Notes from Honduras

POPENOE: HONDURAS NOTES 255

NOTES FROM HONDURAS

Wilson Popenoe Guatemalan race. In the highlands of Central

Escuela Agricola Panamericana Guatemala, around 8000 to 9000 feet, grows a wild avocado. Our botanist Louis Williams Tegucigalpa considers this a new species and has given it i I can hear you ask, "Why are we interested the name Persea nubigena. There is still a in Honduras?" Perhaps some of you may even possibility that the Guatemalan race may be thinking along the lines of the Biblical have had its origin in this wild form, or in one character who inquired, "Can any good thing of several others, very similar in character, come out of Nazareth?" which are being discovered in Guatemala and Honduras. For several years we have been trying to make Escuela Agricola Panamericana a trop The West Indian race has been even more ical outpost of the avocado industry. We are elusive. Recently, however, the botanist Paul situated in the very heart of the region where Allen has found a wild avocado in Costa Rica the West Indian and Guatemalan races may which may be the thing. I believe I saw this have had their origin. Around us grow wild in Panama, years ago, but I was not able to species of Persea of interest as possible root- get botanical specimens. stocks. We are afflicted by root disease to a The Rootstock Problem perfectly magnificent degree, thus enabling us Apart from what I trust is a laudable curi to give potential new rootstocks the acid test. osity in finding out where our cultivated avo Because of favorable climatic conditions, we cados came from, the search for wild forms can propagate new varieties and bring them has its practical aspect—an aspect which has into production so rapidly it fairly makes your assumed great importance in California. I head swim, thus enabling us to get a prompt refer to the problem of rootstocks. Particu reading on some of their possibilities for other larly in heavy soils—which are abundant in regions, such as yours; And we don't have southern California—avocado trees have died any hurricanes to bother us. We don't even by the thousands, as all of you are aware. have respectable earthquakes. The pathologists are convinced that a fungus, If I have convinced you that something good Phytophthora cinnamomi, is responsible. This for Florida might come out of this Nazareth, organism appears to be common in that state I will comment on a few of the lines we are and in many other regions. It has been iso following. I will commence by talking about lated from sick avocado trees in Peru, in Hon a subject of somewhat recondite interest, but duras, and 1 believe in El Salvador. I do not which in the end may have practical impor know much about its occurrence in Florida, tance. but some of you who are familiar with the sit Wild Avocados uation can talk about that. For many years I have personally been at It has been—and is— the feeling in Cali tempting to trace the three cultivated avocado fornia that commercial avocado culture in that races back to their wild progenitors. Time state will be limited to certain areas unless and again I have thought I had them pretty a rootstock can be found that is more resistant well tied down, only to see them slip through to Phytophthora than any of those which has my hands when new information was brought been used to date. Since quarantine restric to light. For some time now, our California tions have made it difficult to import seeds of colleagues have been chasing the Mexican avocados and related species into the United race from the Rio Grande down to the Isth States, we have hoped that we might be of mus of Tehuantepec, without having found it, assistance by making some preliminary trials as yet, in a state which was convincingly wild. in Honduras. We have been materially as Carl Crawford of Santa Ana, California, has sisted in this work through having withus spent a lot of time and money on this quest, two eminent botanists, one of them Louis Wil in which it is quite probable that he will ul liams, whose name has already been mentioned, timately be successful. the other Paul C. Standley, who is the out I myself have devoted more attention to the standing authority on the flora of Central 256 FLORIDA STATE HORTICULTURAL SOCIETY, 1951

America. These two men have been busily at longing to allied genera of the Lauraceae, work rounding up wild Perseas. such as Nectandra and Ocotea have so far So far, only one thing has shown promise proved to lack congeniality. The same is here. This is Persea Schiedeana, known in true of Bielschmiedea (Hufelandia) anayt a Mexico as chinini, in Guatemala as coyo, and tree from Guatemala which bears a fruit in El Salvador and Honduras as chucte and strongly resembling a good-sized avocado of supte. It is a wild, but usually not common tree the Mexican race. in all these regions—and goes clear down to Incidentally, we have had in our plot num Costa Rica where it is known by the name yas. erous seedlings of rather primitive forms of The fruit is good to eat. It is highly esteemed the Mexican race, brought from Mexico and in the state of Veracruz, Mexico, and also in Guatemala, as well as seedlings of the West parts of Guatemala, El Salvador, Honduras Indian and Guatemalan races, and up to now and Costa Rica. It has been planted in Florida the Mexican seedlings have shown a stronger —George B. Cellon had a tree or two at Mi tendency to die from root diseases at an early ami, and there were a few at the old Plant age than the West Indians; though in our Introduction Garden on Brickell Avenue. All nurseries we have lost many West Indian of these were killed by cold, I believe, before seedlings before they were a year old. Per they had a chance to come into bearing. The haps not much importance can be attached to coyo may be slightly more tender than any of this observation. With us at least, the avo our cultivated avocados, but perhaps if we cado is extremely sensitive to differences in keep it under ground (that is, as a rootstock) soil texture. In a nursery we established last it will get by. The interesting facts are that year, about a quarter of an acre, all the trees it seems to be a fairly congenial stock for the did well except those in an area some 40 avocado (we have healthy three-year-old trees feet in diameter, where they died before the budded on it) and that where avocados on buds had reached suitable size for transplant West Indian roots have died out, it has so far ing. The soil in this small area was sticky, shown considerable resistance to whatever it sandy clay a few inches below the surface. is that kills avocados on our heavy, poorly New Varieties drained soils. There is a tendency for the It is exactly forty years since we introduced stock to outgrow the scion, but no more so than the Fuerte Avocado from Mexico and I budded has been the reverse case with many of our the first trees in the West Indian Gardens at Guatemalan x Mexican hybrids budded on Altadena, California. In spite of the fact that West Indian. Fuerte now accounts for more than 75% of Several years ago a species which has been California's commercial production, time has determined as Persea floccosa was introduced shown that it is not satisfactory in all avocado- into California from the mountains near Ori growing regions. And in spite of the fact that zaba in Mexico. The budwood I brought from literally hundreds of seedlings have since ap that place was used on West Indian seedlings peared and seemed promising commercially, and we lost it. At the College of Agriculture there is still a "variety problem." Most of the in Los Angeles it was saved, and Professor local seedlings have turned out to be what Schroeder told me, when I was there a few George B. Cellon used to call "seven day months ago, that it seemed to be showing con wonders." siderable resistance to root disease. It also There have been some interesting develop seems to be a congenial stock for the avocado, ments. When David Fairchild started me on a as far as can be judged at present. When we ten-year exploration of tropical America, I was saw the fruit in Mexico it looked so much like told to look for one-pound avocados of good a small avocado of the Guatemalan race that quality and good bearing habits. At a recent I did not suspect it was a distinct species. annual meeting of the California Avocado In a plot which we established here at the Society I voiced my grievance: they had made Escuela to test wild avocados and other species me throw away ten years of my life, for now as possible rootstocks, Persea nubigena from they want nothing bigger than an eight or Guatemala has so far shown no promise. Most ten ounce fruit. As you know, there is still of our seedlings died before they were large a strong prejudice against purple avocados. enough to take the bud. Several species be Which reminds me that George B. Cellon once DIJKMAN AND SOULE: MANGO SELECTION 257 told me that he had never ceased to regret ing for Dr. Fairchild thirty years ago!" We having chosen Trapp and Pollock as the first picked out a lot of promising trees and cut two varieties to be put on the market commer budwood. Some went to California, some went cially; he had developed what I believe you home with me to Honduras. folks call "consumer resistance" to purple Of course there were many trees which were fruits which exists to this day. not in fruit at the time of our 1947 visit, so The alternate-bearing habit of the Guate we decided to go back again in 1948, at a malan race seems gradually to be driving this slightly different season; and this time some of race out of the industry, at least so far as the lads from Texas joined us, and we under California is concerned. Just this year the stood your own Ivey Futch was planning to Variety Committee of the California Avocado come. He did not show up—maybe a hurricane Society had to take Nabal, one of my pets, off blew him temporarily off the map. Anyway, we the approved list. I don't blame them. Nabal did our best without him and even visited is a magnificent fruit—one of the finest of its several other avocado-growing regions. race. I chose it in Guatemala, way back in The result of these two expeditions was 1916, because it was such a fine fruit and some 40 selections, which were planted in Cali the parent tree was carrying a tremendous fornia, in Texas, and in Honduras; and sub crop. I gave it the name "Nabal" which is an sequently we sent budwood of some of the Indian word meaning "abundance." When they most promising to Florida, to South America, threw this back at me in California, not long and even as far as Johannesburg, South Af ago, I defended myself strongly. "Sure it rica. I do not think any of these introduc means abundance," I said, "abundance every tions has yet matured fruit in California, but third year." here in Honduras (because, as I tell every I am afraid we are not prepared, here in one, here we have the sort of climate folks Honduras, to give Florida avocado growers think they have in California) we had mature as much assistance in the matter of new va fruit on some of the 1947 selections twenty rieties as we hope to give the Californians. months after insertion of the buds. Since But I want to tell you briefly what we have that time, we have fruited about 25 altogether, been doing. In 1947 Harlan Griswold and and some of them look very promising, so others of the California Avocado Society de much so in fact that we have named and de cided it was time to go back to the native home scribed two, which we call Aztec and Toltec. of Fuerte and get some more varieties with We propose to go on giving Mexican names to the same background—crosses between the further good ones which show up; I have al Guatemalan and Mexican races. It happened ready chosen Zapotec and Huastec and was that a resident of Atlixco had got the fever, going to use Mixtec until someone mentioned probably (I assume) from having heard how that it would be pronounced "mistake" and Fuerte had succeeded in California, and he might eventually prove to be a bit too ap had planted an orchard of about 4000 seed propriate. lings. These were probably 15 or 20 years I do not know what to expect of these va old, hence of mature size. rieties in Florida. If any one of them pans Louis Williams and I joined the Califor out, I imagine it may prove to be in the Ridge nians, and as we went through that wonderful section, rather than South Dade. As far as we collection of potential varieties I thought to can see, there is no West Indian blood in any myself, over and over again, "What a time I of them. Some lean toward the Guatemalan would have had if I could have dropped into an side, some toward the Mexican. The former avocado paradise like this when I was explor may be the ones most worth trial.

A TENTATIVE METHOD OF MANGO SELECTION

M. J. DlJKMAN AND M. J. SOULE, JR. Meeting of the Florida Mango Forum held at Fort Lauderdale on July 11th and 12th, no University of Miami doubt observed the striking number of new varieties on display. Since most of the new Coral Gables varieties shown at its exhibits have been ob Those of you who visited the 10th Annual tained from hybrid seedlings of unknown or 258 FLORIDA STATE HORTICULTURAL SOCIETY, 1951

conjectural parentage, the Mango Forum a (11). In this work of scanning the thousands few years ago appointed a committee of judges of trees scattered over the state, the Forum whose task was (and is) to maintain quality has provided the necessary preliminary selec standards as high as possible for this material, tion upon which further improvement must be in other words to stimulate progressive se based. lection by awarding recognition only to the It should be emphasized that the varieties very best new varieties. selected thus far have nearly all been the re Now that plantings of good and reasonably sult of chance crosses or segregations. In a good varieties have become rather extensive, few cases, we know or assume the identity of the time has arrived for Florida to put her the female parent of a given seedling but there mango industry on a solid basis by adopting a are few authenticated instances of a properly large-scale systematic breeding and selection safeguarded cross having produced a named

program. variety. (This startling fact however was also true of the majority of deciduous fruit crops The Present Status of Selection up to 1900 and is still true of most tropical The varieties of mangos in Florida at the fruit crops.) present time represent the culmination of Difficulties in Mango Selection some 4,000 years of effort by mankind to im prove this "queen of fruits." Over the past While improvement in the mango follows 200 years, but particularly since the turn of the general principles of crop breeding and the century, many of the choice Indian and selection, it nonetheless encounters many ob Indochinese varieties have been imported into stacles. The mango has flowers of two types, this country. Through generations of selec perfect and staminate, appearing in varying tion of their seedlings, the introduced varie proportions in the same inflorescence. Both ties themselves have undergone a culling pro normally have but a single fertile stamen and cess for adaptability to our climate and soil. thus do not lend themselves well to pollination. Self-sterility is suspected in many varieties. With the discovery of the inarching method Usually the mango is cross-pollinated in Na of vegetative propagation in India, the plant ture, but varying degrees of self pollination ing of monoembryonic varieties became fea are also known to occur. Artificial pollinations sible on a commercial scale (1, 5, 6). Later, of mango varieties, both crosses and selfings, in the United States, the Philippines and Ha have met with very little success, usually less waii, the less tedious, cheaper methods of bud than one percent of the flowers developing to ding and grafting were provided to the rapidly mature fruits (2, 4, 9, 24). expanding mango industry (5, 7, 13, 14, 22). In addition to the above-mentioned charac The budding on polyembryonic varieties has ters connected with the flowering and bearing been superseded by budding monoembryonic of the mango, the question of embryony must varieties until at present one rarely finds a be considered. While pollination of the flower polyembryonic variety being planted even in and subsequent fertilization of the egg is con dooryard cultures (12, 16, 18, 21, 23, 25). sidered essential to the development of the The question of stock/scion relation cannot fruit, additional embryos may arise in the yet be regarded as solved. Important in this imcelllar tissue. The fertilized embryo is us connection is Dr. Fairchild's information that ually hybrid in nature while the nucellar em buds of superior seedlings of the Saigon, bryos are exact duplicates of the mother tree. worked on the polyembryonic terpentine seed While the two types of embryos may be dis lings proved to be superior in flavor according tinguished in the very young stages of the to many mango fanciers to the monoembryonic fruits, the lack of distinctive vegetative char stocks from Indian varieties. Since the poly acteristics in most of the mango varieties pre embryonic sorts come from Indochina and the cludes a separation of the plants resulting Philippines, this might indicate intraspecific from a polyembryonic seed until they have quality preference between these varieties. fruited. Since the percentage of polyembryonic The selection of new varieties in Florida has seeds in a variety depends upon physiological been aided materially through the formation and environmental conditions as well as its of the Mango Forum by giving the growers a genetic constitution, the phenomenon assumes place where they can display their discoveries a role of considerable importance for the DIJKMAN AND SOULE: MANGO SELECTION 259 breeder as well as the grower (8, 9, 10, 19, The above system was developed and per 20). fected in the East Indies by the Dutch for The mango provides an excellent example of rubber, coffee, quinine, tea, and other crops. heterozygosis in fruit crops as evidenced by The results obtained have entirely justified the numerous varieties which have been the expense, as for example, in thirty years produced in the past. In its long his the production of rubber was increased four tory, the mango has been crossed and re- fold (from 500 kg. per hectare to more than crossed countless times until most of the pres 2,000 kg. per hectare). Such a breeding and ent varieties now possess a complete or nearly selection program was possible with these complete lack of uniformity in their offspring, crops only through organization of the com a genetic instability which obviates the pos mercial growers and the concentration of sibility of obtaining pure strains. The exist large amounts of capital in the enterprises. ence of polyembryony in certain varieties has Taking Hevea, the chief source of natural likewise tended toward the isolation of various rubber, as an example, the Far Eastern plant characteristics that have persisted through ings were started on a small scale with unse- many generations. Thus one finds in the pres lected seedling offspring of the Wickham and ent varieties two lines of development: (a) a Cross importations. By 1910, the area in He behaviour leading to constant combination vea had grown to over 400,000 hectares, all (and recombination) of characteristics through seedling materials. A short time later the its ability to cross and self pollinate and (b) world demand for rubber rose high enough to a source of isolation and perpetuation of induce the plantation owners to organize as characters through polyembryony. sociations which established their own research Selection and Breeding in Other Crops stations. With government assistance, the re In the preliminary stages of selection with search stations began selection and breeding other crops, polyclone breeding gardens con work on an industry-wide scale. The indi sisting of trees possessing some good qualities vidual tappers on each plantation and native but lacking others are established with a view holding marked the highest yielding trees in to combining as many factors as possible. The their tapping tasks. The production from these resulting seeds are sown in large-scale se trees was compared, plantation by plantation, lection experiments and selection for fruit area by area. The next step was the formation quality and tree vigor is begun on the trees. of a series of test gardens, on the individual Such seedling-population gardens are planted plantations and at central locations for each many years in succession to obtain as many rubber-growing area, where buddings and different combinations of factors as possible. seedlings from these high yielding trees could As fast as undesirable elements show up, they be compared with one another. The great are eliminated or the trees are budded with in range of climate and soils in Java, Sumatra, dividuals approaching the ideal form. Natural Borneo, Malaya, Indo-China, and Ceylon led cross-pollination between these selected trees to the development of varieties selected for will thus gradually concentrate the desirable their adaptability to certain areas and con characteristics, and new progeny gardens are ditions. At the same time, investigations on in turn planted from these selected seedlings. methods of propagation, methods of tapping, This process is repeated as many times as soil and fertilizer requirements, rootstock desirable. studies, and diseases and pests were being Parallel to this system of poly-clone breeding carried on. As fast as clones or seedling gardens, mono-clone gardens are necessary to families were developed by the research sta determine the rate of self-pollination and the tions, they were released to the growers, first results of inbreeding and to observe eventual for small-scale plantings and tests in their recombinations which might open up new pos particular locality, later for large-scale plant sibilities. ings. Thus, in the 30 years from 1910-1941 Concurrently with the breeding gardens, the when the Pacific War broke out, the areas best material available is tested in clone gar originally planted to unselected seedlings were dens with the clones showing the greatest supplanted by selected seedlings and primary promise being released to commercial growers clones, then by secondary clones and secondary and private interests. seedling families. Since the end of the War, 260 FLORIDA STATE HORTICULTURAL SOCIETY, 1951

a few tertiary clones have been released for peel, disease resistance, resistance to skin planting (3). blemishes, keeping qualities, shipping qualities. Mango Selection (2) Characteristics of importance in tree The development of the mango industry in selection: Florida up to the present time has followed Low stature and earliness of bearing (to in many respects the history of rubber in the avoid wind damage), vigor, productivity, hardi Far East prior to 1910. Choice varieties from ness to cold, disease resistance, adaptability India, Indo-China, the Philippines and other to soil and climatic conditions, regularity of Asian sources as well as West Indian selec fruiting, self fruitfulness. tions were introduced by individuals and by Judgement op Fruit Qualities the U. S. Department of Agriculture. These Flavor, fragrance or aroma, fibrousness, varieties in turn have been subjected to a pre-ripening around the seed, color, and ship process of acclimatization and selection to ping qualities are among the most important meet the tastes and fancy of the American characteristics for the selection of parent public. Generations of seedlings and budlings trees for further improvement. Of these from these varieties have been propagated characteristics, the first two are the most dif until today there exist many thousands of ficult to judge objectively; consequently, to trees scattered over the southern half of the acquire the highest constancy and skill in peninsula. judgement, as with other products graded on This area may logically be compared to an the basis of taste and flavor (tea, coffee, cacao, immense breeding garden in which the results etc.), the judges should be appointed for life of the hybridization of the increasingly com or at least a long period. Every effort should plicated clones and seedlings obtained from be made to ensure complete objectivity in the parents improved by mild selection are mark testing. For example, samples of the fruits edly evident. Although this primitive way of to be tested should be submitted on numbered improvement—through slight selection for trays designated in such a way that the iden fruit quality and growth vigor of the trees ac tity of the fruit is not known to the committee. cording to the taste and appreciation of the In as much as standard tests for flavor and steadily increasing numbers of growers, nurs aroma for mango varieties do not exist, ex erymen, and others—has considerably enlight periments should be made to determine wheth ened and to a certain extent has solved some er the samples should be slices or cubes taken phases of the first step in selection, the time from the outer flesh, the flesh near the seed, has come to put mango selection on a scientific or made into puree; whether the samples basis, to apply here some of the lessons and should be swallowed or merely rolled around techniques obtained with the breeding and se in the mouth and expectorated to preserve an lection of other crops. The cultivation of uninfluenced taste susceptibility for following mangos in Florida has already grown into an samples; whether the samples should be from important source of income and has an even a single fruit or several fruits of each variety ; greater potential. The unique advantage of whether the judges should be blindfolded dur being the only subtropical area in the con ing the testing; and whether samples should tinental United States where the mango can have the peel removed or left on. The question be grown successfully on a commercial scale of aroma should especially be given considera should not be under-estimated. The present tion in the testing, mainly to eliminate overly financial interest and the future prospects re strong or otherwise objectionable scents. In quire a planned breeding and selection pro this respect success was obtained in the Far gram. In this connection, the following points East by olfactometric checking of products as are offered towards developing a practicable, cacao and coffee, which hitherto were mainly balanced program for improvement: graded by taste tests (17). (1) Characteristics of economic importance An exact method for determining the fiber in fruit selection: content is difficult to achieve but a workable Pleasing flavor, good aroma, firmness of standard may be derived through the flavor flesh, bright color of flesh, absence of fibers, tests; i.e., testing to ascertain whether the small size of seed, absence of pre-ripening fruit is with or without objectionable strings. around the seed, acceptable size, bright color of An additional method is that of halving the DIJKMAN AND SOULE: MANGO SELECTION 261 fruit lengthwise to see what proportion of the rows 30 feet apart. This gives a density of fibers adhere to the flesh when the two halves 10 clones per 2 acres, 9 test varieties and one are twisted apart. standard variety (arbitrarily Haden until Standard tests for pre-ripening around the enough data are obtained to permit the use seed, keeping quality, disease resistance, blem of another variety better suited for the pur ish resistance, and shipping quality of the fruit pose). The trees will suppress each other in should be set up using statistical methods to the rows but will develop strong branches record the changes in color and firmness of the toward the open lanes between the rows. fruit in a unit of time, the size, number and The use of a hedge row system is amply prevalence of skin discolorations, and the ef justified by the results obtained with testing fect of type of containers, wrappings, tempera numerous other crops (coffee, rubber, tea, qui ture, humidity, and light on these. nine, oil palm, coconut, agave, sugar cane, The size of fruit acceptable to the market etc.) as it has been proved that clonal varia can be ascertained through sample shipments bility towards yield, growth, disease suscep to the various wholesale fruit centers and the tibility, etc., is not affected by the close plant data obtained used as a criterion in fruit se ing in the rows. The advantages lie in the lection in field tests. larger number of test trees per area and the Field Selection greater protection from wind damage than in During the past few years a number of new the conventional square or triangular test varieties have been planted on a commercial patterns. scale in Florida; however, in no single case The data per replication obtained from the do any of these varieties possess all of the test planting should include yields, individual desired characteristics of the ideal mango tree growth (height, girth, and spread), in fruit and tree, nor have productivity and other cidence of disease, earliness of bearing, and field tests been made with them. (It may be resistance to drought and particularly for truthfully said that heretofore selection has Florida resistance to cold. Pruning to keep been made on the basis of the individual the trees low should eventually be included in grower's conception of what he wanted in a the test program. variety rather than as a result of a planned It may be pointed out that the yields ob systematic program by even a small segment tained from the hedge row plantings will pro of the industry.) vide an index as to the relative productivity It is of primary concern to the commercial of a test variety compared to the standard grower that he knows as much as possible but they will not give absolute values as to about the variety on which he is risking his the yields obtained with conventional planting capital; to this end, he should insist that ade patterns. One of the prerequisites for the se quate tests be made before a variety is re lection of the standard variety should be a leased or recommended for commercial record of its productivity in a conventional planting. planting pattern. This apparent defect is also The present 20-odd commercial mango va more than balanced through the space-saving rieties can serve as a nucleus for standard features of the hedge row system. clone tests. While they have been selected Considerable thought should be given to the by the growers as being suitable for the pur location of the testing grounds. These should poses, few, if any, production and growth be located so as to be representative of as records exist. Since these varieties constitute much of the entire mango growing area as the basis for comparison for the new varieties possible. being developed, it is imperative that they be The clone tests may also be in concurrent tested also. use as a nucleus for the breeding program. The proposed clone test consists of random Since the varieties represented in the tests ized row plantings surrounded by a buffer will be those with the highest promise for row, each planting comprised of 48 budlings marketability, seedling trials should be planted per clone (variety) in replications of 6 trees. from those clones selected as the recurrent These budlings should be planted preferably parent for back-crossing. The selection in in hedge rows (narrow spacing in the rows), these clonal seedlings should be made on the the trees 6 feet apart in the row, with the basis of ideal characteristics present in the 262 FLORIDA STATE HORTICULTURAL SOCIETY, 1951

non-recurrent parent.* Trees showing the de LITERATURE CITED sired characteristics from that non-recurrent 1. Bhat, S. S. (1946). Nursery practices in Mango grafting. Punjab Fruit Jour. 10(37): 19-22. (Indian parent should be propagated for back-cross Farming 4: 254-256, illus. 1943). 2. Bijhouwer, A. P. C. (1937). A contribution to the purposes. This may be done on a field scale knowledge of the flowering and fruiting habits of the in suitably isolated bi-clone breeding plots or Mango tree. (In Dutch). Wageningen. H. Veenman and Zonen. 106 p., illus. in tubs, if necessary. In the bi-clone plots, 3. Dijkman, M. J. (1951). Hevea—Thirty years of re search in the Far East. Miami, Fla., University of Mi pollination between the trees will take place ami Press. 381 p. illus. 1951 (In press). naturally. With the tub plants, the desired 4. Dudgeon, Winfield (1929). The morphology of Mangi- fera indica. Proc. of XVI Indian Sci. Cong. 1929: crosses may be facilitated by placing a screen 230-231. 5. Feilden, G. St. C. (Comp.) (1936). Vegetative propa over the plants and pollinating them by plac gation of tropical and sub-tropical fruits. Imp. Bur. ing a beehive inside the enclosure. Owing to Fruit Prod. Tech. Commun. 7: 1-67, illus. 6. Firminger, T. A. C. (1864). Manual of gardening the practical difficulties involved in the pol for Bengal and Upper India. London, R. C. Lepage and lination of plants within enclosures the bi- Co. 558 p., illus. 7. Higgins, J. E. (1910). Shield-budding the Mango. clone plot method is, however, much more Hawaii Agr. Expt. Sta. Bui. 20: 1-16, 2 pi., 4 fig. 8. Horn, Claud L. (1943). The frequency of polyem- desirable. bryony in twenty varieties of Mango. Proc. Amer. Soc. Hort* Sci. 42: 318-320, 1 fig. While clone testing or a breeding program 9. Juliano, Jose B. and Cuevas, Numeriano L., (1932). are long-term, continuing projects, methods Floral morphology of the Mango (Mangifera indica L.) with special reference to the Pico variety from the Philip have been developed with other crops for pines. Philipp. Agr. 21: 449-472, 1932-33. 10. Juliano, Jose B. (1934). Origins of embryos in the shortening the fifteen year cycle between gen Strawberry Mango. Philipp. Jour. Sci. 54(4): 55S-663, erations. With Hevea, a nursery test tap 3 pi. 11. Kent, O. M. (1946). The Florida Mango forum. method has made it possible to shorten this Fla. State Hort. Soc. Proc. (1945). 58: 182-186. period to 10 years. It is possible that a method 12. Lynch, S. J. and Krome, Mrs. W. J. (1948). Mango varieties originating in Florida. Proc. Fla. Mango Forum for the pre-selection of young mango seedlings 1948: 8-23. 13. Lynch, S. J. and Nelson, R. (1949). Mango budding. may be worked out in the future although it is Florida State Hort. Soc. Proc. 1949. difficult to predict which characteristic common 14. Lynch, S. J. and Mustard, M. J. (1950). Mangos in Florida. Florida Dept. Agr. 82 p. to both juvenile and mature plants will prove 15. Ochse, J, J. (1931). Vruchten en vruchtenteelt in Nederlandsch-Indie. 181 p. illus. (In Dutch). G. Kolff to be applicable (3). & Co., Batavia. 16. Oppenheimer, Ch. (1947). The acclimatisation of Further continued importations of important new tropical and subtropical fruit trees in Palestine. varieties from the Far East should be under Jewish Agency for Palestine, Agr. Res. Sta. Rehovot. Bui. 44: 1-184, ill., tables (in English) Mango, p. 28-58. taken. Some of the most desirable being the 17. Roelofsen, P. A. (1939). Onderzoekingen over bein- vloeding en behoud van de kwaliteit van Robusta markt Golek, Am Manis and Mana Lagi from In koffie. (In Dutch). Arch. v. d. Koffie cult, in Ned.- donesia (15), and cool climate ecotypes from Indie. 13: 151-282. 18. Sturrock, T. T. and Wolfe, H. S. (1944). A key high altitude belts in South East Indonesia to Florida Mango varieties. Proc. Ann. Meet. Fla. State (and possible other regions). Hort. Soc. 57: 175-180, 1 fig. (Biol. Abs. 19: 19801, 1945). 19. Webber, H. J. (1931). The economic importance of apogamy in citrus and Mangifera. Proc. Amer. Soc. ACKNOWLEDGEM ENTS Hort. Sci. 28: 57-61, bibl. 8. 20. Wester, P. J. (1912). Embryony of the Mango. The writers thank Dr. David B. Fairchild, Philipp. Agr. Rev. 5(2) : 80. 21. Wester, R. J. (1924). A description list of Manero The Kampong, Coconut Grove; Dr. T. R. varieties in India: an addenda. Philipp. Agr. Rev. 17: 283-292. Alexander, Chairman, Dep't of Botany at the 22. Wester, P. J. (1925). The Mango. Philippine Dept. University of Miami; Dr. H. S. Wolfe, Chair Aprr. and Nat. Resources Cir. 15, rev., 14 p., illus. 23. Wolfe, H. S. and Lynch, S. J. (1942). New va man, Dept. of Botany of the University of rieties of Mango for Florida. Proc. Ann. Meet. Fla. State Hort. Soc. (1942). 55: 116-119. (Biol. Abs. 17: Florida at Gainesville for their interest. 22453, 1943). 24. Young, T. W. (1942). Investigations of the un *—(For example, clone A bears well and has high quality fruitful ness of the Haden Mango in Florida. Proc. Ann. fruit, while clone B is resistant against a certain dis Meet. Fla. State Hort. Soc. 55: 106-110, 1942. (Also ease. Those seedlings from the progeny of clone A Cornell Univ. Abs. of Thesis 1942: 483-487, 1943). having B's disease resistance will then be selected for 25. Ziady, M.A.F. El, (1932). Selected Mango varieties backcrossing on clone A.) in Egypt. Min. Agr. Booklet No. 6.

STEM PROTECTION OF YOUNG FRUIT TREES FROM FROST

David Sturrock the United States in regions susceptible to occasional winter frosts, there has been a West Palm Beach great deal of thought given to protection Ever since Citrus trees have been grown in against damage from the frosts that strike