony- only causing losses to seed collectors, but also limiting chus ununguis (Jacobi)) over a large area in Montana regeneration. With the increasing demand for more and following the application of DDT brought this point into 932 Fifth World Forestry Congress Proceedings focus.There are, no doubt, grave arguments on both the woolly aphid (A delges nusslini C. B.) on young firs. sides in the controversy of chemical versus biological con- Schradan and Systox applied by paint brush during the trol of forest insects. But there is, I am sure, complete summer also gave good control against the poplar borer agreement on one point: when man must intervene, then (SaperdapopulneaL.) (5, 16). he must act in a way and with materials that will least Systemic solutions may be injected into the transpira- affect the controlling biotic factors upon which ultimately tion stream of the xylem directly through a hole bored into depends the lasting equilibrium of the forest community the trunk or by a leaf-shaped hollow knife driven into the As Metcalf has said, "The most elegant use of insecticides sapwood. The transport of the material is then effected lies in their selective use to preserve populations of bene- by the transpiration stream, and its distribution into the ficial insects and thus to create the environment for a crown region depends, apart from environmental factors, joint chemical and biological attack on the pest species." on the water-conducting system of the tree.Among (9, p. 12) conifers, the most complete distribution is in the tree Agricultural entomologists have called attention to the species with spiral ascent of sap, while in the species with physiological selectivity of schradan, which is not toxic sectorial ascent, the distribution is restricted to only a on contact with such important aphid predators as lady- sector (17). Limited lateral diffusion also occurs from bird beetles, lacewings, and syrphid flies, yet is highly the xylem into the phloem. toxic to aphids and mites. These destructive insects are Because of the rapid and intensive distribution over the among the insect groups for which there had been no larch crown, the injection method is considered superior effective control in the forest. Furthermore, various other to the band method in controlling thrips and the larch systemics,suchasSystox and Thimet,arerapidly casebearer.Systox, dimefox, and Thimet introduced absorbed into the plant tissue when applied to the bark through a hole bored in the trees proved successful and or foliage and thus do not leave residues toxic to most fast in controlling larvae of the balsam gall midge on predators, yet they kill the insects sucking the plant balsam fir, but dimefox had also a phytotoxic effect. juices. Larvae of the red-headed pine sawfly on red pines were Selective toxicity is also achieved by seed treatment controlled with similar success (4). and soil or root application of systemics. The selective It appears that both injection and band methods of action of systemics in these applications results from the application will have use on ornamentals, in parks, etc.; presence of the toxicant within the plant tissue where it and, as suggested in Europe, they can be economical in affects most sucking and some chewing insects but does mixed stands on trees of superior value (16). not come into contact with predators and parasites. The The protection of young seedlings from insect attack beneficial insects that prey upon the poisoned host are not by application of insecticides as a seed coat or as a affected to any appreciable degree because of the rapid granular side dressing has become possible with the de- detoxification of organophosphorus compounds within velopment of highly persistent systemics, for instance the tissue of the host insect (9). Di-systonorThimet.Seedorsoilapplicationsof systemics are longer lasting, increase the selectivity, and Methods of Application reduce the hazard of handling toxic materials Most of the research with systemics against forest in- When a systemic insecticide is applied as a spray to the sects has taken place during the last decade, and naturally foliage of trees, the material or its metabolite is absorbed many of the principles involved in the processes of and translocated in the phloem, usually at a slower rate absorption, translocation, and detoxification of the toxi- than material transported in the xylem. cants within the forest trees are not sufficiently known nor Foliage spray shows more promise against forest pests the techniques developed enough for present large-scale than other methods of application; it has also been tried use under forest conditions. more extensively.Because of the high toxicity of most Several compounds have been used experimentally systemics to warmblooded animals, however, spray appli- against forest insects; of these, Systox, schradan, Metasys- cation from the ground requires special precaution. Systox tox, dimefox, and Thimet were more intensively tested, and Metasystox, in 0.05 percent concentration, were using various methods of application. successfully used against sucking insects,leaf-mining The treatment of the basal portion of the tree trunk by larvae of moths, and certain beetle larvae.The well- a band saturated with systemic solution has been shown known balsam woolly aphid, Adelges piceae (Ratz.), and to be a very useful way of rapidly applying insecticide to its relatives are highly destructive, and they are difficult to protect the entire tree. The material is absorbed by the reach by contact insecticides because of their protective bark and is initially translocated by the sieve tubes of the woolly cover.Spraying with Systox and Metasystox in phloem more intensively upward than downward. Later 0.05 percent concentration (1.7 to 4 ounces of actual it diffuses into the xylem, whence it moves more rapidly material per acre, according to size of firs) gave good into the crown region. The bark treatment was found to control on reproduction and in nurseries (5, 18). be most effective during spring and summer, when trans- Among the leaf miners, good control with Systox was location is most active. This method is easy to use, no obtained against the larch casebearer when applied in the heavy equipment is required, and, because the material is early fail before the insect constructed its case, or in the absorbed rapidly, it does not harm beneficial insects. spring before pupation.Fall application of Systox in On larches, both Systox and Metasystox were effective diesel oil against the European pine shoot moth gave against thrips (Taeniothrips laricivorus Krat.) and young complete control, as did Systox alone against Laspeyresia mining larvaeofthelarchcasebearer(Coleophora pocatolana Zell. laricella (Hbn.)). Metasystox was also successful against The time of application was found very important also Forest Protection 933 in the case of leaf-mining weevils (Rhynchaenus spp.) Rudinsky, J. A., 1959. Systemics in the control of forest and certain borers (Cryptorhynchus lapathi (L.), Saperda insects. Jour. Forestry 57(4): 284-286. , L.C.Terriere,and D. G. Allen,1960. populnea L.). Control of the borer larvae by this method Effectiveness of various formulations of five test insecticides on was possible only when the application was made before insects infesting Douglas-fir logs.Jour. Econ. Ent. 53: they entered the wood. There are a number of other Ruehm, W., 1958. Zur mechanisch-chemischen und oekolo- sucking and boring insects against which systemic sprays gischen BekaempfungdesRiesenbastkaefers(Dendroctonus micans Kug.). Z. ang. Ent. 43(3): 286-325. have been used successfully (5, 18). Smith, R. H., and R. E. Lee, 1957. Black turpentine beetle. U.S. Dept. Agric., Forest Service, Forest pest leaflet 12. Prospects for Future Use Vité, J. P., 1957. Trial controls of larch insects by inject- ing trees with systemic insecticides.Hoefchen-Briefe. 10(2): In conclusion,itisevident that systemics will not 61-94. entirely replace the conventional insecticides, but will be , and J. A. Rudinsky, 1959. The water-conduct- used against certain insect groups and in situations where ing systems in conifers and their importance to the distribution of trunk-injected chemicals. Contribs. Boyce Thompson Insti- there has been no satisfactory control. Certain important tute 20: 27-38. advantages in the use of systemics over the conventional Wachtendorf, W., 1954.Ueber die Einsatzmoeglichkeiten insecticides are as follows: innertherapeutischerPraeparate imForstschutz.Anz. f. The selective toxicity of various systemic insecticides Schaedlingskunde. 27:166-167. Whitten, R. R., 1953. Elm bark beetles.Leaflet No. 185. to only harmful species results in the preservation of U.S. Dept. Agric. beneficial insects. Wygant, N. D., 1959.Bark beetle control. Jour. Forestry Protection occurs at surprisingly low rates of appli- 57(4): 274-277. cation, which yet result in more complete distribution within the plant. RESUMES New shoots grown after the treatment may still be Lutte contre les insectes forestiers au moyen de produits protected by the systemic within the plant, thus eliminat- chimiques: nouvelles méthodes, y compris lesin- ing frequent application. Also, insects such as mites and secticides systémiques aphids, feeding in concealed places protected from contact L'utilisation de produits chimiques pour la lutte contre les insecticides, can be reached by systemics. insectesforestiersdestructeurs,telsquescolytes,perce-bois, insectes vivant dans lesoletautres,estd'originerécente. Seed treatment before planting may protect the D'importants progrès ont été réalisés en ce qui concerne la lutte seedling from destructive insects for a considerable time. contre les scolytes, et les insecticides ont en grande partie rem- Many basic aspects, however, such as mode of absorp- place les méthodes mécaniques pdnibles et bien souvent inefficaces. tion, translocation, and detoxification of systemics within En utilisant une emulsion de bromure d'éthyle dans de l'eau au lieu d'orthodichlorobenzène dans une solution huileuse, on a pu the tree, as well as environmental effects on these proc- réduire dans de grandes proportions le coat de la lutte contre les esses, must be better understood and compounds less scolytes partout oIl l'on trouve de l'eau en quantités suffisantes, toxicto warmblooded animals found belore practical sans avoir a transporter 80 pour cent du volume utilisé pour les methods of large-scale application under forest conditions pulvérisations. Les pulvérisations au sol a l'aide de ces insecticides fumigatoires ne sont efficaces que sur les essences a écorce mince canbedeveloped. Nevertheless,researchtodate et lorsque l'infestation est concentrée a la partie inférieure du demonstrates that systemics will have a very important tronc. place in forest insect control. La mise au point des hydrocarbures chlorurés, notamment le DDT etle lindane dont les propriétés de rémanence sont de longue durée, a permis pour la premiere fois d'empêcher que References l'infestation ne s'étende a certains arbres affaiblis ou a certaines Anon., 1956.Forest protection in the U.S.S.R. plantations,et de protéger les grumes venant d'être coupées 10(3): 130-132. contreles déprédations des scolytes, des perce-boiset autres Becker, W. B., and H. G. Abbott, 1960. Lumber down- insectes destructeurs. De nouveaux composes établis selon diverses grading losses due to insect damage to small unseasoned pine formules se sont récemment révélés efficaces pour la protection sawlogs. Jour. Forestry 58(1): 46-47. des grumes de qualité supérieure. Le present rapport mentionne Gibson, A.L.,1943.Penetrating sprays to control the certains effets nocifs de ces insecticides sur les insectes utiles. mountain pine beetle.Jour. Econ. Ent. 36(3): 396-398. Les insectes s'attaquant aux racines, notamment les larves de Giese, R. L., D. M. Benjamin, and J.E. Casida, 1958. scarabées, les larves de taupin, les charançons et les scolopendres, Results of trunk implantation of systemic insecticides in coni- constituaient autrefois un problème très sérieux dans les planta- fers. Jour. Econ. Ent. 51(3): 400-401. tions et les pépinières de certaines regions du globe et l'on n'y Hochmut, R., 1958.Systemicke insekticidy v ochrane lesa. connaissait aucun remède efficace.Mais maintenant, l'utilisation (Systemic insecticides in forest protection).Lesnicka prace de DDT ou de lindane, soit en poudrages, soit en pulvérisations, 37(12): 552-555. est devenue la méthode standard de lutte contre ces insectes. Lyon, R. L., 1959.Directions for using lindane sprays to Les essais effectués avec divers produits tels que DDT, lindane control pine engravers.Pacific Southw. Forest & Range Exp. et "Sevin" sont assez prometteurs et laissent espérer qu'il sera Sta., Forest Service, Misc. paper No. 33. possible a l'avenir d'empêcher également lesdéprédations des Marusov, A. A.,1959.Chimikati v borbe s vreditelami insectes s'attaquant aux cones et aux graines. lesomaterialov.(Chemicalsinthecontroloflog-infesting Lorsqu'on découvrit que divers composes organiques phos- insects). Lesnoje Chozyaistvo. Nov.: 49-50. phoreux ayant la propriété de tuer les insectes sont absorbés et Massey, C. L., R. D. Chisholm, and N. D. Wygant, 1953. se répandent a l'intérieur d'une plante ou d'un arbre, de nouvelles Ethylene dibromide for control of the Black Hills beetle. Jour. possibilités s'ouvrirent en matière de protection forestière, notam- Econ. Ent. 46(4): 601-604. ment contre les insectes pour lesquels on n'avait jusquelà trouvé Metcalf, R. L.,1959. The impact of the development of aucun traitementefficace. Les diverses marques "schradan," organophosphorus insecticides upon basic and applied science. "Systox", "Metasystox", "dimefox" et "Thimet" ont été plus ou Bull. Ent. Soc. Amer. 5(1): 3-15. moms intensivement essayées contre les insectes forestiers, prin- Morrison, H. E., 1957. Controlling symphylids. Agric. Exp. cipalement les ddfoliateurs et les térébrants. Sta., Oregon State College, Circ. Inform. 574. Diverses méthodes d'application ont été utilisées, parmi les- Reynolds, H. T., 1954.Entomological aspects of systemic quelles ii faut mentionner les applications au sol, le traitement pesticides. Agric. Chem. 9(7) :28. des graines,lesapplications aux troncs des arbres au moyen

934 Fifth World Forestry Congress Proceedings d'une bande saturée, les injections de solution systémique dans le infestaran árboles y plantaciones ya debilitadas y evitar los daños systèmecirculatoire du xylème,etlespulvérisationssurle causados anteriormente por los escarabajos, barrenillos y otras feuillage. especies destructoras, a los troncos recién cortados. Recientemente se han ensayado otras fOrmulas que han resultadoeficaces para la La grande importance des insecticides systémiques repose sur En el presente trabajo lefait que leur faculté de selection physiologique peut être protecciOn de trozas de alta calidad. utilisée pour tuer lesinsectes nuisibles sans nuire aux espices también seseñalan algunos efectos deletéreos observados en utiles(schradan).Cettesélectivitéest également réalisée au estos insecticidas. moyen d'applications au sol et, dans d'autres méthodes, par une Los insectos dañinos para lasraIces, especialmente, ciertas tissu des plantes (Systox, larvas, y los sinfIlidos constituian anteriormente un serio problema absorption tellement rapide dans le en las plantaciones y viveros de diversas partesdel mundo y no "dimefox") que les animaux qui les broutent ne sont pas mis en existia un control eftcaz para ellos. La aplicación del DDT o del danger. lindane, en polvo o por aspersiOn, se ha convertido en el método Le present rapport passe en revue les autres avantages pré- corriente para controlarlos. sentés par lesinsecticidessystémiques, notamment Ia grande Los experimentos hechos con las dos sustancias mencionadas activitérésiduelledecertainsd'entreeux,leurdistribution y con el Sevin han señalado la posibilidad de quequizá se ileguen régulière dans l'ensemble de la plante et le fait qu'ils s'emploient a impedir también los daños causados por losinsectos que atacan en faibles quantités.Ii indique en outre les importants problèmes el cono y las semillas. qui se posent en matière de recherche en ce qui concerne l'utilisa- Asimismo, el descubrimiento que varios compuestos orgánicos tion des insecticides systémiques dans la lutte contre les insectes a base de fósforos, con propiedades insecticidas, sonabsorbidos y forestiers. trasladados dentro de las plantas, brinda nuevas posibilidades en materia de protecciOn forestal, especialmente, contra los insectos Control Qulmico de Insectos Forestales: Nuevos Métodos, para los cuales no hay un control eflcaz.Se han hecho experi- mentos más o menos intensos con schradan, Systox, Metasystox, Inclusive los Sistémicos dimefox y Thimet para determinar su eficacia en la lucha contra El control quimico de ciertos insectos forestales destructivos los insectos forestales, los chupadores y barrenadores. tales como el escarabajo que ataca la corteza, el insecto xilóf ago Se han ensayado varios métodos de aplicaciOn,incluyendo la y otros que viven en el suelo, son de origen reciente. Deespecial aspersion del suelo, el tratamiento de las semillas, el anillaje del importancia son los adelantos para el control del escarabajo, con tronco, la inyección de una solución sistémica enla corriente métodos en que los insecticidas han reemplazado a las tediosas y transpiratoria de la parte leiIosa y la aspersion del follaje. a menudo ineficientes operaciones mecánicas.Con el uso del La gran importancia de los sistémicos reside en el uso de su dibromuro de etileno en emulsion de agua en vez de la ortodi- selectividad fisiolOgica para matar los insectos destructivos sin chlorobencina en soluciOn oleaginosa se ha reducido grandemente dañar a lasespecies beneficiosas(schradan).La selectividad el costo del control del escarabajo en amplias zonas que cuentan también se consigue con la aplicaciOn al suelo y otros métodos con suministros abundantes de agua, porque se ha eliminadola en que la absorciOn en los tejidos de laplanta es tan rápida necesidad de transporte del 80 per ciento del volumen usado en (Systox, dimefox) que los insectos beneficiosos que devoran a la aspersion. La asperskSn hecha desde tierra con estos insecti- los destructivos no corren peligro alguno. cidas fumigantes es eficaz solamente cuando se trata de árboles En este trabajo se mencionan otras ventajas quebrindan los de corteza delgada y la principal parte infestada es la regiOn sistémicos, inclusive los duraderos efectos de algunos de ellos, su inferior del tronco. distribuciOn pareja por toda la planta y la pequeña cantidad El perfeccionamiento de los hidrocarburos clorinaclos,espe- requerida.Se señalan también algunos de los problemas de cialmente el DDT y el lindane con sus propiedades residuales de investigación en el uso de lossistémicos contra losinsectos larga duración hizo posible, por primera vez, impedir que se forestales.

Biological Control of Forest Insects: The Role of Parasites and Predators

BLAIR MALCOLM MCGUGAN Associate Director, Forest Biology Division, Canada Department of Agriculture, Ottawa, Ontario, Canada

The widespread use of modern insecticides to protect question has no simple answer, and a discussion atthis forest resources has enjoyed much publicity and has time would hardly be appropriate. I would,however, like captured the confidence of the general public and many to review rather briefly the variousapproaches to con- foresters. This complacency has been attacked by fisheries trolling insect populations now available orunder study experts, wildlife biologists, conservationists, and sections as a prelude to a few words on oneof the classical ap- of the general public who criticize the wholesale and proachesthe use of parasites and predators. repeated dissemination of powerful and persistent poisons. Undoubtedly, the potential hazard to other forms of life Chemical Insecticides can be greatly reduced by the development of more Reference has already been made to chemical in- selective insecticides and more efficient formulations and secticides, and they have been discussed elsewhere in these methods of application.However, the basic questions meetings. Briefly summarized, broad spectrum insecticides remain:(1) Can insect populations be regulated or can not be expected to produce permanentpopulation eradicated by insecticides or do they simply provide tem- regulation or to eradicate foreign intruders. They or their porary relief?(2) Are there other satisfactory methods more selective descendants willalways retain a valuable of regulating the abundance of forest insects? The first place in forest management. However, the aerial applica-

Forest Protection 935 tion of insecticides is no longer a proposal that can be Hormones and Growth Substances accepted without human and other natural resources being Advances in insect physiology have shown the feasibil- given full consideration.This tempering influence has ity of using various 'hormones or growth-controlling sub- increased the interest in other means of control. stances to interfere with the metamorphosis or rate of development of insects. The full potentialities must await Disease Organisms the isolation, characterization, and perhaps synthesis of Forest entomologists have been quick to appreciate the the active compounds. The short- and long-term effects potentialities of disease organisms and have pioneered in will also require careful consideration when the physi- their study and use. The future of this approach is the ologist and biochemist have made further progress. subject of a separate paper being presented at these meet- ings.Suffice it to say that both native and exotic pests Parasites and Predators are potentially susceptible to this modern method. One of the most widely known methods of insect con- trol is the use of insect parasites and predators. Since the Cultural Control turn of the century, when a citrus scale was so spectacu- The importance of this approach has also been recog- larly controlled in California by the introduction of a nized in the program. I would like to stress, however, that predator brought from Australia, the natural home of the the forest environment with its long rotation periods and scale, a great many attempts have been made to obtain the acceptance of moderate injury without serious eco- control by this method with many degrees of success or nomic loss makes this approach particularly suitable. failure.Clausen (1956) has summarized the results in Experiment and demonstration in this field are most dif- the United States, and a similar compilation is nearly ficult and time-consuming but may produce, in the long complete for Canada. An organized program has been run, very satisfactory and economical methods of control. conducted against about 25 introduced insects that attack Obviously, the method is only applicable where stand forest or shade trees.Useful results are reported for 11 conditions or management techniques are responsible for of these species, despite the lack of critical assessment in insect abundance. many of the minor projects. Perhaps the most striking success in North America was with the European spruce Tree Breeding sawfly which, after posing a real threat to spruce forests The breeding of trees to rigorous standards, including in eastern Canada and the Northeastern United States, is insect and disease resistance,isa promising field of now held at very low levels by a complex of introduced endeavour. The long-term nature of this approach makes parasites and a virus disease (Bird and Elgee, 1957). research collaboration between tree breeder and ento- Other marked successes include the satin moth, gypsy mologist a vital necessity.Unless some mechanism of moth,oriental moth, and the larch casebearer, and resistance is established and the tree characteristic in- promising results are currently being obtained for the volved clearly identified, tree-breeding programs will re- balsam woolly aphid and the winter moth.Parasite main empirical and successful results largely a matter of releases have also been made against about 12 native chance. pests, but in no case have significant effects been observed. These results emphasize the difficulty of increasing the Genetics and Beba'viour effectiveness of the parasite-predator complex of native speciesat least in large continental areas. Introductions In recent years the behaviour patterns and genetic against native pests in tropical and sub-tropical islands variability of species are being exploited as a means of have been somewhat more successful (Simmonds, 1959). control.The now famous screwworm program isa Attempts are also being made to breed more efficient practical application of this approach. Female flies mate parasites and predators. However, for the rest of our only once, and male flies can be sterilized by radiation discussion we may readily confine our attention to the use techniques without affecting their mating behaviour. When of parasites and predators against introduced pests. Let such males are released in numbers over several genera- us also assume for simplicity of presentation that the tions, the effect on the population level has been striking term "parasite" includes predators where applicable. (Baumhover, et al., 1955). An intriguing answer to the The number of forest insects to reach foreign soil only gypsy moth problem in the Northeastern United States by to cause serious damage is unlikely to decrease in the face of modern commerce. Elaborate quarantine and regula- using genetic means has been proposed by Downes tory procedures may delay but cannot be expected to (1959). Crosses between certain "strong" races and the stem this flow. Elton (1958) contends that species will "weak" North American race of gypsy moth produce gradually occupy all the suitable environments available sterile females and apparently normal males.If these to produce a more homogeneous and generally richer male progeny, which carry the "strong" characteristics, fauna.If this is correct, we can expect further forest survive and mate freely in the field, a built-in control insect problems amenable to the manipulation of parasite mechanism would result. These approaches are depend- complexes. Although past achievements have been com- ent on a thorough knowledge of the biology and behaviour mendable, can we not expect greater success in the of the species throughout its range and an understanding future?To this end we might examine the current of its genetics.Unfortunately, such information for even methods of biological control, the underlying assumptions, our better-known forest insects has not reached the point and the limitations in our present knowledge which hinder where these possibilities can be exploited. a more refined approach.

936 Fifth World Forestry Congress Proceedings When an insect flourishes in a new environment, it is portant is the lack of assurance that the answers obtained considered to have escaped from its regular complex of will apply equally in the new environment. In a recent mortality factors, including its parasites. The introduction paper, Balch (1960) contests the need for such exhaustive of at least the major elements of the parasite complex ecological studies overseas and stresses instead the value should, therefore, reduce the damage, perhaps to a toler- of the broadest possible search and collection program able level. Fortunately, the tolerable level in the forest is leading to experimental releases in the problem area of all more attainable than in most agricultural situations where promising material. maximum productivity and a blemish-free product are When parasite material does become available for virtual necessities. release, are we in a position to handle it to best advan- The assumption inherent in the previous statement is tage? A review of biological control projects in North that parasites form a vital part of the natural control America emphasizes the rather ad hoc and limited con- complex and either actually regulate the pest population sideration that has been given to the release, initial estab- or markedly reduce its average density.This thinking lishment,subsequent spread,and ultimate impact of underlies all known biological control projects although introduced biological control agents.In contrast, much the dynamics of natural populations are not yet well more attention has been given to methods of handling understood.Conflicting theories of population dynamics and shipping insects, rearing regimes, and propagation based on deductive reasoning or simplified laboratory ex- techniques, all with very worthwhile results. These studies periments are currently being debated by international have frequently produced the only biological information authorities on the subject.They are handicapped by available beyond knowledge that a species is a primary semantics and the lack of adequate data on field popula- parasite of a certain stage of the host in question. But tions. In the interim, it is reasonable to accept the im- let us examine some of the principles underlying the portanceofparasitesasavalidassumption,but release and establishment of introduced parasites. recognizing that considerable variation may exist from one Itisgenerallyacceptedthatreleasedmaterial situation to another. An insect which fluctuates widely should be free of disease and hyperparasites. This re- in abundance in its native environment is not as likely to quires that material be released, usually as adults, after be satisfactorily controlled by parasites as one which is being reared through one or more stages, either in the rarely, if ever, numerous in its original habitat. country of origin or in the problem area before release. Accepting this basic assumption on the importance of Under the latter circumstances, rather elaborate quaran- parasites, the usual biological control program begins with tine facilities are required to prevent the escape of un- the collection of parasites where the host is most abundant desirablematerial. Thesefacilitiesshouldinclude in its natural range. Collection is easy, and encouraging controlled rearing chambers to allow close synchroniza- numbers of the more common parasites can be obtained. tion with host development in release areas. If they do not become established or the degree of con- The minimum or optimum number of parasites to trol isstill inadequate, the search usually shifts to areas release at one point and time has been debated at some where the host is characteristically less abundant or where length.Evidence from past successes and failures only the climatic and forest conditions closely approach those emphasizes the academic nature of the question. Success- of the new environment. The assumptions behind such ful establishment has resulted from as few as six females actions are several. Where the host is never abundant, and four males, as in the case of the holly leaf miner in we may expect to find parasites which are causal elements southern British Columbia (McLeod, 1954). On other in the maintenance of low population levels.Collecting occasions, many thousands released at different times and where forest and climate approximate conditions in the places have failed to result in establishment. In practice, problem area is based on the theory that there are the numbers are usually dictated by availability.It is biological races or strains of parasites.Indeed, there is fairly obvious, however, that releases of less than several evidence that certain parasites are more abundant and hundred specimens have little chance of success. More presumably more important at certain population levels important considerations are the condition of the para- and that marked variations do occur in such important sites, their synchronization with host development, and the characteristics as cold or heat tolerance. In most biologi- choice of the actual release site.These crucial factors cal control programs, the existence of such attributes is are usually left to the intuitive judgment of the entom- assumed rather than demonstrated. ologists concerned with the project. Many serious forest insect problems remain unsolved Action subsequent to the release of parasites has despite the efforts described above. It must be assumed taken many forms.Unfortunately, there have been too that either parasites are not a critical control factor or many instances where no organized attempt has been the search has not been broad enough in perspective. made to assess the results.Responsibility to follow the Some authorities (Simmonds, 1959) have recommended sequence of events would seem a natural corollary to the that where the problem warrants it, broad ecological or authority to introduce new biotic elements. The assump- biocoenotic studies be undertaken in the natural environ- tion appears to be that a subjective appraisal of the status ment. These studies could indicate the "key factors" in of the insect problem combined with limited recovery data population control and whether or not alternate or is adequate. If the problem is reduced or eventually dis- reservoir hosts are critical to the success of certain para- appears, the established parasites are given a large share sites.This proposal is quite sound but, unfortunately, of the credit.It is obvious that the first efforts in the assumesthatourpresent knowledgeofpopulation search for and release of parasites must be accomplished dynamics will allow a full appreciation of the interactions with some dispatch.However, if the results are not of a parasite complex with its host. Perhaps more im- readily apparent and the overseas program is to be intensi- Forest Protection 937 fled, a sound appraisal program in the release areas as- host abundance, it may in no way influence fluctuations sumes greater importance.Here, again, we are faced in host numbers from year to year. A parasite which is with the inadequacy of our present knowledge of how capable of attacking only a fixed proportion of the host, natural populations behave and operate.This is well regardless of the host's abundance, obviously cannot regu- illustrated by the quite different theories advanced by two late population level. Rather, this ability may be found contributors to a recent symposium on biological control. in parasites which fluctuate in abundance even if at com- Baich (1960)argued for the prompt release ofall paratively low levels.Morris (1957) has discussed this available parasites on the theory that thisis the only question of appraising and interpreting mortality factors valid test of their suitability and that only advantages can atconsiderable length, anditisevident that more accrue from the establishment of many parasites.In significance must be attached to variations in parasitism contrast, Chant (1959) appealed for a more cautious ap- from year to year than to its absolute value. proach, once the major parasites had been tested. Addi- Any measure of parasitism remains of limited value tional releases should only follow a rather thorough unless it can be compared with other mortality factors knowledge of each new species. He also advocated the and with the population level of the host. Forest entomo- release of one species at a time to allow a more critical logists have long been interested in developing sampling appraisal of impact and perhaps to avoid ill-advised techniques that will allow meaningful inter-area or inter- releases. year comparisons.In Canada, the current vogue is the 4. Mass colonization and liberation programs have development of sampling techniques and regimes that will been used frequently in the past and have attracted much provide for the construction of life or mortality tables. public attention and support. It is most doubtful whether Thesetablesaresimply a numerical accounting of such actions are justifiable. In certain orchard problems, mortality over a series of generations in a particular plot. annually reared stocks of predators are used as an adjunct They allow a comparison of mortality factors regardless of to chemical treatments. In forests, however, the area, unit stage effected and provide a true measure of impact from value, and length of rotation make it necessary to depend year to year. This approach was popularized by the work almost entirely on the high fecundity and dispersal capa- of the Green River Project (Morris and Miller, 1954) bilities usually found in insects. At the same time, the which seeks an understanding of the spruce budworm in natural spread of parasites may often be greatly aided the balsam fir forests of New Brunswick. Life tables and by appropriate releases at intervals throughout the estab- associated observations have now been made for about lished range of an introduced pest. 12 generations and a variety of forest conditions. The The preceding remarks have been designed to make two budworm outbreak ceased in 1958, and an elaborate points clearthat the use of parasites and predators to analysis of the data for the outbreak period is under way. control introduced forest insects has been more an intui- Sampling is being continued into the endemic period, tive art than a science, and that further refinement de- where a considerably different control complex may exist. pends toa large degree on progressin population The volume of data associated with a lengthy life table ecology. Whether an art or a science, biological control study, such as the Green River Project, can be fully must be judged by the results obtained, and we have analyzed only by modern electronic means. These com- already noted that some measure of success resulted in 11 puters allow population data to be rapidly compared by out of 25 programs conducted in North America. Figures the most advanced mathematical techniques, with various are not readily available for other areas, but I suspect that deductive theories and population models. A considera- a similar ratio of success to failure would apply. Being tion of population models and their construction is beyond familiar with the complexities of these situations and the the scope of this paper, except to state that any realistic problems that faced early workers, I consider this a rather mathematical model must be an expression which mimics enviable record which speaks highly for the insight and the effects of weather, habitat, other organisms, food, energies of those responsible.Unfortunately, however, and chemicals on the population density of the insect in we have no clear evidence as to why we failed in some question (Watt, 1959). Such a comprehensive model de- cases and were successful in others.This situation can pends upon the development of suitable mathematical be corrected only by gaining a better understanding of formulations describing closely the mechanism of individ- how insect populations behave. In recent years, there has ual factors.Outstanding examples are to be found in been a worldwide interest in population dynamics, and recent contributions by Miller (1959), who has described literature on the subject has mounted rapidly. Not only in appropriate terms the interaction between the spruce has there been marked progress in theoretical considera- budworm and one of its parasites, and by Holling (1959), tions, but long-term field experiments are now providing who has developed from experimentation and field studies much needed data for analysis. The results have already a much clearer mathematical understanding of predation provided much ofinteresttothebiologicalcontrol and its components. These findings, and ultimately the specialist.I would like to comment on some of these comprehensive model, will provide for a much more developments and indicate their possible significance. thoughtful approach to any biological control situation It has been common practice to express the interaction than has hitherto been possible. of parasite and host as a percentage and to assume that the impact isdirectly proportional to the percentage The most serious disadvantage of the life table ap- parasitism.Some years ago, Bess (1945) and more proach is the amount of time and staff required to obtain recently Morris (1957) showed that such figures are a volume of sufficiently accurate data.It is, however, the grossly misleading.Although a high percentageun- most satisfactory approach available for gaining a full doubtedly indicates a real effect on the general level of understanding of a major insect problem.

938 Fifth World Forestry Congress Proceedings Recently, Morris (1959) has presented a comparatively Holling, C. 5., 1959. The components of predation as revealed by a study of small mammal predation of the European pine simple method for appraising the influence of a single sawfly. Can. Ent. 91: 293-320. factor on population numbers from one generation to McLeod, J. H., 1954. Statuses of some introduced parasites and another. He has shown for two forest insects, the black- their hosts in British Columbia. Ent. Soc. B. C., Proc. (1953). headed budworm and the European spruce sawfly, that a 50: 19-27. Miller, C. A., 1959.The interaction of the spruce budworm, measure of larval numbers in each generation, at a time Choristoneura turn iferana (Clem.), and the parasite Apanteles when the incidence of certain parasites can be appraised, furniferanae Vier. Can. Ent. 91: 457-477. will provide a reliable estimate of abundance in the next Morris, R. F.,1957.The interpretation of mortality data in generation.If this method is found to be widely ap- studies of population dynamics. Can. Ent. 89: 49-69. 1959. Single factor analysis in population dynamics. plicable, it will be of great value in biological control Ecology 40: 580-588. work, where the introduced parasite is selected for com- and C. A. Miller, 1954. The development of life parison with host abundance. A high correlation would tables for the spruce budworm. Can. J. Zool. 32: 283-301. indicate the parasite to be a "key factor" in population Simmonds, F. J., 1959. Parasites and predators as biological con- trol agents.Invitation paper presented at the joint meeting regulation. of the Ent.Soc. Amer., Ent. Soc. Canada, and Ent. Soc. Ont., In conclusion,therefore,the use of parasites and Detroit, Michigan, December, 1959. predators has been a reasonably successful means of com- Varley, G. C., 1959. The biological control of agricultural pests. bating introduced forest insect pests.However, the as- Jour. Royal Soc. of Arts 107: 475-490. sumptionsunderlyingthisapproacharenotwell Watt, K. E. F., 1959. A mathematical model for the effect of densitiesof attacked and attacking species on the number understood and require that biological control programs attacked. Can. Ent. 91: 129-144. be essentially empirical in nature. The greatest handicap is the lack of an adequate understanding of population RESUMES dynamicsVarley (1959), in discussing the biological Lutte biologique contre les insectes des forets: Role des control of agricultural pests, has pointed out this same parasites et des prédateurs deficiency and stressed the need for increased support of Les effets secondaires peu désirables des insecticides chimiques all types of population study. He also quite properly ont stimulé un renouveau d'intérêt pour les autres méthodes de stressed the need for more work on the taxonomy of lutte contre les insectes. Bien que nous ayons a notre disposition parasitic groups as a vital tool for both population studies plusieurs nouvelles techniques pleines de promesse, la méthode and biological control efforts. classiqueutilisée pour lamanipulationetl'accroissement du complexe des parasites et des prédateurs jouit encore d'une vaste Broadly based population studies are attracting a great application dans le milieu forestier oii les exigences de Ia lutte deal of attention throughout the world.In Canada, in ne sont pas trop rigoureuses. Un certain succès a étéobtenu particular, much effort is being devoted to the collection contre les fléaux indigènes, notamment dans les lies ayant un of adequate field data upon which to build comprehensive climat semi-tropical ou tropical.Toutefois la méthode semble population theories. Several techniques have already been convenir davantage aux insectes introduits dans un nouveau milieu favorable, a la suite de transplantations forestières. En Amérique forthcoming which are of immense value to biological du Nord, 11 sur 25 programmes organisés pour la destruction de control projects.These developments and advances in ces insectes ont fourni des résuitats utiles. Bien que ce soitlà un entomology generally are providing exciting possibilities résultat honorable, tous ces programmes, qu'ils aient mené au for the progressive research worker. In this perspective, succés ou a l'échec, ont été plutôt guides par l'expérience, et considérablement génés par une comprehension peu suffisante de the use of parasites and predators will occupy an im- l'acroissement dynamique des populations d'insectes. Des progrès portant place in forest insect control, and therefore should spectaculaires ont été récemment réalisés dans ce domaine, et enjoy the full support of all concerned with forest protec- ont fourni des notions et techniques de grande valeur. Les cher- cheurs canadiens ont énorrnément contribué au développement tion. des techniques d'échantillonnage, des mdthodes analytiques, et des expressions mathématiques pour les composantes des rapports References entre la voracité, l'action des parasites et la densité. Tandis que Baich, R. E., 1960. The approach to biological control in forest nous profitons avantageusement des progrès actuelsréalisés dans entomology. Can. Ent. In press. ledomainedel'accroissementdynamiquedespopulation Baumhover, A. H., A. J. Graham, B. A. Bitter, D. E. Hopkins, d'insectes, l'emploi de parasites et de prédateurs devrait devenir W. D. New, F. H. Dudley, and R. C. Bushland, 1955. Screw- une méthode plus efficace et pius pratique pour unedestruction worm control through release of sterilized flies.Jour. Econ. plus complete des insectes introduits a la suite de transplantations Ent. 48: 462-466. forestières. Bess, H. A., 1945. A measure of the influence of natural mor- tality factors on insect survival.Ann. Ent. Soc. Amer. 38: Control Biológico de los Insectos Forestales: El Papel de 472-481. los Parásitos y los Predatorios Bird, F. T., and D. E. Elgee, 1957. A virus disease and intro- duced parasitesas factors controlling the European spruce Los efectos nocivos secundarios de los insecticidas quImicos sawfly, Diprion hercyniae (Htg.), in central New Brunswick. han estimulado un nuevo interés en los otros métodos de control Can. Ent. 89: 371-378. de insectos.Aunque -hay varios métodos recientemente intro- Chant, D. A., 1959. Paper presented in symposium on approaches ducidos que prometen éxito, el tradicionalmente empleado para to biological control at the joint meeting of the Ent. Soc. Amer., manejar y acrecentar el grupo de parásitos y predatorios suele Ent.Soc. Canada, and Ent.Soc. Ont., Detroit, Michigan, aplicarse todavIa en aquellos ambientes forestales que no re- December, 1959. quieren medidas de control muy radicales. Con este método se Clausen, C. P., 1956.Biological control of insect pests in the han logrado algunos éxitos al combatir plagas nativas, parti- continental United States.Tech. Bull.1139, USDA, Wash., cularmente en islastropicales osubtropicales.Sin embargo, D.C. parece haber resultado más apropiado contra los insectos intro- Downes, J. A., 1959. The gypsy moth and some possibilities of the control of insects by genetical means.Can. Ent. 91: ducidos en un ambiente nuevo y favorable. En Norteamérica 661-664. se han obtenido resultados de utilidad en 11 de los 25 programas Elton, C. S.,1958. The ecology of invasions by animals and organizados contra los insectos forestales introducidos en el pals. plants. John Wiley and Sons, Inc., New York. Aunque ésto puede considerarse como un éxito bastante estimable, Forest Protection 939 todos los programas en cuestión, hayan sido un éxito 0 Un fra- de muestreo y de análisis y han obtenido formulas matemáticas caso, han seguido un criterio más bien empIrico y se han visto para los componentes predatorios,la acciOn parasitaria y la impedidos por la falta de conocimientos sobre la dinámica de Ia proporciOn de densidad entre ambos elementos. A medida que población insectiLLos adelantos hechos recientemente en este vayan aprovechándose los adelantos actuales en los conocimientos campo son notables y han aportado valiosos conceptos y métodos de Ia dinámica de la poblaciOn, aiimentará el uso de los parásitos técnicos a Ia silvicultura.Los silvicultores del Canada han con- y de los predatorios como medio eficiente y práctico para regular tribuido considerablemente al perfeccionamiento de los métodos la abundancia de los insectos forestales introducidos.

Microbiological Control of Forest Insects As a New Approach

THOMAS A. ANGUS Insect Pathology Research Institute, Sault Ste. Marie, Ontario, Canada

In this paper I shall be discussing a number of para- tabular data, illustrations and the like, I found it in the sites that have minuteness or smallness of size as a ifies of my colleagues, so my selection of examples reflects common characteristic. A suitable title for this paper convenience as much as it does any other factor. might then well be"Microbioiogical Control of Forest Although it is known that the rickettsia and nematodes Insects as a New Approach." do cause disease in insects, so little is known of these The idea of using disease-producing microorganisms associations that it is difficult to properly assess their to control insect numbers is not new, and from 1880 potentialascontrol agents.They are beyond doubt until 1940 there were several attempts, with varying worthy of much more study than is accorded them, and degrees of success, to develop such a method. Failure I am certain that there are many pathogens of insects in to persist in this work has been attributed to a number of this group still to be isolated. causes, but an important factor was the spectacular suc- When we turn to the protozoan parasites of insects, cess of the chemical insecticides. As we can all remember, we are faced with the difficulty of describing in a few it was difficult to resist the feeling in the 1940's that a words a vast subject that has become the domain of the final answer to the insect problem was close at hand. In specialist. A most interesting example is found in Thom- 1960, there is a realization that chemical insecticides, son's work on Perezia fumiferana, a microsporidian para- especially those of wide host-range, are not altogether an site of the spruce budworm Choristoneura fumiferana unmixed blessing. The emergence of resistant strains of (Clem.), which is a serious pest in our Canadian forests. insects, the disturbance of food chains or damage to other The pathogen occurs in many of our budworin popula- life-forms useful to us, and the ever-present hazard of tions, and, after much painstaking study, Thomson finally toxicity for vertebrates are but a few of the many prob- succeeded in unravelling its life cycle. He found that lems that beset us. there are some 25 developmental stages of the parasite. Dr. Steinhaus, in a recent address, said that there are Larvae may become infected by ingesting spores of the at least 80 species of bacteria, 215 species of viruses, 460 protozoa which have been released from the bodies of species of fungi, 250 species of protozoa, and more than killed diseased insects and, if infected early enough, may 100 species of nematodes capable of killing their insect succumb to the disease in the same season. If the disease hostsand that these 1,100 known pathogens are only a is contracted late in the larval life, a "carrier" adult will fraction of those that surely exist.This will serve to emerge that lays eggs which will yield infected larvae. indicate the scope of insect microbiology. Far from being A high level of mortality is not characteristic of this an embarrassment of riches, this very diversity of forms Perezia infection, but the effects are subtle and very far- presents increased possibility of manipulation by man, reaching, for the parasite retards larval and pupal develop- and since the pathogens are living agents, they are pos- ment and reduces pupal weight, adult longevity, and sessed of power to adapt, specialize, and mutate to more fecundity.It is obvious that the establishment of such a effective forms. It is our task to discover and, if possible, parasite in a disease-free population might have far- use them. reaching effects. Because it is an obligate pathogen, the Speaking broadly, insects are affected by the same production of significant quantities of infectious material types of microbial pathogens as the vertebrates. I should would not be easy, but the technical problems are not like to discuss some of these forms briefly and indicate insuperable and could be accomplished in insectary rear- with some practical examples their potential usefulness ings. An attractive feature of such a parasite is that once in the control of forest insects. In the time at my disposal introduced it has the capacity to perpetuate itself.Suc- I can only make a selection. If my choice seems to be too cessfully introduced, it might have a significant effect on narrowly national, this is not because of any belief on my controlling insect numbers. part that the Canadian contribution excels. Much of the Many of the early attempts at microbiological control Canadian work in insect pathology is centered in Sault of insects involved the use of fungi of various kinds, and Ste. Marie, which is my home base. When I was seeking there has been much controversy about the results ob- 940 Fifth World Forestry Congress Proceedings tamed. Beyond question, entomogenous fungi do attack leased.Ifa susceptible insect ingests some of these and kill tremendous numbers of insects, but this mortality polyhedra, the protein of the polyhedron is dissolved occurs sporadically and may be under the control of away in the gut, the infectious virus particles are released, factors that will not permit man's intervention, at least and the insect becomes infected.Practically all of the at the present state of our knowledge. In Canada, Mac- known polyhedroses are speciesspecific,attackinga Leod has studied in some detail certain aspects of 3 single insect species or very closely related forms. groups of fungi considered to be pathogenic. The first The breakdown of the spruce sawfly population in comprise species of the genus Hirsutella, which are often Eastern Canada isan almost classic example of the foundassociatedwithdeadinsects.Althoughthe ability of a virus disease to reduce insect numbers. The Hirsutella isolates are effective laboratory pathogens, they original epizootic was accidental, in that we do not know produce, relatively speaking, a poor spore crop, and we how the virus was first introduced, but since then, Dr. have not as yet devised practical methods for the produc- Bird has shown that it is possible to successfully introduce tion of material for field use. Another potentially useful the virus disease into healthy populations.In 1950 a group is found in the genus Beauveria. These have been virus-free infestation of Diprion hercyniae was discovered isolated from more than 60 different insect species in near Sault Ste. Marie, and in that year 7 trees were Canada, and many of the host insects are forest pests. sprayed with a virus suspension.This population has A group of fungal pathogens that has attracted much been sampled every year since then, and it is evident study is the genus Empusa, some species of which pro- that the virus is firmly established and has spread widely duce a thick-walled, fairly resistant resting spore.This from the release point. particular stage has attracted a good deal of attention, Another example is provided by Neodiprion sertifer for it would seem to be the logical form to use in micro- (Geoff.), the European pine sawfly which in 1949 was biological control attempts.Unfortunately, although we causing important damage in plantations of Scotch pine, can detect it in killed insects, it has not yet been produced Pinus sylvestris L. in southern Ontario. In Europe, this on synthetic or artificial media. This is an area of re- insect is largely controlled by a polyhedrosis, but the search which is very promising and which may pay rich North American populations were apparently disease- dividends, for very many important forest insect pests are free.In 1949, Bird obtained a few dead larvae from susceptible to infection with Empusa species. Sweden and built up a supply of virus.In 1950, this It is known that some entomogenous fungi require con- was used in very successful field tests, and the disease has ditions of high humidity for germination and invasion. If since been used each year as an effective field control. these weather conditions do exert a dominant role in the There is also evidence that the virus persists in the popu- initiation of fungous epizootics, this may seriously limit the lation so that someday we may find that the European scope of possible utilization. We should, however, be care- condition also holds for North America. ful not to apply, holus-bolus, an explanation that is true Thepolyhedrosesofthenunmoth,Lymantria only for a particular situation. In many tropical areas and, monacha L., and of the gypsy moth, Porthetria dispar indeed, in some temperate areas prolonged periods of L., are known to be very important factors in reducing high humidity are quite common, and these areas may be insect numbers in Europe.Polyhedrosis diseases have quite suitable for the utilization of fungi.If it should been found in many Canadian forest insect species, and ever prove possible to temporarily modify the weather these include many of our most serious lepidopterous and conditions in a specific area to conditions of higher hymenopterous pests. The spruce budworm suffers not humidity (and thisis not inconceivable), it might be only from a polyhedrosis but from another virus disease possible toinitiate a fungous epizootic with increased called a granulosis, and these are being intensively studied certainty of success. in Canada at present. I have done less than justice to the Insect pathologists recognize some 4 or 5 genera of virus studies, for this is a very active field and many viruses causing disease in insects, and several species of useful results have been achieved. We are optimistic three of these have been extensively studied in Canada. In that with further study we will be able to develop satis- 1930, the European spruce sawfly, Diprion hercyniae factory methods for utilizing viruses more widely in (Htg.), was discovered in northern New Brunswick and control programs. the Gaspé area of Quebec. In the succeeding ten years it Many of the bacteria found in insects are saprophytes had spread to the Northeastern United States. In 1936, that have been ingested fortuitously with the insects' disease was found in laboratory rearings and, about 1938, food. Most of them find the insect gut an unfavourable it was observed in many field areas. By 1943, the insect environment and soon die out, but it has been observed populations were reduced by the disease to the point that certain stress conditions, such as starvation, over- where their damage was no longer important. Later, Dr. crowding, unsuitable food, elevated temperatures, and F. T. Bird demonstrated that the disease was a poly- the like, alter the metabolism of the host so that condi- hedrosis. tions become more favourable for the survival of such Polyhedrosis is so called because of the shape of the bacteria.It is not surprising, therefore, that some of inclusion bodies which are found in diseased and dead these bacterial species have been mistaken for pathogens insects. These inclusions are protein crystals that encase and used in attempts to control insect populations. By thevirusparticleswhicharedistributedrandomly and large,field trials of these "accidental" pathogens throughout the polyhedron. When an insect larva dies of have yielded disappointing results. a polyhedrosis, the cadaver is extremely fragile and con- Many bacterial species, however, are truly pathogenic, tains enormous numbers of polyhedral bodies. When the and their introduction into an insect generally leads to cadaver ruptures or is broken, the polyhedra arere- disease. Some of the best known of these are found in the Forest Protection 941 genus Bacillus, which comprises a large group of rod- possibility of using microorganisms in the control of some shaped bacteria that, under appropriate conditions, form insects.I have used the word "some" advisedly, for a very resistant endospore. Within this group is found microbial control offers no universal panacea.Such a Bacillus popilliae, the causative agent of milky disease in hope would be unrealistic and unjustified. the Japanese beetle. This organism is the active agent in I think it should be realized at the outset that using a a very successful, widely used commercial insecticide. microbial control agent will not be as straightforward as Another species is Bacillus larvae, which causes American the use of a chemical insecticide. The microorganisms foul brood in honeybee larvae. are living forms, and so we shall have to develop methods Heimpel, in 1952, isolated from diseased larch sawfly that will not decrease their virulence or viability. Some larvae a strain of Bacillus cereus and showed that it was of the infectious agents I have discussed, as for example, pathogenic, because while growing in the gut it produced the polyhedralviruses,Bacillusthuringiensis and B. atoxicenzyme,lecithinaseC,whichactson the popilliae, are very resistant to ordinary variations in tem- phospholipids of the larval gut. When the gut is damaged perature and humidity, but extremes of heat, desiccation in this way, bacteria are able to pass into the hemocoele or humidity should be avoided. We will definitely have and initiate a fatal septicemia. The isolate was effective to take a careful look at such traditional practices as only in a narrow group of insects, and Heimpel showed combining fungicides and insecticides;at the kind of that the limiting factor was the pH or hydrogen-ion con- wetting agents which are compatible with these new centration of the gut contents. In most lepidoptera the gut products, and so on. With the exception of some of the is too alkaline to permit germination of ingested spores or fungi, most of the known pathogens act as stomach successful establishment of the bacteria. poisons, that is, they must be ingested, so we will have to There is, however, a group of bacteria very similar to unlearn some of the methods we have developed for use Bacilluscereuswhich cancausediseasein many of the chemicals which are contact poisons. lepidoptera.These strains we classify as varietiesof Our first forest sprayings with Bacillus thuringiensis Bacillus thuringiensis, which was first isolated nearly 50 were made with oil carriers for the understandable reason years ago from diseased flour moth larvae (Anagasta that all our spray equipment, assessment techniques, etc., kuhniella (Zell.)). A closely related variety also causes were developed for oil sprayings. However, it should be death in the larvae of Bombyx inori, the silkworm. A remembered that the original use of oil was dictated in mystery of long standing was that young cultures were part by the problem of achieving a low-volume, high- harmless, but sporulated cultures were rapidly lethal. concentration spray with fat-soluble, water-insoluble in- When killed larvae were inspected there was no evidence secticides like DDT, aldrin, rotenone, and so on. To use that the ingested spores had germinated. Obviously some a plebeian metaphor, we are forcing our pathogen into a sort of a preformed toxic was involved. coat tailored for another customer. Because some of our The contemporary studiesof Bacillusthuringiensis most promising pathogens are best applied as biologically date back about ten years, and the elucidation of the quiescent entities, we have a good deal of latitude about puzzle has been truly an international accomplishment. timing, since volatility is not a problem. We can therefore We now know that when a B. thuringiensis cell sporulates contemplate the use of stickers, such as the water-dispersi- it also produces a parasporal body or crystal made up of a ble, water-insoluble resins, unsuitable for conventional protein which causes gut paralysis in a very wide range insecticides. of Lepidoptera.The toxic crystalissoluble only in These difficulties of application are minor in the light alkaline conditions, hence its success in insect species of the many advantages that are possessed by a microbial resistant to B. cereus.Purists have been quick to point pathogen. An advantage that will have great appeal is the out that the B. thuringiensis effect is more closely akin to lack of toxicity for other life forms. If effective microbial a poisoning than to a disease. pathogens can be developed, the benefits that will accrue The first effect of the toxin is paralysis of the gut which to the salmon fishing industry, for instance, would make it inhibits feeding, and this occurs very soon after con- feasible to use products many times more expensive than taminated foliage is ingested. In some cases, this primary preparations now in use. Most of the insect pathogens toxemia is lethal of itselfin others, it paves the way for are comparatively narrow in their host specificity, and a slower but inevitable septicemia. Growing as a "dis- this would minimize damage to existing useful insect ease" organism in a susceptible insect, little toxic protein parasites and predators. is produced, but under synthetic growth conditions toxic As a final thought, I should like to stress the importance crystals are easily and plentifully produced. The crystals of continued fundamental research into the nature and are very stable, almost inert, and are without effect on causes of insect diseases. The contemporary interest in most other life forms. In view of these qualities, it is not Bacillus thuringiensis provides an excellent case history. surprising that Bacillus thuringiensis is now being pro- This organism was isolated almost fifty years ago, and in duced commercially as a microbial insecticide.It is not subsequent field tests there were attempts to introduce it yet possible to accurately assess the potential of prepa- into insect populations; the results were ambiguous. When rations based on B. thuringiensis in forest operations and modern research demonstrated the source of toxicity and this will have to await the result of field trials now in the site of action of the toxin, it was possible for the first progress. We have shown that in laboratory tests a very time to use the organism rationally. In commercial pro- wide range of forest Lepidoptera arekilled by this duction, conditions are arranged so that maximum yield of pathogen. the toxic crystals is achieved. Understanding the nature I hope that the few examples I have referred to will and the mode of action of the toxic protein, we can apply help you understand why we are optimistic about the the material at the appropriate time and in an appropriate

942 Fifth World Forestry Congress Proceedings condition to achieve the desired result.Briefly, the early Tanada, Y. Ann. Rev. Ent. 4: 277, 1959. Thomson, H. M. Can. J. Zool. 36: 309, 1958. workers attempted what modern research has shown us to Steinhaus, E. A. Principles of insect pathology.McGraw-Hill, be well-nigh impossible. The work with the sawfly viruses New York, 1949. has shown that once introduced into an appropriate insect population, these virus diseases will persist and spread. RESUMES This is because we are dealing with an extremely infectious La lutte microbiologique contre les insectes nuisibles aux agent which is capable of overwintering in its host insect forêtsune méthode nouvelle in a viable condition. If we attempt to use B. thuringiensis On a pu observer au cours de ces dernières années un regain in this way the results will be disappointing.If, however, d'intérêt en ce qui concerne l'utilisation des micro-organismes we capitalize on the effect of the toxic crystals and use dans la lutte contre les insectes.L'idée a connu une popularité the microorganism as an insecticide, B. thuringiensis can accrue a la suite de découvertes récentes dans le domaine de la pathologie des insectes. be a very effective agent. The decision to use a microbial Ce texte étudie en termes généraux tin certain nombre de preparation as an insecticide or as a disease agent can be pathogènes des insectes en se fondant particulièrement sur des made only when we thoroughly understand the pathogen, recherches faites au Canada sur les espèces d'insectes nuisibles aux forêts. Les pathogènes du type protozoaire et du type champignon the host, and their interrelationship. ont fait l'objet d'essais en laboratoire mais on n'a pas encore Further study of some very promising pathogens is découvert les moyens de les employer de facon pratique sur le limited by the difficulty of obtaining adequate amounts terrain.Les virus pathogènes ont parfois été a l'origine d'une of infectious material, and this applies especially to the reductionspectaculairedu nombre desinsectesetcertaines espèces ont été introduites avec succès stir laterrain oà elles se protozoans, the viruses, and some of the fungi and sont maintenues et d'oà elles se sont répandues a partir du point bacteria.Those working with mammalian and avian d'introduction. viruses have developed techniques for growing their Le Bacillus thuringiensis qui sert de base a un certain nombre pathogens outside the natural host, but this has not yet de produits microbiens commerciaux en preparation agit plus efficacement comme insecticide pour une destruction rapide que been accomplished for the protozoan and virus diseases comme pathogène provoquant des maladies. of insects. The development of such a method lies in the Si les pathogènes affectant les insectes doivent être utilisés de field of fundamental research, and when it is finally ac- facon plus efficace dans la lutte contre les insectes nuisibles aux complished it will have important theoretical and practical forêts, ii faudra mettre au point de nouvelles méthodes d'applica- implications. As an example, the development of a tissue tion qui ne diminuent pas leur efficacité biologique. culture method for insect viruses would enormously sim- Extirpación Microbiológica de los Insectos de los Bosques plify the assay of virulence, and this, in turn, would como Nuevo Sistema facilitate the selection of more virulent strains. En los t'iltimos afios se ha despertado nuevo interés en el In my introductory remarks I stated that microbiological empleo de micro-organismos para laextirpación de insectos. control was a new approach. The word "approach" has Esta idea ha cobrado mayor interés ain con motivo de recientes descubrimientos en la patologla de los insectos. been defined as "the taking of tentative or introductory Se tratan aquI, en términos generales, varios patógenos de los steps with a view to full accomplishment," and I have insectos con referencia especial a los trabajos efectuados en el used the word in this sense.I will not prophesy where Canada con las especies de insectos de los bosques. En estudios de laboratorio se han investigado los patógenos protozoarios y the path will take us or how long will be the journey. fungosos, pero todavIa no se han hallado métodos eficaces de The distant fields still look green, and I hope that we go emplearlos en el terreno. En ocasiones, los patógenos virulentos forward with your sympathetic support and approval. han causado reducciones considerables de los insectos y se han introducido con buen éxito en las poblaciones de insectos, donde han perdurado y se han extendido desde el punto inicial. References El Bacillus thuringiensis, que es la base de varios productos For those interested in more details of some of the pathogens microbiales que se tiene en proyecto producir en escala comercial, mentioned, the following references may be useful: se emplea con más eficacia comb insecticida para la extermina- Bergold, G. H. Viruses of insects, in Handbuch der Virusfor- ción rápida, más bien que como patógeno para producir enfer- schung.Springer-Verlag, Vienna, 1958. medades. Bucher, G. E. Proc. Tenth Tnt. Cong. Entomol. (1956) 4: 695, Para que los patógenos se puedan emplear más eficazmente en 1958. el exterminio de las poblaciones de insectos de los bosques, es Heimpel, A. M., and Angus, T. A. Bacterial insecticides.Bact. necesario perfeccionar nuevos métodos de aplicación que no Rev. (In Press) 1959. reduzcan su eficacia biológica.

Forest Protection 943 Cultural Control of Forest Insects

A. D. VOUTE Institute for Biological Field Research, Arnhem, The Netherlands

Introduction Fluiter thinks that the eggs of this beetle, which are laid In this study, only those measures that are taken for the in the ground, get sufficient heat for development only purpose of giving the forest a certain resistance to the out- when the sun's rays can reach the ground.That a break of insect pests are understood to be "cultivation Brachyderes pest can be combated by causing a young measures." For this reason chemical and mechanical plantation to form a closed canopy as quickly as possible control will not be discussed, no more than biological is in conformity with this opinion. control, such as the mass breeding of insect enemies and Every forester will try to do this, so no special provi- diseases. sions need be made regarding this maxim. Apart from this, the forester will try to create as Although they no doubt belong to our cultivation favourable a climate for the growth of the saplings as methods, neither selection or resistance to diseases and possible.This is a climate in which extreme conditions pests, nor biological control measures such as the intro- are preventedlittle wind, slight changes in temperature, duction of pest enemies or diseases, will be paid attention It to, as these methods have been dealt with in other papers. and an equable and rather large quantity of moisture. The problem of how far it is justified to plant foreign will be possible to control the numbers of insect species species of trees in regions where they have to suffer from that cannot develop on a large scale, under such condi- certain enemies will not be entered into either.In this tions,if the fulfilment of these measures is of primary connection, we think, for example, of the planting of consideration.Generally speaking, however, it will be Japanese larch in Western Europe, where it is attacked by impossible to combat insects that are sensitive to extreme Cephalcia alpina (Klug), and of planting Picea abies conditions by creating such, as they would exert an un- (L.) Karst in the West European plain. favourable influence on the development of the forest itself. When we confine our inquiries in accordance with what has been said above, we have, in order to get a better The Influence of Cultivation Measures on the understanding of the problem, to trace first of all what Tree-Insect Relationship may be the cause(s) of any favourable or unfavourable The quality of the tree influences its role as food or result of cultivation measures. These measures may exert habitat for insects.Since these two functions have not an influence (a) on the climate, and through this on always been sharply distinguished, they will be discussed noxious insects; (b) on the relation between tree and together. insect; (c) on the relation between the insect that causes It is a well-known fact that the trees in a forest are not damage and its enemies or diseases; and (d) on the rela- always of the same value for insects. This difference is tion between the insect that causes damage and other caused not only by the hereditary disposition of the tree, factors. but also by the conditions under which the trees have In the following paragraph these relations will be speci- grown up or live at present. By means of cultivation fied with the help of a number of examples chiefly taken methods, it is possible to alter these conditions to a con- from our factual knowledge of European trees, after which siderable extent.This is made possible by means of we will discuss the way in which forests should be treated manuring and by moisture su ply. for the purpose of making the chance of the occurrence Drying symptoms which affect the trees may appear if of pests as small as possible. a plantation is exposed to desiccating winds. Insects feed- ing on roots may cause a similar effect.In the Nether- Cultivation Measures Exerting an Influence on the lands effects caused by Brachyderes incanus L. are, in Climate and, Through This, on Noxious Insects nearly all cases, followed by one that is caused by Retina The forester can modify the climate of a forest to a buoliana. Schiff. fairly high degree by thinning out, ways of felling, plant- ing, undergrowth, etc.It goes without saying that such The Influence on Synchronization operations exert an influence on the insect population. In many cases, insects need a certain stage of develop- There are only occasional cases where changes in the ment of the tree for particular vital functions. Thus, the climatic conditions in a forest exercised an influence on spruce sawfly (Lygaeonematus abietum Htg.) needs bud- the insects thems&ves to such a degree that the existence ding trees.Because of this, a tree can be affected only of the latter was threatened. during a very short period. Synchronization of this stage Brachyderes incanus L. can develop only as long as and the presence of female insects able to lay eggs is the foliage has not yet formed a closed canopy.Dr. therefore necessary for the occurrence of the pest. This 944 Fifth World Forestry Congress Proceedings principle has been excellently elaborated by Thalenhorst. resistance or an influence on the quality of the food?Or Cultivation measures for the purpose of preventing do other factors play a part as well? this synchronization can be taken by making sure that the phase of development of the tree is reached at a Moisture Supply moment when the insects are not in the stage referred It is generally known that most bark beetles can affect to above. a tree only if the latter's moisture conditionis poor (Van This may be done, e.g., by making use of species of Tubeuf)(e.g.,IpstypographusL.).Schweidtfeger trees budding either very early or very late. This means proved that the resin flow is responsible for it. He found that in the Netherlands, with respect to Lygaeonematus, that if the tree is in good condition, the flowingresin anticipation of the time of budding of the spruce should prevents the beetles from penetrating. Therefore, aspell be aimed at, which, however, involves the danger of of dry weather will promote a bark beetle pest,especially possible injury by night frosts. For many other insect on soils that are not apt to retainmoisture. A consider- species, such as Tortrix viridana L., Nygmia phaeorrhoea able fall of the subsoil water, caused by drought, willbe Donov., Gillecttella cooleyi, etc., a retardation of the time highly injurious, whereas under normal conditions the of budding of the trees would, to a large extent, protect roots can reach the ground water. them from being affected. Such anticipation or retarda- Similar relations exist with regard to manyBuprestides, tion can rarely be brought about by cultivation measures. e.g., Agrilus viridis and A.occipitalis, and with respect Retardation might be caused by spraying certain chemi- to Retina buoliana Schiff. cals. However, this procedure cannot produce the desired Thus, cultivation measures intended to exert a favour- effect more than once, and so is outside the scope of the able influence on the moisture supply of the tree counter- present study. act the occurrence of pests.This should be taken into The period during which there are trees that are at the account, especially when the soil is tilled.Van Goor stage where they may be affected can be shortened in demonstrated that on certain soils 'digging deep has an such a way that only a small part of the insect population unfavourabie effect on the moisture supply. Practice has can develop and reach the stage in which the eggs are laid. shown us that Scotch firs, planted on such deeplydug This measure might be taken in the case of Lygaeone- soils are easily affected by Retina. matus abietum, by making use of uniform pine stands, The development of predatory animals and parasites i.e., with stands in which all trees bud at the same time. can be influenced by noxious insects.The parasite popu- If this method is applied in planting trees, mixtures of lation can be kept up to the mark, by a rich biocoenosis mountain and plain spruce are to be avoided, and in with many intermediate hosts, so that they candeal the thinning process, trees budding before or after the effectively with the plant's enemies, as has beendescribed other trees in the stand are to be removed. To what by Schneider. In the case described by him, Oreta carnea extent this measure may be successful if taken with re- was least dangerous in gambirgardens lying on the edge spect to L. abietum, as far as I know, has not yet been of the virgin forest. examined. Conditions of life for predatory animals and parasites can be made as favourable aspossible. Mice cannot occur The Influence of Cultivation Measures on the Relation in such numbers that any influence on the populationof Between Noxious Insects and Their Enemies or Diseases animals that cause damage to the forest is to beexpected, Cultivation methods may exert an influence on the unless they have available cover. In some cases parasites extent to which insects may be reached by their enemies. not only need hosts in order to be able to laytheir eggs, Wood mice, as powerful predatory animals, may deal but other reserves of food as well. This has been demon- with insects hibernating in the litter on the forest floor strated with respect to a parasite of Popillia japonica (Holling). During one observation it appeared that on Newm. (see Cory, Langford, and Bickley).For this a steep slope, for some unknown reason, wood mice let reason, cultivation measures shouldaim at maintaining the chrysalises of Lygaeonematus erichsonii alone. By these reserves.Observations of this kind are scarce for taking cultivation measures, this slope could be made Dutch forests.Yet,it seems of importance that our habitable for mice, so that they could effectively combat cultivation measures should aim at the occurrence of the pest (Voflte). honey-giving plants in our forests. On citron seedbeds a parasite of Phyllocnistis citrella Enemies of predatory animals may be kept in check. Staint, a caterpillar leaf miner, could find its host only We see, e.g., that plant lice are often protected fromtheir when the leaf's cuticle was thin. By shading the seedbeds enemies by ants; moreover, ants intensify the reproduc- and keeping them moist, the action of the ichneumon fly tion of the lice, at the same time reducing theirnatural could be promoted in such a way that 100 percent of mortality. Measures taken with a view to preventing the the hosts would be parasitized.Although citron is not appearance of the ants will, in many cases,counteract planted in forests, this example may be given here, as the the occurrence of lice pests. In this connection, itshould citron plant is a tree. be pointed out that the ant population in our forests is, to a large extent, determined by theundergrowth (Quis- Manuring pel, Westhoff), so that itis possible to take certain Investigations made by Oldiger and others have shown measures by means of which the structureof the ant that the death rate of many species of caterpillars in their population can be favourably influenced. various stages can be considerably raised by means of Promoting the reproduction of ants in a forest may efficient manuring of the wood. To what this influence is counteractpests.Thereisan extensive amount of due is not fully known. Is it an increase of the tree's literature on this subject, from which it appears that there

Forest Protection 945 are important differences of opinion (Gosswald, Wellen- prehensive survey of the problems that exist in the field of stein, Elton).It seems to me that the proposition that forest hygienics. Some of them, however, relating to what the amount of damage done by a large number of insect has been said above, will be briefly discussed. species feeding on needles or leaves is favourably re- In the first place, attention should be paid to the health duced by the presence of red ants is hardly disputable. condition of the tree.The better the condition of the The same is true with respect to birds.They will tree, the greater will be the amount of damage it can hardly ever stop pests, although the opposite is often sustain before it will suffer seriously from it. The mass assumed(see Henze).Moreover,it has never been of leaves or needles is larger on a healthy tree, and its exactly proven that the presence of birds prevents pests. recuperative power islikewise greater.Consequently, Theoretically speaking, however, the control of insects the same number of noxious insects that may crop short by birds in cooperation with parasites is no doubtpos- a tree with little growing power will leave a considerable sible (Tinbergen, Klomp). Be:sides, in winter, birdsby number of leaves or needles on a tree with great vegeta- specializationcanremoveconcentrationsinplaces tive force. Moreover, the vital tree will recover sooner where noxious insects occur in large numbers, e.g., Pis- and more completely from the damage. sodes piniphilus eaten by woodpeckers. As longas the Added to thisis the fact that a goodly number of opposite has not been proved, we may therefore suppose pests do not fully develop before the growth of the tree that, under certain conditions, a large bird populationmay is stagnant.This may happen during development as a counteract the occurrence of certain pests. result of unfavourable conditions but also at a time when The composition of the forest greatly influences the the forest trees are full grown. The spruce budworm composition and density of the bird population (Tinber- comes to full development in such forests. gen).Promoting the bird population istherefore a Hesseling held that many pests occur only in forests cultivation measure that can no doubt be recommended. where the health condition of the trees is poor.Gen- Pfeiffer, who succeeded in raising the bird population to erally speaking, this is probably not true. In many cases, a height that had not been known before, has conducted however,pestsare promoted under such conditions. important research into the way of promoting it. Luitjes could prove that Diprion pini and Cephalcia Cultivation measures may perhaps exercise an in- alpina coincided with periods in which trees that had not fluence on the occurrence of diseases. been affected likewise showed less growth with respect The work done by Kovacevic and his cooperators in- to thickness. dicates that through the selection of the wood species it Naturally thisis true of so-called secondary insects, is possible to exercise an influence on the moment of for which, by definition, trees must be in a poor condition outbreak of a disease. This means that it must be possible to make them acceptable for insects. Such insects, how- to decrease the intensity of pests by taking cultivation ever, are hardly ever of economic importance, e.g., most measures promoting the occurrence of diseases. bark beetles. On the other hand, we should not forget The nature of the soil may influence the occurrence the occurrence of nonsecondary bark beetles, like Ips of diseases among cockchafer grubs (Niklas). How far typographus, and of Retinia and other insects on trees cultivation measures in such cases will be able to in- that are suffering from desiccation. tensify the disease is difficult to predict. Drying, especially, even if it is of a temporary nature Shepard observed a relation between fungal diseases and not easy to notice, exerts a strong influence on the and forest type on the spruce budworm (Choristoneura occurrence of insect pests. fumiferana (Clem.)). The higher the evaporation, the With a view to the possible occurrence of insect pests less the mortality of the caterpillar. we should therefore aim at a forest, the condition of which is as good as possible, while special attention should be The Relation Between the Animal That Causes Damage given to the moisture-retaining properties of the soil. and other Biotic and Abiotic Influences If the latter form a restrictive factor for the development Insects that cause damage to plants can develop in of the forest, much caution is required in planting an other crops or in a milieu without economic importance. undergrowth which may act as a moisture competition of Ophyderis fullonica bores holes in the citron fruit, the plantation. The following may serve as an illustra- whereas its caterpillars live on weeds (Kalshoven). tion. On the poor soils in the Netherlands, the moisture Myelophilus piniperda lays its eggs in dying trees and supply of forests is in many cases brought to a minimum. is,in this respect, without economic importance. The If such forests, often of Scotch pines, are provided with imagoes however, feed on healthy twigs and may seriously an undergrowth of shrubs that evaporate much moisture, damage the trees on which they live. there is a chance that the trees will suffer even more from Hylobius abietum develops in roots of dying trees, drying, and because of this will be more easily affected, e.g., in stubs; their imagoes may inflict serious damage to especially in dry years, by bark beetles, Retinia, etc. saplings(Escherich).The same istrueof Oryctes The richer the biocoenosis, the larger the variety of rhinoceros, feeding on coconuts, whose larvae live in predatory animals and parasites will be, and the greater rotting wood (Kalshoven). also will be the possibility for them to affect an insect In these cases it is desirable that the cultivation meas- species, the number of which is increasing, and the smaller ures should be directed to the food resource, to which the chance of their occurrence on a large scale.This no harm of economic importance is done by the insect. means that in richly variegated forests the chance of the occurrence of pests will be smaller.It is to be remem- Forest Hygienics bered, however, that a richly variegated undergrowth It is not part of my plan to give in this article a com- should not result in a poor condition of the trees, which, 946 Fifth World Forestry Congress Proceedings by drying. sites et a un grand nombre d'animaux prédateurs que les forêts as has been pointed out above, may be caused ne comportant qu'une seule espéce d'arbres. A rich biocoenosis will not be able to eliminate the La broussaille peut servir de refuge aux souris, qui remplissent injurious effects of drying. un role utile en mangeant un grand nombred'insectes nuisibles However, the principle to start from is that, as far as hibernants. S'il existe une concurrence importante pour l'utilisation de l'eau the soil permits, in planting a forest the largest possible entre la broussaille et les arbres, la disparitioti des arbustesest variety in the plantation should be aimed at. également desirable du point de vue de l'entomologie de la forét. Special attention should be given to the shrub and herb Ii est préférable de sacrifier la faune protégée par la broussaille layer of the forest, which consists of indigenous wood et d'assurer des arbres sains. Dans certainscas,l'application de méthodes culturalesest species, on which many insects occur. Foreign species, possible, méthodes visant certains animaux nuisibles, mais ne which are hardly affected, will scarcely contribute to the conférant pas a la forêt une résistance plus générale contre les enrichment of the animal community (Voüte). invasions.Ainsi, les infestations de scolytes peuvent être évitées Care should be taken that dying or dead parts of those par l'élimination des arbres mourants, leBracyderes incanus en veillant a ce que le feuillage des jeunes forêts se referme rapide- plants in which noxious insects can freely develop on a ment afin que grace au couvert les du soleil ne puissent large scale are eliminated from the forest. Felled trunks pas atteindre le sol, etc. are to be transported before, e.g., ips typographus or Le contrOle biologique par I'importation de prédateurs,de Myelophilus piniperda have developed in them, as these parasites ou de maladies, ou par la selection d'arbres offrant une species afterwards affect healthy trees and cause heavy résistance aux insectes nuisibles n'est pas étudié dans lepresent damage. document. Summing up, we may say that our aim should be a Lucha contra Insectos Forestales por Medio de Métodos healthy forest, with a variegated undergrowth of indigen- de Cultivo ous herbs or shrubs, and the absence of large numbersof A fin de evitar plagas causadas por insectos y reducir los efectos dying trees (either blown down by a gale or felled ones). de la pérdida de follaje, los silvicultores deben procurar el cre- Birds, mice, red ants, and other predators of our noxious cimiento de árboles sanos, preferiblemente en bosques mixtos con insects must be promoted as much as possible. una capa de vegetaciOn formada por matas y hierbas. With regard to special noxious insects, much research La condición de los árboles puede mejorarse por medio de la humedad y fertilidad adecuadas del suelo.El abono ha dado is needed to develop special methods to prevent out- resultados protnisorios en el aumento de la mortalidad de orugas breaks. From this research results may be expected, but que viven en el pino escocés. they will be long-term experiments. Among the most Lascondicionesque imperan en bosques mixtosofrecen fascinating experiments are those done on the spruce caracteristicas más favorables para los parásitos y para muchas clases de predatores, que las que se encuentran en bosques de budworm in Canada. A team of scientistsis working una sola especie de árboles. on this problem. The results obtained to date are re- Las capas de matas ofrecen buena cubierta para los ratones markable, and more encouraging results are expected. que resultan Ctilesal devorar grandes cantidades de insectos It is necessary that experiments be established like the nocivos que estén invernando. De existir una competencia importante entre los árboles y las Canadian spruce budworm experiments, for other pests matas por el agua disponible, es conveniente eliminar las matas, can be controlled only by applying insecticides. aun desde el punto de vista de la entomologIaforestal. El creci- miento de árboles sanos es más importante que el enriquecimiento RESUMES de la fauna que se logra con matas. En algunos casos, es posible Ia aplicacin de métodos de Contrôle cultural des insectes des forêts cultivo contra pestes especiales, pero con ello no se le da a! Afin de prévenir les invasions d'insectes et de réduire la perte bosque una resistencia general contra plagas.AsI por ejemplo, de feuilles ou d'aiguilles des arbres, les forestiers doivent s'effor- podrá prevenirse una plaga de escarabajos de la corteza Bra- cer de rechercher des arbres sains, si possible en forêts mixtes, cyderes incanus, eliminando árboles apestados y permitiendo que possédant un couvert bien développé d'arbustes et d'herbes. el follaje del joven bosque se cierre rápidamente para que los L'état des arbres peut être amélioré grace au contrôle de rayos del sol no puedan ilegar al suelo, etc. l'humidité et de Ia fertilité du sol. Le fumage qui augmente la En este trabajo no se hace mención del control biológico por mortalité des chenilles vivant sur le pin sylvestre, a donné des medio de la importación de animales de presa, parásitos o en- résultats encourageants. fermedades, ni de la selecciOn de árboles por su resistencia a Les foréts mixtes constituent un milieu plus propice aux para- insectos nocivos.

Forest Protection SPECIAL PAPERS L'influence du terrainsur la vulnérabilité du peuplier a 1'Agrilus viridis L.v. populnea Schaeff. (Coleoptera, Buprestidae) dans 1'Italie septentrionale

GIOVANNI M. ARRU Istituto de Sperimentazione per la Pioppicultura, Casale Mon ferrato, Italie

Dans l'Italie septentrionale et en particulier dans la Les oeufs, de forme elliptique, longs d'environ 1,5 mm. plaine du Pô, la plantation des peupliers ces dernières sont rassemblés, au nombre de 4 a 15,selon nos années a augmenté considérablement, a tel point qu'ils observationsdans des groupes imbriqués les uns dans ont conquis des terres oui ils n'avaient jamais été cultivés. les autres, et protégés par une sécrétion blanche, solide Jusqu'à ces derniers temps, la culture était iimitée aux et résistante.Les groupes, de forme circulaire ou sub- plages de structure friable, ou modérément friable, avec effiptique, sont déposés a n'importe quelle hauteur sur une nappe d'eau peu profonde. Aujourd'hui, a Ia suite le côté de l'arbre exposé au soleil, c'est-à-dire entre N.E. de grands investissements récents, la culture a été étendue et N.W., avec deux maxima au E.S.E. et S.S.W. au-delà de ces terres pour en occuper d'autres qui souvent Les larves sortent après 10-15 jours d'incubation, et n'y sont pas aptes. a l'aide de leurs mandibules, pénètrent directement dans En effet, tous les terrains ne se prêtent pas a la culture l'écorce. d'une essence aussi delicate que le peuplier;en outre, De couleur jaune-créme plutôt clair, de forine spatulée, l'emploi de plantes a accroissement rapide a conduit a elles présentent un prothorax élargi, oa on distingue une la diffusion de sujets d'une belle venue, capables d'exten- region munie de petites asp'rités, traversée par un sillon sions spectaculaires, mais très exigeants spécialement en longitudinal sclérifié; leur corps présente une depression ce qui concerne l'approvisionnement en eau, qui doit dans le sens dorso-ventral. être abondante et constante durant la saison chaude. Des qu'elles sont entrées dans l'écorce, une partie Certains clones s'accroissent rapidement et se montrent des larves se dirigent vers le haut et une partie vers le trèsrésistants aux maladies(Pollaccia elegans Serv., bas, en se maintenant toujours dans la zone sub-corticale. Melampsoraspp.,Dothichiza populeaSacc.etBr., L'épiderme se dessèche selon le parcours des galeries cancer bactérien, bactérioses, etc.) et a certains insectes superficielles et, a cause de la croissance de l'arbre, se (Phloeomyzus passerinii Sign.) mais seulement quand fend;iise forme ainsi une fente irréguiière, toujours ils se trouvent sur des terrains aptes et quand ils sont orientée dans le sens de la heuteur de l'arbre, et qui a, traités suivant des techniques de culture appropriées. au centre, les oeufs. Les larves, après avoir parcouru un trajet variable de Quand ces conditions ne sont pas respectées, l'arbre 2 a 6 cm., changent de direction et suivent une route s'affaiblit et se trouve dans un état de débilité qui le différente, de sorte que lesgaietiess'étendent et se predispose aux attaques des divers parasites. croisent en désordre sur une region de forme elliptique ou Parmi les parasites, l'Agrilus viridis L. var. populnea sub-rectangulaire, de dimensions variables, qui peuvent Schaeff., qui auparavant était a peu près inconnu, et qui atteindre jusqu'à 10 cm. en direction de Ia hauteur de est aujourd'hui très répandu et provoque des dégâts l'arbre, et 4 ou 5 cm. dans le sens transversal. non négligeables, suscite un intérét particulier. Chaque lesion occupe en général un tiers environ de la circonférence de l'arbre. Notes sur Ia biologie de l'Agrilus viridis L. var. populnea Dans la couche corticale, les galeries s'enfoncent et se Schaeff. croisent a des niveaux différents. Les larves, au fur et L'insecte est un coléoptère Bupreste de la famille des a mesure qu'elles grandissent, creusent dans des zones Agriles, long de 7 a 8 mm., large de 1 mm., 5 a 2 mm, plus profondes jusqu'à pénétrer dans le bois d'oü elles 5, de couleur généralement vert bronze changeant, dont peuvent sortir pour revenir dans l'écorce; mais lorsque certains exemplaires vont du vert métallique au bronze l'écorce se dessèche, sur la surface attaquée, les larves ou même au bleu pale. l'abandonnent définitivement, et pénétrent dans le bois, Aux environs de Casale Monferrato (Piémont), les qui, a son tour, se dess'che, jusqu'au coeur de l'arbre; aduites commencent a apparaItre au debut de juin et l, elles vivent pour le reste de l'été et hivernent. s'accouplent; la ponte commence 10 ou 15 jours après Parvenues a maturité, les larves préparent une cellule et continue jusqu'à Ia mi-juillet. de forme ovoIdale allongée (de 9 a ii mm. sur 2 mm. a 948 Fifth World Forestry Congress Proceedings 2.5 mm.) oü elles passent leur nymphose, qui, a 200 C., peupleraie sur un terrain limoneux-sableux, près du bord dure entre 20 et 30 jours. d'un dépôt naturel de cailloux.Tous los arbres de la Les adultes se dispersent après avoir creusé dans le premiere file et quelques-uns de la seconde, c'est-à-dire bois qui les sépare de l'extérieur une galerie longue de ceux qui par leur proximité avec le dépôt de cailloux se 1 cm., 5. trouvaient sur un terrain plus sec, furent attaqués par Nous arrivons ainsi au printemps suivant et le cycle l'Agrilus. recommence.L'insecte a donc tine génération par an. Dans un troisi:ème cas, on constata une forte attaque de l'Agrilus; environ 2.000 arbres sur 3.000 étaient atteints. Plantes attaquées Ii s'agissait de peupliers plantés presque tous très super- L'insecte attaque tous les peupliers depuis les clones ficiellement, a environ 40 cm., dans un terrain non sélectionnés (Populus x euramericana (Dode) Guinier irrigué. Les arbres places dans des trous plus profonds, cvv.) jusqu'aux formes vulgairement dites "canadiennes" et par consequent en mesure de pouvoir bénéficier de (? Populus deltoides Marsh. var. monilif era Henry x P. plus d'humidité étaient les seuls sur lesquels on ne nigra L.), "Caroliniane"(? Populus deltoides Marsh. remarquait pas la presence de Buprestes. var. missouriensis Henry x P. nigra L.), et aux peupliers Les cas exposés ici sont les plus significatils, mais ii blancs (Populus alba L.). n'est pas rare d'observer les dégâts causes par l'Agrilus viridis var. populnea dans les rangées situées sur des Causes prédisposantes berges a un niveau notable au-dossus de l'eau; en bordure Comme nous l'avons déjà dit, l'insecte, rare au cours des routes sur un terrain très compact; sur des terrains des années passées, est aujourd'hui de plus en plus fré- présentant une forte teneur en argue; en presence de quent. Sa diffusion est liée essentiellement a un état de couches d'inhibition superficielle (plaques calcaires, ter- rains asphyxiés, etc.) faiblesse de l'arbre, provoqud par les conditions du terrain Ii faut noter que dans tous les cas cites, les arbres, en general, et, de facon plus nette, par le manque d'eau. au moment øà l'Agrilus pondait,c'est-à-dire en juin- Ces conditions se présentent fréquemment dans le:s ter- juillet, se trouvaiont en état de faiblesse et dans l'impos-. rains sableux ou caillouteux et dans los terrains au sous- sibilité do fournir a la partie négétative la quantité d'eau sol très permeable oà la nappe d'eau n'a pas de pos- nécessaire. Le fait se produit autant a cause du manque sibilité de rernontée. d'eau du sol (c'est le cas le plus frequent et le plus Ii est evident que la manque d'eau ne permet pas a evident) qu'à cause d'un développement insuffisant de l'écorce de pouvoir réagir avec assez de promptitude et l'appareii radical. de force aux attaques de i'insecte et que celui-ci, d'autre Iiest bon de preciser que lesattaques d'Agrilus part, a la possibilité de choisir les arbres qui se trouvent observées par nous, se remarquaient toujours sur des dans un tel état. L'Agrilus, en effet, n'attaque jamais los peupliers au cours de la premiere année do plantation; plantes vigoureuses. dans la technique de culture communément pratiquée, De nombreuses observations ont été faites qui con- on utiise do petits peupliers de pépinière, âgés de2 ans, firment ce que nous avons dit, et on a mis en ouvre des qui sont transplantés en automne ou au printemps mais, experiences appropriées pour en fournir une démonstra- en touscas,presque complètement privésd'appareil tion: nous rapportons ici les experiences les plus sig- radical. nificatives. Ii est clair quo, quand arrive le printemps et quo les Au printemps 1959, on pianta a l'Institut d'Expéri- bourgeons s'ouvrent, l'arbre ost encore privé de racines mentation pour la Populiculture, une rangée de 55 petits etvitsurlesreserves précédemment accumulées;si peupliers,disposes en bordure d'un terrainsableux- l'arbre est en mesure de reconstituer rapidement son limoneux, entouré d'un fossé de 70 cm. de profondeur apparoilradical,ilpeut surmonter le "choc" dela environ. La plantation fut effectuée selon la technique transplantation; mais s'il n'y parvient pas, ou si après normale, avec des trous de faible profondeur (60 cm.). avoir repoussé sos racines, celles-ci ne trouvent pas dans Au debut de mai, alors que los peupliers avaient déjà le terrain des conditions adéquates, la crise do la trans- des bourgeons d'environ 10 cm., cinq de ces arbres plantation s'aggrave,so prolonge et dure encore au furent soumis a un traitement particulier, qui consistait moment do la sortie do l'Agrilus. a les secouer et a les plier presque jusqu'à terre une fois L'attaque de la part de l'insecte ost facilitéo par los pour semaine, de placons a arracher les jeunes radicelles années sèches,soit parce que ceiles-ci aggravont les et a diminuer par consequent l'apport d'eau. Des Agrilus inconvénients déjà indiqués, soit parce qu'elles favorisent aduites,élevésen laboratoire,furent périodiquoment l'apparition en masse du parasite, qui aime beaucoup la lâchés sur le terrain. chaleur. Les arbres soumis au traitement décrit, furent les premiers a étre attaqués et on y trouve los oeufs avec bien Les degáts 15 jours d'avance par rapport a ce qui se produit sur Les degâts sont en général graves, étant donné qu'ils les arbres non taités. Par la suite, avec la venue de la so produisent sur des arbres déj.à affaiblis. Doplus, ils los sécheresse de i'été,losarbres en position d'angle, en affaiblissont encore et favorisont les attaques ulterieures de contact avec le fossé sur deux côtés, et qui se ressentaient champignons tels que Dothichiza populea Sacc. et Br. et le plus do la sécheresse du terrain, furent attaqués a leur Cytospora spp. et cellos do quelques insectos, on particu- tour. her Cossus cossus L. et Paranthrene (= Sciapteron) Un autre cas intéressant fut observe, également au tabaniformisRott.,quimanifostentiinepréférence printemps1959, quand on planta.àdemeurre une marquee pour les arbres déjà atteints, sur lesquels us Forest Protection 949 déposent les oeufs le long des bords de cicatrisation des d'assurer, là oü l'irrigation est possible, un apport blessures produites par l'Agrilus. Nousavons Pu observer, d'eau constant et abondant au cours des mois de en certainscas,que 40% deslesionscausées par mai-juin et juillet.Ceci signifie que les interven- l'Agrilusétaient compliquCes par lesattaques de P. tionsdoivent être faites nettement plustot que tabaniformis. d'habitude, en particulier dans les sols oü sous une Quand les blessures sont nombreuses (nousen avons légère couche de bon terrain agraire, la presence de compté jusqu'à 35 par metre linéaire), on peut direque cailloux ou de sable est évidente; les de l'écorce sont condamnés et aussitôt envahispar d'effectuerlaplantation en trous profonds d'au Dothichiza populea. moms 80-100 cm., de facon que le jeune peuplier Ii faut remarquer que les arbres ainsi affaiblis,avec de soit solidement enraciné dans le terrain et que les vastes zones de bois sec jusqu'à la moelle sont facile- jeunes racines se développent en profondeur oü ment arrachés par le vent, surtout si le pic_vert*, a la l'humidité est plus abondante, et, de plus, qu'elles recherche de larves, y a pratiqué des trous. ne soient pas arrachées par d'éventuels vents vio- Quand l'arbre est en mesure de réagir, la cicatrisation lents; est assez rapide et devient totale au bout d'un ou 2 ans. de remuer profondément le terrain, sur toute la Si les lesions sont en nombre supérieur a 5par arbre, surface du champ, dans lecas de terrainstrès ii convient de remplacer les sujets atteints. compacts ou asphyxiés. La lutte RESUMES The Influence of Soil Conditions on the Vulnerability of La lutte directe contre l'insecte peut être effectuéeen the PoplartoAgrilusviridisL.var. populnea combattant l'adulte ou les larves. Schaeff. (Coleoptera, Buprestidae) in Northern Italy Dans le premier cas, ii s'agit d'empêcher la ponte,en The author,after explaining briefly the biology of Agrilus aspergeant les troncs qui risquent d'être atteints, avec viridis, L. var. populnea Schaeff.(Coleoptera, Buprestidae) ex- des insecticides au contact persistant. Les difficultés d'une amines the activities of the insect in relation to the condition of telle méthode sont évidentes. the soil in which the poplars affected are being cultivated. The insect has a generation period of one year and it attacks Dans le second cas, la lutte est menée contre les only trees weakened or suffering from the "shock" of trans- larves nouveau-nées, en intervenant avant qu'elles s'en- planting, aggravated by adverse conditions of the terrain. foncent dans lebois, Among the causes which predispose trees to the attacks of au moyen d'aspersions ou de Agrilus, the author cites those which prevent a rapid resumption badigeonnages sur les troncs atteints, d'une solution de of the growth of the tree; the most important is the lack of water Parathion au l,52o/o de produit actif pur. Une telle in sandy or pebbly soils, on embankments, or in compact and méthode,déjà employee contre d'autres parasites du unaerated ground. peuplier (Cryptorhynchus lapathi (L.), Saperda carchar- Finally, the author discusses the means of preventing damage ias L.), a été expérimentée avec succès l'an dernier. and combating the insect. Ii conviendrait beaucoup mieux pourtant de prévenir La Influencia del Terreno en la Vulnerabilidad del Alamo les dégâts au moyen d'une série de mesures parmi les- al Agrilus viridis L. v. populnea Schaeff. (Coleoptera, quelles nous suggérons: Buprestidae) en Italia Septentrional de ne pas planter les peupliers dans les terrains El autor, despuës de exponer brevemente la biologIa del Agrilus capables d'affaiblir les arbres; viridis L. var. populnea Schaeff. (Coleoptera, Buprestidae) trata Ia actividad del insecto en relación con las condiciones del suelo d'utiliser, parmi les clones sélectionnés,ceux qui ont en que se cultivan los álamos atacados. l'appareil radical le plus robuste(ex. Populus x. El insecto se reproduce anualmente y ataca solo a los árboles euramericana (Dode) Guinier cv. "I 214") parce debilitados o que sufren el efecto del trasplante, agravado por que ceux-ci, poussant des racines plus vite et plus malas condiciones del terreno. Entre las causas que predisponen a los ataques del Agrilus el abondamment, ont la possibiité d'explorer une plus autor cita las que impiden una rápida reposición de crecimiento grande surface de terrain,et, par consequent, de del árbol; Ia más importante es Ia falta de agua en los suelos s'étendre là oü les conditions sont meilleures; arenosos o pedregosos, en los ribazos o en terrenos compactos y asfixiados. El autor trata también los medios de prevenir los daños y de *Picas viridis L. Ayes. Picidae. combatir aJ insecto.

950 Fifth World Forestry Congress Proceedings Virus Control of the Sawfly (Neodiprion sertifer Geoff.)

CLAUDE F. RIVERS Agricultural Research Council, Virus Research Unit, Cambridge, England and MYLES CROOKE Forestry Commission of Great Britain, London, England

Introduction layer in the sediment at the bottom of the container. The supernatant liquid was discarded and the polyhedra Neodiprion sertifer Geoff. is, in Britain, a pest of young partially purified by centrifugation, so that a reliable pine woods, and epidemics most frequently occur when estimate of virus concentration could be made. A Petroff- the trees are between 4 and 12 feet in height. Attacks Hauser counting chamber was used to estimate the num- usually persist for two to four years but, although the ber of polyhedra per millilitre of water. Virus disease in defoliation produced is striking, do not usually result in larvae was confirmed by means of heat-dried, Giemsa- tree death. A marked reduction in growth does, however, stained, haemolymph smears examined under the oil- occur. The native Scots pine, Pinus sylvestris L., is com- monly affected, but attacks on the introduced lodgepole immersion lens of a microscope. Trial 1.In June 1956, a heavy infestation of Neodi- pine, P. contorta Dougl., are usually more severe than prion sertifer was located in a two-acre shelterbelt of those on Scots pine whilst, in pine/spruce mixture, it is Scots pine and Sitka spruce near Thetford, Norfolk. The not unknown for feeding to occur also on the spruce. stand was of very uniform growth and well isolated from In Europe, the collapse of outbreaks is often brought other pines by arable ground, thus making it highly about by a virus disease of the larvae. In North America, suitable for experimental purposes. When the attack was where Neodiprion sertifer is an , having discovered, the larvae were mature and the infestation a been first discovered in New Jersey in 1925, this virus vigorous one. No unhealthy larvae were found, and the disease did not, apparently, occur until it was deliberately infestation was allowed to develop naturally until the introduced.Bird (1953) obtained several virus-killed following year. larvae from Sweden in 1949 and propagated material In mid-May 1957, each pine tree, of average height which he used in field tests in Canada in 1950-52. These just over seven feet, was found to carry between 4 and trials gave highly successful results, and in a later paper 10 colonies of third instar larvae. The application of the Bird (1955), speaking of the virus, says that "in general, virus suspension was made at this time, using a knapsack ithas replaced insecticides in controlling this sawfly." sprayer fitted with a T boom carrying twoceramic jets Stocks of virus have been supplied to workers in the size 000, and operating at a pressure of 40 p.s.i.The United States, and Beal (1958)says, "Now we un- virus suspension contained 200,000 polyhedra per ml. hesitatingly apply suspensions of the virus by means of water.Forty-one litres were applied to approximately airplanes to sawfly-infested plantations, with consistently 180 pines at the south end of the block, the foliage being good results." thoroughly wetted by the spray. A further 4.5 litres, Although the virus disease occurs naturally in Britain, containing 400,000 polyhedra per ml., were applied over it does not always appear as early in an outbreak as approximately 1A acre next to the heavily sprayed section might be wished. The artificial introduction of the virus by walking through the area with the boom held above at an early point in the outbreak offers, therefore, an op- the head. The remaining 1½ acres were left untreated; portunity of reducing damage and increment loss.This it is possible that some small amount of virus may have paper describes two simple trials conducted by staff of the reached this control area, but the senior author, who Virus Research Unit of the Agricultural Research Council applied the spray, does not believe that any appreciable and the Forestry Commission. The virus suspension used contamination of the control area took place. in the trials was received from Dr. F. T. Bird, to whom A fortnight after spraying, dead and diseased larvae we express our thanks. were found in the heavily sprayed section. Threeweeks Materials and methods. The virus suspension was pre- after spraying, counts made in randomly placed 15-foot- pared in Dr. Bird's laboratory from maccrated diseased square plotsthroughout theheavilysprayed section Neodiprion sertifer larvae which had been allowed to rot showed an average of four living larvae per tree. At this in water at room temperature for several months. During time, in the lightly sprayed section, a few colonies of this time the polyhedra settled out and formed a white diseased larvae were found, whilst in the control section

Forest Protection 951 no virus-diseased larvae were found, and a proportion of and it is difficult to find batches of larvae on any shoots." the trees were heavily defoliated. An inspection of the treated area was made in mid- Eggs collected from the sprayed and control sections in June, and at that time, it was difficult to detect any May 1958 were reared in the laboratory, and all the larvae defoliation caused by the 1959 larvae. One small group emerging from them died from the virus disease in the of pines, surrounded by Sitka spruce, had, however, gone second instar. An inspection of the plot revealed that unnoticed at the time of spraying and had not been disease was general throughout the area; the trees in the treated; three of these trees were badly defoliated. sprayed area had been reinfested, but the larvae had all succumbed before causing damage. The colonies in the Discussion unsprayed control section were similarly affected. We The attempt to repeat, in a simple fashion, Bird's work have found that very much less virus is required to infect on the virus control of Neodiprion sertifer has been the earlier than the later instars of insects, and it is pos- successful, and there seems to be no doubt that this sible that sufficient virus was released in 1957 to infect control technique can and should be used in British the first instar 1958 generation.Another possibility is outbreaks of the sawfly where the virus disease does not that numbers of the 1957 generation larvae received sub- appear naturally at an earlystage.The polyhedral lethal doses of virus, which was passed on by transovarian viruses have a long storage life and are unaffected by infestion to the 1958 generation. To test this latter pos- long periods outside the insects' tissues, so that there are sibility, twelve female pine sawflies were collected from no supply difficulties associated with the method. Further the shelterbelt in October 1958 and caged over a young advantages include the specificity of the virus, ensuring potted Scots pine tree at the laboratory. This tree had that beneficial insects are not affected, and the fact that not been infested with Neodiprion sertifer at any time and control can be achieved over succeeding generations of had never been used for virus work. In 1959, all the the sawfly. To deal with larger outbreaks than those dis- larvae emerging on the potted tree died with the virus cussed here would entail !the use of larger power-operated disease in the first instar. Although N. sertifer was very machines for applying the suspension than were used in scarce in the shelterbelt in 1959, virus was demonstrated our trials, but there would be no great difficulty in finding there also. suitable equipment. Trial II. The second trial was located near Ballachu- lish, Argyll, and was carried out in 1959. The crop in- References fested by Neodiprion sertifer comprised a total of some Beal, J. A., 1958. Status and trends in forest insect research in five acres of Scots pine, of variable height from 3 to 15 the United States.Proc. Xth mt. Congr. Ent., Vol. 4, pp. 323- feet, and occurring in scattered groups or larger patches 330. within a matrix of Sitka spruce, Picea sitchensis (Bong.) Bird, F. T., 1953. The use of a virus disease in the biological Carr. Defoliation had occurred in 1957 and 1958, but the controloftheEuropean pinesawfly, Neodiprion sertifer (Geoff.) Can. Ent., Vol. 85, pp. 437-446. intensity of the attack had varied greatly. In some parts 1955. Virus diseases of sawflies. Can. Ent., Vol. 87, of the crop, the defoliation was very light, whilst in pp. 124-127. others, only current year's needles remained on the trees. At the time of treatment the stages present we:re from RESUMES egg to second instar larvae. Emploi de virus contre les lophyres (Neodiprion sertifer Spraying was carried out on May 5th, using a Kiekens Geoff.) Whirlwind 75 knapsack mist blower, which emits a much Les essais effectués conjointement par le Centre de Recherche smaller droplet than did the knapsack sprayer used in sur les Virus (Virus Research Unit) du Conseil de la Recherche Trial I.The virus suspension used contained 500,000 Agricole et la Commission Forestière ont démontré qu'un agent polyhedra per milliitre of water, to which a wetting agent, pathogène polyédrique de la larve du Neodiprion sertifer Geoff. Sovix, had been added. The application rate was 1½ peut être utilisé pour lutter contre les manifestations de ce lophyre. Cette maladie des larves du lophyre sévit a l'état naturel en gallons per acre.The main objective of the operation Grande-Bretagne, mais dans les cas oh elle n'apparalt pas dans was control of the infestation, and for this reason, no les premiers stades de l"ruption,le virus peut être introduit unsprayed control area was left. A small group of artificiellement au moyen de puivérisations dont l'effet est rapide "indicator" trees were sprayed twice so that the local et continu. forest staff could readily observe the results of the disease. On these, all larvae were dead one week after spraying. Uso del Virus para Combatir el Insecto, Neodiprion A random collection of twelve colonies was made two sertifer Geoff., que A taca al Pino weeks after spra4ng, and of these, eight colonies con- Los experimentos conjuntos llevados a cabo por la Seccidn de tained many diseased larvae, and the other four colonies Investigación de Virus del Consejo de Experimentación AgrIcola y la Comisión Forestal han demostrado que la enfermedad became diseased a few days later. Another random col- poliédrica de Ia larva del Neodiprion sertifer Geoff., puede ser lection of twelve colonies was made three weeks after utilizada para combatir la plaga de este insecto. La enfermedad spraying,and ofthese,seven contained only dead, ocurre naturaimente en Ia Gran Bretaña, pero en los casos en diseased larvae and the others, diseased larvae.Four que no brota durante las primeras etapas de la plaga, suele intro- ducirse artificialmente (mediante la aspersion de liquidos con ci weeks after spraying, the forester in charge of the area virus poliédrico en suspension) y resulta un método rápido y reported that "the control has produced drastic results, continuo de combatirla.

952 Fifth World Forestry Congress Proceedings El Espolvoreo como Sistema Para Combatir Plagas Forestales

MANUEL Nnii& Y JOSE A. TORRENT Instituto Forestal de investigaciones y Experiencias Madrid, España

Para combatir las plagas de insectos hemos utilizado, mm2; en la B, 20 granos; y en la C, 400 granos. Estas en el transcurso de los iiltimos años, diversos productos cifras no tienen más valor que el relativo de granos y sistemas de aplicación.Las plagas forestales atacan sedimentados, pues los cristales se situaron horizontales normalmente grandes extensiones de monte y es necesario en el suelo, y distinta impregnación tendrIan otras super- combatirlasen pequeñosperlodosde tiempopara ficies situadas en diversos ángulos. No obstante, sirven aprovechar la época en que el insecto es más vulnerable. como demostración evidente de la gran cantidad de polvo Por otra parteelsistema elegido tiene que serlo que se pierde cuando sopla la más ligera brisa. Algo suficientemente económico para que sea rentable.A- análogo ocurre con relación a las ascendencias, provoca- tendiendo a estas consideraciones hemos desarrollado una das al ser calentado el suelo por el sol. técnica de espolvoreo que, en la mayorIa de los casos, ha resultado el sistema más eficaz, económico y práctico. Aparatos Nos referimosal espolvoreo en masa, por formación Los más utiizados ban sido los espolvoreadores a de nubes, durante las horas de calma atmosférica, por motor de parihuelas, transportados por dos hombres. La medio de aparatos terrestres. elección de este aparato es debida a que las mayores extensiones tratadas han sido de encina (Quercus ilex L.). Experiencias La poca altura de estos árboles permite la utilización de Fueron iniciadas en 1952 y encaminadas principal- aparatos ligeros, con motor de 1 HP, que alcanzan perfec- mente a combatir la Lymantria (Port hetria) dispar L. y tamente las copas.Tambidn tienen la enorme ventaja la Tortrix viridana L. en los montes de encina, Quercus sobre los aparatos más pesados, que necesitan ser trans- ilex L. portados sobre ruedas, de poder transitar por cualquier Utilizando cualquier tipo de aparato, al espolvorear clase de terreno. En los encinares, montes de arbolado con viento o durante las horas centrales del dIa, se gasta muy claro, de relieve poco accidentado y sin matorral, una gran cantidad de producto y se impregnan de una ha sido el aparato que ha resuelto el problema de su manera irregular y deficiente las hojas y los insectos. El tratamiento.El rendimiento obtenido como media, en espolvoreodurantelashoras de calma atmosférica, más de un millón de hectáreas tratadas, ha sido de 9 normalmente al amanecer, al atardecer y a veces durante hectáreas por hora. Como su utilización por dIa ütil la noche, nos dió resultados altamente satisfactorios en de trabajo ha sido de 2 horas 50 minutos de media, su cuanto a una mayor impregnación y uniformidad en la rendimiento medio por dIa es de 25 hectáreas.General- repartición del polvo,al mismo tiempo que se gasta mente se trabaja con equipos constituIdos por 7 aparatos. menos de la initad del producto. La separación entre ellos es de unos 40 metros, con lo El poco peso de las partIculas de polvo hace que se cual el equipo cubre un frente de unos 300 metros, difundan en la atmósfera con la más ligera brisa o uniéndose la nube formada por cada uno de los aparatos ascendencia, mientras que calma (velocidad del viento para constituir una nube ünica que va depositando los menor a un metro por segundo) las partIculas se van granos de polvo que impregnan el monte. El abasteci- depositando lentamente y recubren homogéneamente todo miento de insecticida se realiza por medio de caballerIas el follaje, asI como a los insectos aunque estén refugiados. que lo transportan a lomo. Se obtuvieron fotografIas de tres series de 3 cristales También se han utilizado aparatos de ruedas, con ahumados dispuestos de 10 en 10 metros en una lInea motor de 9 HP.Solo pueden emplearse en terrenos perpendicular a la dirección de desplazamiento de un llanos. Con ellos se ha obtenido un rendimiento medio equipo de aparatos espolvoreadores a motor de parihuelas por dIa ütil de 36 hectáreas. (distanciados 40 metros). Cuando paso el equipo por La econoinla de este tipo de espolvoreo es evidente si la lInea de la serie A, el viento era de un metro por se considera que el costo total de tratarniento de una segundo; para la B, tres metros por segundo, y para la C, cero metros por segundo, o sea calma absoluta. En hectárea de encinar es del orden de las 130 pesetas. Sin la serie A se observó una irregularidad en el reparto embargo los ensayos realizados con preparados lIquidos, del polvo. En la B, una gran irregularidad y deficiente además de ser menos eficaces, han resultado: la pulveriza- sedimentación. En la C, el reparto fue uniforme y muy ción a 160 pesetas por hectárea, Ia atomizaciOn a 154 abundante el depósito de granos.Realizado un conteo, pesetas por hectárea y la nebulizaciOn a 165 pesetas por resultó, para la serie A, una media de 100 granos por hectárea.El espolvoreo por medio de aviones, que se Forest Protection 953 ha utiizado para terrenos accidentados, ha resultado a El ahorro de producto con la utiización del espolvoreo 273 pesetas por hectárea. en las horas de calma atmosférica es extraordinario, lo que permite una gran economia reflejada en los bajos Insecticidas costos de tratamiento por hectárea. Se han empleado productos en forma de polvo, para Los aparatos alcanzan grandes rendimientos debido a combatir diversas plagas, a base de D.D.T., H.C.H., que su acción se proyecta en amplias fajas de terreno. Lindano, Malathion y Endrin principalmente.El más La economla que se logra con la pequeña inversion para empleado ha sido el D.D.T. al 10%. La media de kgs. adquirir estos sencillos aparatos es también muy conside- por hectárea de este producto utilizado con los aparatos rable. El empieo de los mismos por equipos hace que terrestres ha sido de 8,25. la eventual averIa de alguno de ellos no sea causa de La composición fIsica del insecticida es muy importante paralización alguna. Lo que es muy importante dada la para el espolvoreo por formación de nubes. El producto normal urgencia de la lucha contra las plagas. debe ser de gran finura: un 97% debe pasar a través del Otras ventajas de los productos en forma de polvo son tamiz de 200 mallas. La humedad no debe ser superior su fácil transporte y el hecho de estar preparados sin a! 1%. El peso especIfico aparente del producto debe que se necesite manipulación alguna en el campo que estar comprendido entre 0,45 y 0,55. Es de destacar la siempre está sujeta a errores en la dosificaciOn. Por esta gran importancia económica que tiene la variación del causa pueden vigilarse las caracterlsticas flsico-qulmicas peso especIfico aparente. Hemos comprobado que con un del producto desde su preparación en la fábrica.La producto de peso especIfico 0,75 son necesarios 9,75 carencia de agua en muchas regiones hace imposible fre- kgs. por hectárea y para otro de peso especIfico 0,50 cuentemente el tratamiento con productos lIquidos. bastan 8 kgs. por hectárea. 0 sea se ahorran 1,75 kgs. Finalmente, los productos en forma de polvo tienen por hectárea. escasa persistencia, desapareciendo con la liuvia y ci viento.Esta cualidad, que en ocasiones se ha citado Extensiones tratadas como desventaja del polvo para las tratamientos insectici- Desde las primeras experiencias hasta la actualidad, el das, tiene la virtud de que, una vez efectuada la acción Servicio de Plagas Forestales ha venido tratando, por directa con los insecticidas de contacto sobre el insecto, este sistema de espolvoreo, las siguientes extensiones: no causa persistentes trastornos al conjunto de insectos que pueblan el monte. Con ello se consigue que la En 1953 4.925 has. parasitaciOn de los insectos perjudiciales supervivientes En 1954 19.279 has. sea iricrementada pues la reducción de los parásitos es En 1955 66.452 has. minima. Ta! es el caso de los tratamientos de lepidOp- En 1956 149.972 has. teros que se efectuan cuando las orugas son pequeñas y En 1957 214.951 has. por tanto no son afectados por eltratamientolos En 1958 299.161 has. parásitos más importantes, o sea los que atacan a las En 1959 177.123 has. orugas desarroiladas, crisálidas y huevos. TOTAL.. 931.863 has. Hemos comprobado en numerosos casos, especialmente en la Lymantria (Porthetria) dispar L. la aniquilación Poriniciativaparticular,debidoalasenseñanzas por parasitación de los focos que quedaron por defectos recibidas en los cursillos celebrados por dicho Servicio, del tratamiento, asI como el gran aumento del porcentaje se han tratado unas 800.000 hectáreas. de parasitación en las zonas infestadas próximas a las tratadas con polvo. Esta cualidad demuestra la superiori- Ventajas dad del polvo sobre los preparados liquidos en gas-oil o Aunque no creemos quese pueda aconsejar este fuel-oil, que, por su gran persistencia, liegan a influir en procedimiento para toda clase de plagas y tipos de monte, el complejo biológico del monte. sI es posible afirmar una serie de ventajas de tipo general, RESUMES que merecen se estudie su viabiidad para muchos casos particulares. Dusting as a Method of Fighting Forest Diseases En muchos casos hemos comprobado la mayor eficacia To combat the most important forest pests, the method used in Spain is mass dusting through the formation of clouds during de los productos en forma de polvo sobre los preparados the hours of atmospheric calm (wind velocity less than one meter lIquidos acuosos con el mismo producto activo y cantidad per second). Light dusting equipment is used for producing the por hectárea. Especialmente en el combate de la Tortrix dust clouds, because of its ample maneuverability in forest areas. viridana L., Lymantria (Porthetria) dispar L., Malacoso.- The use of this method results in a considerable saving in dusting material, and a degree of efficiency because of the uniform and ma neustria L. y Lymantria monacha L., plagas de abundant penetration of the stand. primera importancia en nuestro pals.Aparte de esta In the last seven years almost two million hectares have been eficacia directa sobre el insecto, la mortalidad de la plaga, treated by this method. con la utilización del polvo, ha sido mayor por la uni- The cost of treatment by this procedure has been the most economical of the various methods tried. The total cost is about forme impregnación de la totalidad de la superficie del 130 pesetas per hectare. monte. Esta impregnación es superior a la conseguida The physical conditions of the dusting product, namely its con las gotas de lIquido debido al pequeño tamaño de fineness, humidity and apparent specific gravity, must be given los granos que les permite penetrar en los refugios donde special care in order to obtain good results. This dusting method has a great advantage over spraying se encuentre el insecto, como en el caso de la Tortrix treatments,especiallyifpreparations withgas-oil orfuel-oil viridana L. excipients are employed, because of the powder's poor persistence, 954 Fifth World Forestry Congress Proceedings since it disappears through the action of rain or wind so that its Près de deux millions d'hectares ont ététraités par cette effect on forest fauna is minimum. As a result, the natural mCthode au cours des sept dernières années. biological struggle complements the chemical fight. Le traitement par ce procédé revient moms cher que tous les autres essais entrepris. Son cofit, dans l'ensemble est d'environ 130 Le poudrage comme méthode de lutte contre les fleaux pesetas a l'hectare. forestiers Conditionsphysiquesduproduit:pourobtenirdebons On utilise, en Espagne, pour combattre les plus importants des résultats,il faut veiller tout particulièrement a sa finesse, son fléaux forestiers, le poudrage massif que l'on obtient par la forma- degré d'humidité et a son poids spécifique apparent. tion de nuages pendant lesheures de calme atmosphérique Ce poudrage offre un grand avantage sur les traitements par (vitesse du vent inférieure a un metre par seconde). Pour le liquides, notamment les preparations comportant des excipients lancement des nuages, on se sert d'équipes d'hommes munis de de gaz-oil ou fuel-oil, a cause du peu de persistance du produit poudreuses légères et faciles a manoeuvrer. On obtient de cette qui s'évapore sous l'action de la pluie et du vent, ce qui rend facon une économie considerable du produit et une grande effi- minime son influence sur la faune forestière.Grace a cela, la cacité, du fait de l'imprégnation copieuse et uniforme de la surface lutte biologique naturelle devient un complement de la lutte boisée. chimique.

Forest HygieneCombined Biological Forest Protection By Birds, Red Forest Ants, and Forest Spiders

HEINZ RUPPERTSHOFEN Maim, Germany

We attach more importance to the life of the forest than to be mobilized or to be returned to daylight in order to the wood of the short-lived plantations, as we are well to give the forest its natural protection. Where the forest aware that the prosperity of our people is being inter- suffers, man has made a mistake somewhere. woven with the health of the forest, which not only gives to country and town the necessary water and many cul- Forest Protection by Spiders tural and economic values, but which also gives us, in Foresters have realized that, in spite of all the con- the restlessness of the present, sources of relaxation and siderable progress of humanity in all areas of research, new creative power.History teaches us that people of we must not lose contact with nature, and thatthe earth a high cultural standard were damned to when will remain sound only if we keep sound and clean they sinned against their forest.Prairie,desert, and forests and waters. flying sand were the end! To find contacts with nature and to intensify them, to For this reason, we work in "Forest Hygiene." The care for and to further the aspiration of natural forces fundamental idea is as follows: A plantation of trees is for harmony in the partnership for lifethis must be our not yet a forest but, at best, a wood plantation. There duty.Close co-operation between science and practice, belong to a forest not only trees and bushes, but also in the cultivation and the building-up of the forests, birds, ants, forest spiders and the ground bacteria. When ignoringallfrontiers,isnecessary.The Fifth World cultivating a forest, as with a young man, I have to do Forestry Congress in August and September 1960 is a protective inoculations with the natural protective factors good forerunner and pioneer. if the forest shall prosper. It is astonishing how the forest My theme for the Congress belongs to Section III: accepts this assistance and what chain reactions result. Forest Protection. In its ideas, however, it goes beyond The utility of birds is a well-known fact in all countries practicing forestry. The protection of birds is thus being this scope, as it comprises the whole life of the forest. promoted, and nesting-boxes are often being brought to In 1950, we experienced a calamity in our forest. the wood plantations. But with this we do not yet have Maybug grubs destroyed an eight-year-old pine grove. a forest! Two members of the partnership of life ofthe Only a small part remained sound, in which we found forest have been joined, but there are still missing many some nests of the red forest ant. During the new planta- which we know, and certainly much more of which we tion of the forest we made branches of the ants' nests only have a presentiment. Therefore, the more perfect a available. The German professor Gösswald of WUrzburg forest foundation is and the more forest members we can had developed some processes which were very simple bring into the new, or even the old forest, the sounder for this purpose. the forest grows. In the course of our experiments we reached a special In agriculture, there is today no crop protection with- dexterity, and after six years we could count from two out the indispensable poisonous substances. The great original ant colonies more than 600 branches. Today, plain-area economy yields, apart from the atmospheric after ten years, there are approximately 1,000 nests on an influences on the insects and fungi, many possibilities for area of 1,000 hectares. By these ants, a permanent pro- attack, which can be removed only by means of chemistry. tection of the coniferous forests was obtained, which cost In the forest, things are different.Here there are still very little and cannot yet be estimated in its results for available many natural means of defence, which need only the maintenance of the health of the forest.

Forest Protection 955 As the first chain reaction there appeared many wood- this case, the lack of housing had obviously been the rea- peckers, feeding mainly on ants but picking off the trees son for the little colonization and small dissemination of the harmful caterpillars as well.The woodpeckers in- bats. Now special holes for bats and also for owls were creased by 400% within ten years. Thereupon, the ant brought into the forest.The hunting time of the day- nests were protected by wire frames.Four nests per birds was now extended to the twilight and night by owls hectare are sufficient in order to protect the forest against and bats."The forest won again life"and there ap- insects if other factors also appear, of which we shall peared naturally many other companions of the afore- speak later on.The distribution of four ant nests per mentioned forest members,in the flora of the forest hectare is still today being adopted in northern Finland appeared likewise, by bird-borne seeds, many grasses, and in Sweden. herbs, and bushes, which otherwise would never have The long-lived ants (workers, 4-6 years; queens, 20 been planted by man, but which were very useful, not only years) are very useful for the biological equilibrium of for improvement of the ground and the inner forest the forest. This we affirmed after the natural increase of climate, but also for forest protection, i.e., for the birds the woodpeckers, when we furnished tie forest areas pro- breeding in the underwood and in the hatches. tected by ants with nesting-boxes made of wood and Also, by the ant colonies grass and herb seeds were concrete for titmice and other small birds. By intensive carried off, and there appeared in the neighbourhood of forestry there disappeared from the forest hollow trees the ants' nests in the radius of 50 meters a light greening in which the birds had nested previously. The lack of of the forest ground. In the stock of pine trees, thereby an housing for the birds, therefore, had to be alleviated. improvement of the ground was reached, the result of Like the woodpeckers many small birds feed mostly on which was, besides the maintenance of health of the stock ants and thus are bound to the station. Furthermore, they of trees, a measurable increase of growth. prefer being in the neighbourhood of the ants, because Where you can obtain in your forest a combination of these keep their nests free from vermin. bird and ant protection together with some bats and The birds catch ants, and clean their feathers by means owls,the biological equilibrium has already been es- of them; during this procedure the ants secrete formic sentially improved. The seed coming out of the seed acid, by means of which the birds get rid of mites and cover, the baby plant, and the growing tree need, apart other vermin. Since the ants are living more or less in from the necessary life space and sun and rain, the natural colonies of from four up to one hundred nests, we began companions of the flora and fauna.The safest pre- to make for the birds colonies of nesting-boxes with up requisite for this is, however, the actually most perfect to 100 breeding holes, which were situated in protected combination of biological protection by birds, ants, bats, placesand systematicallydistributed over theforest birds of prey, owls, and ladybugs, up to the spiders (idea of Dr. Bruns, Hamburg, Ornithological Protection and carabus beetles. Station). From this main part of the birds' protection The assignment of ladybugs and beetles is well known there resulted, at the beginning of the breeding period, in America and has already been applied successfully. lines of travel from station to stationas with a fortifica- The mistake can, however, most probably be found in a tion system.In forest districts which were specially one-sidedstrongincrease without the endeavour to threatened by insects, these forest protection stations were obtain a combined permanent biological protection. laid out correspondingly closer. After an observation time of three years in small The expenses for this protection were low, as the price experimental areas, the combination of bird protection for a wood and concrete box in Germany is only ½ dol- together with ants, and the assignment of forest spiders lar. The control of nesting-box colonies and of the ant has proved to be the most effective combination. With stations is being taken over by the school classes of the gradations of Coleophora laricella Hbn., Tortrix viridana, region.Thus, there is not only forest protection, but, and Lygaeonematus abietumPristiphora abietina, the moreover, youths take over a duty which has a scientific combination of birds, ants, and spiders was most success- air and which they fulfil with enthusiasm. ful. All youthsat 10-14 yearsarrive at the "Research Apart from this success, the aforementioned protection and Discovery Age." Then they are to take over functions factors remained in the forest as a permanent and con- which they find here with me in our forest. The youths, in tinuous protection, as in their subsistence they are more groups of 2 to 5 boys and girls, take care of an ants' or less independent from the parasites.The ants rear or birds' protection station, consisting of 50 to 100 nests bark lice, the spiders feed on the crowd of flies and each. They clean the nesting-holes of the birds, count midges, and the birds participate or, on the other hand, the eggs, inspect the "wools" and the birds' excrements diminish the number of ants and thus restore, again and for parasite pests and thus give much applicable material again, equilibrium to the forest. into the hands of science, for which otherwise one would I was told several times that the re-colonization of the have had to spend very much money. This task has, for ants and the installation of nesting-holes were unnatural the youths, besides the biological effect, an educational measures which would disturb the biological equilibrium value, as it unites the youths with the forest and with the and could provoke damages. This is not right! In today's homeland. The respect for creatures wins a place in the economic forest, trees with natural holes are missing, and hearts of the children, and they esteem also the life of the there is no space any longer for dry and withered trees, smallest forest inhabitant, as they have come to know its quite apart from the fact that here the ants are exposed value. to especially strong persecutions.Damages out of the By the erection of bird protection stations in our forest forestcan only encroach on theagriculturalareas, we also obtained a re-colonization of the bats. Also, in whereas out of the wood plantation, with its one-sided 956 Fifth World Forestry Congress Proceedings increase of parasites without biological counter-balances, is not provable.The stated strong increase of forest the insects or fungi encroach on the remaining country spiders in ant districts can likewise not be explained. as well. In a biologically built-up, sound forest there will In thisfield, our research isstill continuing. By the always be recorded positive effects for the remaining observations made, however, we hit upon the idea of using country against atmospherical extremes and parasites forest spiders for biological forest protection as well. coming from the vegetable and the animal kingdoms. Unfortunately, up to now nobody has worked on this By the offer of nesting-holes we can advance the subject, and, with great trouble, literature concerning the colonization of birds and bats. As far as the ants are con- spiders was gleaned.The results are recapitulated as cerned, this is not quite so simple. Here we have devel- follows: oped two processes. Seven hundred and sixty of the twenty-two thousand In the early spring, when nature is for the first time known kinds of spiders exist in Germany. In America, exposed to tie sun's rays and when the entire ant popula- there are many more. In this great plurality, the spiders tion is more or less on the nest surface, some queens are comprise thirty-one families, of Which twenty-nine families taken out, and with approximately 20 to 40 litres of nest are represented in the forest. On one and the samekind contents, eggs, ants, and building material a new branch of plant there can be more than two hundred spiders. is founded. For this are needed an old stump or a piece These figures are mentioned in order to prove that it is of round timber, put into the earth, on top of which the impossible for the practical forester to know all kinds new ant stateisestablished.Professor Gösswald has systematically.What the practical man can be told, published in Wurzburg a pamphlet regarding the estab- however, is, above all,the knowledge of the different lishment of ant branches, which can be obtained at any functions.It is sufficient if we can distinguish the spiders time in Wiirzburg. At those places where woodpeckers by their net building, such as "wheel-net," "crest-net," live, the new ant state has, at first, to be protected by a and "cover-net" grabs. Besides these, there are also many wire frame. spiders which do not build any nets but which catch A second possibility for the formation of ant states their victims in a leap. These jumping grabs are useful presents itself some weeks later in spring When the ants for forest protection in a limited way only, as they are not set about the natural nest distribution, when the winged so muc;h inclined to stationariness as the net-spiders.Im- queens and male ants go on the wedding flight. By means portant are, above all, the wheel-net spiders, to which of catching nets which are tilted over the nests, the belong the families of the cross spider and the crest-net ants can be caught, and in a terrarium the copulation spiders which can catch all flying insects by means of their takes place. As with the bees, afterwards the male ants narrow-meshed nets. die, and the females bite off their wings in order to go The natural degree of dissemination of the spiders in immediately on to the egg laying. a biologically sound forest is fifty to one hundredand With these queens new states can be established, if, fifty spiders per square meter. If there are less than fifty in the first process, folk mass is added. By means of the spiders,the biological equilibrium isappreciably dis- ant states thus won, after four fruitless experiments of turbed.Taking, furthermore, into consideration that a the new forest foundation, a most effective success could single spider destroys, in her life of eighteen months, an be recorded in the district for experiments with forty-two average of two thousand insects, one fully realizesthe nests on fourteen hectares. Grubs of the cockchafers had importance of spiders for forest protection. The females again and again destroyed the pine cultures, until the ants, of our German wheel-net spiders (Araneus ocellatus and reinforced by bird protection (starlings), removed the Araneus diadematus) make, in autumn, solid and com- predicament. pact spun bags with approximately one hundred eggs We had a similar case with the older pine stands which each. The well-hidden cocoons can, with some dexterity, had been suffering from plant wasps.The Nematus be easily found. came again and again, flying with the general wind direc- After hibernation the cocoons let out, in spring, tiny tion from the west to our forests. Thereupon, a protective and fine young spiders which, during the first shedding barrier consisting of several hundred ant heaps was made, phases, are different in colour from the parents. These which within a few years presented a permanent protec- young spiders are, for us, especially important, as they tionfortheattackedforests.Besides theartificial spin in teamwork a net umbrella above the top shoots of branches, there came into existence natural branches be- the trees and thus protect the young shoots against flying cause of the concentration of parasites.In one case, a insects.After the first sheddings, the spiders spread, colony increased from seven to forty-two nests. The result and the at first very small nets (five to ten centimeters) was a strong increase in the number of woodpeckers. enlarge continuously and are later on the ground as on Some of the ant nests were two to three cubic meters in the trunks and in the tops of the trees. Here, in Germany, size. about one: hundred kinds of the cross spider are living in Where the ants had been colonized there appeared, as the forest. From the Mediterranean Sea there arrived the I have already mentioned, a revival of the fauna and flora wasp spider, which advances more and more to thenorth. of the forest. The dead ground became green, and at She appears in America, too, and completes the hunting the sites of old deserted ant heaps an especially abundant area of the cross spiders, as she does not spin her nets growth of trees, caused by the deep accumulation of so highvertically fifteen to twenty centimeters extended humus, could be noted.Furthermore, there could be above the ground. Her cherry-sized baggy cocoon con- noted in forests protected by ants an important retro- tains from three hundred to four hundred eggs.They gression of bark and rind beetles. These animals must are firmly and in all directions anchored on ground plants. be continously disturbed by the ants, but the combat itself The young spiders slip out after one month, but hibernate

Forest Protection 957 in the protective covering and gnaw through it in the early to late autumn. The most important forms we find on spring.This spider is very useful and important in the theforest ground are Linyphiidae(80), Erigonidae forest. (157) and Iycosae (70).In the region of herbs and The utility of the aforementioned spiders is that we plants, there are, above all, the cover-nets of the Liny- can gather and preserve the cocoons. Three cocoons of phiides (Linyphia triangularis) and the wheel-nets of the the wasp spider, however, brought onto a new forest Meta segmentata.In the forest supervised by me, the plantation a thousand spiders, which can catch two L. triangularis is the most disseminated spider, which pro- hundred thousand flying insects.As far as the other tects our cultures up to an age of fifteen to twenty years kinds of spiders are concerned, many more cocoons are and which is to be found at heights of six to eight metres. necessary. They can, however, still be amply found in The "caps" of the young spiders are very close-meshed autumn and shortly before the beginning of winter, and and durable and contain, on an average, thirty to fifty then only need to be protected against persecutors in spiders, which disseminate very quickly and are eager nature and against the inclemencies of the weather, if weaveresses. we wish to have an efficient army against predicaments In the region of bushes, there are, above all,the caused by insects.I have in my forest some spider scaffold-netsand mesh netsof the Theridiides and colonies, which involve specially favourable prior con- Dictynides, which catch the biggest prey. In such nets ditions for the increase of the spiders.As with the I even found hornets.In the region of forest trees, we "main point of bird protection" and the ant colonies, frequently find in Europe, as well as in America, on this is a strongpoint out of which I can obtain, at any the lower trunk and under the bark, Clubionides, Salti- season, assistance against harmful insects.Besides the cides, and Segestriides.In the region of the tops of first method, the gathering of the cocoons and bringing the trees, partially also on the young plants, predominate, these to forest culture areas, later on, in May, I can cut however, the Philodromides, Thomisides, Clubionides, out of the densely populated colonies "caps" of young and Araneides. All species shed six to eight times and spiders from the side-shoots of the plants, gather them in mostly after sixteen months are fully grown. big cartons and then bring them to the desired areas where Salticides (springing-spiders) catch their prey in wide I can put them into the soil or onto plants, or put them and accurate leaps. Lycosides (wolf-spiders) have eyes into bark slots of older trees.There isstill possible a on stalks in three rows, and because of this arrangement third method by seizing the female spiders before egg of the eyes, they can observe in all directions. The Thomi- laying and by forcing them to lay their eggs in captivity. sides are crab-spiders which likewise do not build any nets. Experiments are being scheduled which should be fin- The weaving spiders(Theridiidae) have eight eyes ished this spring, but which could not be executed because arranged irregularly.They are likewise very important of lack of time. for forest protection. The copulation of the old animals Why is our knowledge of spiders so limited?Is the takes place in May, and in June and July the young reason the human aversion to these animals? If, in Ger- ones slip out of the about one hundred eggs contained in many, two human beings have become embroiled with the cocoon, which is situated under the bark. The worth one another, we say that they are "spider-hostile." This of the cross spiders consists, as already mentioned, in the saying is especially adopted with regard to matrimony, hibernation of the eggs in the cocoons and in the young as it is well known that the female spiders kill and eat up spider "caps" in spring. The later large nets are works of their males after copulation. The old civilized peoples art and require great wariness. A net with a diameter of regarded these things differently. They had a connection thirty-five up to forty centimeters has on the threads a to nature that we have mostly lost. In the Greek legend, hundred and twenty thousand adhesive nodules. "Arachne" (Araneusthe cross spider), the daughter of Idmon, was metamorphosed into a spider by Athena, The correlations between spiders and insects, their main Idmon was a purple dyer, and Arachne was a weaveress. food, are manifold.Everywhere insects are, there are also spiders.The spiders themselves are very sensitive The oldest scientist of the world, who has bequeathed with regard to the already described small miracle of their to us his observations, was Aristotle. He described the organism.By actionof warmth and wind thefine spiders very exactly in their way of living and utility. organism easily dries up.If we wish to further the in- This small living creature is a prodigy. Mostly we find crease of spiders, we consequently have to take care of eight eyes, occasionally kinds with no eyes.All species the shade and humidity. A natural forest culture, which are distinguished by the arrangement and number of gives living space to the lower growth and herbs, renders eyes. The chop tentacles, perforated by two venom tubes, possible a domicile in the forest and gives the necessary are a miracle of nature. These chop tentacles consist of essential requirements of life for the spiders. seven parts and, with the males, pass through a special transformation. With the last shedding, the first segment A one-sided measure is chemical pest control in the of the male's chop tentacle becomes clublike and thick forest.Itis true that the chemical industry often has and contains the seminal fluid. The lung sacs are under prevented the worst, but chemical means of pest control the airholes in the hindquarters of this tiny creature. brought into the forest are no ideal and lasting solution. Mostly we find six spinnerets on the spiders. These are The partnership for life of the forest isentirely un- set with microscopically small bristles.The Tegenaria balanced by such violent measures, and catastrophes has four hundred, the Pordosa soccata, three hundred, caused by parasites recur in shorter and shorter periods. and the Segestroa has barely one hundred bristles per As the economy of forestry cannot bear, in the long run, spinneret. a chemical pest control, a retrogression of the forest areas The catching season of the spiders lasts from April would be the result.This, however, would again have a

958 Fifth World Forestry Congress Proceedings negative effect on the country, i.e., sinking of the ground- oiseaux, chauves-souris), indique un moyen d'atteindre ce but. En raison de son caractère nature!, ii s'agit là d'un moyen simple water level, a beginning karsting, erosion, and stepping. et evident. We, therefore, have to put an end to these unnatural La lutte chimique contre les parasites de la forét ne représente manipulations brought into the most important and almost qu'une mesure monovalente. last natural living space which has been left for us. The Mon rapport traite de la protection des forêts au moyen de centres utilisant les oiseaux (colonies de nids), les fourmis et les forest has to be maintained in its natural state and in its araignées et dont on confie la surveil!ance aux ëcoles. De ce fait, natural partnership for life, connected with a natural on assure non seulement Ia protection des forêts, mais encore on rationing, so that it radiates again and again force and assigne aux jeunes une fonction revêtant un caractère scientifique health into the remaining living space on earth. et dont us s'acquittent avec ardeur. Des groupes de deux a cinq garcons ou fil!essont charges d'une station de protection des "Don't consider the smallas insignificant," Goethe fourmis ou des oiseaux, comprenant chacune de 50 a 100 nids. says, and a wise man of the Orient says likewise: "There Outre son caractère bio!ogique, cette fonction offre aux jeunes une are three animals which prevent the end of the world: valeur educative, car e!le les rattache davantage a la forêt et a The bee, pollinating the blossoms and making the fruit Ia patrie. Le respect des creatures occupe la place qui lui est due, et les enfants apprennent également a respecter la vie des plus grow; the angle-worm, producing the humus; and the ant, petits habitants de la forêt dont la valeur leur a été révé!ée. keeping the harmful insects off the forest."Forest and La combinaison oiseaux-fourmisainsiquel'utilisationdes wood zoology is necessary, because we do not wish to araignées des bois s'est révélée la plus efficace pour assurer la obtain "forest therapy," but "forest hygiene."Forest protection des forêts. Ii est a regretter, toutefois, que jusqu'à present, personne ne se zoology, however, is forest hygiene and has to be pursued soit intéressé a la question de l'utilisation des ara.ignées des bois according to the principles of human hygiene, with the pour la protection des forêts. final objective of preventing organic catostrophes by a Avec cette communication, je me propose d'exposer les résu!- more and more perceptible elimination and confinement tats de nos experiences et des recherches effectuées avec l'aide de of their causes. savants et d'étudiants. In my report to the Fifth World Forestry Congress Higiene Forestal: la Protección Biológica Forestal Corn- concerning the experiment stations in the forest super- binada que Prestan las Ayes, las Hormigas Rojas y vised and cared for by me with ants, spiders, birds and bats, I wish to show a way how this aim can be achieved. las Arañas This way is simple and evident, because it is natural. Nuestra premisa es la siguiente:Al cultivarse Un bosque, los árboles nuevos y los viejos reciben una inoculack5n protectora que The results which I have gleaned from the investiga- le dan los elementos protectores naturales. tions, with the assistance of scholars and students, have En el bosque existen todavIa muchos medios naturales de been made accessible to all foresters in the world by the proteccidn que solo tienen que ser aprestados o determinados circle,"ForestHygiene,"andits para dar a los árboles una protecciOn natural. El secreto consiste German working en cuidar y contribuir a! crecimiento de los elementos naturales homonymous journal. Detailed specifications will follow, que armonizan el consorcio vital. with the exclusive purpose of helping my venerated En este informe sobre "ProtecciOn Forestal" relacionado con model and teacher, Professor Gösswald, in Wurzburg, the !os experimentos forestales llevados a cabo en el bosque, bajo !a Presidentoftheworldwide workingcircle"Forest direcciOn de! autor, con hormigas, arañas, ayes y murciélagos, se desea demostrar la forma en que puede alcanzarse este objetivo. Hygiene," on his way, which, after all,applies to the El método es simple y evidente porque es natural. maintenance of forests on the earth. El control qulmico de las plagas forestales puede considerarse I wish to finish with a word which should apply to como una medida unilateral. America as well as to Germany and all other countries on En este trabajo se describe la protección forestal realizada por the earth: !as ayes en co!onias de nidos artificia!es y por los criaderos de arafias y hormigas al cuidado de los niños de las escue!as. De "A people which plants forests and esta forma no solamente se obtiene una protecciOn forestal, sino builds schools cannot perish!" que también se estimula a la niñez para que se encargue de !abores decaráctercientifico que contribuyen a cultivar sus RESUMES entusiasmos juveniles. Los niños están divididos en grupos de 2 a 5 estudiantes de ambos sexos que se encargan de cuidar una Protection biologique combinée des forêts assurée par estaci6n protectora, de hormigas o ayes, de 50 a 100 nidos cada lesoiseaux,les fourmis rouges des boisetles una. Esta tarea tiene un doble propósito, e! biológico y el educa- araignées tivo, que familiariza a Ia niñez con los bosques y tierras de su L'idée est la suivante:lors de la mise en exploitation d'une patria. Además, se crea cierto respeto por las cosas vivas y e! forêt, on fait a la forét, jeune ou vieille, une inoculation préven- niño aprende a apreciar los pequeños habitantes del bosque y tive a l'aide des facteurs naturels. l!ega a reconocer su valor. La forêt elle-même possède de nombreux moyens naturels de Esta combinación de ayes y hormigas y la crIa de arañas ha defense qu'il s'agit tout simplement de mobiliser ou de mettre en demostrado ser la más eficaz de todas. valeur pour lui assurer une protection naturelle. Nous devons Desafortunadamente, hasta ahora nadie habIa considerado la nous intéresser aux forces naturelles, et les ddvelopper, afin de posibilidad del empleo de arañas como medio de protecciOn garantir une certaine harmonie de vie. forestal. Mon experience personnelle des centres de recherches fores- En este trabajo se describen los experimentos realizados y Jas tiers utilisant les facteurs naturels préventifs (fourmis, araignées, investigaciones efectuadas con !a ayuda de maestros y alumnos.

Forest Protection 959 Experiences With Chemical Insect Control in Czechoslovakia

J. KUDLER Ministry of Agriculture, Prague, Czechoslovakia

Like the forests in all of Central Europe, the forests helicopters in forest protection is being planned for later. of Czechoslovakia are also prevailingly formed by pure stands, which are sometimes subject to disasters caused Organization and Techniques of Chemical Treatment by various insect species. The active control of insect of Forest Stands outbreaksin Czechoslovakia consists,firstofall,in The bases for map and terrain demarcation of forest effective chemotherapy, which is closely connected with stands requiring special treatment are given by careful modern techniques.Our present protection techniques supervision, recording, and forecasting of insect pests. reflect both the experiences of long standing and the All this activity is ensured, according to regulations in contemporaneouslevelofscientific,biological,and force, by the forestry personnel, together with the record technical knowledge. and forecast services of forestry research institutes. The forest enterprises and superior administration organs are Active Preparations responsible for planned ensuring and directing the con- Against various foliage-destroying insects, chiefly some trol measures. families of the order Lepidoptera and Hymenoptera, con- The preparation of smaller areas doesn't require special tact preparations with a DDT base are commonly used. organization measures, because the hand-operated and In the control of harmful species of the order Coleoptera, terrestrial apparatus are owned by individual enterprises better results have been obtained by using BHC or a themselves.Theairplanesforlarge-scaleprotection mixture of both active preparations. The active prep ara- operations must be secured by arrangement with the civil tions are used in the form of dust(5% Dynocide, accord- aviation organization (Aerolet).The aerial fieldsare ing to the resistance of the insect, in a dosage of15to chosen withasgreatalengthaspossible.While 50 kg. per ha., or 12% BHC, in a dosage of30to50 previously the storage of dust in sacks required special kg. per ha.; against grubs, 200 to300kg. per ha.), or in dry recesses, this inconvenience is now eliminated, be- the form of light oil preparations for fogging purposes cause the active aerosol solutions are stored in barrels. (10% DDT or BHC aerosol in a dosage of 4 to 6 kg. The chemical treatment is carried out against the most per ha.) susceptible stages of the insects(the youngest cater- Experiments indicated that the aerosols cause less pillars, the imagoes at the beginning of their feeding be- residual effects than the dusts, so that those are more fore sexual maturity, etc.). The stands are treated in the suitable for the control of foliage-destroying insects on early morning or attwilight, because the favorable large areas.Spraying or drenching with preparations in weather conditionsat those times enable the needed the form of emulsions show favorable results in con- sedimentation of the preparations. trolling the bark-eating or timber-boring insects because Good results may be achieved even when the air is ofconsiderable residua.The question of using the moving; nevertheless, the velocity of air movement must systemics or other insecticides with a phosphorus base not exceed lm./sec. in thermic fogging, 2m./sec. in dust- against sucking insects and the insects damaging leading ing, and 4m./sec. in using fine spray-fog. Heavier winds shoots and buds isstill under consideration.All com- or rains hinder an application of this kind.It is assumed monly used insecticides are national products. that the engine-driven apparatus may spray 1ha. in about30mm., and the hand-operated apparatus, in 15 Spraying and Dusting Machines minutes. A plane with a disposable load of 1,000 kg. Insecticide dusts are released into the atmosphere by is capable of dusting about33ha. or fogging about means of various hand-operated or power-driven dusting 200 ha. per flight.In fogging, the orientation of planes machines or by aircraft, according to the extent of insect by portable marks or small balloons at 20 m. intervals invasion.Reliable aircraft dusting apparatuses are of is of large importance, because ocular orientation con- Soviet type.For the release of hot aerosols a hand- cerning thetreatment ofindividual spray swathsis operated pulsationgenerator (RAG) and a mobile absolutely impossible. From the standpoint of safety, a thermomechanical generator were developed in Czech 0- minimum flight height of 10 m. above the treetops is slovakia in1953.Since1953,a fine spray-fog is applied. allowed. The aircraft operations may be advanced by At the present time,aircraft control prevails in our establishment of provisional airfieldssituated close to country. The previously used airplanes had a disposable the menaced foreststands.Difficult hand-loading of load of 600 kg. (type Siebel) and 200 kg. (type Cap). insecticide dust into the airplane is eliminated by using Recently, airplanes with a disposable load up to 1,000 kg. insecticide solutions, which may be loaded by means of (typeBrigadyr)are prevailinglyused.The useof pumps.

960 Fifth World Forestry Congress Proceedings The effectiveness of chemical control is secured by may be more rapidly put in balance by penetrating from observing and recording the insect killing on several adjoining stands. However, by acute injuries, e.g., by nun control plots. The actual results of chemical treatment moth, the treatment of such focusses may be justified, may be determined by calculating the difference of insect where in spite of high natural mortality of this insect, numbers in a given unit (area, tree) before and after the severe damages might occur prior to its disappearance. treatment. In the areas that are periodically menaced by mass insect outbreaks, itis necessary to devote special attention to Application of Insecticides Against Bark-Eating and the protection of birds, ants and other natural enemies Timber-Boring Insects of harmful insects. The contact preparations with DDT and BHC base in the form of dusting and spraying are also successfully Economics of Chemical Control applied in trap-tree control of bark-eating insects, notably The proportion of treatment costs to salvage values the spruce borer (Ips typographus L.). The emulsions (economic, sanitary, aesthetic, etc.) forms a fundamental of long-term toxic residue are notably recommended for index of the economics of chemical insect control in the this purpose. Such preparations may be, according to the forest stands. In this way, damages reaching the amount recent research results, successfully and repeatedly ap- of many millions of crowns were prevented in Czecho- plied to round timber in the control of Trypodendron slovakia.In addition, more than 4 million crowns were lineatum Oliv., occurring in mass outbreaks in Czecho- saved by using aerial fogging instead of dusting against slovakia.Dusting of the whole round timber surface insect pests in the years 1956-1958. with the mixture of DDT and BHC (1:1) requires a dosage of 1½ kg. per cubic meter; this treatment must ProspectiveApplicationof ChemicalsinForest be repeated after 5 to 7 days or after rain. In spraying Protection 5% emulsions, the dosage of about 5 liters per cubic meter is fully sufficient. The residual effects vary in the As long as fundamental preventive measures and range of 3 to 4 weeks.In controlling the above-men- biological control of insect pests are not thoroughly tioned insects, the most effective means is soil disinfection studied, and as they don't attain clearer forms, chemo- of timberyards by drenching with dinitroorthocresol and therapy will be one of the most significant means in anthracene oils in emulsion form (concentration 5%, controlling the disasters caused by forest insects.In the dosage according to the soil character, 4 to 5 liters per forest protection program, efforts are made for the prepa- square meter).Large damages may be prevented by ration of insecticide fertilizers to be applied in forest early hauling of attacked timber and itsdisinfection. nurseries and areas to be afforested, and also for the The problem of timber-boring insects is studied with the reduction of phosphorus insecticidetoxicity,forthe goal of finding effective attractants.The treatment of improvement of preparations to be effective in depth, living trees by means of arsenic intoxication is tested in and for further improvement of needed technical equip- our forestry practice, notably from the point of view of ment. Permanent biological studies make it possible to the chemical barking problem. However, the joint re- giveprecision tothe terms of chemical treatments, search of this question with the problem of bark-eating especially with respect to the possibility of their combina- and timber-boring insect control gave no satisfying results. tions with natural and artificial biological protection. Directing of Chemical Control With Regard to the RESUMES Natural Biological Protection of Forest Stands Les experiences faites en Tchecoslovaquie en matière de lutte chimique contre les insectes With respect to the fact that the commonly used con- tact insecticideskill not only the harmful insects but En Tchécoslovaquie, la lutte active contre la propagation des insectesforestiers prendsurtoutla forme de chimiothérapie also the useful constituents of forest zoocenosis, the efficace. Les insecticides de contact a base de DDT sont couram- chemotherapy must be reasonable and cautious, and it mentutiliséscontrediffdrentesespècesdelépidoptèreset may be fully applied only in protecting the forest stands d'hyménoptères. On a obtenu de meilleurs résultats dans la lutte which are obviously endangered by mass outbreaks of contre certaines espèces de coléoptères en utilisant le BHC comme base ou un mélange des preparations actives susmentionnées. A insects.The negative influences of chemical treatment l'heure actuelle, on préfère aux poudres (preparations a 5-10% may be reduced by using the preparations of less residual en doses de 30 a 50 kg. par hectare) des preparations sous forme effects (aerosols, instead of dusting) in appropriate bio- d'aérosols ou de brouillards très fins (preparations a 10% en doses logical terms. The application of DDT and BHC mixture de 4 a 6 kg. par hectare). Ce faisant, ii a été possible de di- is not recommendable in large area control, because the minuer d'une manière sensible le prix de Ia lutte mende sur de grandes étendues,et également d'amoindrir leseffetsnégatifs negative influences on the zoocenosis are amplified by sur les autres organismes vivants de la forêt, car les aerosols ont using this mixture. Regarding the fact that the susceptible démontré que leurseffetsrésiduels étaientinsignifiants.Des stages of the majority of our harmful insects appear in emulsions d'insecticides actifs et dotes d'effets résiduels prolongés sont utilisées avec succès sur des arbres-pièges pour y détruire les spring, while the whole of the zoocenosis is still relatively insectes mangeurs d'écorce et des térdbrants. La propagation de inactive,itis convenient to start the chemical control ces derniers dans les chantiers de bois est enrayée par des pul- immediately after mass occupation of tree crowns by vérisations ou par des désinfections du sol au moyen de dinitro- harmful insects. In this way both biological (the effects orthocrésol et d'huiles d'anthracène. On étudie l'utilisation d'insec- being more selective) and economic requirements (pre- ticides systémiques ou autres contre les insectes a sucoir et ceux qui s'attaquent aux jeunes pousses et aux bourgeons. vention of management losses, lower dosage of prepara- Les insecticidessont libérés dans l'atmosphère par diverses tions, etc.) are fulfilledIt is also more convenient to poudreuses a main ou a moteur, au moyen d'un avion ayant une treat small areas, where the useful part of zoocenosis charge utile de 1.000 kg. En 1953, on a construit en Tchëcoslo-

Forest Protection 961 vaquie un générateur pulse de brouillard a main (RAG), un del control de grandes areas y que disminuyeran los efectos générateur thermomécanique portatif, et une installation de vapo- negativos sobre otras zoocenosis de los bosques, ya que el aerosol risation montée a bord d'un avion.Les avions utilisés dans Ia indica menores efectos residuales.La emulsiOn de insecticidas protection forestière sont groupés au sein de l'organisation de activos, significativos por sus efectos residuales de large duración, l'aviation civile, Aerolet. On envisage l'utilisation d'hélicoptères se aplican con éxito a fin de aumentar Ia efectividad del control dans un proche avenir. de insectos xiiófagos y barrenillos. Su aparición en las madererlas En ce qui concerne l'efficacité des insecticides de contact sur se controla mediante la aspersiOn o la desinfección del suelo, l'ensemble de la vie forestière, ii faut souligner que la lutte chimi- empapándolo con aceites de dinitro-ortocresol y antraceno. La que est menée avec prudence et en fonction des conditions biolo- utilización de los sistémicos y otros insecticidas contra las especies giques, aux seulesfins de protéger les peuplements forestiers chupadoras einsectos que danan los principales plantones y directement menaces. La recherche forestière s'efforce constam- yemas, se enduentra en proceso de aplicaciOn. ment de perfectionner Ia lutte contre les insectes forestiers. Cepen- Los insecticidas se esparcen en la atmósfera mediante espol- dant le but essentiel a longue échéance de la sylviculture tchèque voreadores manuales o mecánicos, o desde aeroplanos con carga est de passer de peuplements pursqui sont périodiquement disponible hasta los mil kgs. En 1953 se diseñaron en nuestro pals l'objet d'attaques des insectesà des peuplements mixtes. un generador manual de fina aspersion (RAG), un generador termomecánico móvil, y un equipo de aviación para esparcir una Control Quimico de Insectos Forestales. Experiencias en fina niebla. Los aeroplanos utilizados para la protecciOn de los Checoeslovaquia bosques están comprendidos en la organización de aeronáutica civil,Aerolet.Para el futuro,se proyecta Ia utilizaciOn de En Checoeslovaquia, el control activo de las plagas de insectos helicópteros. consiste, primordialmente, en Ia quimioterapia efectiva.Para Con respecto a la prolongada efectividad de los insecticidas de combatir las diversas especies de lepidópteros e himenópterosse contacto sobre toda Ia zoocenosis de los bosques, se aplica el usan comunmente insecticidad de contacto a base de DDT. Los control quimico con cautela y en apropiados térniinos biológicos mejoresresultados,paracontrolar losefectoscausados por tan solo en la protecciOn de las masas arbóreas inmediatamente especies de coleópteros, se han obtenido a base de BHC o deuna amenazadas. La investigaciOn forestal se mantiene activa, con el mezcla de los citados compuestos activos. Al presente, en lugar fin de mejorar el control de los insectos destructores del árbol. de polvos (compuestos a! 5-10% con dosis de 30 a 50 kg. por Sin embargo, la tarea más fundamental de largo alcance que lieva ha.) se le da preferencia a la aplicacion de compuestos en forma a cabo Checoeslovaquia en el ámbito forestal, es la de cambiar de aerosol o fina aspersion (compuesto al 10% con dosis de 4 a las extensas masas arbóreas puras, que son atacadas periOdica- 6 kg. por ha.). De aill que Se redujeran esencialmente los costos mente por plagas de insectos, por masas arbOreas mixtas.

Use of Ants in Protecting Italian Forests

MARIO PAVAN University of Pavia, Pavia, Italy

The usefulness of some species of ants of the "Formica State for the Demesne Forests (Azienda di Stato per ruf a-group" for the protection of forests against insect le Foreste Demaniali) (A.F.) has been asked for and pests is known. The study of the subject was planned in immediately obtained; these are organs of the State for Italy from a scientific and practical point of view in 1950. the protection, development and rational economic ex- As a complex scientific basic problem we havecon- ploitation of the woods of all the national territory. The sidered the census of the ants of the Formica ru/a-group G.D.F. has undertaken the task of providing almost all overallthecountry,theirgeographicdistribution, finances for the practical and scientific work and has biology, ecology, usefulness, and damage to the woods, authorised the F.C. and the A.F. to collaborate com- followed by experimental laboratory controls in many pletely with the Chair of Agrarian Entomology of the sections. University of Pavia (E.U.P.) and has charged the writer As a practical problem we considered the possibility with direction of the operations. of utilising the useful species of the Formica ru/a-group This has permitted the organisation to obtain, on a for the protection of the Italian woods, with biological national scale, the necessary complete and deep collabo- control of forest insect pests and the eventual protection ration between the scientific research and the technical of the woods against the damage-causing species be- forestal department.In 1955, before the heavy quill- longing to the same F. ru/a-group. quennial, the E.U.P. also gave a course of adjustment for selected persons of the F.C. and A.F. Methods To obtain the necessary diffusion of the fundamental Organisation. The initial vast programme of work was notions regarding the whole scientific and practical sub- developed gradually and has had a continuous increase ject, courses of adjustment have been given in E.U.P., in the help of technical and administrative organs with as well as lessons and lectures; various papers have been which this programme was developed; it has therefore written and distributed by the G.D.F. to all dependent been possible to continuously increase and intensify the organisations. A film (16 mm., with soundtrack, 30 work. The collaboration of the General Direction for minutes) for practical and teaching aims has been pre- Mountain Economy and for Forests (G.D.F.) (Ministry pared. of Agriculture and Forests), which directs the Forestal Under E.U.P., various fundamental biological problems Corps of the State (F.C.), and the Administration of have been studied (related to resistance and adaptability

962 Fifth World Forestry Congress Proceedings of the interesting species to peculiar surrounding condi- required from a minimum of two to a maximum of 15 tions; related to the aggression against insects, with study days' captivity in the barrels, to wait for climatic con- of ant poison; etc.). ditions favourable for making the transplantation.This Census. The "census" of the natural populations of the last fact has also been well tolerated by the ants, with a Formica ruf a-group has been carried out with the collab- very low mortality rate.During transport under un- oration of 1,500 agents of the F.C., belonging to about favourable climatic conditions (excessive heat), it was 500 Forestal Stations. forbidden to travel in the hottest hours of the days, in Of the national territory, only the mountainous part order to avoid mortality. that has been divided into Alps (North Italy)and The sites of the newly transplanted nests were pre- Apennines (North, Central and South Italy) has been pared either in underground tree trunks or by removing sprouts of old tree stumps to encourage the descent into considered. the earth of the queen in the first phase after the trans- Materials necessary for collecting standardised samples plantation. Generally, the nests have been transplanted in of populations of ants and formularies, particularly made numbers from various units up to various tens of units to collect the data for the census, have been sent from in a fairly compact colony, the nests being at a distance E.U.P. to 500 Alpine forestal stations and to a part of of 20-50 metres from each other.It has always been those of the Apennines.All the collected data have forbidden to mix diverse species, and the precedence up been concentrated at the E.U.P., and here they have been to now has been given to Formica lugubris Zett., with studied and elaborated with the collaboration of the as- some modest pilot experiments with Formica ru/a L. sistants, Dr. G. Ronchetti, Dr. A. Baggini and Dr. M. L. Valcurone, and of various technicians. Results Transplantation. For the part regarding transplantation of the nests, the results of the experimental biological Census.Three thousand sample populations of the research and the census of the natural populations have Formica ru/a-group have been obtained, as well as another been taken as a base. The data on the number of nests 54,000 data relating to such populations and to the woods of the most interesting natural colonies have been con- in which they are "guests." Up to now, we have studied a trolled in situ for the choice of the population destined to thousand samples of populations.In the census of the be transplanted. The practical problem of carrying out Alps of another 135,000 hectares of woods of Abies alba the transplantation was the more interesting to solve, the Mill., Picea excelsa Lk. and Larix europaea DC. have further the useful species was taken from the place of been found another 250,000 nests belonging to four origin, away from the natural area and into different useful species, Formica lugubris Zett., F. ru/a L., F. climatic conditions and surroundings; therefore, for the aquilonia Yarr., and F. polyctena Först. These species are choice of transplantation site, the criterion was followed present only on the Alps. Nests of F. nigricans Em. and of putting the population in conditions very different from F. nigricans var. cordieri Bond. have also been found on that of the place of origin, with the aim of verifying the Alps and the Apennines, but these species are not the adaptability of the species. useful for biologicalcontrol.The census of 80,000 hectares of woods of several species of Pinus have given An initial transplant has been carried out in the woods very scarce results (in 2,000 hectares about 3,000 nests of Pinus nigra Am, and P. sylvestris L., which, apart of F. lugubris, ru/a, and polyctena). from having the above characteristics, were badly in- The species most widespread on the Alps is Formica fested with caterpillars of the Lepidopteron, Thaumeto- lugubris followed by F. ru/a, F. aquilonia and F. poly- poea pityocampa Schiff, in order to evaluate the efficiency ctena, which is very rare and found in only two stations. of the transplanted ants in the defence against this very In the woods of broadleaf on the Alps the useful dangerous insect. species of the Formica ru/a-group are generally missing, In the woods of transplantation the phases of adapta- with only a few nests of F. aquilonia and F. ru/a being tion of the ants and their influence on the population of found. indigenous insects and on plants have been observed. Formica nigricans and F. nigricans var. cordieri are As regards techniques of transplantation, the criteria always found with a small number of nests, generally already noted from the research of Gösswald in Germany either on the margin of or outside conifer forests. have been adapted to our conditions and needs.To The Alpine area of forests of Abies, Picea, and Larix, transport the populations, plywood barrels have been in which 250,000 nests of the useful species were found, used, strongly made, one hectolitre in size, with a well- is only 25% of the Italian Alpine forest areas adapted closing lid and a hole covered with a mesh to allow air to the Formica ru/a-group: it is therefore calculated that to enter. The transplantation to broken ground has been the nests of the useful species in the Italian Alpine ter- carried out with all possible means. The long transference ritory could be more than a million, with the calculated journey was made preferably with a long trailer transport- population of 300 billion worker ants (with an average ing 250 barrels of one hectolitre.As a general rule, of 300,000 workers for every nest) having a total weight from every original nest is collected the material to form of 2,400,000 kg. (8 mg. on an average for every worker). a transplantation nest consisting of at least two barrels Wishing to have an idea of the practical significance for ofmaterialwith 200,000-500,000 workerantsand biological control of the woods against the insect pests 10-100 queens, according to the quantity present in the we have used this data to calculate that if every worker original nest.The transplants have always been made could devour every day a quantity of food equal to 1/20 in the spring, after the melting of the snow in the place of the body weight, the food devoured in a day would be of origin. The transfer journeys (up to 1,000 km.) have 120,000 kg. The annual average period of food activity Forest Protection 963 of the workers, for themselves and for the necessary doses positive also regarding the practical problem of the defense of regurgitation destined to nourish the larval population, of the forests against dangerous insects.Therefore, the can be calculated as 200 days; therefore, altogether they studies of various biological problems, which has only devour annually 24,000,000 kg. of food. been started, and the practical utilisation of transplants Sixty per cent of the food, as far as we have been able for the defence of the forests will grow larger. to see, could be made up of living prey, that is, insects As regards biological control by means of the ants of mostly damage-causing: because of this, the population the Formica ru/a-group, each state has particular problems of the useful species of the Formica ruf a-group of the resulting from its geographical and climatic conditions. Italian Alps will destroy, in a period of annual activity of However, in many countries it is possible to find com- 200 days, 14,400,000 kg. of insects. These data show the munal aspects regarding the scientific study of biological positive significance of these natural populations of the control with the ants and their practical value. It is aus- Formica ru/a-group for the protection of the woods of picious, therefore, that these studies will extend outside A bies, Picea and Larix of the Italian Alps. the range of the Formica ru/a-group and outside the geo- Transplantation. The first transplantation of Formica graphical region in which, up to now, the studies have lugubris from the Alps to the Apennine woods infested been principally carried out. And it is also hoped that with Thaumetopoea pityocampa has given sharply positive the wish of the International Commission for Biological results for biological control, for the infestation of these Control (C.I.L.B.) for an international centre for this woods has been enormously reduced by the presence of study in Italy will enter into a phase of practical and of the transplanted ants. the widest possible application, with an extended iiter- Successive transplantations on the Apennines up to 600 national collaboration. The importance of this subject, km. southeast of the Alpine locality of origin, and in whether from a scientific point of view or a practical one, woods also constituted differently from those of the place also in relation to the new growths that forests must have of origin (from Alpine woods of Abies, Picea and Larix in future in all the world, justify every effort to enlarge and to pine woods of the Apennines), have given results of deepen this knowledge. adaptation which are sharply positive in spite of conditions of altitude, latitude and climate, in quite unfavourable Reference surroundings. Great adaptations have also been observed Pavan, M., 1959.Attività italiana per Ia lotta biologica con in the technique of construction of the ant hill by means Formiche del gruppo Formica ru/a contro gli insetti dannosi of the needles of Pinus (various species), very much alleforeste.Ministerodell'Agricoltura e Foreste,Collana longer and heavier, and therefore difficult to employ, Verde, 4: 1-80. whether for construction of the ant hill or to obtain neces- RESUMES sary results in the control of conditions surrounding the nest.Populations transplanted eight yearsago have Protection biologique des foréts italiennes au moyen de integrally adopted new construction materials for their fourmis nests. Le problème de Ia lutte biologique avec les fourmis du groupe Formica ru/a contre les insectes nuisibles aux forêts, en Italie a Adaptation has also been obtained regarding the con- été défini en 1950 suivant un plan scientifique et pratique corn- struction of the ant hill partly from broadleaf (especially prenant le "recensement" et l'étude des populations naturelles stir Fagus). leterritoire national et des essais pratiques de transplantation d'une quantité convenable de nids de fourmis, en vue de leur Cases of intolerance to the new unfavourable conditions acclimatation hors des lieux d'origine at dans les conditions les such as dryness, dusty soils, lack of winter snowfall, lack plus variées. of food, etc., and the choice of locality different from that Les travaux, effectués en étroite collaboration avec le Ministère where the nest was artificially founded, are found and de l'Agricniture et des Foréts, Direction Générale pour l'Econo- studied. mie de la Montagne et pour les Forêts, ont été organisés et con- duits par la Chaire d'Entomologie Agraire de l'Université de Numerous cases of reduction of infestation of insect Pavie. forest pests by means of the transplanted ants have been Le "recensement" des populations naturelles de fourmis du found, for example, apart from against Thaumetopoea territoire italien effectué avec la collaboration de 1.500 agents du pityocampa, also against the Hymenopteron, Nematus "Corps Forestier"del'Etata fourni 54.000 données,3.000 échantillons de populations appartenant aux 4 espèces utiles des erichsonii Hart., dangerous to Larix, the Coleopteron, Alpes italiennes, c'est-à-dire Formica lugubris Zett., F. ru/a L., F. Omophius lepturoides Fabr., and the ant, Camponotus aquilonia Yarr., F. polyctena Foerst., et a F. nigricans Em., F. herculeanus ligniperdus Latr., dangerous to the conifer nigricans var. cord ieri Bond. qui vivent tant stir les Alpes que forests, etc. The data and the material collected are still sur les Apennins, mais qui ne sont pas utiles dans la lutte bio- in course of study and elaboration. logique. L'importance pratique des 4 espèces utiles pour Ia defense des The ants of the Formica rut a-group have not shown forêts (en particulier Abies, Picea, et Larix) découle du fait que, negative aspects, and, therefore, considering their useful- sur les Alpes, elles ont plus de 1.000.000 de nids dans lesquels ness, the rule of their protection has been introduced into vit une population évaluée a 300.000.000.000 d'ouvrières; on pense que ces dernières, pendant la période d'activitë annuelle the forestal internal regulations. évaluée a 200 jours, peuvent détruire 14.400.000 kilos d'insectes. Nous avons utilisé l'espèce la plus répandue, Formica lugubris, Conclusion pour d'importantes transplantations, des forêts des Alpes aux bois The complex problem of biological control with the des Apennins, portant ces fourmis vers le sud en des lieux situés ants of the Formica ru/a-group in Italy has become clearer jusqu'à 1.000 kilomètres de leur lieu d'origine. Ces transplanta- tions ont donné des résultats nettement positifs dans la lutte contre with this work in its essential terms and in its scientific la Processionnaire du Pin (Thaumetopoea pityocampa Schiff.) and practical importance. The results obtained are sharply et ont permis d'observer également des reductions efficaces des

964 Fifth World Forestry Congress Proceedings devastations causees par de nombreux autres insectes nuisibles aux pos Forestales del Estado, ha suministrado 54.000 datos, 3.000 forêts. muestras de poblaciones correspondientes a cuatro especiesitiles (Formica lugubris Zett., F. ru/a L., F. aquilonia Yarr., y F. Protección de los Bosques ItalianosPOTMedio de las polyctena Foerst.) limitadas a los Alpes italianos, y F. nigricans Em., F. nigricans var. cordieri Bond. que habitan en los Alpes y Hormigas Apeninos, pero que no son ütiles para el control biológico. El problema del control biológico de los insectos dañinos al El signiflcado práctico de las cuatro especies ñtiles para la bosque, mediante el empleo de hormigas del grupo Formica ru/a, defensa de los bosques (especialmente Abies, Picea y Larix) pro- se planeó en Italia en 1950 en un nivel cientIfico y práctico, viene del hecho que estas especies tienen más de un millón de basado respectivamente en el censo y el estudio de las poblaciones nidos con una población calculada en 300 mil millones de naturales del territorio italiano y en experimentos prácticos que obreras. Estas podrIan destruir 14.000.000 kgs. de insectos en un se realizaron con la transferencia de una adecuada cantidad de perlodo anual de actividad, calculado en 200 dIas. nidos de aclimatación a las situaciones más diversas y apartadas Las especies más difusas Formica lugubris se han utilizado del lugar de origen. para importantes transferencias desde los Alpes hasta losbosques La tarea se realizó con Ia colaboración continua del Ministerio de los Apeninos, unos 1.000 kms. a! sur del lugar de origen. Con de Agricultura y Bosques, la Direcch5n General para la Economfa estas transferencias se han obtenido positivos resultados inmediatos de Montañas y Bosques y tuvo por centro la Cátedra de Entomo- ha asegu- logla Agraria de la Universidad de Pavia. en el control del Thaumetopoea pityocampa Schiff. se El censo de las pobiaciones naturales en territorio italiano, rado la reducciOn de Ia infección de numerosos insectos dañinos lievado a cabo con la colaboración de 1.500 agentes de los Cuer- a los bosques.

Dispersion Alarmante de Platypus sulcatus (Col. Platyodidae) en Argentina

FRANCISCO H. SANTORO Ingeniero Agrónomo, Administración Nacional de Bosques, SecretarIa de Agricultura y GanaderIa, Repáblica Argentina

En Argentina, el eucalipto fué la primer planta huésped mericana cv. '1-154') que reempiazO al alamo criollo en sobre la cual Juan Brethes halló en 1908 a Platypus sul- 1938. Tomando en cuenta este año, se infiere que en el catus Chapuis; también señaló que los insectos adultos Delta del Paraná (bonaerense y entrerriano) y en los examinados procedIan de las provincias de Buenos Aires, terrenos no aluviales de la provincia de Buenos Aires,los Corrientes y Misiones. Diecinueve anos después de esta bosques cultivados de alamo mussolini son atacados cita, aislada y nada significativa desde el punto de vista aproximadamente descle hace 15 aflos. Para la provi'ncia forestal, Juan Bosq, al comprobar que los daños' de Platy- de Santa Fe la antigtiedad es de 4 afios. pus sulcatus sumados a la acción de los vientos hicieron Con respecto a eucaliptos, cuyo cultivo en masa co- caer 300 árboles de álamos en 8 hectáreas de unaisla del menzó en Argentina en 1943, se estima que la propaga- Delta, determina por primera vez las graves consecuencias ciOn del insecto ya cubre una década. que provoca la presencia de este insecto. Es muyposible Esta ojeada retrospectiva permite Ilegar a la conclusiOn quelosejemplares caIdoserande "alamocriollo" de que las salicáceas y eucaliptos han constituIdo y cons- (Populus nigra cv. italica) que a la sazón, 1928, era la tituyen el principal factor que posibilita la alarmente especie que se cuitivaba. Este antecedente revelarIa que dispersiOn de Platypus sulcatus, conclusiOn avalada por el en la provincia de Buenos Aires hace 40 años2el plati- hecho de que las especies forestales indIgenas cultivadas pódido ya estaba radicado y que ha ido ampliando su area son más resistentes que las exóticas. Estasusceptibilidad de dispersion paralelamente con el aumento de superficies diferente siempre se verifica en parques pOblicos y priva- destinadas a plantaciones con criterio forestal. Con mayor dos. exactitud puede opinarse que una de las especies que más Hasta el presente en las provincias de Mendoza, San ha contribuIdo iltimamente a esa dispersiOn de Platypus Juan, Neuquén y RIo Negro, que tienen importante su- sulcatus ha sido el "alamo mussolini" (Populus x eura- perficie de salicáceas o eucaliptos, no se registran datos sobre la existencia del platipódido, en cambio en las 1El daño consiste en una galerIa de forma de laberinto que provincias de Buenos Aires, Santa Fe, Entre Rios y Ju- surca en piano casi horizontal toda ia sección normal del fuste desde que alcanza 15 cm. de diámetro, a partir del cual no hay juy, se van señalando periOdicamente nuevas localidades medida que represente un limite para el ataque; orificios circu- cuando la edad de las plantaciones es rayana a los 6 0 lares de 2.5 mm. de diámetro, abiertos en la corteza y expulsion 7 aiios. Esta dispersion adquiere traiscendencia real, en de aserrIn son los signos exteriores que hacen ostensible la activi- virtud de que la forestación que hoy se encara, tiende a dad de los insectos adultos. Los orificios se localizan a cualquier altura del fuste y en plantaciones en masa de 7 años se ha liegado conjurar el deficit de madera aserrada y por lo tanto el a determinar un promedio de 4 oriflcios por árbol y unporcentaje daño del insecto afectará a cualquier industria que exi- de 80% de ejemplares atacados. ja ci empleo de madera sin defecto. Sin perjuicio de dsto, 2 todos los cálculos se han descontado los 6 primeros años, también bosques de salicaceas y eucaliptos impiantados por considerar que los Orboles permanecen inmunes al no contar sus troncos con el diámetro mInimo citado precedentemente. con otros objetivos sufrirán reducciones enla composición Forest Protection 965 cuantitativa de sus masas por la tronchadura del fuste de A través de esta información objetiva se compren derá muchos individuos. el justo calificativo de alarmente con que se denomina a A continuaciónseconsignanlaslocalidadesque la dispersidn de Platypus sulcatus en el pals. Es evidente, poséen plantaciones de salicáceas y eucaliptos con criterio que si no se encuentra algün método de lucha eficaz y industrial; en su mayor parte fueron iniciadas en el perIodo económico podrIa Ilegar a comprometer la forestación con 1945-49. A partir de 1954, comenzaron a observarse con especies cultivadas ya consegradas, pero susceptibles, y mayor frecuencia los daños del coleóptero que reflejaron obligar a intentar su reemplazo por otras más resistentes honda preocupación entre los silvicultores y sobre todo por que su combate ofrece todavIa dificultades técnicas que se adecüen a las necesidades industriales. En este y económicas. sentido varias observaciones han permitido advertir que ciertas especies producen gomas o resinas, por ejemplo: Campana "paralso" (Melia azedarach), "ailanto" (Ailanthus altis- Delta Provincia de Buenos Aires Luján sima), "pinotea" (Pinus taeda), que impiden la penetra- Magdalena ción de los insectos adultos y al envolverlos en esos pro- 25 de Mayo ductos de excreción paralizan su actividad dañina. En Provincia de Santa Fe { Chabás ciertoscasos,especies forestales susceptibles liegan a Provincia de Jujuy ( Palpalá obturar el orificio de entrada con un tapón de naturaleza Concordia Provincia de Entre RIos Delta liberiana generado por el cambium en el transcurso del L Gualeguaychii perlodo de crecimiento del árbol, pero a pesar de ello muchos insectosadultos consiguen realizar los daños A tItulo ilustrativo se comunica que en 1958 se localizó a este platipódido en "plátanos" (Platanus acerifolia) tlpicos. plantados en calles de la ciudad de Buenos Aires; como complemento se transcribe los lugares de otras provincias Referencias donde se halló Platypus sulcatus, pero sin tener cono- Golfari,L.,1958.Condiciones ecol6gicas del cultivo de las salicáceas en la Argentina. Rev. mv. Agr., XII (2): 17 3-224, cimiento de haber atacado árboles de bosques cultivados. Bs. As. Puerto Bemberg Santoro, F. H., 1957.Contribución al conocimiento de la bio- Provincia de Misiones Santa Maria logIa de Platypus sulcatus Chapuis (Col. Platypodidae). Rev. mv. For., 1(3): 7-19, Bs. As. Provincia de Tucumán { Tacanas Provincia de Corrientes { Sin localidades RESUMES Por otra parte, asI como la lista de localidades se acre- The Alarming Spread of Platypus sulcatus in Argentina cienta notablemente, en la que corresponde a especies This paper makes an approximate estimate of when the dis- forestales cultivadas susceptibles, se sigue agregando cada persion of Platypus sulcatus began in Argentina, on the basis of vez mayor nilmero de ellas, de las cuales algunas tienen the cultivation of exotic species of trees for forestry purposes. importancia económica y otras carecen de significación It also gives a list of localities with important plantations of willows and eucalyptus where the damage caused by that coleop- forestal o se encuentran en la etapa experimental. teron isalready causing grave consequences. The paper states that the dispersion of Platypus sulcatus takes place along parallel "acacia blanca" Robinia pseudoacacia lines with the increase in acreage planted with willows or eucalyp- "alamo criollo" Pop ulus deltoides cv. tus, which justifiesapplying the adjective "alarming" to such carolinensis dispersion. "alamo mussolini" Populus x euramericana cv. The author reports on the cultivated species of exotic forest '1-154' trees which are subject to attack and finally warns that, unless "alamo l98"* Populus x euramericana cv. effective and economical ways of fighting the pest are made '1-198' available, Platypus sulcatus will become a potential factor in "alamo 72"* Populus x euramericana cv. limiting forestation for the production of defect-free wood. '1-72' "alamo 42"* Populus x euramericana cv. Propagation alarmante du Platypus sulcatus en Argentine '1-42' La présente communication établit approximativement l'époque "alamo 3Q"* Populus x euramericana cv. a laquelle remonte la propagation du Platypus sulcatus en Argen- '1-30' tine, en consequence du boisement en essences exotiques cultivées "alamo plateado" Populus alba selon les normes forestières. "sauce alamo" Salix alba var. calva On y trouve également Ia nomenclature des localités ayant des plantations importantes de salicacées ou d'eucalyptus, déjà sévère- "ciprés calvo" Taxodium distichum ment atteintes en consequence des ravages causes par ce coléop- "eucalipto camaldulensis" Eucalyptus cama(dulensis tère.L'auteur de la communication établit le parallélisme qui "eucalipto tereticornis" Eucalyptus tereticornis existe entre Ia propagation du Platypus sulcatus et l'extension tou- "olmo" Ulmus sp. jourscroissantedessurfaces a peuplement de salicacées ou "cedro" Cedrus sp. d'eucalyptus, ce qui justifie l'emploi de l'adjectif "alarmante" pour qualifier Ia propagation de cet insecte. Platanus acerij'olia "plátano" On y trouve également la designation des essences forestières "casuarifla" Casuarina stricta exotiques cultivées qui sont attaquées et, en dernier lieu, l'aver- * El ataque a los álamos 198,72, 42 y 30 fué comprobado tissement qu'en l'absence d'une méthode de lutte efficace et peu en 1957 por el Ingeniero Agrónomo Adolfo E. Fernández, en la cofiteuse,le Platypus sulcatus devient un facteur éventuel de Estación Forestal del Delta. limitation du boisement destine a la production de bois non tare.

966 Fifth World Forestry Congress Proceedings L'utilisation des aerosols dans la lutte chimique contre les ennemis de la forét

EL. CONSTANTINESCU Bucharest, Roumanie

Fumigen "F-3" et Cometox entralné par les courants atmosphériques de faible inten- "F-3"est un produit fumigène contenant comme site, assurant ainsi un bon effet. materiel actif DDT et y HCH. On le livre sous la forme Par temps calme, le brouillard se maintient dans le de barres d'une forme cylindrique ayant un diamètre de peuplementpendantpluslongtemps. Lesaerosols 10, cm., hauteur variable et le poids entre 0,25-1 kg. peuvent êtreutilisésdans des conditions variées de On l'allume a l'aide d'une amorce fixée a la partie temperature et d'humidité. supérieure. La fumigation résulte de la combustion sans La norme de consommation pour assurer une efficacité flamme de la substance. optima est de 6-8 kg./ha. Par le temps calme, les nuages de furnée produites par Le produit a une grande efficacité dans la lutte contre le "F-3" montent lentement etsediffusent presque les chenilles défoliatrices du premier au troisième age et uniformCment dans l'atmosphère øà us se maintiennent aussi contre les insectes adultes. dans l'air pendant plus longtemps. La furnée peut être Pour les normes qu'on vient d'indiquer la mortalité a entraInée par les courants atmosphériques d'une vitesse variéde 90 a 100%. atteignant 3 m./s. et déplacée sur de grandes distances. RESUMES Les dimensions des particules des aerosols produites par le "F-3" sont comprises entre 5-15 microns. The Use of Aerosols in Combating Forest Pests With Le "F-3" a été utilisé dans la lutte contre les défolia- Chemicals Fumigène "F-3" and Cometox are two products made in teurs du peuplement des feuilus et des résineux ayant Rumania and used in the form of aerosols to combat forest pests la consistance de 0,7-1, hauteur de 10-30 m., et le relief with chemicals. plat ou accidenté (dans la region montagneuse). Their active ingredients are DDT andHCH. Ce produit trouve une large application dans les ter- The "F-3", available in the form of sticks, finds wide applica- rains très accidentés, oü les moyens de transport ter- tion in rugged areas where there is no air or ground transporta- restres ou aériens ne sont pas utilisables. tion.Standard consumption is 10 to 20 kilos per hectare. This product is very effective against leaf-eating caterpillars in their La norme de consommation est de 10-20 kg./ha. first stages and against insects, killing from 85% to 100%. La dispersion de la fumée produite par les fumigènes Cometox is an insecticide available in the form of a reddish- places a une distance de 30 x 30 m., assure un degré brown liquid. It may be sprayed as an aerosol, hot or cold, with satisfaisant d'enveloppement pour toute la frondaison. vibrators of the Swingfog type or with compressors of the Helma, Fontan type.Standard consumption is between 6 and 8 kilos Le produit a une grande efficacité contre les chenilles per hectare. This insecticide is very efficient in combatting leaf- défoliatricesa leurs premiers ages(1-111)contre les eating caterpillars from the first to the third stages, and also insectes (Saperda populnea L., Melolonuha sp., et al.) le against the adult insects, killing between 90 and 100 percent. pourcentage de la mortalité vane entre 85-100%. Uso de Rociadas en la Lucha contra los Enemigos del Le produit Cometox est un insecticide ayant comme Bosque por Métodos Quimicos materiel actif DDT et y HCH dont le portant est du type brun El fumIgeno "F-3" y el Cometox son dos productos de fabrica- pétrolier.On lelivresous forme deliquide ción rumana que se utilizan para rociar en la lucha contra los rougeâtre. enemigos del bosque por medios qulmicos. Sa densité est de 0,91., la viscosité 1,25° E. et a la Sus materiales activos son el DDT y el y HCH. temperature de 20° C., et le pourcentage de toxification El "F-3" se encuentra en forma de barras y se utiliza en gran est de 3,33. escala en regiones accidentadas donde no se pueden utilizar medios de transporte aéreos o terrestres. El promedio de consumo es de Ii peut être diffuse sous forme d'aérosols chauds ou 10 a 20 kgs. por hectárea. Este producto es muy eficaz contra las froids a l'aide des appareils de type pulsateur Swingfog orugas deshojadoras durante las primeras etapas de su vida, asI et des compresseurs de type Helma; Fontan. como contra los insectos.El porcentaje de mortalidad oscila entre ci 85 y ci 100%. Les aerosols chauds diffuses a l'aide des appareils El Cometox es un insecticida que se suministra como no portatifs distances entre eux de 3 0-40 m. se diffusent lIquido de color marrón rojizo. Puede ser pulverizado en rociados presque uniformément dans la frondaison tout entière du frIos o calientes, por medio de aparatos tipo pulsador Swingfog y peuplement, en luiassurant un enveloppement satis- de los compresores tipo Helma, Fontan. El promedio de consumo es de 6 a 8 kgs. por hectárea. Este insecticida es muy eficaz en la faisant. lucha contra las orugas deshojadoras desde su primera hasta su Le brouillard produit par les aerosols monte lente- tercera etapa de crecimiento y también contra insectos adultos. ment, se diffuse dans tout le branchage, et peut être El porcentaje de mortalidad oscila entre el 90 y el 100%.

Forest Protection 967 Comments immediate control we prefer to apply enough spray to compensate for the vagaries of application often encount- Robert L. Furniss (U.S.A.): ered during practical control operations.The effects Dr. Fettes told us that we must refine our forest spray- upon fish and wildlife have not been excessive.Only ing techniques so as to cause less damage to wildlife, and about two percent of the treated area of nearly five million he indicated ways to do this. acres has had to be sprayed more than once. I believe we can all agree with him that our goal In conclusion, I would say that no magic formula should be to control insect pests with minimum hazard to applicable to all conditions is likely to be developed for other forest fauna. As custodians of forests and wildlife, forest spraying. Through research we must continue to we must manage and protect both these resources, though, improve the effectiveness of our control methods and, at times, we may have to favor one over the other. Every when spraying is necessary, to search for ways to mini- tree cannot be saved from insects, nor every fish protected mize detrimental side effects. By positive action of this from the effects of spraying, but we can and must insure kind we can allay fears that have been aroused in the that neither forests nor wildlife are needlessly sacrificed. public and forestall precipitate legislative action that might Dr. Fettes pointed out that spraying is an emergency deprive us of the use of aerial spraying as a tool in forest measure to he used as a last resort. There must be urgent protection. economic and biological need for control to warrant action. We cannot spray every spot of insect infestation, Noel D. Wygant (U.S.A.): for that would be too expensive, and the hazard to wild- Doctor Rudinsky has presented an excellent review and life would be greatly increased.Also, it would be un- summary of the recent advances in chemical control of necessary, for in most cases nature will do the control bark beetles, root-damaging insects, and cone and seed job without cost and without harm to other forest fauna. insects. He has given special emphasis to the status of As Dr. Fettes stated, our spraying methods were de- systemic insecticides and their advantages over other types. veloped empirically.Less than two decades ago we His paper leaves little to comment upon. learned that DDT applied from airplanes would control I take minor exception to his first statement that "the forest defoliators that previously had run rampant. This use of insecticides in the forest is, for several good reasons, gave us a tool for increasing forest production by reducing not the most desirable way to control destructive insects." insect-caused losses.In using this tool, we encountered His reason for this statement is "the adverse effect the new problems that had to be solved. Some of them are insecticide may have on the various biotic factors upon still with us. whose activity depends the equilibrium of the complex One perplexing problem on large-scale spraying proj- forest community." In some cases, this reasoning may not ects is to determine why fish may suffer heavy mortality be compatible with a forest management objective. If the in some streams and little or none in others. Trout that objective of the forester is to manage the forest for its are killed by spraying can be replaced from hatcheries maximum , insecticides may be needed to and the cost charged tocontrol.But can runs of maintain the equilibrium and produce this maximum crop. anadromous fish also be reestablished? The solution of Growth in the use of chemical control will be directly these and related problems requires coordinated research proportionate to (1) the economic return, (2) rate of by forest entomologists and wildlife specialists working development of safer and more effective materials, and together. (3) how well research is able to determine how and when For safety and economy, the trend in spraying is to use to apply the insecticide with the least disruption of the larger and larger airplanes flying higher and higher. This natural control factors and the least disturbance of the creates problems. It is more difficult to control where the forest fauna. spray falls, hence to keep it out of streams and lakes. The optimism of Doctor Rudinsky in the future of sys- Another problem created by high flying, as indicated by temic insecticides is well founded. However, some impor- Dr. Fettes, is that DDT concentration is increased through tant barriers to large-scale use stand in their way. Many evaporation, thus increasing the possibility of adverse are too toxic to animal life to consider extensive aerial effects upon wildlife. application.Their cost of production is high. The me- Dr. Fettes advanced the concept that the key to con- chanics for adequate absorption through the foliage and servation of fish and wildlife on spraying projects is translocation of the insecticide must be determined. minimum dosage that will achieve acceptable control. Ways and means of integrating chemical, biological, Before agreeing fully with this, we need to define "ac- and cultural control must be developed so that one corn- ceptable control" and to take time into account.In plemeTts the other. Doctor Rudinsky mentions one means Oregon and Washington, our aim in spraying against the of accomplishing this with some of the selective insecti- spruce budworm has been to achieve near-perfect control cides that kill the pest insects but do not kill the important on well-delineated control units in one application so as parasites and predators. He mentions that we are on the to minimize respraying. On other areas, such as in eastern threshold of great advancement through development of Canada, where trees are sprayed to save them from year this group of chemicals. In the meantime, our presently to year until the outbreak declines naturally, a lower known, nonselective insecticides may be used in one of degree of control may be considered acceptable. two ways to accomplish the same objective: (1) Treat After experimenting with lower dosages, we returned only those areas where the complex of the pest, parasites, tO and stayed with one pound of DDT in one gallon of and predators is unfavorable; and (2) Use the insecticide fueloil per acre.This is more than istheoretically at the proper time to produce a selective action on the necessary, but to be certain of attaining our objective of pest insect.

968 Fifth World Forestry Congress Proceedings The control of the Engelmann spruce beetle in Colorado eign predator introductions in our research effort to find a with ethylene dibromide emulsion is an example of treat- method for controlling the balsam woolly aphid (Chermes ment of only certain areas. Three species of native wood- piceae). This insect threatens to wipe out Fraser fir in the peckers control this insect in standing spruce, except when Appalachian Mountains of the Southeastern United States. large numbers of beetles build up in windthrown trees and We have released small numbers of 6 species of foreign cull logs. Chemical and logging control are used only in predators at different points in the 1,000-acre infestation the amount and extent necessary to bring a favorable during 1959 and 1960. We considered it desirable to balance between the beetle and woodpeckers. introduce as many species as feasible into their new envi- Doctor Rudinsky's report should convince us of the ronment so that their effectiveness might be measured in need for (1) an accelerated research program to develop as short a time as possible.It seemed feasible to release new and better chemicals specifically for control of forest relatively small numbers of each species to assess effective- insects;(2) more research on the biology of the pest ness in terms of environmental adaptability, searching insects and their natural enemies for information needed ability, and biotic potential. Furthermore, a highly effec- for timing and wise use of the chemicals; and (3) close tive predator might be one which, released in small nUm- coordination of research effort in chemical, biological, and bers, can build up rapidly, spread, and control the aphid. cultural control in a common goal to develop complemen- Perhaps the most perplexing question is "to what extent tary methods. We must learn how to use all methods to should predators, to be introduced, be studied in their insure the maximum forest cropnot biological control native environment?" Complete biological information, alone, not chemical control alone, not cultural control though desirable, is not essential, since the biology of the alone.More often than not, we shall find one alone species in its new environment will probably exhibit inadequate. strong differences. However, we feel that certain basic knowledge of life history and habits is necessary. In our William H. Bennett (U.S.A.): initial study of introduced species we have experienced Dr. McGugan has clearly pointed out (1) that earlier difficulties due to lack of this basic information. work in the biological control of introduced forest insects has had its weaknesses from a scientific standpoint, and Clarence G. Thompson (U.S.A.): (2) that there is need for expanded basic research on Investigations in microbiological control have followed population ecology. more or less along the same lines in the United States as Research workers have lacked knowledge of the many the Canadian work just described by Dr. Angus. Our complex factors that affect the imported insect, its natural experience with protozoan parasites has been limited but enemies, and the host tree. Important controversial issues bears out the observations reported from Canada.In have arisen from failure to understand the ecology of most addition to the fungi reported by Dr. Angus, we have also introduced insects.Some of these issues are:Should been investigating members of the genus Metarrhizium. exhaustive ecological studies of the parasite be made in These fungiappear in nature toexert considerable the country of its origin, or is it more important to make influence in populations of certain insects, particularly the such studies in the new environment? When parasites soil-inhabiting ones. While attempts to control defoliating become available, what is the proper number of individ- insects with applications of fungus spores have usually uals to release at one point, and when should the parasites been disappointing, this may be the result of improper be released? Should a combination of all available para- timing of application. The unreliability of weather does, sites and predators be liberated, or should we set free one as Dr. Angus pointed out, make the success of foliage ap- species at a time, so that a critical appraisal of each one's plications doubtful in many parts of the world. Many value can be made? defoliating insects, however, pupate in the soil or duff of With the reasonably good success already attained in the forest floor and, in fact, may spend the greater part of establishing foreign parasites and predators in North the year there. The moisture conditions are much more America, we are encouraged to look forward to even bet- stable and reliable here than they are above ground on the ter results. Recent research in population dynamics and tree foliage.It is quite possible that treatment of the the use of electronic equipment and statistical techniques forest floor may give much better results than foliar appli- to analyze the mass of data facilitate a scientific and cations, at least with some insects and fungi. realistic approach to biological control. These new devel- While we have been able to culture a number of the opments are of significance not only because of the need Entomophthoraceae (Empusa), they have proved very for improved controls of exotic insects already with us, difficult to handle. Limited success has been reported in but also because additional and more dangerous ones are introducing fungi of this group into populations of certain likely to be introduced. New research should also improve agricultural crop pests such as the spotted alfalfa aphid our understanding of the part played by native parasites in California. in controlling native forest insects. In all studies, it will Natural epizootics of virus diseases in insects are fre- be important to remember that extremes in physical fac- quently so striking that they have caught the attention of tors may obscure the role of parasites and other natural a number of entomologists throughout the world. As the enemies of our forest pests. outstanding work in Canada has demonstrated, the viruses can be manipulated to reduce insect populations, often R. Joseph Kowal (U.S.A.): drastically.The major obstacle to widespread use of Mr. Bennett has raised some interesting questions in these pathogens as control agents has been the difficulty his prepared commentary on Dr. McGugan's excellent of mass production. Once this problem is solved, their paper. His questions have particular application to for- use should become widely adopted. In the meantime, our

Forest Protection 969 present limited means of production should suffice for vegetation thatwill provide suitable cover forsmall introduction of viruses into susceptible populations where predatory vertebrates such as wood mice.Parallel ex- they do not naturally occur and, in some cases, where amples might be mentioned for North America, notably natural occurrence is delayed to the point of excessive the small mammals that prey upon such insects as the timber loss. sawflies, which spin their cocoons in the leaf litter, and Dr. Angus is an acknowledged authority on the bacteria some lepidopterous larvae that seek shelter from high pathogenic to insects and he has modestly refrained from temperature in the litter on the ground, are favored by a acknowledging that he and Dr. Heimpel have been major diversity of ground cover. contributors to our present knowledge of the mode of The multiplicity of interactions within the total com- action of the Bacillus thuringiensis complex. munity are so complex that, with our present understand- The dramatic effect achieved by some of the newer ing of them, their complete analysis exceeds our ability. "microbial insecticides" should not blind us to the value Nevertheless, as Dr. Voflte points out, "the richer the of some of the more subtle diseases such as that caused by biocoenosis, the larger the variety of predatory animals Perettsia fuiniferana just described by Dr. Angus. A and parasites will be. ..." and the greater will be the permanent addition(not a replacement)tonaturally regulatory influence of these organisms. occurring biological control factors may be of much This concept is in harmony with the statement that I greater economic value than a drastic but temporary con- have frequently made to the effect that environmental trol measure.Simply lowering the fecundity of a pest complexity leads to stability, and simplicity to instability insect may be sufficient, in some cases, to allow other of communities. natural control factors to maintain the insect at econom- In summing up, Dr. Voflte points out that any practice ically acceptable levels. that encourages a high degree of health, that removes material from the forest in which noxious insects can Samuel A. Graham (U.S.A.): multiply, that encourages the activities of predatory and To be asked to comment on this thoughtful paper by parasitic insects, or that creates conditions or situations Dr. Voflte is a privilege and an honor. I am pleased with that are physically undesirable for the pests will serve to the assignment, not only because the subject is one of reduce the hazard of insect outbreaks. special interest to me, but also because of my personal One other point, implied, but not specifically mentioned admiration for the author. in his discussion of the cultural control of forest insects, The classification of cultural control measures accord- deserves comment. The cultural procedures are designed ing to physical and biotic effects is a logical division. The only to protect the forest against excessive populations physical influences, chiefly temperature and moisture, are of pests. In other words, the objective is not the extermi- often subject to cultural manipulation, as Dr. Voitte points nation of the harmful insects, but rather to hold down out, by the regulation of stand density. Encouragement of their number to a level that will cause littleor no early closure reduces the ground temperature below a economically significant damage. This is a point of view point favorable for some insect species. Later in the life thatissometimes unrecognized by forest managers, of a plantation, appropriate thinning operations may so especially in North America. Some of them, all too fre- reduce competition for moisture between trees in the quently, think that even a minimum amount of defolia- stand that good health of the trees is maintained, and the tion, or the death of a few suppressed and overmature chances that they will be injured by certain insects will be trees from the attack of bark beetles or other pests con- reduced.In the United States, comparable thinning of stitutes a hazardous situation. As a result of fears gen- pine stands has eliminated the deleterious effects of some erated by this opinion, they sometimes urge vigorously sucking insects. (For example, the pine spittle bug, the the application of direct control measures, when inex- oyster shell scale, some woolly aphids, etc.) pensiveculturalpracticeswouldadequately prevent The biotic effects he separates into three categories, economically significant damage to the forest. i.e., the interaction between the tree itself and the insect, One should bear in mind that the fine virgin forests the interactions between the insects and their natural of the Americas have developed in spite of the presence enemies, and the complex interactions that occur within of insects and disease-causing pests.In fact, these or- thetotal community or biocoenosis.The firstbiotic ganisms have been among the chief regulatory influences category includes all those characteristics of the trees in these forests and have removed the sick and decadent that result either from their genetic constitution, or from trees, thus making space for the young and vigorous. their physiological condition as influenced by the various They also have brought about natural thinning in over- cultural treatments to which the stands may be subjected. dense stands and have created favorable conditions for In North America, at present, these treatments will usually natural regeneration of some forest types. involve the wise use of the axe and the saw, whereas, in Thus, in a way the pests have been "Nature's Forest- the more intensively managed European forests, other ers."In managed stands man desires to use materials formerly destroyed by the pests, and in attempting utiliza- more refined techniques may be applied. tion, he frequently makes mistakes, creating conditions The interactions between the insects and their natural that lead to excessive insect populations. Many of these enemies may also be regulated by cultural practices. errors in management might be avoided if we followed Dr. Voâte mentions the possibility of encouraging nectar- the procedures indicated by "pest" activities in natural producing plants, for the benefit of parasites that require forests. sweet fluids for food, and the encouragement of ground Dr. Voflte has indicated some of the ways in which 970 Fifth World Forestry Congress Proceedings the above objectives may be accomplished. He does not clearly shows that the chance of outbreaks can be reduced, imply, however, that pests can invariably be regulated so that emergencies demanding expensive directaction through cultural practices.Nevertheless, his discussion should be relatively infrequent.

Session D Forest Fires Incendies de foréts Incendios de Bosques )

Meeting Protection Objectives in Difficult Years

R. H. LUKE Fire Protection Officer, New South Wales Forestry Commission, Sydney, New South Wales, Australia

Variations in the Degree of Fire Danger in Forests and it is usual to allocate only small staffs to full-time duty During every hour of every day there is little variation on fire protection. in the flammability of buildings and of their contents, so These few specialists require the periodic assistance of that the state of alertness required in a city fire department personnel from other units of a forest service to carry out is constantly at a high level. all necessary pre-suppression work as well as the discovery The fuels in a forest are not protected from the ele- and suppression of fires. ments, and their quantity and general conditions vary from When the normal extent of the fire season is confined season to season, and their flammability, from hour to to three or four months in a year, the majority of forest hour. service personnel have little to do with fire protection for The risk of fire occurrence in forests also varies, as it the remaining eight or nine months. During this lengthy is difficult to sustain a full public awareness of the need period of virtual stand-down, it is natural that this staff for care when hazard varies so much, apart altogether should lose some of the alertness and skill demanded from the variable risk of lightning strikes. during the fire season proper. Fire danger, a term which broadly covers the chances If each fire season were of similar intensity and dura- of fires occurring, and their subsequent behaviour, must tion this would present no special problem, for, as each assess the degree of hazard and risk, as well as the influ- season approached, a programme of preparation and ence of weather conditions, which again are not only training could be carried out to bring the staff to the variable but difficult to predict. requisite peak of efficiency for known sets of circum- Because of the wide variation in conditions of fire stances. danger found in forests and in grasslands, the degree of There are few forest regions in the world where fire preparedness and alertness necessary in these areas varies seasons occur with uniform intensity or are confined with- completely from that of a city fire department. There are in definite seasonal limits A succession of very mild times when rural fires may develop into major conflagra- seasons requiring little fire protection effort results in a tions within minutes of starting, but there are also long cumulative loss of preparedness and skill, so that the onset periods during which fires will spread slowly, or when of even a moderale fire season may find a forest service there is no possible chance of their starting at all.To lacking the degree of efficiency necessary to counter such maintain full-scale alertness at all times is, therefore, un- a situation. necessary and uneconomic. The staffs of forest services Should a difficult fire season develop after a long series have many duties to perform other than fire protection, of mild to moderate years, this situation could be aggra-

Forest Protection 971 vated to an extent that few members of the staff would information available from reliable records over a longer have personal knowledge of serious fire situations. period. It is essential, therefore, that forest services should not A search of distant records for accounts of major fires only develop fire protection organisations of sufficient is essential if the full possibilities of a difficult fire season flexibility to meet the particular demands of difficult years, are to be assessed. but should also ensure that key personnel are able to Fire history may be studied for a continent, country, recognise these difficult years before or as they develop. province, district or single forest, and may be general Portents of a Difficult Fire Season or detailed.It requires the preparation of a fire occur- As a pre-requisite to all planning in forest fire control, rence map, illustrating the locations and dates of past itis necessary to compile the fullest possible details of fires. past fire history, including the behaviour of fires within The provision of a fire history for any forest unit the full range of fuel and weather conditions which might provides the basis for a more detailed appreciation of be encountered. climatic conditions in relation to fire occurrence. Table Any detailed fire history should embrace a period of 1is an example of basic climatic and fire history data at least ten years, and should have due regard to other for the Taree Forestry District, N.S.W., Australia.

Table 1. Example of basic climatic and fire history data. Fire History for the Taree Forestry District of 2,900,000 acres (overall area) including 413,000 acres of State Forest (S.F.). Climatic data for the town of Taree, N.S.W., Australia, Long. 152°58' E., Lat. 31°55' S.

Item Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mean monthly rainfall 200 334 281 303 397 505 470 Probable monthly rainfall pattern during a 10-year period. 0-199 points 6 6 4 4 3 2 3 200-399 points 2 1 4 3 3 3 3 400 points and over 2 3 2 3 4 5 4 Probable 3-monthly rainfall pattern during a 10-year period. A-S-O S-O-N O-N-D N-D-J D-J-F

0-599 points 4 3 3 1 1 600-1,199 points 3 4 4 5 5 1,200 points and over 3 3 3 4 4 Mean max. temp. (F) 67 72 76 80 83 84 83 Highest ever recorded 93 94 104 109 111 114 110 Mean mmtemp. 44 47 52 56 61 62 62 10-year fire history (1950/59). No. months of mild fire danger 8 7 6 4 5 6 8 No. months of moderate fire danger 2 3 2 3 2 3 2 No. months of severe fire danger - 2 3 3 1 - Total fireslO years 34 54 139 176 132 45 15 Total acres of S.F. burnt 1,260 1,174 25,862 91,926 37,932 5,556 1,090 Record for worst year (1951/52). Rainfall, points 106 100 189 21 119 139 978 No. of fires 8 22 66 55 30 8 8 Acres of S.F. burnt 260 293 23,254 64,956 10,605 2,726 184 NB. It would, of course, be desirable to extend this information over the full 12 months and include details of such things as frost occurrence, relative humidity pattern, monthly wind roses and typical diurnal fuel moisture patterns as are available.

In evaluating the probable severity of any fire season tionsinthe weather pattern.Local marketing and the principal factors to be considered are stated below. silvicultural practices and the effect of past fires do have a positive bearing on fuel quantity and arrangement. Quantity of Fuels The amount of grass and similar surface vegetation is The State of Fuels largely a reflection of growth during preceding months or To be complete, this study should embrace causes as years, so that any complete study of fuel quantity should well as effects. Frosts, snow, dew, wind, air temperature, have regard to the extent and distribution of precipita- humidity and rainfall exert an influence on the curing of tion during the period of fuel build-up. grasses and other annuals, and on the moisture content Except in the case of leaf fall in deciduous forests, of all fuels. Variations from normal often indicate definite the extent of forest litter is not greatly affected by varia- trends to the extent that certain forest services use sea-

972 Fifth World Forestry Congress Proceedings sonal indices to measure the cumulative effect of such a The Study of Fire Behaviour major factor as precip'itation in the possible development To deal with all exigencies of a difficult year, this of fire seasons. further study must be carried out on a broad basis by the average forester, and in detail by the fire control A Detailed Study of Current and Anticipated Weather research worker. The rate of fire spread, the incidence Conditions of crowning and spotting and resistance to control, have The behaviour of air masses and fronts is of special to be studied in relation to fuel quantity, state and types, significance, for itis wind, created in the main by the wind velocity,temperature,slope and variousother movement of air masses, which plays a major role in the factors.This involves the detailed recording and study measurement or estimation of fire danger. Wind direc- of all individual fire reports, followed by controlled fire- tion is important because its source influences air tem- behaviour field studies to fill in any gaps in fire report perature and humidity (and consequently the fuel state), data. while its velocity directly affects the rate of fire spread. Following consideration of the above factors, dispatch- The detailed study of current conditions and anticipated ers' guides are necessary to set out in the simplest pos- trends in weather and fuel state should be continued sible tables or graphs the requirements, in manpower and throughout any normal fire season, and abandoned only equipment, needed under various circumstances.(See when no further possibility remains of fires occurring. exampleTable 2.)

Table 2.Dispatchers guide for fires starting in plantations of Pinus radiata in Southern New South Wales, Australia. Degree of Fire Danger Extreme Extreme (Upper (Lower Very lhnit) limit) High High Moderate Low Probable extent of fire danger in days during a 4-month period for various types of fire season. Mild season (4 in 10) - 11 22 28 60 Moderate season (4 in 10) 2 14 35 45 25 Severe season (2 in 10) 2 5 24 35 29 25 Probable maximum rate of spread of fire. Forward spread in chains per hour 130 75 35 15 8 4 Perimeter in chains per hour 295 175 80 40 27 14 Area, in acres, one hour after start 700 250 60 15 6 2 Minimum suggested requirements for earliest possible attack. Men 50 30 12 6 4 2 Tankers 4 3 2 1 Bulldozers 2 2 Expected period, in hours, to bring fire under control 5 2to4 lto2 ½ ½ ½ NB. It is not considered necessary here to supply full details of the method of fire danger assessment. However, Extreme danger (upper limit) involves the following conditions: Temperature over 100° F.; Relative humidity below 15°; Fuel moisture content 2-3%; Wind speed in excess 25 m.p.h. in the open and of 5 m.p.h. in a pine plantation stand. Under such conditions fires in cured grasslands may travel at speeds up to 10 m.p.h. and in open eucalypt forest up to 6 m.p.h. Crowning is a common phenomenon under such condi- tions, and spot fires may commence several miles in advance of a main fire head.It is possible that six such days will be experienced during a 10-year period in many parts of South-Eastern Australia.

Meanwhile, other studies should have been made of Congress has his own particular bases of comparison, the causes of fires, the reasons for these causes and for the and although Australia is here used for illustrative pur- common points of fire occurrence. Because the relative poses, the general principles, if not details, are applicable value of these studies varies greatly between and within elsewhere. countries,itisneither possible nor necessary here to In developing forest fire protection organisations many detail how such studies should be organised. The es- countries are concerned with grasslands to the extent that sential point is that there should be in each forest service grass occurs in or immediately adjacent to forests.In personnel with the necessary training and interest who Australia, however, forests are generally surrounded by will ensure that every part of the fire control organisation large areas of grasslands which are susceptible to major is keenly aware of seasonal and synoptic trends. fires once the grass cover is sufficiently cured. When, as is often the case, there is a high degree of hazard in both Definition of a "Difficult Year" in Relation to forests and grasslands, there is little differentiation be- "Below Average" and Average Fire Seasons tween grass and forest fires, so that the term "bush fire" In considering the intensity of fire seasons there is no is used, irrespective of the fuel in which the fire burns. In world-wide basis of comparison. Each delegate to this Australia, therefore, rural fire protection is by no means

Forest Protection 973 the sole concern of the Forest Services.There are, in very high, while from 6 to 12 days of extreme fire fact, throughout Australia some 300,000 volunteer "bush" danger may be experienced during the season. firefighters organised into some 5,000 separate brigades. In forests, a period of three months in the late winter As the number of firefighters normally available to the and spring, during which rainfall has been 30% or more Australian Forest Services totals some 5,000, itcan be below average, is generally accepted as the indicator of seen that the role of these Forest Services in rural fire a severe forest fire season. With the periodic occurrence protection can be a major one only if foresterscan provide of hot, dry, windy conditions, a very high to extreme some specialservicetothe community outsidethe degree of danger can be reached. Under conditions of relatively narrow limits of forest fire protection. extreme fire danger, fires may spread at a maximum sus- Australian fire seasons are normally classified as mild, tained speed of about 10 miles per hour in grasslands moderate and severe(i.e.,difficult). A mild season and 6 miles per hour in open eucalypt forests, while in resultsnormally from favourablerain-failconditions, certain areas, at least, any new fire must be treated as which maintain forest fuels in a sufficiently moist state having a million-acre potential. or maintain grassland in a sufficiently green state to In the forests of Western Australia, the annual fire inhibit the ready spread of fire.In certain dry inland season follows a fairly uniform pattern, because the rain- areas a mild season could result when prolonged drought fall during the summer season seldom exceeds one inch has so reduced the amount of surface vegetation that, in per month. general, insufficient fuel remains to support fire. InSouth-EasternAustralia(i.e.,SouthAustralia, A moderate season is usually ushered in and sustained Victoria, New South Wales and Southern Queensland), by a rainfall pattern of average or slightly belowaverage where rain falls in a much more variable pattern, it could intensity, so that hazard remains at a moderately high be anticipated that, during a 10-year period, 3 mild, level for lengthy periods, and reaches avery high stage 4 moderate and 3 severe seasons might be experienced, during periods of hot, dry, windy weather. while at intervals of perhaps 7 to 15 years, exceedingly difficult seasons could be encountered. A severe or difficult season is experienced ingrass- In Table 3 will be found an outline of forest fire history lands following any widespread and heavy accumulation in New South Wales, Australia, for a 10-year period of cured fuel.Except for short periods following light which illustrates the distribution and relative severity of rains, fire danger reaches at least to the level of high to various fire seasons.

Table 3. Forestry Commission of New South Wales, AustraliaTen-year fire history and record of expenditureon fire protection. A B C D E F G H 1949/50 L 1,690 71 4.2 100 13 0.2 1950/51 M 1,852 101 5.0 125 49 0.8 195 1/52 E 2,404 381 15.8 1,006 1,303 21.3 1952/53 L 2,131 253 11.9 171 8 0.1 1953 /54 D 2,153 339 15.7 534 165 2.7 1954/55 L 2,321 292 12.6 138 15 0.3 1955/56 M 2,423 244 10.1 247 43 0.7 1956/57 D 2,733 253 9.3 644 117 1.9 1957/58 E 2,895 346 11.9 968 459 7.3 1958/59 L 2,927 219 7.5 195 11 0.2 Averages 2,353 250 10.6 413 218 3.6 Key to Columns. A Fiscal year, corresponding to the fire season. B = Classification of fire season; light (L), moderate (M), difficult (D), extremely difficult (E). C Total expenditure of all Forestry Commission activities in LA thousands. D Expenditure directly charged to fire protection in LA thcusands. E = D as the percentage of C. F = Number of fires attended by Forestry Commission staff. G = Area of State Forests burnt, in thousands of acres. H = G as a percentage of the total area of State Forests.

General Organisation of a Forest Service to Meet These activities must be so integrated that, as far as Fire Control Emergencies possible,additionalfireprotection needs arefulfilled In organising any forest service, the frequency and from within the department. While further assistance may have to be sought from outside sources on occasion, the relative severity of fire seasons should be considered, costs of such assistance tend to soar beyond the scope of both in organising the fire control section or division, and normal departmental budgets. all other activities of the service. Organisational features requiring special emphasis are: 974 Fifth World Forestry Congress Proceedings Staff Organisation and Works Programme If past fire history discloses that there is a "march" in the fire season within any administrative unit, the pos- As stated earlier, there is no justification for the con- sibility exists of transferring equipment from one dis- tinued maintenance of the fire control staff of a forest trict to another as required. The provision of central serviceatalevelnecessaryto meet only periodic stores to house emergency fire equipment is another well- emergencies. known means of improving flexibility at reasonably low The number of full-time fire control specialists must cost. therefore be kept low.In Australia, for example, only 2% of staff are employed in this way, 80% are employed The listing of such equipment as bulldozers, etc., in the part-time on fire protection, apart from their attention hands of other government agencies, logging contractors, to a variety of other duties, while the remainder are em- etc., and the making of provisional contracts with such ployed on fire protection only during difficult years. contractors, is another familiar device, as, too, are f or- wardarrangements made tocharteraircraftfora Fire control specialists are engaged in such activities as There is scarcely need to fire-behaviourresearch, the preparation of basicfire variety of fire control tasks. plans, the development of equipment, and many other enlarge on the matter of equipment, provided that plan- details of organisation before and during fire seasons. ning visualises a flexible system of call. Most of the detailed responsibility for fire control meas- ures remains the responsibility of local administrative Access staffs, in addition to their many other duties in the fields It is in the planning and construction of forest access of marketing, forest management, silviculture, road con- roads and trails that the special needs of fire protection struction, etc. may best be served. It is therefore essential that all other activities should A logging road designed solely for the extraction of be organised so that this administrative staff may be freed timber may have little use for fire control purposes, but for fire duty, as required, during any fire season. In any if forest road location is related to such factors as fuel difficult year these other activities must suffer, so that types and topography, protection needs can often be planning must provide for flexibility in these activities as catered to.Similarly, a logging road having only a tem- well as fire protection. porary life for that purpose may be improved for subse- quent use in fire control. In all such cases, it is necessary Staff Training to consider the added costs in relation to the advantages to As every fire season approaches, some degree of train- be gained. ing is necessary at every level. The intensity, nature and extent of training will vary in accordance with the extent Preparation of Fire Plans to which individuals will carry out fire duties. The value A written fire plan for any forest or district should of practical field exercises should be emphasised. In the consist of three parts.The first part should utilise all endless controversy between foresters regarding complete relevant details of past fire history in relation to causes protection versus prescribed burning, opponents of the and to a variety of such other factors as weather, climate, latter should concede its value in familiarising staff in the and fuel types.The second part should deal with the use of equipment, in field organisation, and, perhaps most general policy to be followed, and should be reviewed at of all, in a sound knowledge of fire behaviour. When the intervals of several years. The third part should cover fire prevention programme has been so successful that administrative detail which might vary from year to year have become a rarity, these considerations are of and must be rewritten prior to each fire season. even greater importance. While fire control specialists assist in providing the A basic principle is that as many staff members as is information for the first two parts mentioned, the revision possible should be trained as leaders, able to take charge of the annual fire plan is essentially a task for local forest of the untrained reinforcements who are relied upon in managers, who must put into effect their own plans. an emergency. Once the onset of a difficult fire season While most fire plans provide for a degree of prepared- can be forecast, it will be necessary to intensify training ness, day by day, appropriate to each assessment of beyond that required for a normal season. hazard or danger, it is seldom that an attempt is made to Equipment specify the preparedness required for fire seasons of vary- ing severity. The fire control equipment located on forests is usually During a difficult season, a series of days, weeks or even adequate for average conditions but will not meet the months of above-averagefiredanger willstrain any full requirements of difficult years. organisation to a far more searching extent than the While it is not possible, for example, to supply all the requirements of an occasional difficult day during an fire tankers needed for any emergency, slip-on units are average season. usually held in readiness so that general-purpose vehicles may be converted at short notice for fire control use. In Any fire plan must therefore provide for the recognition order that these vehicles will prove suitable for the stress of a difficult season, and should set out the special meas- of firefighting in difficult terrain, it may be desirable to ures to be then taken. In preparing plans, full emphasis purchase trucks of more rugged construction, or of greater must also be given to the possibility of difficult conditions carrying capacity, than isnecessary for their normal developing before or after the "official" fire season. Staff operation. The additional cost of the latter vehicles is part is apt to take belated or insufficient action at such times, of the premium for adequate protection. leading to unexpected fire disasters.

Forest Protection 975 Organisation During a Difficult Fire Season Local variations of climate, topography and vegetation, Assuming that fire control specialists and forest man- together with the overall wealth and resources of a coun- agers can recognise difficult fire seasons as they develop, try, are among the factors to be considered. The protec- they should immediately implement the special measures tion of watersheds, grasslands and rural communities may required by the fire plan. be as important as that of forest growing stock and may The most obvious of these measures is in the field of therefore influence the size of any planned organisation. fire prevention. Men are transferred to fire prevention If local communities can be organised to accept some patrols; greater use is made of press, television and radio responsibility in the field of rural fire protection, their publicity; a greater degree of supervision is given to all efforts should be encouraged at government level by the forest operations; and a closer check is kept over the provision of low-cost equipment and by taxation rebates issue of permits for burning off. for the construction of firebreaks or other pre-suppression measures. A balance sheet can be drawn up, comparing Detection manning and all other prevention details of the cost of any protection plan, and of the losses sus- the fire plan are similarly placed on an emergency footing. tained under such plan, with the scale of losses which If necessary, reinforcements are brought from any other occur when there is no protection. By the law of diminish- region not subject to similarly severe conditions. ing returns, a point might be determined beyond which All advance arrangements made with other fire preven- further expenditure on fire protection appears unprofitable. tion authorities are checked, and appropriate steps are taken to implement all co-operative provisions of the fire There are certain fixed charges for pre-suppression plan. Arrangements are made for special weather fore- activities which have to be met every year and which con- casts, while preliminary contacts are made for the engage- stitute a minimum expenditure for any mild season. The ment of emergency labour which may be needed for fire- cost of suppression and of its associated activities will fighting. The efficiency of all equipment is checked at reg- fluctuate with the type of season experienced but cannot ular and frequent intervals. be forecast in advance. In short, every possible step is taken to prevent fires Table 3, which shows the proportion of fire control from starting, and, should they start, there must be an expenditure to total expenditure within the forests of New adequate early attack with a rapid organisation of men South Wales, Australia, in recent years, illustrates fluc- and equipment to reinforce the initial effort. tuations which may take place in the budgetary control During a difficult year, it is reasonable to expect that of most forest services. prevention publicity, coupled with a more general public It is necessary that those authorities which provide the recognition of increased risk, will minimise fire occurrence. funds for forestry activities should recognise that fiscal Should more than one outbreak occur, the organisation requirements for fire control will vary from year to year, will be strained to the utmost, for it is too much to expect and that provision of some reserve fund for firefighting is that all fires will be fully controlled by the initial attack. needed if the problems of difficult fire seasons are to be Under conditions of high air temperatures, exposure to met adequately. radiation from flames, work at high pressure in rough terrain, and lack of adequate rest, firefighters must be Conclusion rapidly exhausted.While the replacement of relatively untrained rank and file is mainly a problem of securing In preparing this paper, the writer has been acutely further numbers,thevariousfirebosses and "key" aware that the subject is of varying importance to the operators are most difficult to replace. countries represented here. As the result of continuing Co-ordination is difficult, and any new fire controller research in North America and in other continents, fire taking command of the whole situation is likely to be control has, in many of its aspects, become a science. It handicapped by difficulties in the rapid planning of his is difficult, however, to see how in the practical applica- campaign and of communicating his requirements to his tion of these scientific principles it can be other than an scattered work force. art. A particular difficulty in dealing with a major fire which Any detailed study made of forest fire losses in most cannot be held at its head is to ensure that control lines countries will show that almost all major damage occurs are established and firmly held along its flanks to counter during a relatively few days of the very severe conditions the effect of any wind changes which might otherwise spread the fire further. encountered during the occasional difficult season.It is possible that, during one week of a ten-year period, losses These matters can scarcely be dealt with in more detail in this paper. The U. S. Forest Service has published a are incurred which are greater than those for the other number of guides to the details of the organisation neces- 519 weeks of the same period. sary to fight major fires. The application of such broad Most forest services now plan their protection activities principles to local conditions should be examined by every for average conditions and provide for a degree of flexi- forest service likely to encounter major fire situations. bility for the periodic bad years. Fire control achievements during a number of average years may cause foresters to Financial Considerations overlook some disastrous circumstances of the past which It is not possible to specify what proportion of the might occur again. They must closely examine this pos- funds allocated to a forest service should be spent on fire sibility and make all necessary special plans to recognise protection. and cope with the difficult years of the future. 976 Fifth World Forestry Congress Proceedings RESUMES conformément au plan de lutte contre l'incendie. Si des feux se déclarent, il faut se rendre compte des possibilités qu'ils ont de se Comment assurer une protection suffisante dans les années propager et envoyer des renforts provenant des différents points difficiles de secours figurant dans le plan. Ii n'est pas possible d'indiquer avec precision la proportion des Dans les forês, le degré de risque d'incendie vane considé- ressources financières que le service forestier devrait mettre a la rablement du fait que la quantité et l'état du materiel combustible disposition de l'organisation de lutte contre l'incendie. Ii est toute- sont sujets aux dilférents changements saisonniers et autres. Le lois evident qu'un montant plus ou moms fixe sera nécessaire risque, ou la possibilité qu'un feu se declare, ne reste pas toujours chaque année pour les activités de prevention et que le montant constant, alors que les conditions atmosphériques, qui influent nécessaire pour combattre l'incendie et pour les autres activités sur l'évolution d'un incendie, sont ëgalement extrêmement vari- pendant la saison fiuctuera selon la gravité d'une telle saison. ables et difficiles a prédire. Le danger d'incendie, somme de ces facteurs et indicateur des Ii est important, par consequent, que les gouvernements et les possibilités de déclenchement d'incendie évoluant de certaines autres propriétaires forestiers reconnaissent qu'il est nécessaire de facons, est par consequent, lui-même, sujet a de vastes change- prévoir un fonds de reserve pour permettre a un service forestier ments d'une saison a l'autre et a de rapides changements d'un d'equilibrer son budget dans sine année difficile. jour a l'autre et même d'heure en heure. Dans certains cas les Le present document a pour but de souligner le fait que la feux de forêts peuvent se transformer en conflagrations quelques plus grande partie des pertes causées par de vastes incendies se minutes après qu'ils se sont déclarés; mais dans la plupart des produisent pendant des périodes de pointe relativement brèves, autres cas, le feu ne prend pas ou se propage lentement. souvent a intervalles irréguliens, et d'insister pour que non seule- Ii n'est donc pas justiflé de maintenir un état d'alerte constant ment chaque service reconnaisse ce genre de situations au fur et contre les incendies de forêts. Alors que les différents aspects de a mesure qu'elles se produisent mais encore prévoie une organisa- ce problème peuvent exiger une étude a plein temps de la part tion souple, susceptible d'être élargie a bref délai. de quelques spécialistes, la lutte contre l'incendie n'est qu'un tra- vailsaisonnier pourlamajoritédu personneld'unservice Métodos para Lograr los Objetivos de Protección en Años forestier. Dificiles Ii est evident par consequent qu'après la "morte" saison ordi- El riesgo de incendios en los bosques varIa en sumo grado segrin naire, les services forestiers doivent faire un effort considerable sean la cantidad y las condiciones de las materias combustibles afin d'être prêts a faire face a toutes les éventualités d'une saison que están sujetas a una diversidad de cambios estacionales y a d'incendies même moyenne. otras modificaciones. El riesgo o la posibilidad de que se origine Si la saison des incendies se révèle être une saison difficile, ce un incendio no es siempre igual, por cuanto las condiciones probléme est accentué et l'organisation doit faire preuve d'un meteoroalgicas que influyen la modalidad de los incendios también degré considerable de souplessesil'on veut éviter les pertes Situations dange- son extremadamente variables y de difIcil pronóstico. importantes qui pourraient accompagner des Por lotanto, el peligro de incendios, como suma de estos reuses. factores, y en calidad de indicio del origen y de la modalidad Avant d'entreprendre sine planification ddtaillée a cette fin, il de los mismos, está sujeto, a su vez, a las grandes variantes que eSt nécessaire d'étudier les circonstances accompagnant une saison se producen en cada estación del año, asI como también a los difficile.Ceci a deux fins: d'une part, découvrir la mesure pro- bable des demandes maxima qui peuvent être faites a l'organisa- rápidos cambios que ocurren dIa a dia y aun de hora en hora. tion; d'autre part (et ceci est de la plus haute importance) être En algunas ocasiones los incendios de bosques pueden transfor- a même de reconnaItre les symptômes d'une saison difficile avant manse en conliagraciones a los pocos minutos de haberse iniciado, qu'elle ne se produise et pendant son evolution. mientras que en otros casos los incendios no se pueden iniciar, o La plupart des pays utilisent le système bien connu de rassem- su propagación es muy lenta. blement et analyse des statistiques relatives aux incendies afin de Por lo tanto, no se justffica el mantenimiento de sin servicio de déduire du passé les éléments de saison, temps, lieu et autres cir- alerta constante contra el peligro de incendios.Si bien los constances de l'évolution des incendies qui peuvent influencer leur diversos aspectos inherentes al control de incendios pueden llegar evaluation des futurs besoins de l'organisation.Si la fréquence a hacer necesario sin estudio de tiempo completo por parte de des incendies et l'ampleur des dommages ont considérablement unos pocos especialistas, el trabajo de control, en 51, es una ocu- diminué au cours des dernières anriées, grace asix efforts couronnés pación de tiempo parcial para la mayorIa del personal del servicio de succès dans la lutte contre l'incendie, il convient de fouiller les forestal. dossiers et de se reporter a des situations graves a des époqueS Por lo tanto, es evidente que después del perlodo anual normal plus anciennes car ii n'est jamais bon de fonder une structure de inactividad virtualmente total en las tareas de control de administrative uniquement sur des tendances passagères. incendios, durante la época en que éstos no suelen producirse, Ii se peut qu'on n'accorde pas suffisamment d'attention a l'éva- sea necesario hacer esfuerzos considerables si el servicio forestal luation du degré de danger inherent a chaque saison au fur Ct a ha de encontrarse preparado para las exigencias que impone aun mesure qu'elle évolue.Le degré d'importance que l'ondoit una temporada normal de incendios. attacher aux différents facteurs variera d'un pays a un autre, mais Si la temporada de incendios resulta ser dificil, este problema ii est essentiel qu'il y ait, dans chaque service forestier, un nombre se agrava y se necesitará sin grado considerable deflexibilidad suffisant de personnes ayant une bonne formation spécialisée pour en la organización si se desean evitar las pérdidas mayores que tenir le reste du personnel au courant des details des tendances pueden acompañar a estas situaciones de peligro. saisonnières. Antes de que se comience a preparar cualquier plan detallado Dans l'organisation générale d'un service forestier, et pour faire que contemple este objetivo, es necesario estudiar lascaracterIs- face aux besoins de la lutte contre l'incendie, ii faut tenir compte ticas que son propias de una temporada dificil. El objeto de ello de la fréquence et de la sévérité relative des saisons d'incendie. Un es doble: por una parte, debe determinarse el alcanceprobable grand nombre d'autres tâches doivent être poursuivies et comme de las exigencias máximas que pueden llegar a imponerse a la Ia lutte contre l'incendie a priorité pendant la saison "officielle" organización; por la otra, (y ésto es de maxima importancia) des incendies, il faut obtenir une certaine souplesse dans l'ensem- poder reconocer los sIntomas de una temporada dificil antes y a ble du service. La formation du personnel dans les tâches rela- medida de que ella se produzca. tives a la lutte contre l'incendie est nécessaire tous les ans mais La mayorIa de los palses hacen uso del bien conocido método au cours d'une année difficile ii faut accorder plus de tempsa de compilación de antecedentes sobre los incendios, con ci pro- cette question importante. pósito de deducir del pasado los datos referentes a temporada, La valeurd'opérationsdefeuprescritespour permettre lugar, tiempo y otras caracterIsticas inherentes a la modalidad d'acquérir une comsaissance de l'évolution du feu n'est pas a de incendios, con lo cual se puede facilitar la determinación de négliger. futuras exigencias para la organización. Dans la preparation de plans de lutte contre le feu ii faut Si gracias al éxito de los esfuerzos realizados para Ia prevención souligner particulièrement les besoins pendant les saisons difficiles de incendios en años recientes ha sido posible reducir a niveles ainsi que les cas d'urgence qui peuvent parfois se produire en bajos la incidencia de incendios y la extensi6n de los dafios que dehors de la saison normale ou "officielle" des incendies. Au cours ocasionan, resulta oportuno buscar antecedentes sobre las situa- d'une saison difficile, tous les details d'organisation sont intensifies ciones más serias producidas en años más remotos, ya que en Forest Protection 977 ningtn momerito es prudente basar las exigencias de la organiza- incendios. En el transcurso de una temporada diflcil deben inten- ción exciusivamente en tendencias transitorias. sificarse todos los pormenores de organización de acuerdo con Es posible que no se preste suficiente atención a la determina- los planes para el control de incendios.Si los incendios se pro- ción del grado de peligro inherente a cada temporada a medida ducen, debe determinarse su potencial de propagación y adoptarse que ésta transcurre. El grado de importancia que ha de conce- y ponerse en ejecución las medidas de refuerzo que el plan prevé derse a cada uno de los diversos factores varIa de un pals a otro, con recursos de emergencia. pero es esencial que todo servicio forestal cuente con un ntmero No es posible aseverar con exactitud la proporción de los adecuado de personal especialista, que tenga suficiente entrena- recursos financieros del servicio forestal que deben ser puestos a miento para mantener al corriente al resto del personal sobre disposición de la organización para el control de incendios. Sin los pormenores de las tendencias de la temporada. embargo, es evidente que todos los afios será necesaria una suma La frecuencia y Ia relativa intensidad de las temporadas de más o menos fija para ciertas actividades de pre-supresión, y que incendios deben tomarse en cuenta para la determinación de las las cantidades requeridas para la supresión y otras actividades necesidades del control de incendios. Debido a que el control de durante la temporada principal de incendios fluctuarán de acuerdo incendios tiene prelación con respecto a muchas otras tareas que con Ia severidad de cada temporada. deben realizarse durante la temporada oficial de incendios, es Por lo tanto, es importante que los gobiernos y otros pro- necesario disponer de una adecuada flexibilidad a través de todo pietarios de bosques reconozcan la necesidad de crear un fondo el servicio.El entrenamiento del personal en los trabajos de de reserva si el servicio forestal ha de tener un presupuesto equili- control de incendios es necesario todos los años; pero en años brado en un aflo diflcil. difIciles debe consagrarse una mayor parte de tiempo a esta El objeto de este trabajo es el de recalcar el hecho de que Ia importante cuestión. mayor proporción delaspérdidas importantes causadas por No debe desestimarse el valor de los ejercicios con incendios incendios se produce durante perlodos de peligro máximo relativa- ordendos, como medio para adquirir conocimientos sobre las mente breves y que con frecuencia se presentan a intervalos diversas modalidades de los incendios. irregulares. Además, se desea destacar la necesidad de que cada En la preparación de los planes para el control de incendios servicio no solo reconozca las situaciones peligrosas a medida qiie debe hacerse hincapié en las necesidades durante anos diflciles éstas se producen, sino que proporcione un tipo de organizaciOn asI como también en las emergencias que a veces suelen pro- flexible que pueda ampliarse en forma casi inmediata si la situa- ducirse fuera de lo que es normal en la temporada "oficial" de ciOn asl lo impone.

Aerial Support of Ground Firefighters

ARTHUR W. GREELEY Assistant Chief, Forest Service, U. S. Department of Agriculture, Washington, D. C., U. S. A.

Airplanes have been used on a planned basis in forest ants; scouting; on-the-line personnel transport; and be- fire control in the United States for more than forty years. hind-the-line transport of personnel and supplies. U.S. Army planes flew planned fire detection patrols as Systematicaerialdetection using carefully designed early as 1919. In the following year, Army planes dropped flight routes is proving to be a satisfactory substitute for cargo on several large fires. For the next ten years use of detection from fixed lookout points in some situations. aircraft for firefighting remained at a low level.Then, For these assignments small four-place airplanes, such as during the nineteen-thirties, people began to give more the Cessna 180 or 182, Piper PA 22 and 24, or Beech attention tothissignificant firefighting tool, including Bonanza, are used. Generally, the patrol flight is laid out experimenting with cargo dropping and jumping with so that the plane may be in the air for two hours or more. parachutes. The first jumps to actual fires were made in Most of the airplanes used have a high-wing configuration 1940. The first operational smokejumper unit was estab- that affords good visibility for the observer. These ships lished that same year. Since then the airplane has been also have the capability of slow flight when that is required as important to the U.S. firefighter as has the portable for more intensive study of terrain. pumper. Airplanes used for transporting smokejumpers must be This paper describes the principal ways in which the of larger size than those used for detection patrol. No less U.S. Forest Service now uses airplanes in fighting wildland than two jumpers are dropped on a fire, and it is desirable fires that occur within the Forest Service area of fire pro- to have at least four jumpers on the flight.In addition, tection responsibility. Many of the methods and techniques the plane must carry the spotter and the jumpers' fire- described are likewise used by a large number of other fighting equipment. Airplanes used for jump planes vary in size from the twin-engine Beechcraft Model 18, used firefighting organizations in this countryFederal, State, with four jumpers, to the Ford Trimotor, used with eight, and private. to the Douglas DC-3, which can carry 16 fully equipped Principal Uses of Aircraft in Support of jumpers and two spotters. Ground Firefighters Helicopters can be used for jumping. In helijumping, a firefighter wearing protective clothing similar to that of Aircraft are commonly used in perhaps a dozen differ- the smokejumper jumps from a slow-moving helicopter ent ways in support of firefighting personnel. Of these, the from an altitude of not more than 12 feet above the principal uses are: fire detection; transportation of smoke- ground. A helijumper does not use a parachute but jumps jumpers; cargo dropping; dropping of chemical fire retard- directly to the ground. This method is used for inacces- 978 Fifth World Forestry Congress Proceedings sible areas where the helicopter itself cannot land. Because corps. Smokejumpers are used toprovide faster attack large helicoptersare not commercially available,the than can be accomplished by smokechasers traveling on small two- to five-place ones are used for this work. the ground. The unique thing about smokejumpers is Both airplanes and helicopters play an important part their means of getting to a fire. Once there, they function in dropping chemical fire retardants. Some of the models in the same manner as do other well-trained firefighters. now in use and their capacities are: In a typical smokejumper operation, orders for jumpers Airplane tankersStearmans-105 gallons; Grum- are received by the unit dispatcher. Heorders the air- man TBM-500 gallons; Consolidated PBY1,200 plane engines started, and the required number of smoke- gallons;NorthAmerican B-251,000gallons; jumpers with their equipment loaded aboard the airplane. Lockheed PV-2--1,000 gallons; and DeHavilland He briefs the pilot and the smokejumper spotter regard- Beaver Seaplane-125 gallons. Helicopter tankers, such as the Bell 47 G-2 and ing location of the fire, expected weather, and other con- Hiller 12-E, can carry 35 gallons, and the Republic ditions influencing the mission. The smokejumpers put Alouette can carry 130 gallons.Because of their on their protective suits and parachutingequipment while small capacity, their use is usually limited to spot the airplane engines are warming up or while the plane fires and to terrain too rough for fixed-wing planes to maneuver. is enroute to the fire. Upon arrival in the fire area, the spotter, in collabora- Techniques of Aircraft Use in Support of tion with the pilot, selects the jump spot near the fire and Ground Firefighters determines the flight direction and altitude required for Fire Detection the jump. The spotter points out the fire and the jump spot to the smokejumpers and gives them final instruc- The use of airplanes for fire detection involves the prin- tions. He positions the jumpers in the plane for jumping ciple of flying at predetermined time intervals over flight and inspects their equipment. The spotter then directs the routes which are carefully designed to give the degree of pilot by hand or other signal in the approach run over seen-area coverage considered necessary to meet time the jump spot and signals the smokejumpers when to step standards for fire discovery. Routes can be varied, on a out of the airplane. planned basis, to allow for changes in probability of fire During the 20 years this method of firefighting has starts. Flight intervals, or flight schedules, can be varied, been used, 18,491 jumps have been made to fires by also on a plan-wise basis, to allow for changes in either Forest Service smokejumpers, and as many more for risk or hazard. Advantages include reduction in capital training, for rescue missions, or for other purposes. No investments and maintenance costs for lookout structures fatalities have occurred in flying or parachuting, but and communication to them, as well as some reduction in smokejumpers have lost their lives in other phases of this operating costs. Disadvantages include the greater risk of a long time interval between the start and discovery of a operation. fire, especially at night, and also the reduction of available trained manpower within the protection area compared Aerial Application of Fire Retardants with the manpower that would be present to man lookout Since 1956, Forest Service use of aerially applied fire stations. retardants has increased from a few thousand gallons per Detection patrol routes are worked out and drawn on year to more than 3,300,000 gallons in 1959. The retard- a map for each combination of foreseeable weather and ants now used most extensively are sodium calcium borate fire hazard conditions. In mountainous areas, patrol routes and sodium, or swelling-type, bentonite clay.Both are are usually parallel to the major drainages. This arrange- applied in the form of a slurry. These retardants are more ment allows the observer to look directly up or down the effective than water by itself. secondarydrainages.Flightsacross major drainages Sodium calcium borate mixture, usually called by the restrict the ability of the observer to see behind secondary short name of "borate." weighs about 10.2 pounds per and minor ridges. Desirable flight altitude must be care- gallon, is viscous, highly abrasive, and is toxic to some fully calculated. vegetation. Bentonite mixture weighs about 9 pounds per In a fire detection patrol, the observer should con- gallon.It is also viscous and moderately abrasive.It is centrate his attention on the assigned flight strip for his not toxic. Borate is almost as effective after it dries as it particular flight. He should observe in a systematic man- is when it is wet. Bentonite's effectiveness lies in its water- ner. He should spend about half his time searching the holding properties. It dries in two to three hours and then area up to about 15 miles ahead. During the remainder has little or no fire-retardant value. Bentonite mixture is of the time he should search areas which will soon be usually dyed to make it more visible. Good results are hidden from his view. Airspeeds of 80 to 120 miles per obtained with mixtures containing 4 pounds of borate per hour are most suitable for fire detection patrols. Vegeta- U.S. gallon of water, or 314 pound of swelling-type ben- tive type, general topography, weather, experience and tonite clay per U.S. gallon of water. Special mixing and training of pilot and observer are important in selecting handling equipment, including mixer, pumps, and tem- the best flying speed. An airplane pilot alone is seldom porary storage tanks, are needed at the airbasesfrom used for fire detection patrol. Teamwork between the which the tanker planes take off. pilot and the observer is essential to successful conduct of These retardants are most useful when: (1) forces this work. present on the ground are having difficulty in stopping a fire along a small section of its perimeter; (2) ground Smoke jumping forces or smokejumpers will be delayed in reaching a fire, Smokejumpers are the paratroops of the firefighting and a holding action is desired for a short time; and (3)

Forest Protection 979 a fire is too hot to permit direct ground attack. These the hands of the plans chief and the fire boss within retardants cannot be depended upon to stop a fire burning minutes after the observations have been completed. in heavy fuels with a great output of heat. Time and firefighting costs can be saved by using For effective results it is necessary to release the retard- helicopters to transport firefighters to a fire, or to or ant from the airplane at an altitude of less than 150 feet between partsofalargefirethat are not readily above the vegetation. Otherwise it will drift and spread accessible by road. Men delivered singly or in small too thinlyEven under the best conditions, such flying is groups by helicopter to a remote part of a fireline may hazardous.Retardants dumped from less than 50 feet arrive an hour or two sooner than they would by any above the ground can strike with sufficient impact to cause other form of transportation; and they arrive physically fatal injuries to personnel on the ground. The Forest Serv- fresh and ready to go to work rather than arriving ex- ice now uses a minimum height of 75 feet above vegetation hausted after an arduous climb to their assigned sector. and obstacles. This elevation is difficult to maintain in hot, In addition, helicopters provide many advantages in turbulent air over mountainous topography. Pilots must patrol and holding operations after the fire has been con- be carefully selected, have adequate experience in moun- trolled.The number of men needed for holding a fire tain flying and in agricultural spraying or other low-level once it is controlled is normally much smaller if a heli- flying. They must be specially trained in dropping retard- copter can be kept available for this stage of fighting the ants. The airplanes used must be highly maneuverable, fire. capable of slow, stable flight, and must be able to carry at Special rubberized nylon fabric tanks have been de- least 100 gallons of mixture. veloped for use with helicopters in transporting and Good radiocommunication betweenaircraft,and applying water or fire-retardant mixes. The accuracy of between aircraft and ground-control units, is essential. placing these materials with the helicopter is much better Airplanes for applying fire retardants should have tanks than it is with fixed-wing aircraft.However, quantities with very large dump gates. Some of the best have dump that can be carried by helicopters now available to the gates that comprise the entire bottom of the tank com- Forest Service are significantly smaller than the loads that partment. For designs now in use, optimum capacity of can be carried by airplanes. tank compartments is from 100 to 200 gallons. Com- Helicopters can serve a unique function in laying fire partments may be larger, if the dump gate is so designed hose across country. A technique has been developed by as to give required control over the rate of discharge. which helicopters can lay 1,000 feet of 1½-inch rubber- In making an attack on a small fire, the pilot usually lined dacron fabric hose, or 1,500 feet of 1½-inch un- receives his instructions from the fire dispatther. Upon lined linen hose, in about one minute. The technique arrival over the fire, he searches the area for ground per- involves a tray from which the hose feeds out as the sonnel and, if possible, establishes radio communication helicopter flies.By this method, hose can be laid ac- with them. He may receive further instructions from the curately over most vegetative types and in most topogra- ground crew. He briefly studies the fire and general phy at a much more rapid rate than is provided by any topography, then plans his drop run. He maneuvers into other method of stringing out fire hose. The tray and position, makes his drop run, then circles back over the remaining hose can be jettisoned by the pilot should area to check on results. He reports results observed to that prove necessary. This method permits use of water appropriate ground personnel or to other units as directed. for firefighting in places that otherwise would have to be On a large fire, or a group of small fires, where several dry, because topography or vegetative cover would make airplanes are used to apply retardants, a "lead" airplane hose laying by hand impractical. may be used. The plane is flown by the "lead" or super- vising pilot. This "lead" plane, which may also be called a "bird dog," may also carry a specially designated fire Special Training Required to Obtain the Best Use of control expert whose job is to coordinate aerial operations Aircraft in Firefighting to make them most effective in working with ground units. Training Smokejumpers He has the title of "air-attack boss," and he directs the A smokejumper must be a highly qualified firefighter. group of planes assigned to make drops on his fire.If He must know woodsmanship, use of tools, fire behavior, there is a large number of planes flying over a fire area, something about weather, and the other things in which special air-traffic control measures must be taken, in- a firefighter is trained.In addition he must know his cluding setting up traffic lanes. special job of air attack. Smokejumpers are drilled intensively on all phases of Use of Helicopters jumping. They must know their equipment and how to Helicopters can be used for most of the purposes for use it.Each item has a specific purpose and must be which fixed-wing aircraft are used. They have clearcut properly adjusted and correctly used. To illustrate, a web advantages for certainfireassignments, and clearcut strap is built into the suit the jumper wears, under the limitations for others. crotch, down each leg, and fitted under the arch of each For scouting forest fires, helicopters provide the ideal foot.When properly adjusted, this strap absorbs the mobile observing platform. Flight can be so close to the opening shock of the parachute. A loose-fitting para- terrain that the observer has very little difficulty in clearly chute harness could cause serious injury to its wearer. seeingpersonnel,equipment,fueltypes,detailsof Jumping procedures and techniques are exacting. A topography, conditions of firelines, and other items of jumper must leave the airplane in a specified manner to importance. The outstanding advantage, though, is that be in a position to prevent entanglement in the shroud this detailed scouting information can then be put into lines, injury from the shock of the opening chute, or

980 Fifth World Forestry Congress Proceedings malfunction of the chute when it opens. The main chute gain altitude rapidly if corrective measures are not ap- is of a special design, with tails and slots. The tails pro- plied instantly.Itis important that ground personnel vide forward movement which must be accurately judged. who order these drops understand the flying problems the The two slots permit the chute to be steered. A jumper pilot must solve to fill the order. needs to know precisely what he is doing to coordinate Key fire men are rated each year by a standard rating his rate of fall, his forward motion, and his steering to system which recognizes their training, experienceand make an accurate spot landing. performance. The men are issued a card showing the fire An auxiliary chute is carried on the chest for use if overhead or specialist positions they are qualified to fill. the main chute malfunctions. This chute is also different This procedure insures assignment of only men who are from the standard manufacture.It has no pilot chute considered qualified to fill all key fire jobs. to pop out of the container and assist in its deployment. When the container is opened the chute falls out into the Coordinating Use of Aircraft In Suppressing a jumper's arms. He then may throw it where it can open Campaign Fire without becoming entangled with the main chute. When a fire boss is given air-support forces as part of Landing is usually performed in rough terrain.To his total resources for putting out a fire, his coordinating avoid steep or rocky slopes or dense stands of timber problems are greatly increased over those which exist that might collapse his chute, the smokejumper is trained with only a ground attack. The air arm available to a fire to hang the parachute over a tree. He may then let him- boss is a costly tool. It is expensive, and wasteful unless self down to the ground with a rope he carries for this it is effectively used. Use of air facilities must be closely purpose. Landing directly on the ground is accomplished, coordinated with other parts of the suppression job to using a rolling technique called the "Allen Roll." To the bring about an effective fire control effort. jumper, hitting the ground in a chute is like jumping The current basic organization for firefighting used by from the second floor of a building. This rolling tech- the U.S. Forest Service provides for division of the total nique of landing is intended to dissipate the shock. forces into three groups, each under the charge of a The Forest Service requires that a smokejumper suc- principal assistant to the fire boss. These units are under cessfullycompleteallphasesoftraining,including the plans chief, the line boss, and the service chief. Each practice jumps, before he is assigned to fire work. This of these units may use aircraft as part of its assigned work. requirement is a major reason for the enviable safety The plans chief isresponsible for intelligence, maps, record of no fatalities in jumping operations during the records, safety, and other information. He will need to twenty years since its first use by the Forest Service. use both airplanes and helicopters for scouting.The Special training is required for aircraft pilots to fly the service chief has under him the air officer who arranges various kinds of firefighting missions.Flights are fre- for aircraft, retardants, and maintenance of equipment, quently made inrugged, mountainous terrain under including aircraft. The line boss has charge of all direct adverse conditions of limited visibility and turbulent air. suppression action and, operating through an air-attack Since experience in this type of flying is difficult to obtain, boss, directs application of chemical drops. special training must usually be provided. There must be close liaison between all of these groups In low-level mountain flying, pilots must know weather in their air work. The service chief's staff includes an conditions and how weather is affected by terrain. They air-traffic manager who provides services to the air-attack must be able to analyze predicted weather.Moving boss. The air-traffic manager must so coordinate aircraft storms in their flight area can close mountain passes and that the highest priority job has clearance in the air at block escape routes. Rain or clouds may restrict visibility. any particular time. This requires knowing the needs of Wind currents in a thunderstorm can tear an airplane the respective claimants for airspace and air time and so apart. Canyon walls, ridges, and peaks create updrafts, scheduling aircraft that there will be no interference in downdrafts, and swirling eddies.The air gets thinner the air.If there is more than one aircraft in the air at with altitude and consequently does not provide as much one time, each pilot must have knowledge of the other's lifting power at higher elevations as it does at sea level. presence and mission.Air time must not be wasted. The pilot must be able to take all these things into ac- Orbiting time is costly and must be avoided as much as count and still leave a margin of safety in every move he possible. makes with his plane. Continuously available and positive communication be- Special training is also required for the pilots and all tween aircraft, and between aircraft and ground personnel, other personnel working with the bulk dropping of chemi- is required. The air-attack boss, usually riding in a lead cals to suppress a fire.Effective use requires that this plane, receives his orders or requests for materials from be done from an altitude of less than 150 feet above the the line boss or one of the latter's unit men on the fire. vegetation on a predetermined target.This differs from He, in turn, directs the planes where to make their drops agriculture spraying, which is usually done over fairly as required by the line boss to meet line priorities. Placing flat land in long, straight runs. The pilot of the tanker materials at the right place at just the right time is the plane must usually maneuver constantly because of the objective. terrain. He has only a few seconds in which to accurately Different aircraft with the same general mission must make the drop. Topography and weather conditions must be so directed as to not interfere with each other.If a be quickly and carefully analyzed. Piloting a tanker plane line supervisor wants a small, direct hit on a new spot where the load is dropped all at once presents special fire he may want the drop made with a helicopter. This problemsImmediate release of a relatively large weight aircraft must have immediate clearance for air use, and from the aircraft in a few seconds causes the aircraft to the air-traffic manager may have to stop or divert air

Forest Protection 981 tankers. Then he may immediately want to get them back chaud et turbulent et en region de montagne. Les pilotes charges to their task within the same general area. de ces missions doivent être soigneusement sélectionnés et avoir All such recu un entralnement intensif. actions require full knowledge of operating procedures, Lorsque plusieurs avions sont utilisds pour un même incendie, trained and experienced personnel, and tightly coordinated Iacoordination de leurs mouvements présente des problèmes organization and management of the entire fire operation. spéciaux. Un avion de tête, appelé in "bird dog", peut être utilisé. L'homme qui se trouve dans l'avion de tête coordonne les opéra- The Future of Aircraft Use in Fire Suppression tjons aériennes et dirige par radio les avions citernes, leur mdi- quant oü us doivent déverser leurs produits de facon a répondre In the United States aux desiderata des hommes luttant contre l'incendie au so!. Des Aircraft will not replace the ground firefighter.But mesures spéciales de contrôle du trafic aérien sont parfois ndces- techniques involving use of aircraft can speed up control saires,notammentl'établissementderoutesdenavigation aérienne. time, increase the effective work output of men employed Leshdlicoptèressontexcellentspourlareconnaissance to fight fire, and probably can reduce both acreage burned aérienne et le repérage des incendies, le transport des homnies a and damage from fires.So far, there has been in this Ia ligne de feu et aussi pour certains largages oui la precision country no extensive effort to develop aircraft specially compte plus que Ic volume. designed to meet firefighting requirements. Undoubtedly, Les aéronefs ne remplaceront pas l'homme au so! pour la lutte contre les incendies.Néanmoins, leur utilisation peut permettre the future will see efforts to do this, and also to develop de maitriser l'incendie plus rapidement, d'accroitre le rendement a wide variety of techniques that will make the firefighting des hommes employés a la lutte contre le feu et peut probable- air arm more effective. ment réduire la superficie brülée aussi bien que les dégats causes. Keeping airplanes in the air, or ready to fly,is ex- pensive. Consequently, there will always be limitations on Apoyo Aéreo para Extinguir Incendios de Bosques aircraft use for firefighting. Even within these limitations, En los Estados Unidos, el avión ha venido usándose por más however, the U.S. Forest Service stifi is not making the de cuarenta años como parte del plan de control de incendios forestales.El aeroplano se emplea principalmente para Ia detec- maximum possible use of airplanes in fighting forest fires. ción de incendios, el transporte de paracaidistas, la entrega de Aircraft provide speed and mobility of transportation in materiales, reconocimientos y el lanzamiento de substancias quI- a wide variety of combinations. micas retardantes de Ia combustion. Firefightersinthis Los !lamados "smokejumpers" son las tropas paracaidistas de country have not yet found all the combinations that can los cuerpos de bomberos forestales. En la práctica del Servicio be effectively used. Forestal de los Estados Unidos el paracaidista tiene que ser perito en la extinción de incendios.Además, debe estar per- There continues to be a special need for aircraft that fectamente adiestrado para su misión especial y en las tácticas can hover and land as does a helicopter, but with higher aéreas del oficio. Para ello debe conocer la manera especIfica de load-carrying capacity and lower cost. When such lanzarse desde el avión sin verse envuelto en las cuerdas del a ship paracaidas y sin lesiojiarse cuando éste se abre. Asimismo, debe is developed, there may be added a significant new dimen- aprender a coordinar su velocidad de descenso, su movimiento de sion in the use of aircraft to support ground firefighters. traslaciOn y la dirección del paracaIdas para hacer su aterrizaje en el lugar exacto, el cual se realiza con un movimiento rodante RESUMES que amortigua el golpe a! tocar tierra.El personal tiene que completar todas las fases de su adiestramiento, inclusive los lan- Appui aérien pour Ia lutte contre les incendies de forêts zamientos de paracaIdas, antes de pasar al servicio de extinciOn Aux Etats-Unis, il y a plus de quarante ans que la stratdgie de incendios. Esta es una de las razones que explican porqué el pour Ia lutte contre les incendies de foréts prévoit l'utilisation Servicio Forestal tiene un magnIfico expediente de seguridad, sin d'avions. Ces avions sont utilisés principalement pour le repérage una sola muerte en los veinte años en que ha empleado paracal- des incendies, le transport de parachutistes, appelés "smoke jump- distas. ers", le parachutage du materiel, les reconnaissances et l'épan- El uso aéreo de substancias qulmicas retardantes de la com- dage des produits chimiques retardant l'action du feu. bustión ha aumentado considerab!emente desde 1956, año en que Ces "smoke jumpers" sont les parachutistes des unites destinées se emplearon muy poco, hasta 1959, en que los empleados del a combattre les incendies de forêts. Dans la pratique du Service Servicio Forestal usaron más de tres milliones de galones en la forestier des Etats-Unis, un "smoke jumper" est Un homme haute- extinción de incendios.Las substancias qulmicas que más se ment qualiflé pour la lutte contre le feu. En outre, ii doit être usan son borato de calcio y sodio y arcilla de bentonita. Ambas parfaitement entralné pour sa tâche spéciale d'attaque par la voie son más eficaces que el agua misma. El lanzamiento dcl retar- aérienne.Ii doit savoir comment quitter l'avion d'une manière dante se ha de hacer a una altitud de menos de 150 pies sobre el déterminée afin de ne pas s'empêtrer dans les fils du parachute et nivel del terreno. Esta altitud es a menudo muy difIcil de man- d'éviter les accidents pouvant résulter dii choc cause par l'ouver- tener en las turbulencias que origina el aire caliente sobre irna ture de ce dernier.Ii doit apprendre a coordonner sa vitesse de topografIa montaflosa. Los pilotos que hacen estos vuelos tienen descente, son déplacement en avant et ses manoeuvres de direc- que ser cuidadosamente seleccionados y sumamente capacitados. tion de facon a atterrir exactement a l'endroit voulu. L'atterrissage Cuando se usan varios aviones en in incendio surje otro pro- est réalisé a l'aide d'un mouvement de rotation afin d'amortir le blema especial:la coordinación de los vuelos.Algunas veces choc de l'arrivée au sol.Ces parachutistes doivent passer par suele emplearse un avión guIa, llarnado "perro perdiguero", que toutes les phases de l'entralnement, y compris la pratique du saut, se encarga de coordinar las operaciones aéreas y de indicar a los avant d'être assignds a la lutte contre l'incendie.C'est ce qus aviones tanques los lugares en donde han de lanzar su carga para explique pourquoi aucun accident mortel n'a jamais été enregistré mejor lograr los requisitos de los que trabajan en tierra. A veces au cours des operations de parachutage depuis les vingt années es necesario adoptar algunas medidas para Ia regulación del d'existence du corps de parachutistes du Service forestier. tránsito, incluso el establecimiento de determinadas rutas de vuelo. L'épandage par avion de produits retardant l'action du feu qul, Los helicópteros son medios excelentes para reconocirnientos en 1956, n'en était encore qu'à des debuts modestes, a représentd de incendios, transportar a! persona! hasta el hugar del simestro en 1959 plus de trois millions de gallons lâchés par le Service y para ciertos lanzamientos que requieren mayor exactitud que forestier dans la lutte contre les incendies de forêts. Les produits volumen o cantidad. chimiques les plus généralement utilisés sont soit du borate de Los aviones nunca podrán substituir a! personal de tierra. Pero sodium et de calcium, soit de Ia bentonite, qui sont plus efficaces con el empleo de las naves aéreas se puede dar mayor rápidez que l'eau par elle-même.Ces épandages doivent être effectués a las medidas de control, aumentar Ia eficacia del personal encar- d'une altitude inférieure a 150 pieds au-dessus du so!. Une telle gado de la extinción y probablemente, reducir el niimero de altitude est souvent extrêmement difficile a maintenir dans un air hectáreas quemadas y dañadas por los incendios.

982 Fifth World Forestry Congress Proceedings Study on Outbreak and Spread of Forest Fires in Japan

KATSURA INOUE Hokkaido Branch, Government Forest Experimental Station, Sapporo, Japan

Loss From Forest Fires sheltered from the wind. Such burning is often found in Cryptomeria, which is susceptible to stem fire, particularly The average annual loss of forest area in Japan for the 5-year period, 1953-1957, was about 24,000 ha., which in the case of snags. is 0.1% of thetotal forest area andisvaluedat If we study such facts closely at the burnt area, we can 522,157,000 yen. Such damage is almost entirely due to ascertain the direction of spread and the local wind direc- human factors, but in a few cases, it is caused by physical tion. The height of one-side burning depends upon the factors such as lightning. volume of vegetation and the size of the stem, and in case of major forest trees, the critical height of branches should Consequently, if fire conditions are clarified and ap- propriate protective measures taken, the loss by forest be studied. fires may be greatly reduced. Since outbreak and spread Strip burning. On the burnt area in the forest, one or of forest fires are influenced by three factorsflammable more strips, burnt and unburnt, are found paralleltoward materials, climate, and site conditionsthese factors are the ridge top. Burning is complete in the burnt strips, discussed respectively. accompanied by ground fire, stem fire, and crown fire; and the adjacent unburnt strip is mostly caused by ground Burning Conditions of Flammable Materials fire, which is called strip burningThis fact is considered to be due to a rapid change in wind direction, and it is the In every forest fire, the number of fires and burnt area fire route at the time of a fire which requires further study. by tree species, conifer, broad-leaved, and mixed stands, and treeless land are investigated.With regard to in- Climatic Conditions dividual trees, difficulty of burning, i.e., the distance from the origin of a fire, degree or existence of crown fire, The climatic factors include temperature, humidity, power of recovery after fire, is studied by species. Tree precipitation, and wind, and the relation of these factors spacing,density of planting,area, and their relation to pressure distribution which controls the factors has to burning are studied, and the greater the number of been studied for many years. dead or hollow trees, the greater the danger. Rainfall At the time of fire, since climate and site conditions are complicated, knowledge of such conditions is helpful in Rainfall is influenced by the moisture content of flam- estimating the tendency of burning, but the following ex- mable materials and humidity in the air, and is particu- periment is undertaken to learn the quantitative relation- larly closely related to the interval of rainfall, which is ship. being studied. Experiment Snowfall Measurement of moisture content by species. In the snow-drifting area, the relation of volume of Rate of drying of stems and leaves. snow drifted to the time of snow melting is studied. Relationshipof moisture content of stems and leaves to temperature and humidity. Temperature Turpentine content in coniferous leaves. Fire season is divided into winter and spring for study, Ignition test by species and moisture content. and fire hazard is more frequent when the temperature is Ignition test by live to set fire. low in winter and high in spring. Such occurrence is not Temperature of ignition of stem, leaves, and other due to the physical relation of mean temperature to the flammable materials in the forest. number of fires but is closely related to relative humidity. Movement of Spread Humidity Movements of spread of forest fires are complicated, The influence of humidity on fire has been studied for and some of them to which attention should be paid are many years.The mean monthly humidity, minimum as follows: humidity, number of fires, and burnt area are found to be One-side burning of stem. In stem fires, with one-side closely related. burning, that is, burning particularly on one side of the Although it is clear that the humidity at the time of stem, the bark 60 cm. from the ground becomes black on fireis important,it was discovered in 1935 that, in the windward side but burns tenfold on the leeward. addition,the past humidity isalso influential.With This is because the blaze rises on the side of the stem regard to moisture content of flammable material, the Forest Protection 983 mean humidity takes into consideration not only the windspeed.In this regard, the material for spot fire, present humidity but also the past humidity and is called windspeed for spot fire, the maximum extent of spot fire, "effective humidity." and its distribution are also estimated at the time of each In order to determine this effective humidity, the ex- fire.The physical character and ignition phenomenon, periment formula and thespecifichygrometer were together with ascending rate at the time of a big fire are devised. still unknown. Formula.Suppose the humidity of today is1; that of yesterday, a (provided a< 1); that of the day before Pressure Distribution yesterday, a2; and the day before that, a3, (taking into As stated above, fire is closely related to the climatic consideration previous humidity); and Hm is the daily factor and also to pressure distribution.Since Japan mean humidity; He is effective humidity; then, extends from low latitude to high latitude not in propor- He (n) = (1-a) a"Hm (n). tion to its area, and its topography is complicated, the The value of a is taken as 0.5 in forest fire computation. pressure distribution which is dangerous as regards fire For the effective hygrometer, squared Hinoki (Chamae- is studied by regions in order to meet the conditions of cyparis obtusa) (10 cm. x 10 cm. x 20 cm.) and resin- each area. bonded special plywood are used. A round pole of Tilia japonica, which is used in the U.S., is also used here as Site Condition a fuel-moisture4ndicator stick. Fire is also related to site condition.In this respect, Some assert that, different from wooden houses, com- the relation of such factors as latitude, elevation, direc- bustible materials in the forest are thin or small litter, and tion, or degree of inclination is being studied. The direc- that,therefore,actual humidity at each time is more tion of slope is related to humidity and also is greatly important than effective humidity. This opinion is based on the fact that the time of fire is coincident with the related to heat current at the time of fire. daily change of temperature and humidity. Since we have some indication of local humidity, dur- In order to ascertain easily the humidity in the air, ing the fire season, investigation by the above-mentioned filter paper soaked in cobalt chloride and dried is ef- cobalt chloride test paper and also a topographical analy- fectively usedIf the humidity is over 50%, the color of sis of the burnt area are made. the paper changes into cobalt blue, and if less than 50%, Thecombinedinfluenceofflammablematerial, it changes into pink. The color changes according to the climate, and site condition upon the fire is considered to variation of humidity in the air. be due to the seasonal and regional distribution.In Therefore, in fire season, care should be taken by pay- order to know such distribution, the location of outbreak ing attention to the changes of the color of the paper. of fires by months is marked on the map. Such measures are very effective in inaccessible areas When we apply such means of investigation to the where communication facilities are not available. case of big fires, we can limit the range of dangerous sites of fire. Wind With regard to wind, a study is made on the relation Fire Warning of wind direction to windspeed. Wind direction isin- Fire warnings are issued by the meteorological office, fluenced by the topography, particularly mountains, and together with warnings against fires consuming buildings, on the Pacific coast and the Japan Sea coast between based on such climatic factors as temperature, humidity, the central mountains, thereisreverse influence, and effective humidity, and windspeed, by regions. But in the when the wind blows across the mountains, there is future, such warnings should be issued according not danger of a foehn. We have a big fire hazard when there only to climatic factors but also to the degree of danger, is a northwest monsoon on the Pacific or when a strong includingthe factors of flammable material and site low pressure proceeds to the north on the Japan Sea condition. coast. In the relation of windspeed to the number of fires, RESUMES windspeed, to some extent, brings about a proportionate Etude sur la naissance et la propagation de incendies de number of fires, but excess windspeed brings fewer fires. forets au Japon However, windspeed, relative to humidity, influences the Dans ce rapport,l'auteur examine la situation actuelle en spread of fire, and the following study is being made: matière d'incendies de foréts au Japon et, étant donné que Ia Rate of spread. The relationship of windspeed to rate naissance et l'étendue d'un incendie sont influencées par des of spread is estimated after the fire. facteurstels que les matériaux inflammables, le climat et les It was found in fire conditions de terrain, ii énumère et décrit ces facteurs en detail: tests at a grass site that the rate of spread was L'état d'inflammabilité des forêts est fonction des essences slow in the firstseveral minutes and then increased qui les composent, des conditions de terrain, de Ia distance criti- rapidly, but data at the time of strong wind is unavailable. que entre l'incendie et les matériaux inflammables, de l'espacement des arbres, de la densité du peuplement; l'accent est mis en parti- The relationship of the rate of spread to upper wind, culier sur la propagation de l'incendie, la combustion des troncs particularly to the jet stream, must be studied. plus accentuée d'un côté, l'embrasement des cimes par bandes et, Burning at the time of fire is made under complicated en experience de laboratoire, le rapport de Ia teneur en humidité climatic and site conditions, and if the related fundamental et de la teneur en résine des feuilles et du tronc. Les conditions climatiques sont fonction des précipitations, experiment is conducted only on a small scale, the objec- des amoncellements de neige, de la temperature, de I'humidité tive cannot be attained. effective. du vent, de la vitesse de propagation de l'incendie, des Spot fire.Spot fireisalso important in relation to foyers disperses et de la distribution de la pression. 984 Fifth World Forestry Congress Proceedings Les conditions de terrain sont fonction de la latitude, de materiales inflamables en relación a la especie de los árboles l'élévation, de la direction de la pente et de l'angle de la pente. forestales, el estado de la localidad, la distancia crItica de dichos Les mesures de defensepreventive contre l'incendieet materiales con respectoal incendio,elespaciamiento de los l'alarme dependent de l'humidité, de l'humidité effective et de la troncos, la densidad de cultivo. Se describen particularmente los vitesse du vent, et l'alarme est donnée suivant les conditions experimentos para el estudio de la propagación de incendios, la locales. combustión de tallos y copas. Además, se detallan los realizados Dans les regions inaccessibles de haute montagne oà les com- en una cámara crematoria para establecer larelación entre el grado de humedad y el contenido resinoso de hojas y tallos. munications sont inexistantes, on utilise avec succès du papier- Se estudia la relación entre las condiciones climáticas, el filtre imprégné de chiorure de cobalt pour évaluer l'humidité de Indice pluviométrico, los ventisqueros, la temperatura, la humedad, l'air. la humedad Itil y la velocidad del viento, de una parte, y la propagación de incendios y la distribución de Ia presión, de la Estudiosobre el Comienzo y Pro pagación de Incendios otra. Forestales en Japón El estado de la localidad se describe en términos de latitud, elevación, dirección y ángulo de la pendiente. En este trabajo el autor describe la situación relacionada con Se enumeran las medidas de prevenci6n y alarma de acuerdo los incendios forestales del Japón en la actualidad; y como el con la humedad, humedad étil y velocidaddel viento y con las comienzo y propagación de incendios dependen de factores tales condiciones locales. como los materiales inflamables existentes, el clima y las condi- En partes inaccesibles de las altas montaflas donde no sedis- ciones locales, dichos factores se enumeran y describen en detalle. pone de medios de comunicación, suele usarse conbuenos resulta- 1. Seestudianlascondiciones decombustibilidaddelos dos el papel de filtro mojado en cloruro de cobalto.

Research in Forest Fire Control

J. CAMPBELL MACLEOD Head, Fire Protection Section, Forestry Branch, Department of Northern Affairs and National Resources, Ottawa, Ontario, Canada

The Necessity for Undertaking Forest Fire Research observations by both operational and research personnel will be essential to check hypotheses developed by in- The need for a better knowledge of how to protect vestigators. Determination of how best to make practical forests against fire was never more apparent or more application of newly gained knowledge often calls for a formally recognized than it is today.It is well that this great deal of co-operation between research and opera- recognition is forthcoming, because the increase in world tional staffsiii the field.Fortunately, forest protection demand for forest products, if continued at the present men of both types enjoy an excellentreputation for rate, will make current losses by fire intolerable. enthusiastically supporting their vocation. There is much being said at this Congress about the proper management of forests, yet quite frequently more Development of Forest Fire Research Practice is now known about how management should be carried Although this healthy attitude exists now, support for on than is being implemented. Many foresters responsible forest fire research on this continent did not come quickly. for formulating management practices cannot afford to The first investigators to be assigned to the tasks on a make desirable forest improvements because of the risk full-time basis commenced their studies in the 1920's of fire, though the very term 'forest management' should (1924 in the United States and 1928 in Canada)less imply that the wooded areas concerned are reasonably than ten years, incidentally, after the nuclear theory was safe from this form of destruction. first propounded. No fanfare heralded this beginning, There are some forests that never suffer from fire, and but the dedicated men who initiated the investigations other wooded areas where fire is not a serious menace, laid solid foundations on which their successors still build. but in many of the principal forest regions fire has been By the outset of World War II there were about 20 a most destructive scourge for years without number. full-time, professional fire research men in the United This being so, it is odd indeed that we know so little about States and only four to six in Canadaall employed by it.The remark has been made that less is known today Government services. Today, the numbers are approxi- about some of the mechanisms and physics of fire, and mately 60 in the United States and 16 in Canada. These particularly forestfire,thanis known about nuclear increases in staff are significant but they are not indicative physics,first raised as an hypothesis less than half a century ago. Although man has observed forest fires for of the great change in fire research concepts that have thousands of years, he has gained only a little knowledge taken place in recent years, and indeed are taking place of the fundamental principles governing their behaviour. at this time. The two major changes relate to development Surely the conclusion to be drawn is that extensive forest of means for making concerted attacks on fire control fire research is required. problems by several co-operating agencies and to the This is not to imply that the field man today does not provision of extensive laboratories for use by a wide make intelligent observations of wildfires or that such variety of specialists observationsare unnecessary.On the contrary, such Project FIRESTOP, undertaken in California in 1954, Forest Protection 985 exemplifies the large-scale, co-operative type of investiga- in spectroscopy, is a'ttempting to determine the composi- tion just mentioned.It was defined as "A one-year tion of flame and how it is propogated, at the molecular operational study designed to explore certain aspects of and atomic levels. mass fire build-up and behaviour and to provide the fire Up to this time I have been speaking about activities services with some new aids to mass fire prevention and relating to the full-time research worker. It must be borne control." More than fifteen Federal, State and municipal in mind that some of the most productive investigations governmentagenciesco-operatedinthiseffortand undertaken to date have been made by fire control men valuable assistance was contributed by chemical, aircraft, employed in the field of operations. Fire control organiza- oil,communication andotherindustries.Numerous tions generally encourage those members of their opera- analyses of the field observations have been prepared and tional staffs, who have an aptitude for research, to make the resulting published reports are well known to inter- appropriate studies. ested people in many countries. This type of approach to fire control problems, especially on the scale of FIRE- Research Accomplishments and Current Problems STOP, was unheard of 10 or 15 years ago but now it The subject of forest fire control is frequently con- may be considered a fairly common practice, though the sidered as consisting of four broad categoriespreven- tendency is to conduct such projects over periods greater tion, presuppression, detection and suppression. In many than one year. instances,itis difficult to classify a problem within a The second major change I mentioned was the employ- specific category because the terms are not mutually ex- ment of research specialists and the provision of extensive clusive, but for lack of a better method, I propose using laboratory facilities.Less than two decades ago there these terms as headings for groups of examples of suc- were mighty few forest fire research men on this continent cessfuland current forestfirecontrol investigations. who had received more formal training than a bachelor's Studies conducted in one area may have only little ap- degree; and laboratory facilities usually consisted of one plicability in another, and therefore no attempt was made of the lesser rooms at a few of the forest research estab- when selecting the examples to list them in order of im- lishments. Now the fire researcher is often one who has portance or to ensure inclusion of what might be con- received much advanced training in one or two of several sidered to be the most important ones.It should be scientific disciplines, and he is no longer the poor relation noted also that few, if any, fire research men believe that with respect to laboratory requirements. an ultimate goal has been reached in any oftheir We have already heard of the magnificent buildings for endeavours. fire research recently completed, or now being built in our host country. The provision of equipment designed PreDention for use in them, including such items as large-scale water It may be that fewer formal research projects have models, large wind tunnels, and cavernous rooms where been undertaken in the field of fire prevention than in any fuels can be burned under controlled conditions of rel- of the other categories, though it is obvious that suc- ative humidity and temperature and be observed through cessful work here could be the most rewarding of all. closed-circuit television, is indicative of the current atti- Very important fire prevention investigations are being tude towards forest fire research.In addition to these made with respect to weather modification, including laboratories designed solely for the study of forest fire lightning elimination or reduction.Mr. Barrows has problems, laboratories intended for other primary pur- already given us an excellent account of Project Skyfire poses are lending valuable assistance. A case in point is and an indication of the benefits that might accrue to fire the large, well-equipped Fire Research Laboratory, Divi- control organizations from this work in the future. Related sion of Building Research,at the National Research work isbeing undertaken in several other countries, Council in Ottawa, Canada. This is but one example of including Russia, Australia, Great Britain and Canada. An an important source of help available to fire control men; intensive cloud-physics research project, known as Project similarassistanceisgenerouslyprofferedbyother Alligator, was started in Canada last year and may run for agencies. as much as four additional years.This is another co- Without attempting to make a sharp distinction between operative type project where several government agencies fundamental and applied research, there is no doubt that and forest industries are pooling their efforts,in this increasing emphasis is being given to projects involving instance, under the direction of the Federal Meteorological the former.Progress in technological development in Branch. several fields of fire control is now dependent on a better Surveys and analyses of forest fire causes have been understanding of the basic principles involved. Fire re- made in many areas with a view towards determining search organizations have come to the conclusion, some- where and how the emphasis should be laid towards whatbelatedly,that some oftheir more important educating the public as to the need for care with fire in endeavours will grind to a halt unless knowledge of the woods. In 1957, a very interesting experiment was fundamentals is kept ahead of that required for applica- carried out in Canada by the Quebec Forestry Association tion purposes. An example of this type of work, and one in one district of that Province, when the efforts of many which has not received publicity of which I am aware, is organizations were co-ordinated to drive home the fire a project in forest fire research being undertaken by the prevention message with a saturation publicity program. Commonwealth Society Industrial Research Organization Results were so pronounced that the program is still under in Australia. A member of that organization, Dr. I. S. way, a different district being treated each year. Walker, who last year completed a post-doctorate study Fire prevention through hazard reduction is being suc-

986 Fifth World Forestry Congress Proceedings cessfully developed. Prescribed burning for the purpose is trol men today that one of their greatest immediate needs used in some areas, but methods must be devised for is the provision of accurate weather forecasts.If some making it practical for other regions. A multiplicity of prognosticators are correct, we have not long to wait for chemical vegetation inhibitors are available for use on improvements in this direction. For instance, Capt. H. T. roadsides and fire guards. Logging slash, however, is a Orville, when speaking at the northern California branch most troublesome forest fuel on this continent and else- of the American Meteorological Society last November, where. Utilization of the whole tree is the best answer, predicted that the following objectives, to mention just a but until that is common practice, other means for getting few, would be attained within a few years: rid of it economically must be found. One suggested "(a) Day-to-day forecasts to the public 99 per cent method is to greatly increase the speed of slash decay by accurate with specific times for the beginning and inducing fungus attack. ending of rain or snow. in most countries, forest fires that start as a result of Precise knowledge of jet streams, and their relation industrial operations do not comprise a high percentage tohurricanes and tornadoes and othersevere of the total, and operators are generally willing to enforce storms sound fire prevention measures. However, the increasing Sufficient understanding of weather processes to use numbers of people using the forests for recreational pur- weather modification to clear airports of fog, to poses do not show the same tendency to co-operate,and alleviate droughts, to increase precipitation sub- methods for getting the message to them effectively must stantiallyandtoeliminatehailandlightning be devised.The suggestion has been made in several damage." quarters that psychologists should be brought in to study While we look to the Meteorological Services to provide this problemyet another discipline to be added to the this information, it is up to the fire control research per- growing number employed in the fieldof forestfire sonnel to adequately interpret how current and forecasted research. weather should affect protection practices. One of the most difficult problems the fire control offi- Presuppression cer faces is trying to assess the effectiveness of changes made in his organization.In working towards methods The second of the four categories, presuppression, en- for making such assessments, various procedures have compassing as it does "Activities in advance of fire occur- been developed for rating fire season severity. Such rating rence to insure effective suppression action," includes a systems have been developed in the United States, and wealth of items that have been developed successfully about two years ago we prepared one suitable for use with and many more that must yet be undertaken. the danger-rating system used in Canada. The next step, In both the United States and Canada, the first forest as we see it,is to devise a means of using the severity fire research workers recognized at the outset that some rating as a basis for rating the efficiency of a protection method of measuring or rating the forest fire danger, or organization. An adequate efficiency-rating system would burning condition, was of the utmost importance to any enable an organization to assess the value of any change fire control organization.In the United States, several in its procedures, if only one major change were made in investigators in various parts of the country have studied a season while other activities were held constant. the problem with different lines of approach, and various Fuel-type classification, an essential item of fire control types of satisfactory danger-rating methods were devised; plans, might serve as a final example of a problem in others are still being developed.In Canada, the great presuppression that has been studied but on which much bulk of forest fire danger research was undertaken by the work must yet be done. An approach to the problem in Federal Forestry Branch, with the result that the system Canada is being made through the study of fire behaviour developed there, or slightly modified versions of it,is to try to find a rule-of-thumb method forconverting used in almost all areas afforded protection against fire. cover-type maps to fuel-type maps. Because weather is a common factor in practically all fire danger-rating systems, and since the effect of a given Detection set of weather conditions on a certain type of forest fuel The speed with which forest fires can be reached has is similar wherever it may lie, it seems logical to suppose been increasing rapidly in recent years, and this has, in that a danger-rating method could be devised that would turn, led fire control men to look for ever-better methods have almost universal application. Several years ago, Dr. of increasing forest fire detection efficiency.Observers D. F. Stedman, a chemist at the National Research Coun- operating from cabins on towers and hilltops or from cil in Canada, made tentative proposals for the develop- patrolaircraftstill form the backbone of almostall ment of a recording fire danger meter. Although the meter detection syste:ms. itself would not be complex, development would probably For several decades lookout tower design remained be time-consuming and expensive, but a start on this fairly static, but in recent years new types of towers have highly desirable project is being made this year.The been proposed, and a single-mast type, made from ten- proposed instrument would maintain a continuous record foot sections of lightweight metal alloys, has been used throughout the fire season of all weather effects on various successfully. Tower cabins have been improved in many layers and densities of forest fuels. respects, and the prefabricated, lightweight fibreglass type Weather is of such prime importance in forest fire con- developed in the Province of Alberta, Canada, some years trol, as indeed it is in other phases of forestry, that the ago might serve as an example ofthe trend. Many im- meteorologist has become a key figure in many phases of provements have also been developed for properly locating the research program. It is the opinion of many fire con- the lookout towers, preparing visibility or seen-area maps,

Forest Protection 987 for modifying standard fire-finders to meet special con- than 40 pounds, can pump dirty water for many hours at ditions, and for distinguishing the smoke of a forest fire a stretch, and can produce 40 gallons per minute at a from backgrounds with which it might tend to blend. pressure of 50 pounds per square inch, and eight gallons Within the past ten years much work has gone into the per minute at 250 p.s.i. Undoubtedly there will be con- development of electronic means for detecting fires, but tinuing improvements in pump designcommercial com- no major break-through has yet been attained.Closed petition will ensure that. circuit television has been used successfully on an experi- Since these items play such an important part in fire mental basis in the United States, but operating costs and suppression in Canada, considerable time is spent on other limitations will have to be reduced before the system projects involving techniques for testing pumps and hose could receive widespread use. Experiments with infrared in the field and for methods of handling these items with radiation detection devices for use as fire detectors are dispatch and protecting them from damage. being continued, but the instruments cannot distinguish Water is taken to forest fires in a great variety of ways, the difference between the heat from a fire and that from and within recent years aircraft have been used extensively other sources, nor do they react to a smoke column. Some for this purpose. The Province of Ontario has equipped smokes can be picked up by radar, but this type of fire almost its entire fleet of some 45 Beaver and Otter air- detection does not yet even approach the quality of that craft with water tanks, mounted on the pontoon floats, afforded by a well-trained observer. Development work which can be filled in a matter of seconds while the air- is continuing in all these lines, however, and improved craft is taxiing and which can be dumped on a fire by the performance is bound to be obtained. pilot as a well-concentrated discharge. The Beaver air- Investigators in some areas have come to believe that craft carries about 100 imperial gallons and the Otter on a dollar-for-dollar expenditure basis, aircraft patrol is a more effective means of forest fire detection than fixed about 160. lookouts, especially in mountainous country, where the Air tankers used in the United States are usually coverage of a lookout may be limited to one or two val- equipped with inboard tanks, and some of them have leys.Others think that a fixed lookout system, supple- capacities of up to 1,500 gallons. In British Columbia, mented by aircraft patrol, gives the best results. Certainly, an industry-supported protection organization has pre- aircraft patrol appears to be the only satisfactory means pared Martin Mars aircraft to carry 7,000 gallons of water of obtaining coverage when visibility is much poorer than in one load. normal. However, research workers have not yet come Chemicals, such as wetting agents, were introduced for up with an adequate method for assessing the relative forest fire suppression 12 or 15 years ago, but the use of merits of different detection systems proposed for a given fire-retardant chemicals on forest fires was developed in area. only comparatively recent years. Sodium-calcium-borate, Quite recently, our research organization was posed investigated in the United States and first used in Cali- with a problem that was causing some of the protection fornia, has had fairly wide acceptance in various regions associations concern in this regard.It was pointed out there. Bentonite, or driller's mud, is considered by many that with increasing forest fire danger, there was also to be just about as effective as the borate, and, in Canada increasing loss of visibility owing to heat and smoke haze; at least, it can be purchased and applied at a fraction of the question was asked if there were a direct relationship the cost.Nevertheless, only small quantities have been between percentage loss of visibility and given increases used on fires to date, because itis usually cheaper to in fire danger ratings. The answers to such problems must apply increased amounts of untreated water. Fortunately, be forthcoming if supplementary air patrols are to be made a wide variety of research organizations in several coun- on an objective, routine basis rather than on a hit-or-miss tries are working towards the development of an inexpen- type of estimate. sive, yet more effective, retardant substance. I have mentioned the use of aircraft in forest fire control Suppression several times in this paper and I do not wish to labour the When thinking of accomplishments achieved in the point by dwelling on their many other applications. How- suppression category, it is natural for a Canadian to think ever, mention must be made of the important work being first of those relating to the use of water. Most of that done to take advantage of the helicopter in fire control. country's forested areas are endowed with many lakes and The program of the United States Department of rivers. Water is used on practically all of the larger fires Agriculture, Pacific Southwest Forest and Range Experi- and very often is the sole means used to suppress the ment Station, has pioneered many developments in this smaller ones.In a single year, protection agencies in field and has, in the process, added new words to our Canada purchase as much as three million feet of 1½- language.In the January 1960 issue of that excellent inch forestry hose, although the average annual purchases publication "Fire Control Notes," published periodically would probably be half that amount. During the last year by the United States Forest Service,is a lead article of record about half the forestry hose sold in Canada was entitled "California Helitack Reporti 958." In it can the latex-lined type, weighing less than 16 pounds per 100 be found such words as "helitactics," "helijump," "heli- feet. One of the requirements not yet met is the produc- jumpers," and "helispot," words that will soon be as well tion of a disposable hose for use by smokejumpers and known as heliport is today. others fighting fires in places difficult of access. Many thousands of portable forest fire pumps are kept Economics in readiness to fill hose lines on short notice. Pump devel- Cutting across all factors in forest fire control is the opment has been good. One model now in use weighs less problem of costs and what distribution should be made of

988 Fifth World Forestry Congress Proceeding available funds.It is probable that each major protection RESUMES organization should decide individually what proportion Recherche en matière de lutte contre les incendies de of the budget should go towards detection, towards pre- foréts vention, and so on, but if these decisions are to be made Le present rapport met en lumière le fait que les connaissances wisely, methods for making assessments of the rejative actuelles en matière d'incendies de forts sont insuffisantes et values of applicable factors should be devised. qu'il est indispensable d'entreprendre des recherches plus appro- fondies.Les produits forestiers sont d'une demande sans cesse Economic studies are required in many other inter- croissante qui rend nécessaire une amelioration des méthodes related fields, such as the evaluation of damages and the d'aménagement forestieret,dans certainesi-égions, une telle determination of protection standards.The least-loss amelioration n'est possible que si l'on peut éviter ou tout au moms theory, where protection costs plus damage are kept to a réduire a des limites acceptables les ravages causes par les incendies. minimum, is frequently suggested as a basis for arriving Suit une historique de Ia recherche en matière d'incendies de at suitable forest protection standards, but so far, no forêts pendant le dernier quart de siècle, en ce qui concerne successful means for evaluating losses to the so-called in- notamment les méthodes etleainstallations.Le nombre de spécialistes assignés a cette tâche a triple au cours de cette tangible values has been produced, and there is no unani- période et les laboratoires de recherche ont augmenté dans de mity of opinion as to how standing timber and young plus grandes proportions encore.De nouvelles theories pour growth should be evaluated. s'attaquer aux problèmes et la nécessité d'intensifier les recherches fondamentales sont ensuite brièvement passées en revue. Technology in Other Disciplines On trouvera des exemples des réalisations accomplies et des problèmes gui se posent a l'heure actuelle en matière d'incendies Already in this paper, reference has been made, directly de forêts dans chacune des quatre sections suivantes: defense or indirectly, to more than ten scientific disciplines con- preventive, evaluation et prevision, detection et lutte contre les incendies. tributing to forest fire research. Advances in technology Defense preventive. Des recherches en matière demodification in almost all fields of science and mechanics are pro- desconditionsatmosphériques sonteffectuéesdans certaines regions en vertu de programmes de vaste portée et a long terme. ceeding so rapidly today that the fire control man is hard- L'étude et l'analyse des facteurs causant lea incendies de forêts pressed to keep up to date on even the broadest applica- ont permis d'améliorer les méthodes d'éducation dupublic en tions.Yet, keep up with them he must if he is to take matière de prevention. Des etudes sont egalement en cours en ce advantage of the most useful developments for fire control. qui concerne la possibilité de réduire lea risques d'incendies causes par les déchets d'abattage. Let us take but one possible development as an example Evaluation et prevision. Cette catégorie a de nombreusesrami- the production of cheap, packaged power. ficationsdes recherches considerables ont déjà été effectuées et un volume encore plus important estnécessaire.Lea méthodes In his book, Men and Atoms, Pulitzer Prize Winner utilisées a l'heure actuelle pour l'évaluation du danger d'incendie William L. Laurence expressed full assurance that such sont passées en revue ainsi que d'autres actuellement en cours d'étude.Sont également mentionnés lea previsions météorologi- power would be available to people of this generation. ques, les procédés employés pour fixer le taux desévérité des con- Many scientists have expressed similar views. Perhaps we ditions climatiques saisonnières propices aux incendies, Ia fixation will see power units the size of an office desk, capable of des taux d'efficacité des organisations de protection etla classifi- cation des types de matériaux combustibles. producing, say, 500 horsepower for several thousand Detection.Ameliorations apportées a la conception des tours hours, that could be plugged in to any device of our d'observation, recherches en cours en ce gui concerne les moyens choice. With such units, perhaps we would not be dream- électroniques pouvant être utilisés pour la detection desincendies, et avantages relatifs des postes fixes d'observation etdes patrouilles ing too much to envisage a ruggedly built aircraft that aériennes. could hover at a height of 500 feet or so at predetermined Lutte contre les incendies.Cette section traite de l'utilisation points to replace our present detection system. At the de l'eau et du materiel dont on dispose a cet effet,ainsi que de l'emploi d'avions citernes, de produits chimiques retardantl'action first sign of smoke it could be flown quickly to the source, du feu et d'agents de mouillage, et d'hdlicoptères pourla lutte douse the incipient fire with a chemical suppressant, and contre l'incendie. even apprehend the culprit who carelessly or deliberately En conclusion, le rapport mentionne les raisons pourlesquelles iiest indispensable de procéder a une étude pluspoussée des started the fire. I acteurs économiques et de se tenir au courant desprogrès d'ordre technologique qui sont actuellementaccomplis dansd'autres Conclusion domaines et qui pourraient être utilement appliqués dana lalutte It has been possible in this paper to consider only briefly contre lea incendies de forêts. a few facets of research in forest fire control. While we Investigaciones sobre el Control de Incendios de Bosques may look to the future with the assurance that scientific Este trabajo recalca la necesidad de iniciar nuevas investiga- development will be of great aid to us, we must make ciones sobre los incendios de bosques. La creciente demanda de every effort in the meantime to help ourselves. productos forestales exige una mejora en las prácticas forestales, la cual será posible en algunas areas solo ciiando se logren pre- Every time that a protection organization experiences a venir o reducir a términos aceptables las pérdidas ocasionadas por disastrous fire year, or even a severe individual fire, fire los incendios. control officers learn something that will enable them to Se describe el desarrollo de prácticas de estudios y medios de investigación sobre incendios forestales durante el ilIltimo cuarto provide better protection in the future. Such lessons are de siglo. Durante este tiempo se triplicó el ntimero de profesio- a costly means of learning how to achieve fire control nales dedicados a estas tareas y se registrO un aumento mucho objectives.Forest fire research is the logical substitute mayor en los medios de investigación. Se examinan brevemente los nuevos conceptos para la solución de problemas y se señala for these oft-repeated better experiences; and it can be la necesidad de extender las iiivestigaciones básicas. undertaken for a small fraction of the costs of forest fire Se dan ejemplos de los resultados de las investigaciones de suppression. incendios y de los cuatro problemas que hay que enfrentar en

Forest Protection 989 materia de prevención, pre-supresión (medidas de preparación), Detecck5n. Se describen las mejoras en el diseflo de atalayas, detección y extinción. las investigaciones actuales sobre los aparatos electrónicos para Prevención. Se explica que en varias areas están realizándose la detección de incendios y las relativas ventajas del sistema de investigaciones para la modificación del tiempo por medio de programas a corto y largo plazo. La observación y análisis de centinelas fijos y de reconocimiento aereo. las causantes de los incendios forestales han traIdo métodos más Extinción. Se recomienda el uso del agua y de los aparatos perfeccionados para la prevención de éstos. Se mencionan unos disponibles al respecto. También se describe el uso de aviones estudios sobre la reducción de pehgros de desperdicios. tanques, retardantes quimicos y substancias humedecedoras, asI Fre-supresión.Esta categorIa tiene muchas ramificaciones en como el empleo de helicópteros para apagar incendios. las cuales se han hecho numerosas investigaciones, pero todavIa quedan más por hacer. Se hace referencia a los sistemas actual- El trabajo concluye haciendo referencia a la necesidad de mente en uso para la clasificación de peligros y a otros que están realizar estudios adicionales sobre los factores económicos y de investigándose. También se mencionan los pronósticos meteoro- mantenerse al tanto de los progresos alcanzados en otras dis- iógicos, las tablas sobre la severidad estacional, las de eficiencia ciplinas que puedan resultar dtiles para extinguir los incendios y la clasificación de combustibles. de bosques.

SPECIAL PAPERS Méthodes et pratiques de protection contre les incendies de foréts

DIREzI0NE GENERALE PER L'ECONOMIA MONTANA E PER LE FORESTE Rome, Italie

L'Etat italien est parfois frustré dans ses efforts en l'altitude, les essences forestières qui constituent la forêt, vue du reboisement et du raffermissement des terrains de son état physique-vegetatif (age, densité, repartition de montagne, de la conservation et de l'amélioration du la végétation, existence ou non du sous-bois). patrimoine forestier, par suite du fléau des incendies qui La végétation forestière, comme on lesait,est très causentsouventdes dommages considérables ense diverse, tant dans les différentes zones phyto-climatiques propageant sur de vastes étendues de terrain, détruisant que dans les regions qui, tout en ayant les mêmes limites Ia forêt ou compromettant son avenir. altimetriques,d'exposition,etc.,se trouvent dans des Les causes d'incendiesont d'ordre divers:parfois milieux a climat complètement different. volontaires, d'autres fois dues a l'imprudence, d'autres Dans des conditions écologiques diverses, l'état physi- fois accidentelles. que de la forêt vane, parce que les espèces végétales qui Selondes donnéesstatistiquesfondées, 10%des la constituent sont nécessairement différentes. incendiesseraient düs a la malveillance(volonté de Dans des regions a climat maritime, on trouve ainsi porterprejudice ou dedétruirelaforét); 50% a des forêts oü le feu peut se développer facilement et se I'imprudence (incendies involontaires) et 40% a d' autres propager rapidement, en raison de la facilité de combus- causes(accidentelles ou fortuites,par exemple ala tion des éiéments du sous-bois. Le climat maritime fait foudre, aux chemins de fer, a des courts-circuits, etc.). naltre en Italie, jusqu'à une certaine altitude (variable Les probabilitésd'incendie varient d'une region a suivant l'exposition, la nature du terrain, le régime des l'autre, et en ce qui concerne les causes, dependent de pluies), une forêt absolument caractéristique, appelée facteurs subjectifs et objectifs. "maquis méditerranéen", et constituée par deux plans Le facteur subjectif est constitué par lesens des distincts de végétation. Le plan le plus haut est formé de responsabiités des populations rurales et des personnes végétation essentiellement forestière,et comprend des qui pour un motif quelconque se trouvent en contact avec espèces d'arbres comme le pin maritime, le pin pignon, la forêt (bücherons, chasseurs, touristes, militaires). Les le pin d'Alep, le chéne vert; le plan le plus bas est fonmé incendies involontairessont toujours düsa uneim- de buissons, et d'une végétation embrouillée d'arbustes, pardonnable negligence(allum age de feux,allumettes tels que les bruyères, les genêts, etc.Les pluies peu non éteintes ou restes de cigares ou de cigarettes jetés abondantes dans Iaregion du maquis méditerranéen dans les herbes sèches), actes provoqués précisément par déterminent très souvent un degré élevé de sécheresse des le fait que certaines personnes n'ont pas un sens de com- arbustes et des herbes d'alentour, ce qui les rend facile- prehension suffisante de la nécessité de sauvegarder la ment combustibles; il suffit alors d'une allumette encore forêt du grave mal a laquelle elle peut être sujette, en enflamméejetéeparinadvertance,pourprovoquer consequence d'un geste qui semble extrêmement innocent. l'incendie, qui s'étend, alimenté par la végétation dense Parmi les facteurs objectifs, on doit computer l'endroit, etbroussailleuse(feux de surface ou rasants).Les

990 Fifth World Forestry Congress Proceedings flammes,prenantrapidement devastesproportions, des travaux ou pour une autre occupation légitime. Elles détruisent alors lesarbres de la forêt,entraInant les permettent aces demières personnes d'allumer, avec graves dommages que l'on peut fadilement imaginer. toutes les precautions nécessaires,la quantité de feu Le coefficient d'intensité des incendies düs a l'impru- strictement nécessaire a la cuisson ou au réchauff age des dence, qui pour lesraisons indiquées plus haut est aliments, avec obligation d'éteindre le feu avant de quitter élevé dans la zone rnéditerranéenne, est au contraire l'endroit. beaucoup plus bas dans les regions plus hautes et dans les Dans les endroits limitrophes aux forêts et aux terrains regions au climat continental; dans de nombreuses zones broussailleux, les normes interdisent de brüler le chaume alpines, II est proche de zero, en raison principalement ou autres résidus végétaux a une distance inférieure a de l'absence de sous-bois. 100 m. Pendant la période 1950-59, on a enregistré en Italie A l'intérieur des bois, ou a moms de 100 metres de 14.440 incendies de forêts; la superficie parcourue par le ceux-ci, cues ne permettent pas (a moms d'avoir une feu a été de 170.000 ha. environ (c'est-à-dire 3% de la autorisation de l'Autorité forestière) d'installer des fours superficie forestière nationale), avec un dommage total a chaux, a briques, a poterie, ou des fabriques de potasse évalué a 5 milliards de lires. et d'autres matériaux pour lesquels l'eniploi de com- Les dommages sont particulièrement sensibles pour les bustible est nécessaire. propriétaires de forêts de conifères, surtout si les arbres Elles obligent les Administrations des chemins de sont jeunes, car le patrimoine détruit ne peut être recoil- fer secondaires ou des tramways a vapeur a munir, pen- stitué que par l'implantation artificielle. dant les périodes de sécheresse, les cheminées des locomo- Pour les propriétaires des forêts de feuillus, le domma- tives de filets pare-étincelles, a enlever les feuiles, les ge est moindre, car une bonne coupe de recépage des herbes sèches et les autres matières facilement inflam- arbres frappés, effectuée a temps, suffit a redonner au bois mables du voisinage des voies ferrées aux endroits oü incendié la possibilité de produire un revenu normal a la celles-ci traversent des forêts, et d'éviter, sur ces mêmes fin de Ia revolution. trajets, de décharger du materiel allumé. Les moyens adoptés en Italie pour la prevention et Elles prévoient l'enlèvement des émondes et des l'extinction des incendies sont particulièrement efficaces résidus du travail, et, lorsque c'est possible, le nettoyage dans les Forêts du Domaine de l'Etat. total de la forêt par l'enlèvement des herbes et des us comportent principalement: buissons. le nettoyage des routes périmétrales des forêts par En outre, une propagande anti-incendie a la fois vaste l'enlèvement au printemps des buissons, detritus ou et capillaire est effectuée et stimulée par le Corps fores- autre materiel facilement inflammable; tier; ladite propagande est faite au moyen de la presse, l'ouverture de bandes d'une largeur de 6-10 metres, du cinema, de la radio, de Ia télévision, de conferences et dans lesquelles est effectué un nettoyage analogue; de cours. l'ouverture de bandes para-feux plus larges a l'in- Pendant les périodes oC les risques d'incendie sont plus térieur des forêts, particulièrement sur les crêtes, dans forts, la surveillance des peuplements forestiers est ren- le but d'arrêter Cventuellement le progrès des incendies; forcée, et les equipes anti-incendies sont placées en état la construction de tours d'observation en des points d'alerte. topographiquement dominants; En vertu de la loi italienne, personne ne peut refuser, la constitution d'équipes anti-incendie pouvant inter- sans motif valable, de contribuer a éteindre un incendie venir rapidement, munies de facon constante de tout en forêt. Dans les operationsd'extinction, lit oà la situa- l'équipement apte a éteindre le feu (pefles, pioches, tion des forêts le permet, on emploie également les moyens hachettes, râteaux, flabellums a long manche avec pla- mécaniques du Corps des Pompiers. ques métalliques), si possible transportées par véhi- L'emploi de l'aviation a cet effet est encore en phase cule automobile;ceséquipes sontlecas échéant renforcées par des éléments locaux dans la mesure cor- d'expérimentation. respondant a l'importance de l'incendie; et RESUMES i'apposition, dans les forêts, dans les localités de majeur Methods and Practices of Protection Against Forest Fires transit, de panneaux indiquant l'interdiction de fumer, After first mentioning the causes of forest fires, which may be de laisser des feux allumés, etc. voluntary, due to carelessness, or purely accidental, as well as the Les mesures de prevention et la lutte active contre les subjectivefactors(thepeople'ssense ofresponsibility)and incendies dans les forêts appartenant a des particuliers ou objective factors (location, altitude, species of trees, the vegetation and the physical condition of the forest) on which the chance of a des organismes, dependent pratiquement de l'action con- forestfiresalso depends, and giving some indication of the comitante des Autorités locales et du Corps Forestier de amount of damage, this report describes the practices used in l'Etat. Pour ces forêts, les normes de prevention des in- Italy and the standards in force with respect to preventing and cendies, bien que s'inspirant de critères généraux, varient putting out forest fires. d'une province a l'autre. Ces normes, qui sont incluses Métodos y Prácticas de Protección contra los Incendios de dans les règlements de police forestière: los Bosques 1. Interdisent a qui que ce soit d'allumer des feux dans Este informe, después de iridicar al principio las causas que les bois et dans les terrains broussailleux, ou a une dis- provocan incendios de los bosques, causas que pueden ser volun- tance inférieure a 50 m. de ceux-ci, a l'exception des per- tarias, debidas a la imprudencia o puramente accidentales, asI sonnes qui ont a séjourner dans les forêts pour y effectuer como los factores subjetivos (sentido de responsabilidad de las

Forest Protection 991 personas) y objetivos(lugar,altitud,especies,estadofIsico- caciones del montante de los danos, los métodos y normas que se vegetativo de los bosques) de los cuales depende igualmente el siguen en Italia en materia de prevención y de extinción de los riesgo de incendios de los bosques, explica, después de dar mdi- incendios de los bosques.

Progresos Obtenidosen la Defensa y la Lucha contra Incendios

EMILI0 BENITO España

La importancia de los incendios ocurridos en el aflo de los usados en Canada y Lake States (E.U.A.) que 1953 en España, durante el que se tuvo conociniiento han dado resultados satisfactorios en las provincias de oficial de haberse destruido 13.000 hectáreas, aunque clima marItimo, incluso sin ninguna modificación en las puede suponerse fuese mayor en realidad esta cifra, hizo escalas, el de Canada. Se está haciendo el estudio para comprender a la Administración Forestal la importancia su modificaciOn y uso en las del interior. Se está ensayan- de este problema y en consecuencia creó en 1955 el do también el tipo 8-100-0 empleado por la Southeastern Servicio Especial de Defensa de los Montes contra los Forest Experiment Station.El uso del indicador que Incendios, a quien se encargó de su estudio y reducción. resulte más aconsejable para cada zona se piensa hacer Los métodos hasta entonces seguidos en nuestro pals, obligatorio en su dla. tanto en la detección como en la lucha contra los incendios Torres de vigilancia. Aunque en algunos montes no podian ser más primitivos, toda vez que la primera se existlan ya, se ha incrementado considerablemente su hacla empleando vigilantes de incendios dotados exclu- construcción empleándose torres metálicas de 20, 15 y sivamente de bocinas para dar las alarmas y en los traba- 10 metros de altura. Todas ellas dotadas con: jos de extinción no se utilizaba ningün material especifico. Radiotelefonos. Salvo en algOn monte en el que los El primer paso dado por el Servicio fué asegurar la puestosdevigilanciaestabanenlazadosconlineas recepción de los partes de incendio para tener conoci- telefOnicas a los parques, en cuyo caso se tenla un rápido miento exacto de la gravedad del problema y sobre todo el procedimiento para dar la alarma, no se habla empleado control de los incendios de extension menor de 1 ha. de ningün medio moderno para conseguir la rapidez en los los que hasta entonces no se ilevaba su estadlstica y cuyo enlaces, cosa de la que depende en la mayorla de los nümero expresa los exitos conseguidos en los trabajos de casos la posibiidad de dominar un siniestro. detecciOn y extinciOn. El empleo de los aparatos receptores-transmisores en Consecuencia lógica de ello fué aumentar el nümero de las diez provincias en que se han instalado, ha dado unos partes de incendio y disminuir la cifra media de hectáreas. resultados excelentes en la detecciOn de incendios y De los 967 incendios ocurridos durante el año 1958, 310 además ha facilitado el desarrollo de los demás trabajos fueron incipientes lo que representa un 33,6% del total, forestales.Por consideraciones econOmicas se emplean estando por ello muy lejos todavla del 80% que debe hasta ahora aparatos de modulación de amplitud VHF en conseguirse para tener cubierto este riesgo con vistas a la labandade 80a83 mcs. implantación del Seguro Forestal contra incendios. Alidadas.Para la localización de los incendios, Por el contrario, si consideramos que la superficie que- los puestos de vigilancia se han dotado de alidadas que mada durante dicho aflo fué de 14.967 has. de un total ar- fijan el azimut del incendio y lo transmiten por radio a bolado de 10.049,964 has., lo que representa un 0,148%, la Base de escucha permanente. porcentaje inferior para el mismo año (segün los datos publicados por la ComisiOn Europea de Bosques de la Lucha FAO en su informe 59/7/5142) a la de palses como Extintores. Después de las pruebas realizadas con Polonia, Suiza e Irlanda, de condiciones climatolOgicas diversostiposdeextintoresseadoptOel"Indian" mucho más favorables, podemos afirmar no estar nuestro americano o similar, cargados con agua y detergente. pals retrasado respecto a los demás palses europeos, ya Automóviles con motobomba.Entreeldiverso que ocupa el octavo lugar en porcentaje de superficie que- material recibido de la I.C.A. figuran automóviles todo mada en relaciOn con la total poblada. terreno dotados con motobomba y quince extintores de Los medios que se están poniendo en práctica que nos mochila, que se emplean primeramente para acercar el permiten mirar el porvenir con cierto optimismo, tal vez no constituyan una novedad dentro de las modernas material y obreros al lugar del fuego y posteriormente técnicas forestales a este respecto, sino la aplicaciOn a para el aprovisionamiento de agua a los extintores. Dada nuestra especial orografla y clima de lo ya experimentado nuestra especial orografla, en muy pocas regiones se por otros palses de mayor potencia econOmica. Las prin- pueden utilizar estos coches para combatir desde ellos cipales innovaciones establecidas son las siguientes: directamente el incendio, pero los resultados obtenidos dedicados al abastecimiento y enlace han sido excelentes. Detección En la actualidad se trata de conseguir consorcios con las a. Indicadores de peligro.Se ha ensayado el empleo Diputaciones Provinciales, las cuales atenderlan al sos-

992 Fifth World Forestry Congress Proceedings tenimiento de los vehIculos a cambio de recibir su ayuda posible que este nümero aumente, pero hay que tener en los siniestros urbanos. siempre presente que el enorme esfuerzo que realiza c. Retardantes.Se dispone de "Firebrake" y de los nuestra nación en los trabajos de repoblación forestal aparatos mezcladores y lanzadores desde tierra; pero hace que nuestra superficie poblada se incremente en dado su precio no se puede pensar por ahora en el 100.000 has. cada año. empleo de aviones para su lanzamiento, que esla verdadera utiización de este retardante. La pesadez de RESUMES los aparatos lanzadores, asI como la imposibilidad en Progress in Forest Fire Fighting and Control más del 90% de nuestros montes de transitar fuera de The new detection methods and firefighting techniques which las redes de caminos construIdas con vehIculos motoriza- were introduced in Spain in 1956 have succeeded in lowering the percentage of burnt areas to .148 percent of the total forest area, dos, hará siempre muy limitado el empleo de estos a lower rate (according to statistics published by the European productos. Creemospoderresolveresteproblema Forestry Commission of the Food and Agriculture Organization mediante el empleo de lanzadores más ligeros con pro- in its Report No. 59/7/5142) than that of countries such as ductos más eficaces de los que tal vez pudiera constituir Poland, Switzerland and Ireland, where more favorable weather conditions exist.This indicates that our country does not lag la solución la Bentonita. behind other European countries in this matter; we occupy eighth Estas son en esencja las mejoras establecidas en la place in percentage of burnt area of the total forest area. defensa y lucha contra los incendios, que unidas a una The methods used do not constitute an innovation in modern apertura más completa de cortafuegos, asI como la crea- forestry techniques; they are merely the application to our pecu- ción de "parques de zona" dotados de material con- liar topography and climate of what has already been tested in countries with a greater economic potential. veniente y personal especializado para su empleo, y el In detection work we have begun to use "fire-danger indicators," USO de herbicidas totales en Ia conservación de cortafue- lookout stations, VHF radio-telephone hookups, alidades, and gos, nos permite suponer que cuando estos nuevos medios coordination with commercial airlines in locating forest fires. In firefighting we are using backpack type extinguishers with se hayan aplicado a toda nuestra superficie forestal, salvo water and detergents, all-terrain vehicles with fire pumps, and en casos excepcionales, se tendrá controlado en lo posible chemical fire retardants. este riesgo. Even though the statistics may show in the future an increase En las importantes areas forestales de Galicia, donde in the area burned annually, one must bear in mind that the great se ha instalado este material, ha quedado demostrada su efforts made by our nation in reforestation have succeeded in eficacia como puede apreciarse en el expresivo cuadro increasing our forest area by 100,000 hectares a year. que a continuación se inserta, referente a montes de Pro grès obtenus dans la lutte contre les incendies utilidad püblica: Les méthodes nouvelles de detection et de lutte contre les incen- dies de forêts qui sont pratiquées en Espagne depuis 1956 ont Promedio anual en el Promedio anual en el permis de réduire le pourcentage de la surface brcdée a 0,148% perIodo 1946-56 bienio 1957-58 de la surface boisée totale, ce pourcentage étant (selon les don- Provincias nées que la Commission européenne des Foréts de la F.A.O. a Ntimero de Hectáreas Ni'jmero de Hectáreas publiées dans son rapport 59/7/5142) inférieur a celui de pays incendiosquemadas incendiosquemadas tels que la Pologne, Ia Suisse ou l'Irlande, bien plus favorisés du point de vue climatologique.Ceci nous permet d'affirmer que, La Corufla 14 157,71 17 45,95 dans ce domaine, nous ne sommes nullement en retard par rap- Pontevedra 25 940,37 53 267,58 port aux autres pays européens, notre pays occupant la huitième Promedio anual en el Durante el año 1958 place en ce qui concerne le pourcentage relatif des surfaces brülées de l'ensemble des peuplements. perIodo 1947-57 Les moyens mis en pratique ne constituent pas une innovation Orense 3 137,00 4 6,58 dans le cadre des techniques forestières modernes, ils ne sont que 18 57,05 l'application, a notre orographie et a notre climat particuliers, Lugo 3 203,12 de méthodes déjà expérimentées dans d'autres pays d'une puissance économique supérieure. Su examen confirma lo expuesto anteriormente, re- Pour la detection, on a mis en service des "indicateurs de dan- specto al aumento del nümero de incendios, consecuencia ger", des tours de guet, des relais radio-téléphoniques sur T.H.F., des alidades, et on a organisé la coordination avec les lignes corn- lógica de una estadIstica más matizada, que en este caso merciales d'aviation pour determiner l'emplacement des incendies. puede ser también debida a que las condiciones mete- Pour la lutte, on se sert d'extincteurs portés en bandoulière, orológicasfueron francamenteadversas enelbienio charges d'eau et de detergents, d'autos tout terrain munies de 1957-58. motopompes et de produits chimiques retardateurs d'incendie. Ii peut arriver que les données statistiques futures indiquent La actuación de la Administración Forestal Española une augmentation annuelle de la surfaceincendiée, mais il ne faut a este respecto podrá tal vez ser juzgada equivocadamente pas oublier que, grace a l'énorrne effortaccompli par notre pays Si se examinan los datos estadIsticos anuales referentes al en matière de reboisement, notre surfaceboisée s'accroit de 100.- nümero de hectáreas destruidas por incendios, ya que es 000 hectares par an.

Forest Protection 993 Ecological Effects of Fireon North Swedish Forests

EVALD UGGLA Forest Research Institute of Sweden, Department of Botany and Soils, Stockholm, Sweden

Introduction the litter form a thin cover upon the otherwise undamaged Fire has always been a very important factorin humus layer. The alkalis of the ash can then be absorbed determining the extent and composition of boreal forests. by the humus cover in an easily accessible form, the Even during recent centuries most woodlands have been nitrogen metabolism is increased, and the conditions for subjected to fire in one form or anotherforest fires, most micro-organisms are ameliorated. The destruction burning for crops practised in former times, and the of the previous vegetation has reduced the root competi- present-day controlled burning. Almost everywhere one tion. The temperature at the surface of the soil will rise can find charcoal in the humus layer as evidence of fire. on account of the increased ability of heat absorption of During the present century, fire has been used to an the black humus cover, which favours the germination of increasing extent in the service of silviculture, especially seeds. in the northern parts of Sweden. Controlled burning is In the long run, the fire has an indirectly favourable practised on raw humus grounds, mainly at high levels. influence also by favouring the entry of birch and aspen as It is now generally agreed that a properly conducted, con- pioneer trees into the burnt areas. Every year the leaves contribute a new quantity of litter to the soil, the tempera- trolled burning on ground that is not too dry is the most ture of which rises below the leafless trees in the spring. efficient method of activating the humus and of reducing In a clearing, the density of the humus cover diminishes the labour difficulties in planting and sowing on such land. through, amongst other things, the soil temperature rising The circumstance that fire has come into increasing use and theprecipitationhavinggreateropportunityto in forestry is due to several cooperating factors, some of percolate down to the root system. which will be briefly dealt with here. A feeble forest fire, on not too dry, raw humus ground, After the passage of fire over the humus cover, the can be compared with a controlled burning, but on poor, ashes and carbonized remains of the living vegetation and dry soils, uncontrolled forest fires can have devastating effects. On such soils the activating effects of the fire soon 5'1OC disappear. Since the addition of litter also will be very 30iSLctsh cm inconsiderable for a long time, degeneration of the forest

I hn,.cov.r: soil often results. 600- ,\0O Li.r A0, Aoa H-k,., Temperatures During Controlled Burning 10 A5.BI.hed ky.r Soil Temperature 2co The survival of vegetation and micro-organisms after a fire depends on the temperatures reached in the humus Te,,,p.rtvr. pick-op cover. The severity of the fire is dependent on several 5 c,, obov. oh. .orkc. factors such as the forest type, the quantity and composi- 2OO S cm in ohe 0 roc nd 70fl,iflohercoond tion of combustible material, and the strength of the wind. The moisture content of the soil, particularly in the humus 150 layer, is not the least important factor. A common feature of the measurements during con- trolled burnings was the low temperature in the humus /00 cover as compared with that at the soil surface, which is illustrated in Fig. * Here it is also shown that the tem- perature at the soil surface on the day after the burn was rather high, owing to insolation heat absorbed in the charred layer. The curves also illustrate the characteristic displacement in time, which derives from the low thermal conductivity and high thermal capacity (specific heat) of /150 /830 /?.o/a3O the soil and its content of moisture. 2/6 In another test, however, the temperature at a depth FigureI.An example of the high insulating capacity of the humus cover during a controlled burning.Comparison of the temperature curves the following day shows the heat absorption of the charred * The temperature fluctuations were followed by direct reading ground. on a resistance bridge provided with temperature pick-ups. 994 Fifth World Forestry Congress Proceedings of 3 cm. remained at about 1000 C. for about 20 minutes Air Temperature and then dropped rapidly. In this test, the fire was fairly During a forest fire or a controlled burning the crowns intense, and the humus cover was rather dry. The mois- of the trees are often killed. The problem of resistance to ture content in the F-layer was 17.6% before and 3.7% heat and smoke isvery complicated.Some data are after the burning.The long period at 1000 C. indi- provided on the air temperature during - cates that a zone of condensation was formed at this depth. ing in Halsingland, which might serve as a basis for more The temperature rise was arrested in this zone, owing to thorough investigations. the need of heat for vaporization of the moisture con- Repeated measurements in open flames showed a tem- densed in the soil in the first phase of burning. Only after perature in the hottest part of about 1,150° C. A radia- the water had been evaporated could the fire have a tion pyrometer with a temperature range between 600° chance to go deeper, but at this time the fire front had and 2,200° C. was used. The high temperatures in the passed the test plot, so that the temperature had begun open flame are similar to those obtained inexperiments to drop rapidly. in fire prevention, in which temperatures of about 1,000° It is evident from the tests that the humus cover is an C. are reached indoors, and about 1,300° C. with an ade- excellent thermal insulator, a fact that has often been pointed out. This is partly explained by the condensation quate air supply. of water vapour, formed in the burning of organic matter The temperature at the crowns is determined by absorp- that always occurs in the upper soil stratum during a burn. tion of heat radiated from the heart of the fire and by the As the fire advances, the damp humus cover acts as a cold temperature of the air-smoke mixture. As is well known, barrier where moisture is condensedImmediately below the temperature is highest when the smoke is yellowish- the fire zone there is thus a "sweating zone," which brown to black. The dark type of smoke is formed if effectively prevents the fire from penetrating deeper into combustion is incomplete, for example, when the fire the humus cover.Before this can happen, the moisture front is so broad that the oxygen supply is insufficient, or must be evaporated. when the combustible material is damp, or too plentiful During a feeble forest fire on not too dry soil, or during for the available air. a controlled burning, the high temperature does not, as a For the measurement of the temperatures at the trees, rule, last long enough for the moisture in A01 to evaporate. maximum thermometers recording up to 300° C. were Only if the fire frontisarrested, particularly on dry used. The accuracy of these instruments was tested by the ground, is it likely that the humus cover will burn partly Government Testing Laboratories. During a burning the or completely. On moist sites, the fire will usually con- wind was strong, and the smoke drove down below the sume only slash and litter, dried-out vegetation, and pos- crowns of the seed trees left on the cutand burnt area. sibly the uppermost dry part of the humus cover where Therefore, no damage to these trees was observed. At the air has free access. fire lane, however, the smoke hit the tree crowns,and

3

33 /

5 10

Fire lane wind drove the smoke down below Figure 2.Diagram of a controlled burning. On the open cut area with the seed frees (to the left) the strong the crowns, and therefore no damage was observed. The trees behind the fire lane(middle), however, were engulfed in the smoke, and those parts of the crowns sublected to the yellowish-brown to black smoke, which resultedfrom incomplete combustion, were killed (shaded). The tem- peratures were measured at 3, 6, 8, and 12 m. above the ground.

Forest Protection 995 the temperature was as high as 89° C. at 12 m. above the areas, which had been cut and burnt long ago, the percent- ground, while 68° C. was recorded at the height of 3 m. age of total nitrogen was largely the same as for the If the wind is weak, however, the smoke will hit the areas examined before the controlled burnings. crowns from below, and the temperature falls rapidly with height. In spite of the fact that the bark of an ex- RESUMES perimental tree was ignited, the temperature was 150° C. Effets écologiques du feu sur les forêts septentrionales at 6 m. and only 45° C. at 9 m. above the ground. The suédoises needles of this tree were killed even at 9 m. Les travaux d'enquête furent menés de 1955 a 1958 a partir de Only those parts of the crowns were killed which were brfilages contrôlés dans la province de Hälsingland, par 600 36' de engulfed by yellowish-brown to black smoke.Smoke latitude Nord et 15°36' de longitude Est. Le but de ces travaux which results from incomplete combustion thus seems to était de mesurer les temperatures de la couverture d'humus et de be dangerous for the needles. No damage was done by l'air pendant le brülage, et de préciser les effets du feu sur la végétation et sur la couverture d'humus. Les terrains de coupes greyish-white condensation smoke. avaient été essentiellement porteurs de vieilles foréts d'épiceas, avec une couverture d'humus brut inactif. The Effect of Fire on the Humus Cover La couverture d'humus a très bien servi d'isolant thermique. Dans l'un des essais, la temperature était de 5000 C. plus élevée a Some chemical changes occurring in the humus cover la surface qu'à 3 cms. de profondeur seulement. after the passage of the fire were studied, and samples Lorsque le feu passe au-dessus de la couverture d'humus, ii se were taken immediately before and after the burning, and forme tine zone de condensation qui empêche le feu de pénétrer en profondeur. then at different intervals. The decomposition layer and Etant donné que l'humidité de cette zone doit d'abord s'évaporer the humus material layer (A01 and A02) were sampled et que ceci ne se produit généralement pas pendant le brülage, separately. seuls les déchets d'abattage, la végétation vivante et la partie On the examined cut areas, the pH in the A01 varied supérieure de l'humus oà l'air peut pénétrer sont brülés. La temperature, qui était de l'ordre de 1.1500 C. au niveau des between 4.1 and 4.5 before the burnings.In samples llammes, diminuait rapidement avec la distance et était faible au taken immediately after 7 different burnings, the pH values niveau du sommet des arbres. in the A01 were 6.4, 6.6, 6.7, 6.9, 7.2, 8.4 and 9.5. The Les arbres ne subissent de donimages sérieux que dans les par- last-mentioned sample consisted almost exclusivelyof ties du sommet exposées aux fumées allant du brun-jaune au noir ashes from slash. dues a une combustion imparfaite. Le pH et la teneur en calcium, potassium et phosphore aug- After the controlled burnings the percentage of calcium, mentent dans des proportions considérables après le brülage. potassium, and phosphorus also exhibited a considerable Quelques mois après les brülages, le pH et Ia teneur en calcium increase.There was a definite connection between the étaient tombés dans la couche carbonisée en A. Le potassium et content of acid-soluble salts of calcium and the pH value le phosphore, qui se trouvaient dans les cendres sous forme de sels extrêmement solubles, furent rapidement lessivés. both on burnt and unburnt ground. This has been estab- Dans des regions brfllées plus anciennes, le pH mesure 1O ans lished earlier by several investigators. Through the burn- environ après le brülage est plus élevé que le pH ordinaire des ing considerable quantities of calcium are supplied to the clairières non brülées; les valeurs ne deviennent equivalentes qu'au soil in a form which is easily available to the plants. bout de 25 ans. Among the other constituents of the ash, highly soluble salts of potassium and phosphorus predominate. The con- Efectos Ecológicos de los Incendios en los Bosques del tent of these salts is greatly increased by the burning, but Norte de Suecia they are also rapidly leached out. La investigación se llevó a cabo en 1955-58 en relación con The samples which had been taken at different times operaciones de incendios regulados realizados en la provincia de Halsingland en los 60°36' de latitud Norte y los 15°36' de longi- after the burnings showed that in the incinerated part of tud Este. El propósito fue el de determinar las temperaturas que the decomposition (A01), both pH and content of Ca se desarrollan en la cubierta de humus y en el aire durante el decreased a few months after the burning, and that the incendio, asI como también para fijar los efectos que el fuego leaching of this layer produced a rise in the analytical ejerce sobre la vegetación y la cubierta de humus. Las zonas de corte habian estado cubiertas principalmente con antiguos bosques values in the humus material (A02) immediately below. de pino del norte, teniendo una cubierta de humus ácida. Thus, 3½ months after a controlled burning, the pH value El humus actuó como buen agente aislador termal. En una de in A01 had decreased from 8.4 to 7.0. On an older burnt las pruebas se determinó que en la superficie la temperatura tue area, the pH in A02 was higher than in the A01 6 years de 500° C. más elevada que a una profundidad de tan solo 3 centImetros. after the burning. After 10 years, the pH values in the A medida que el fuego se extiende por encima de una cubierta humus cover were still higher than normal, and it seems de humus, se forma una zona de condensaciOn que impide que el that in the investigated area about 25 years have to pass fuego se extienda hacia abajo. before the values become equal to those from adjacent, La humedad en esta zona debe ser evaporada primero, y ello por lo general no ocurre en forma total durante la quema, de unburnt, cut areas. manera que ünicamente se queman los matorrales, la vegetación Immediately after the burning, the percentage of total viva y la capa superior de la cubierta de humus en la que puede nitrogen had decreased throughout the incinerated part penetrar el aire. of the humus cover, making it evident that some nitrogen La temperatura que fue de más o menos 1.150° C. en las llamas, disminuyó rápidamente con la distancia y en las copas tue had been lost to the air. This, however, does not seem to relativamente baja. be a serious matter in the case of a thick, raw humus Los daflos más serios en los árboles se produjeron dnicamente cover, where, during the experiments in Halsingland, only en aquellas partes de las copas expuestas al humo amarillo- the uppermost part was completely burned. Moreover, parduzco o negro que se formó debido a la combustiOn incom- pleta. most of the nitrogen lost was probably not readily utiliz- Imnediatamente después de Ia quema el pH y el contenido de able by plants. Subsequently, the percentage of total ni- calcio, potasio y fósforo aumentO en forma marcada. trogen appears to have increased again, and on those Algunos meses después de las operaciones de quema, ci con-

996 Fifth World Forestry Congress Proceedings tenido de pH y de calcio habla disminuIdo en la capa carbonizada En zonas quemadas con anterioridad, el pH existente a los 10 en A01. El potasio y el fósforo que se presentan en las cenizas en años de la quema fue mayor que las existencias normales en forma de sales altamente solubles, fueron lavados rápidamente desmontes no quemados; estos valores no se igualaron hasta unos del suelo. 25 aflos después.

The Significance of Fire to World Forestry

ARTHUR A. BROWN Director, Division of Forest Fire Research, Forest Service, U. S. Department of Agriculture, Washington, D. C., U. S. A.

My colleague from Canada has given you an excellent The importance of this deficiency in knowledge of fire report on the need for research, and the wide variety of behavior is well exemplified by the generally accepted research and development activities that contribute to scientific principle that no natural phenomena can be better forest fire control in North America. He has pointed controlled until its operation is completely understood. Its out, too, the complex chain reaction attending the growth consequences are well illustrated by currentfirefighting and destructive behavior of forest firesthe free-burning experience in North America. Each year unfavorable fires that feed on natural vegetation. For simplicity, we re- conditions combine to produce a quota of what our fire fer to them all as forest fires, whether they burn in forest, control men call "blow-up" fires.These fires defy all brush, grass, tundra, or other natural cover. existing methods of control, and their unexpected or un- From his report, I hope you have gained some insight usual behavior endangers the lives of firefighters. Though into the basic relationship between fire and forests as seen they make up only a small percentage of the fires that by our fire research men. Of necessity, this relationship occur every year, they account for 80 to 90 percentof the has been given considerable attention by foresters in area burned in the United States. Blow-upfires create a North America, with practical emphasis on firefighting. situation where our firefighting agencies find themselves Of broader significance are the technical aspects of fire winning the small forest fire battles but losing the big ones. problems as they affect the progress of world forestry. Most of our past efforts have centered on finding faster Let us review very briefly the relationships between man and more effective ways of fighting small fires.This ap- and fire, and fire and forests. Perhaps it is well to remind proach has accounted for most of the progress made. The ourselves that wood will burn. Humanity owes its cultural development of retardants and methods enabling effective development, in large part, to this simple fact. The asso- attack on fires from the air has been described by pre- ciation of wood and fire for man's benefit started when he viousspeakers.Itcarriesthisprogress further. The first learned to release the sun's energy in wood and pro- potential of aircraft for applying control measures at the duce heat at will. right place and at the right time in inaccessible areas can About 2,500 years ago, Greek philosophers regarded greatly reinforce the efforts of firefighters on the ground. fire as one of the four basic elements, along with earth, air, Our original concept was that aircraft could knock down and water. To many, that concept seems long outgrown. or slow down dangerous small fires sothat they could be But, if the concept of fire is broadened to include thermal easily extinguished by small firefighting crews on the energy, then the Greeks were not far wrong after all. ground. It has demonstrated that potential and continues to function as aerial support of ground methodsrather Today, we know a great deal about the earth, the seas, than a cothplete method in itself. But it is being increas- and the atmosphere, and we have kept on learning new ingly employed on big fires to help carry out strategic ways to employ heat energy. But the deceptively simple measures.Its success is more limited for this purpose. wood fire still retains much of its mystery. Research in We expect a great deal of new progress in the way of bet- flame and combustion has brought about much of the ter chemicals and better aerial techniques.But under world's mechanization and industrialization. Behind this some conditions, aircraft cannot beflown for either pur- development were fire and a simple fuel, careful control So even aerial attack represents progress rather of the rate of fuel feed and oxygen access. The gasoline pose. engine is an outstanding example of this. However, re- than a complete solution. search in the behavior characteristics of free-burning, out- At best, a small percentage of uncontrolled high-energy door wood fires which develop their own rate of combus- fires is inevitable even under the most intensive systemof tion has never had this intensive treatment. So we have protection we candevise.Effectivecountermeasures the contradiction, quoted by Mr. Macleod, that the kind against these runaway fires depend on increasing our of fire familiar to man for thousands of years is less well ability to predict their behavior far enough ahead to meet understood than is nuclear fission. We know what fire will exacting time schedules in marshalling large forces of do, and in part we know why, but we do not know enough men and equipment. To predicttheir course in advance, to be able to predict its behavior in the free-burning state. we must increase our understandingof the forces that This gap in scientific knowledge has been a continuing come into play in each situation. This is a tediousbut handicap to progress in forest fire research. challenging research undertaking.It requires a complete

Forest Protection 997 knowledge of fire itself and its varied responses to almost ing forest land.Early in the history of this country, infinite variations in natural environments. fire was used freely to clear forest land for agriculture, Fortunately, basic research in free-burning fires is of clear out heavy underbrush, and improve the amount of vital importance to all fire agencies. In 1955, following forage available for livstock.Most of this use of fire "Operation Firestop," which we carried out in California, was destructive to forest values"burning the woods" the National Academy of Sciences held a symposium on persists today in some parts of our country. the problem of mass fires. The outcome of this sympos- Research studies have demonstrated that carefully con- ium was the creation of a fire research committee, con- trolled use of fire does have a legitimate place in forestry. sisting of key scientists and representatives of fire research The most important service of this kind of fire is the re- agencies. At the start, it was sponsored by the Office of duction of hazardous forest fuels which could start or Civil and Defense Mobilization.Later, the Department feed uncontrollable fires.This is particularly important of Defense and the U.S. Forest Service joined as sponsors. where cutting of timber takes place in overmature stands Through the activities of this committee, the interests of with a high percentage of defective trees. Great volumes all research agencies in fire out of control have been of unmerchantable material remain after logging is com- pooled. A new publication, "Fire Research Abstracts pleted, as you will see in your visit to our coastal and Reviews," now serves these interests, and scientists Douglas-fir logging operations. Such material decays very in many fields are now showing a growing interest in con- slowly and interferes with the establishment of new seed- tributing to the knowledge of this familiar, yet mysterious, lings, planting, and other silvicultural measures. The best process of ignition and spread of fire in woody fuels. A known way to insure against destructive fires during the small, special fund to encourage new research is being set next 10 years and to facilitate management of the land up in our Bureau of Standards. With the help of the is through skilled use of controlled fire to eliminate a National Science Foundation and the National Academy high proportion of the debris.Since fuel volumes are of Sciences in the United States, we are optimistic that heavy, and fire is always a dangerous tool, this burning the physics, the chemistry, and even the ion-exchange can be done successfully only under selected conditions processes in the combustion of woody fuels will become of weather and fuel moisture.Micrometeorological re- much clearer to us in the next few years. search and research in fire behavior should enable us to A step closer to the practical problem of control of greatly refine burning techniques within the next decade. forest fires is the research needed for a better understand- In the meantime, we shall continue in our efforts to pro- ing of the dynamics of ignition and the spread of fires in gressively convert these techniques from an art to a forest fuels.Forest research needs to take leadership in science. this process. We are developing forest fire laboratories In our southern and southeastern regions, prescribed for this purpose. These laboratories will enable precise burning is used in some situations to favor pine over low- control of many variables in fire behavior for the first value hardwoods, prepare seedbeds, and control the time. Small model fires can be repeated at will. By such brown-spot needle disease of longleaf pine.Techniques means, the exact effects of kinds and arrangements of for using fire under these circumstances are well developed fuel, of different kinds of airflow, of changes in air and and can be employed with little damage to an established fuel moisture, of shape of the land surface, and a host of stand. But more precision is needed for prescribed burn- other variables can be studied separately, then in com- ing in plantations or on lands where heavy fuels are bination. By such a process we shall know better what to present. For the most part, fires are used in winter and expect at all times, and we can improve the training of are allowed to spread only against the wind. In each of men for fire control responsibilities. our forest regions, some experimental use of fire for a Under a joint arrangement with the State of Georgia, variety of desired benefits is in progress. the first forest fire laboratory was built at Macon and The second subject concerns the system of rating the officially dedicated in November 1959. A second and daily fire danger based on current weather, condition of somewhat larger laboratory is being completed at Mis- vegetation, and amount of moisture in natural fuels. soula, Montana. It will be dedicated September 12, 1960. These rating systems are empirical, but have proved of Arrangements have been made for interested delegates to such value to fire control agencies that they are con- inspect the Missoula laboratory following the adjournment tinually gaining in importance and use. We have eight of this Congress. Mr. J.S. Barrows, who is giving a regional systems in the United States.Canada, as re- paper on the usual project being conducted on fire-setting ported by Mr. Macleod, has a single system. At present, lightning storms, is in charge of research there. He will we are working to unify our regional systems and, if pos- be happy to tell you more about all aspects of the pro- sible, improve them. Through further research, we hope gram. to make the forest fire danger rating a standard measure- While emphasizing more basic research to serve forestry ment for foresters throughout the world. most effectively, we shall continue to work on all phases The study of the relationships between forests and fire of the applied research outlined by Mr. Macleod in his is not a narrow specialty in forest science. These relation- paper.It will be a process of continually raising the ships control the basic ecology of forest lands and the ceiling on what is known, but of currently applying the natural selection of species on a large portion of the best we know to the solution of fire problems. In this look world's forests; they have sociological and cultural signifi- ahead, there are two subjects in applied research on which cance for man himself, and the potential for determining Mr. Macleod touched lightly.I think they may be of whether the world's most important interest to many of you. will continue to serve man's primary needs. In developing The first is the use of fire as a beneficial tool in manag- a better understanding and control of these relationships,

998 Fifth World Forestry Congress Proceedings we are preparing the way for leadership by professional Etats-Unis sont exposés brièvement sous forme de supplement a la communication precédente présentée par M. Macleod, délégué foresters.It is not enough to turn over the responsibility canadien. for protection from fire to subprofessional firefighters, En conclusion, l'auteur demande qu'on prenne davantage con- regardless of how well trained they may be. We have fire science du role du feu dans la sylviculture et qu'on organise les problems that demand the best of modern technology and cadres professionnels dans ce sens. research in the years ahead. They have been neglected in professional forestry.I am convinced that they need La Importancia de los Incendios para la Silvicultura more recognition. I'm sure there are many other foresters Mundial here who agree. Los incendios son de doble importancia para la silvicultura mundial cuando se recuerda aquello de que "Ia madera arde". RESUMES En Norteamérica son objeto de constante atención las investiga- ciones y los métodos de aplicación destinados a perfeccionar los Importance de l'incendie dans la sylviculture mondiale sistemas de extinción de los fuegos forestales. Se ha adelantado mucho y se espera mayor progreso aCn, aunque no debe espe- L'importance de l'incendie pour la sylviculture mondiale peut rarse una solución completa, con los recientes métodos que emple- s'exprimer en trois mots: "le bois brüle". an la aviación y la quImica. La mayorIa de los fuegos se dominan En Amérique du Nord, les travaux de recherche expérimentale en las areas pequeñas. Pero se ocasiona mucho daño con sOlo et technique destinés a faire progresser les moyens de lutte contre unos cuantos fuegos grandes al año, que no pueden dominarse l'incendieonttoujours retenu l'attentiondesintéressés.Des con los rnétodos ahora en uso. Para impedir su propagaciOn hay progrès considérables ont dté réalisés, et d'autres progrès, mais que conocer mejor las caracterIsticas de estos incendios. non une solution definitive,sont a prévoir, grace a l'emploi La falta de investigaeión básica sobre la propagación de los d'avions et de produits chimiques. La plupart des petits incen- grandes incendios en materiales combustibles s51idos es, hasta la dies sont maitrisés. Mais les quelques incendies de grande enver- fecha, un obstáculo para pronósticos seguros y constituye un gure qu'il est impossible de maitriser avec les mdthodes actuelles obstáculo para ulteriores progresos. A fin de remediar esta causent chaque annde des dommages considérables. Pour réussir deficiencia se ha creado una cornisión investigadora de incendios a limiter l'étendue de ces incendies, il est indispensable de corn- en la Academia Nacional de CienciasConsejo Nacional de In- prendre a fond leur comportement. vestigaciones de los Estados Unidoscon el objeto de estirnular L'absence jusqu'ici de travaux de recherche fondamentale sur la investigación básica por parte de los expertos en ciencias fisicas les incendies se propageant librement qui attaquent des combus- aplicadas a este campo. Además, el Servicio Forestal de los tibles solides limite les possibilités de prevision et a considerable- Estados Unidos está organizando tres laboratorios de investigaciOn ment entravé le progrès.Pour remddier a cet état de choses, de incendios forestales que servirán de centros de investigaciOn l'Académie nationale des sciences et le Conseil national de la básica y aplicada para beneficio de la silvicultura. El segundo de recherche des Etats-Unis (U. S. National Research Council) ont estos centros, situado en Missoula, Montana, será inaugurado el créé une commission de recherche sur l'incendie chargée d'encou- 12 de septienibre de 1960, después del Quinto Congreso Mundial rager les spécialistes a poursuivre des recherches fondamentales de Silvicultura, y estará listo en esa fecha para ser inspeccionado dans ce domaine. En outre, le Service forestier des Etats-Unis por los delegados a este Congreso. procIde actuellemerit a l'organisation de trois laboratoires de La investigación sobre el ernpleo del fuego corno parte del recherche sur les incendies de forêts, qui doivent servir de centre programa de administrack5n de tierrasforestales y el actual pour les travaux de recherche pure et appliquée mise au service esfuerzo para unificar los sistemas de catalogación de los riesgos de la sylviculture. Le deuxième sera officiellement inauguré le 12 de incendio en los Estados Unidos, se estudian en este trabajo septembre a Missoula (Montana) après le Cinquième Congrès brevemente por via de suplemento al anterior presentado por el forestier mondial et pourra être visité par les délégués a ce señor Macleod del Canada. congrés. El autor concluye solicitando que se dé mayor importancia al ILes recherches sur l'utilisation du feu comme instrument d'amé- papel que desempeñan los incendios de bosques en la silvicultura nagement des forêts et les efforts faits actuellement pour uni- y una direcciOn profesional de más envergadura en esta especiali- formiser les échelles de classement des dangers d'incendie aux dad.

Test of Sodium-Calcium Borate inControlling Lake States Forest Fires

GENE A. }fESTERBERG Associate Professor of Forestry, Michigan College of Mining and Technology, Houghton, Michigan, U. S. A. For many years borates have been employed in in- developments in American forest fire control techniques dustry for their fire-suppressant or flame-retardent effects in the past five years. when applied to textiles, paints, paper, insulation, and In 1956, the California Division of Forestry and the U.S. Forest Service, in cooperation with the United States many otherwise highly flammable products. When it is Borax and Chemical Corporation, conducted preliminary available, water is often used in fire suppression work, field tests (3)1 on the fire retardency of sodium-calcium although foresters have long considered using chemicals borate2.Principalingredients of the chemical are a that would increase the cooling effects of water or that would induce a more lasting fire-retardenteffect on 'Numbers in parentheses denote the references listed at the end of this paper. forest fuels.The use of a borate as a chemical fire 2 The chemical is marketed under the registered trade name- retardent, indeed, has become one of the most significant FIREBRAKE.

Forest Protection 999 speciallyprocessedcombinationofcalciumborate plied to fuels well in advance of a fire.Collectively, the (Ca3B60115H20) and sodium-calcium borate (NaCaB5O9 design of these six live-fire tests permitted a rather clear 8H20). In dry storage, FIREBRAKE is a fine, pinkish to evaluation of sodium-calcium borate's effectiveness as a white-colored, water-dispersible powder. For use on forest retardent in controlling Lake States forest fires. fuels as a fire retardent an aqueous mixture of the chemi- It was established that all borate applications would cal (referred to as a "slurry"3) is prepared. be made using equipment and appropriate densities sug- Although the material is normally stored in the powdered gested as minimum treatments by personnel experienced form, in these Michigan tests the slurry mixtures main- with the fire-retardent properties of the chemical. Mr. tained stability in suspension for many days when stored Paul Giguere, of the United States Borax Research Corpo- without agitation in 300- and 500-gallon tanks. ration, supervised mixing the slurry and conducted the applicationsofsodium-calciumborate frommobile Test Objectives ground units. The remainder of the ground crews had no On May 12 and 13, 1958, the Forestry Department of experience with the chemical. Aerial drops of the chemi- the Michigan College of Mining and Technology, in co- cal were made from Stearman and DeHavilland "Beaver"- operation with the Forest Fire Control section of the type air tankers. Michigan Department of Conservation, conducted a series of six live-fire tests to evaluate the suppressant effect The Test Area of this borate.Use of the chemical among California The live-fire tests were conducted on State-owned lands brushland fires had yielded promising results (3). There- in the Baraga Pine Plains about twelve miles southwest fore, the principal objective of these Michigan tests was of the town of L'Anse, Baraga County, Michigan. About to deteimine the effectiveness of sodium-calcium borate 30 acres of dense jack pine (Pinus banksiana) and up- in retarding fires burning in the most hazardous forest land brush were burned during the tests.Brush cover fuels generally recognized in the boreal forests of the consisted of blueberry (Vaccinium spp.), bracken (Pteri- Lake States.In addition, thetests also permitted a dium aquilinum), sweet fern (Comptonia peregrina), practical demonstration of the several types of equipment sand cherry (Prunus pumila), several grasses, and other that may be used for mixing and for applying borate plants related to this "jack pine plains" ecological type. slurry. Most of the live-fire tests were prepared by apply- In addition to these natural fuels, pine tops and limbs, ing the chemical from mobile ground units. Also, numer- cut six months earlier, were moved into the area to com- ous air drops of borate slurry were made from two types plete the test design of certain experiments (Figure 1). of fixed-wing aircraft. The main objective of adding pine slash to certain areas The California trials (3) suggested a need for tests of was to assure a critical test of the retardency of the borate equipment to mix the chemical more rapidly. Therefore, when applied to these more dense accumulations of high- it was in the scope of these experiments to examine more hazardous fuels. thoroughly the problems of mixing and storing the slurry. Each of the six live-fire tests was isolated from the fuels The test design included application of FIREBRAKE of the other experiments and each test had one or more directly to burning natural fuels.Other tests permitted specific objective (Table 1). an appraisal of the chemical's fire retardency when ap- The maximum burning index for May 12-13 was in the range of 25-49 and was classed "very high fire danger." Grass and similar fine fuels were in the "dead term "slurry" is applied to the thick mixture of 4-5 pounds of sodium-calcium borate per gallon of water. A detailed analysis and curing" condition. A very high burning index buildup of the physical and chemical properties of the chemical are occurred in the two-day period of the tests. Some meas- presented in the publication, Firebrake (1). ure of the fire danger is indicated by the fact that 34 spot

Table 1.Test design to evaluate the fire retardency of sodium-calcium borate. Natural, high-hazard fuels of the Lake States forests were used in most tests.* Test Type of Fuels Burned Objectives of the Test Open upland brush with dense, semi-dry pine tops To test: (a) the chemical when applied a day or so before a fire and branches piled 4-5 feet high in two windrows. occurs (Fig. 1); and (b) to evaluate FIREBRAKE as a retardent of fires among dense piles of coniferous slash. 2 Open upland brush with a moderate scattering of To suppress or contain a spot fire by aerial drops of slurry from semi-dry pine slash 12-18 inches deep. chemical-tanker aircraft. 3 Same as 2, above. To develop a safe holding line by applying borate from mobile tractor-tanker equipment. 4 Pine with pile of semi-dry pine slash at the To demonstrate the effectiveness of aerial drops of borate in base. controlling snag fires. 5 Five tons of dry, baled flax straw placed in two To evaluate borate in controlling spread of fire among straw piles. piles; and to check the chemical's lasting qualities as a fire retardent. 6 Twenty acres of dense, young jack pine,2-6 To test: (a) the effectiveness of FIREBRAKE applied in advance inches d.b.h. of a running crown fire; and (b) chemical air drops during such a fire.

* Detailed description of the test design appears in Technical Bulletin 4, Ford Forestry Center (2).

1000 Fifth World Forestry Congress Proceedings fires were suppressed beyond the experimental control line set to contain the three-dimensional fire which de- veloped during Test No. 6.

Results and Conclusions No effort was made to use instruments in measuring fire intensity. Instead, a committee of four men with long and varied experience in Lake States forest fire control work was appointed. The group assigned were: John A. Anguilrn, Chairman (Michigan Department of Conserva- 1k tion); Robert Kolbe (Connor Lumber and Land Co.); 1k Neil LeMay (Wisconsin Conservation Department); and John K. Brownell (United States Forest Service). These men evaluated the effectiveness of each application of the chemical, basing their report on observations of the actual fire tests. A Mixing and Storing the Slurry The committee noticed that, at times, there was a lag in the available amount of prepared slurry. For the most part, the resulting problem was directly attributed to the inadequate size of the storage tanks available during these tests. Lack of experience among the men on the mixing crews also contributed to inefficiency in this operation. Legend Pretreating Forest Fuels Untrcatea dry 1kUnfpeatd Borate, when applied to substantial amounts of the most pine s/ash pine stwn,as Borate - treated, &rsite- treated hazardous forest fuels in the Lake States region, makes a dry pine 5/ash Stumpscr,d chckpvse very effective firebrake.It not only prevented spread of '-' Borote-treated fire, but in the four-foot-high windrows of dry pine slash veqcation in Test No. 1 (See Figure 1), the chemical served as a FigureI.Design for experiment No. I proved a most significant test most effective fireproofing agent.Also, a two-foot-wide of the fire-retardency of sodium-calcium borate(2).Two parallel path of FIREBRAKE-treated fuel stopped the surface fire 200-foot-long windrows of semi-dry pineslash were piled ten feet among a dense ground cover of bracken, blueberry, sweet- apart in a direction perpendicular to the wind. These rows were four fern, and pine slash in Test No. 1. to five feet high and were chemically treated two days in advance of the test in the alternating pattern shown above.Dry pine branches Test No. 5 clearly established that contiguous piles of were scattered to interconnect these rows. straw, hay, lumber, and other inflammable materials can be made safe from fire by borate application.It would appear that chemical treatment of structures adjacent to tendency, and possibly permit a successful holding opera- burning buildings would similarly be protected from tion. radiated heat and windblown embers. When treated with sodium-calcium borate, stumps, Using Sodium-Calcium Borate While Backfiring stubs, and other large-sized wood fuels on the ground will Test No. 3 proved borate to be an excellent chemical not burn even when amid running surface fires in dense for establishing and holding a backfire line.In light, brush. These resinous pine woods, when dry, are nor- mally easily ignited when exposed to surface fires. Chemi- upland brush with scattered semi-dry pine slash, a two- cal was applied to these types of fuels in Test No. 1 and foot-wide treated line is ample.If denser accumulations Test No. 6.In both instances, the treated fuels would of brushy coniferous fuels occur, however, width of the not burn, while nearby untreated fuels of the same type treated line would have to be increased to four-, six-, and condition were readily ignited. or even to an eight-foot width. In Test No. 6 a transect of dense jack pine reproduc- tion was treated with chemical on the south and east Chemical Drops by Aerial Tankers margin of the area. Application was made the day before There were three opportunities to evaluate the fire con- the test was conducted. The committee judged that the trol effectiveness of sodium-calcium borate applied by borate slurry was singly responsible for knocking down aerial drops. Each of the fixed-wing aircraft used in the the fire so it could be contained, controlled, and mopped tests had a tank capacity for about 80 to 90 gallons of up. After this critical test of borate, the evaluating com- mittee reasoned that a chemical fireline could be con- slurry. This proved to be a sufficient quantity of borate structed along a road or other break that may naturally to contain small-area fire targets. However, Test No. 6 occur in dense, young, pine forest types.The borate clearly established that, for maximum effect, aerial drops would insulate these trees from fire, reduce the crowning on running crown fires of a three-dimensional type must

Forest Protection 1001 deliver large quantities (500 to 700 gallons) of slurry in longtemps avant les incendies expérimentaux.Ii a également été one drop. appliqué au cours même d'autresessais.Les conditions des experiences comprenaient l'utilisation de borate sur des accumula- Three aerial tanker drops of borate were made from tions denses de pins de Banks demi-secs, sur des déchets d'abattage about 100 feet above the fuels in Test No. 3. The pilot de pin éparpillés et allumés par endroits, dans un contre-feu, sur placed the first two drops along converging lines to form des chablis secs de pin, sur cinq tonnes de paille de lin sèche en a "V" downwind of the spot fire. These contained the fire piles,et,afin d'en retarder l'avance, sur un incendie de cimes galopant parmi vingt acres de jeunes pins de Banks touffus. as it moved into the wedge of treated fuel. A third drop Une commission d'évaluation fut constituée, composée d'experts was applied directly on the spot fire. Only minor mopup en matière de lutte contre les incendies. Ceux-ci ont présentC leur of small patches of isolated fuels was required.The rapport après avoir assisté aux incendies expérimentaux du Michi- Committee concluded that on small spot fires, low-level gan an cours desquels le borate de sodium-calcium a été utilisé. Ce produit chimique a constitué une protection efficace contre les aerial tanker attack with sodium-calcium borate yields a feux de surfaces parmi les combustibles les plus dangereux. La most effective containing action. commission a également ddclaré que ce produit a réduit l'intensité The "pinpoint" aerial drop of slurry on the 35-foot des incendies de cimes galopant parmi des pins de Banks touffus, et a ignifugé a un degré exceptionnel des matériaux tels que des burning jack pine snag in Test No. 4 proved an effective piles de paille de lin sèche. Des lâchers aériens de borate ont holding action. The first 80-gallon drop retarded the fire. donné d'excellents résultats en retardant l'avance du feu sur des A second drop of FIREBRAKE so suppressed the remain- branches enchevêtrëes et enflammées par endroits.Cependant, ing embers that it was oniy necessary to spend a few les petites quantités de borate qui ont pu être lâchées par les avions-citernes utilisés au cours de la demonstration n'ont pas minutes in mopup work. donné de résultats concluants en ce qui concerne l'extinction de To "knock down" or otherwise contain a three-dimen- l'incendie des cimes. sional, running crown fire in dense jack pine is, indeed, a critical test of a chemical fire suppressant. The pretreated Pruebas del Borato de Sodio Cálcico en el Control de line in Test No. 6 successfully retarded the crown fire Incendios Forestales en los Estados de los Grandes throughout the length of the transect of living trees to Lagos which it had been applied. The aerial drops, however, La tendencia actual hacia la generalización del empleo de did not appear to have a telling effect on this fire. agentes quimicos pararetardarlacombusti5n enincendios sugiere Ia necesidad de conocer mejor los efectos de estas sus- Two conditions explain this single negative action by tancias preventivas. El borato de sodio cálcico tiene ciertas pro- the chemical: (a) the aerial drops did not contain suffi- piedades que hacen recomendable su uso en el control de incen- cient volume of slurry to yield a lasting effect on the fire dios forestales. Mezclado con agua y rociado sobre las materias at any one point; and, (b) the pilots could not fly close combustibles de los bosques, el borato forma una costra blanca que retarda la propagación de incendios. to the fuels while making the chemical drops. The rol- En la region forestal de los Grandes Lagos se efectuarori seis ling convection column (often 200 to 300 feet above the pruebas con materias muy infiamables para determinar la eficacia fire's perimeter) did not permit the pilot an opportunity de este producto qulmico. Se aplic6 el borato con bastante anti- to make low-level drops.Because of reduced visibility, cipación a ciertos conatos de incendio, y también se usó en otros experimentos con fuego activo. Parte de las pruebas consistieron the chemical tankers had to fly above the convection en usar el borato en densos pinares semisecos; en fuegos aislados column at the time the drops were made. Thus, it was de ramas de pino, en contrafuegos, en fuegos de tocones secos de evident that smaller quantities of slurry, when dropped pino, en montones de cinco toneladas de paja seca de lino y como from several hundred feet altitude, were so scattered retardante en un rápido incendio propagado por las copas de un when they reached the fuels that these drops yielded little denso rodal de pinos jóvenes de ocho hectáreas. Se escogió una comisión evaluadora integrada por hombres de if any suppressant effect on such a strongly surging fire experiencia en el control de incendios que presentaron su informe system. después de observar estas pruebas con fuego activo, realizadas en Michigan, en las cuales se usó el borato de sodio cálcico.Este References agente qulmico demostr6 ser la defensa más eficaz contra los fuegos superficiales en las materias más inflamables. La comisión Anonymous,1957. FIREBRAKE.Chemicalforestfire informó también que el producto quImico sirvió para extinguir retardent.UnitedStates Borax and Chemical Corporation fuegos voraces en densos pinares y que tiene propiedades excep- Tech. Bull. FB/l:l-6. cionales para hacer incombustibles a materias infiamables como Hesterberg, Gene A., 1959. Controlling fires in Lake States la paja seca de lino amontonada.El borato arrojado desde timber types with sodium-calcium borate. Ford Forestry Cen- aviones sobre ramas de pino y tocones es un espléndido retarda- ter Tech. Bull. 4:1-21. dor de fuegos aislados. Sin embargo, las pequefias cantidades de Miller, H. R., and Wilson, C. C., 1957. A chemical fire borato que pudieron aplicar los aviones rociadores empleados en retardent. Calif. For, and Range Expt. Sta., U.S. Forest Service la prueba, tuvieron poco efecto en los fuegos rápidos por las copas Tech. Paper No. 15:1-19. de los árboles. RESUMES Essais de borate de sodium-calcium dans la lutte contre Comments les incendies de foréts de Ia region des Grands Lacs John A. Zivnuska (U.S.A.): La tendance actuelle vers une utilisation accrue de produits In commenting on the thorough and excellent paper chimiques retardant l'avance du feuattirel'attentionsurla which Mr. Luke has presented, I can only attempt to nécessité d'obtenir plus de renseignements sur ces produits.Le borate de sodium-calcium possède certaines qualités qui militent emphasize and illustrate further certain of his points. en faveur de son utilisation dans la lutte contre les incendies de In doing this, I will draw on the experience of my home forêts. Mélange a de l'eau et projeté sur les combustibles fores- State of California. Our fire seasons are long, hot, and tiers,le borate forme un revêtement blanc et dur qui retarde is l'avance du feu. dry; our terrain steeply mountainous; our wildland Six essais ont été effectués en vue d'évaluer l'efficacité de ce values are high; and we have developed what are probably produit sur les combustibles les plus dangereux dans les Etats the most highly organized and mechanized fire protection de Ia region des Grands Lacs. Le borate a été appliqué assez organizations to be found in any nation. Yet, our prob- 1002 Fifth World Forestry Congress Proceedings lems differ only in degree from those of any region with Fourth and last, I agree entirely with Mr. Luke's model forest, brush, and grass lands. for determining the most profitable level of fire control Our largest two protection organizations are the Cali- expenditures by balancing additional costs of protection fornia Division of Forestry, which protects some 32 mil- against additional reduction in fire loss. However, after lion acres, and the U.S. Forest Service, which protects more than two years of research onthis question for the 20 million acres in the State. There are four main points California Division of Forestry, I must stress that this which I would like to emphasize, based on the experience apparently simple procedure involves some exceptionally difficult economic problems. The determination of fire of these organizations. damage involves not only the appraisal of timberand First, after the basic fire protection organization has forage damage but also the unresolved issues of the effec- been established, further progress in reducing fire loss is The primarily a problem in meeting periods of extreme condi- tiveness of protection effort in reducing damage. tions when the conflagration potential is high. These are effect of the control effort is confounded by the large num- years of cumulative difficulty in fire control, but even ber of variables involved.The conflagration burning more critical are the short periods of extremedanger. under extreme conditions isat the small end of the For example, the Mendocino County unit of the Division probability curve in terms of occurrence, but this is the of Forestry lost 55 percent of the total area burned in very fire against which we must measure theeffectiveness eight years to a series of sixteen fires occurring in a of fire protection. For the analyst as for the firefighter, single three-day period.Such difficult periods may be these periods of extreme difficulty remain the great chal- associated with difficult years, but they may also develop lenge in fire control. in otherwise normal years or even outside the normal fire Warren B. Gayle (Canada): season. The most disastrous timber fires in a number of years in the Sierra Nevada occurred at the end ofOctober Mr. Greeley has outlined the entire scope of aircraft 1959, several weeks after the close of the usual fire support of ground firefighters. Probably the most impres- season and after heavy rains in the early fall.Clearly, sive role of aircraft is its function as a water bomber. forest officers must be highly sensitive to current weather During the last few years we have experimented with and fuel developments as well as to the pattern of de- various types of aircraft.If 100 gallons does a job on a velopment for the year. fire, then shouldn't 1,000 gallons be better? The latest Second, efficiency and economy in meeting the highly application is the conversion of the Martin Mars Flying variable periods of extreme difficulty require organization Boat to perform as a water bomberan aircraft capable on a broad State- or region-wide basis, withthe individual of carrying 7,200 U.S. gallons. operating units being organized to support and reenforce These aircraft were used in the South Pacific during each other.The California Division of Forestry isor- the latter part of the war and were about to be scrapped ganized into six districts and twenty-nine county units. last year.Six of the leading logging firms in British The county unit personnel and equipment flow freely Columbia formed a new companyForest Industries Fly- across administrative boundaries to meet emergency situa- ing Tankers Limitedto buy the four Mars and convert tions. Thus, in 1954 exactly half of the firefighting time one of them as a tanker and try it outduring the 1960 in Tulare County came from personnel from other units, fire season. while in 1955 the Tulare County fire personnel devoted Let me tell you something about this aircraft. A large, more than 96 percent of their firefighting time to firesin 7,200 gallon tank was installed in the main cargo section, other counties.The Forest Service isalso highly or- and was then partitioned transversely and fore and aft, ganized for such flexibility in fire control, with personnel giving in effect, four tanks of 1,800 gallons each. They being shifted not only among the seventeen National then installed two hydraulically operated scoops which Forests in the State but also between States. can be put down when the aircraft is planing on topof the Third, the financing of fire protection must recognize water at 75 miles per hour. Filling the tanks with 7,200 the highly variable and critical nature of these difficult gallons of water with these two scoops takes only 24 predictedover theusual seconds. periods which cannot be Fully loaded (with a total weight of 160,000 lbs.) the budgetary period. As Mr. Luke has stressed, adequate aircraft can climb at a rate of 450 feet per minute. Of budgeting for fire control requires both a normal operating the narrow ofreservefunds formeeting course, it has limitationsit cannot get into budget and provision valleys and steep country where the Stearman and Grum- emergencies. A high degree of flexibility in these emer- with all gency funds is essential.The Santa Cruz County unit man TBM's perform so well, but from one drop of the Division of Forestry required $108,164 of emer- four tanks, it can spread the equivalent of one tenth of an gency funds in 1948, but in 1955 used only$34 of inch of rain over an area 600 feet long by 200 feet wide. such funds. Furthermore, long experience is required to In other units of measurement, it can spread 2½ milli- show the full range of demands on such funds. From meters of water over an area of 180 meters by 60 meters. fiscal 1951 to fiscal 1959 the Forest Service spent an Assuming that the fire is 10-15 miles from the source average of $4.7 million of emergency funds annually in of water, the aircraft can drop 29,000 gallons per hour. California, with the amounts ranging from a low of $1.5 At the rate of $1,600 per hour flying cost, this means million to a high of $7.2 million. Then the very difficult that we can deliver water on a fire for less than six cents conditions of fiscal 1960 required $17 5 million of emer- per gallon. gencyfundssubstantiallymorethandoublethe Those of you who will be going to British Columbia previous high and nearly 4 times the average for the nine after this Congress will see the Martin Mars in action at years preceding. Port Alberni on September 14th. Don't miss it! Forest Protection 1003 All these things that Mr. Greeley has told us about the runhe can forget all about the fire and concentrate use of aircraft did not just happen. In order to achieve only on the marker. Then, if his first drop is not ac- progress many problems had to be overcomeand if we curate, his correction on his second drop is made very want to advance further, there are many other problems easily. which we must solve. In the time remaining at this session we must identify these problems, and by informal dis- use of Helicopters for Water Bombing cussion, and the help of Mr. Greeley, find some way to Because of their very light payload (30 to 75 gallons), provide even more efficient aerial support of ground fire- to be effective, the retardant must be dropped from a fighters. These are some of the problems: very low altitude.In such cases is there not a fanning Communication effect by the rotors on the fire?With the use of the turbine motor, and much greater carrying loads (S62 and It must always be remembered that the fire bosson the Flying Crane), there should be better dropping and pick- ground has complete charge of all firefighting agencies. up techniques developed. When this is done, the large The fire retardant must be dropped exactly where the fire helicopter may completely replace fixed-winged aircraft boss wants it and nowhere else. as an aid to firefighters. It has happened in the past that the fire boss had an These and many other problems must be solved so area surrounded by an adequate fire guard and wanted that we can make the best use of aircraft presently this certain area to burn out. Then, to his amazement, available, and of others still on the drawing boards. water was dropped exactly on the spot he wanted to burn. We have heard about the use of bird-dog planesa Clive M. Countryman (U.S.A.): light, highly maneuverable aircraft that can spot the fire I think Mr. Inoue's paper brings out once again the and direct the bomber on his final run. This, of course, great similarity of fire control problems throughout the is better than nothing, and we have found it most useful world, particularly that of prediction of fire behavior. for combatting lightningstrikes.Where thereare a which is fundamental to all fire control action. hundred or more strikes burning in the same area, each I was particularly interested in Mr. Inoue's reference must be evaluated, and priority for action is then estab- to the inter-relationships of wind, topography, ocean in- lished by the bird dog. fluences, and pressure distribution to fire weather in But where there are men on the ground, it is essential Japan. Considerable attention has been focused in recent to have radio communication from the firefighters to the years on these effects along the Pacific Coast of this aircraft. When there is a great deal of smoke, the pilot country.This problem is particularly important in the rarely hits the target on the first drophe must be talked California region, where the characteristically weak sum- in, gradually decreasing his under- or overshooting. mer synoptic weather patterns and the sharp contrast between continental and maritime influences result in very Identification of Target Area strong local controls on local fire-weather patterns. For the pilot, the accuracy with which he hits the target Recognition of the importance of the local influences on local weather is now leading to the development of a new can be very frustrating. Even on his final run, he is not branch of meteorological sciencethat of "mountain" really sure of the exact spot where the fire boss wants the or "topo" meteorology. Although research in this field is water. If he has to make a correction on the second run, comparatively recent, it has already indicated that some of he can't really remember the exact spot he was shooting the concepts of air movement in mountainous areas may at in the previous run. be badly in need of revision. For example, downcanyon So we have tried various methods of identifying the winds in the afternoon, when theoretically they should be target area. Where we have a bird-dog plane, and no men blowing upcanyon, have, on occasion, caused firefighters on the ground, we have used aluminum milk bottle caps. great difficulty in the mountains of southern California. These are thrown from the bird-dog aircraft and land on Thought at first to be the result of marine air spilling the foliage and ground, where they can readily be seen over the mountains, recent investigations have shown that by the water bomber plane. This has only been tried in the phenomena often occur when the marine influence is the more open-grown, interior type country and would least. Research has also shown that this windfiow pattern not be effective in the dense coastal forests. occurs far more frequently than commonly supposed and We have also tried paper strips about 10 inches wide, is not confined to coastal areas. Such winds have figured painted with an orange or red fluorescent paint, which prominently in deaths of firefighters in recent years. Re- shows up vividly in open stands or cutover areas, but search has so far revealed some clues to the cause of such is of little use in dense forests. winds, but much work yet remains to be done before they By far the best target indicator is a helium filled bal- can be predicted with a satisfactory degree of accuracy. loon.It is now possible to purchase small bottles of Much of the needed research outlined in Mr. Inoue's helium gas and brightly coloured plastic balloons. These paper is concerned with the environment in which the fire balloons are filled with the gas, made captive with fishing is going to burn. In the past, a major part of fire research line, and are then allowed to rise above the level of the effort, both here and elsewhere, has been aimed at estab- tree tops. lishing the relationship of various phases of fire behavior This seems like a great deal of work to be performed with individual environmental factors affecting that be- on a going fire, but the resulting pilot accuracy is astonish- havior. Such research, of course, is necessary to a basic ing. The pilot no longer has to try to identify the area understanding of fire behavior.Often overlooked, how- by a verbal description as he is coming in on his bombing ever, is the fact that the environmental factors are them- 1004 Fifth World Forestry Congress Proceedings I selves dependent variables.In ordertopredictthe tions, and the experienced men have becomeleaders. behavior of a fire over time and space, we must also be trust that they will not suppress theimagination of the able to predict the spatial and temporal variations of the recruits and that we will see new programmestaking their environmental factors that are going to affect fire behavior. place alongside those already established.Also I hope For example, it is of little practical value to fire control that we will continue to heed the advice and warningsof to know the quantitative relation between windspeed and experience. rate of spread unless we also know how the windspeed is Mr. Macleod has remarked on the great swingtoward fundamental research, and I think that we all realize that going to vary over the area of the fire during the time it results will burn. in 20 to 30 years this approach will be yielding that are beyond our imagination at the moment.On the Allan Roy King (Australia): other hand, he has mentioned the short-termresearch I consider myself privileged to be invited to comment that is undeniably productive but inevitablylimited. Yet, even though we have these two concurrentattitudes, I on Mr. Macleod's paper and to add just a few of my in the gap thoughts on forest fire research. feel that we need more programmes that travel between them. I find that I agree with all of the points the author has For example, we propose to study thefundamentals of expressed and, like him, look back on the wonderful past fire spread with simplified models in wind tunnelsand at and forward to a promising future. We all realize that the same time examine the records ofactual wildfires. this is a period of rapid growth with great opportunity Should we not also use more experimental fires, litby for us all.I am sure that the pioneers of this line of environments, research are pleased that we now can enter into work ourselves for specific purpose in natural and let all the approaches blend together withprogress? from which they were barred in the past because of lack Then, too, basic flame studies using highlysimplified of facilities. systems have been pursued for decades,whilst at the same Throughout the world, money is flowing into the effort, time men have observed given flame phenomenain fires. and yet I wonder whether the supply issufficient.I Should we not try at the moment to institute more pro- wonder because I do not know; in fact, nobody does. grammes steering a middlepath between the extremes? Thus, I would like to stress Mr. Macleod's point on the As a parting remark, I would like to accent theabsolute need for research on the economics offire,anti-fire need to study, not the average fire, but the most severe activity and fire research that, alone, will indicate the five percent that does most of the damage. correct balance of expenditure.Guesses are sufficient These are a few personal ideas that come to mewhen for devotees such as we are,but figuresare most reading Mr. Macleod's paper.I am sure that he would persuasive to those who control finance. be pleased to hear your thoughts and answer your ques- New men are entering the laboratories and field sta- tions now.

Forest Protection 1005