Title STUDIES ON THE YOUNG FRUIT-ROT OF APPLE-TREE Author(s) SHIMA, Yoshichika Citation Journal of the Faculty of Agriculture, Hokkaido Imperial University, 39(3), 143-270 Issue Date 1936-11-20 Doc URL http://hdl.handle.net/2115/12715 Type bulletin (article) File Information 39(3)_p143-270.pdf Instructions for use Hokkaido University Collection of Scholarly and Academic Papers : HUSCAP STUDIES ON THE YOUNG FRUIT-ROT OF APPLE-TREE BY YOSHICHIKA SHUIA (With 7 Plates) Contents Introduction .,. I. Historical Review II. General description of the disease 153 (I) General name 153 (2) Symptoms ." 153 (3) Causal fungus (4) Life History III. Experimental studies on stisma-infection (I) Inoculation experiments determining stigma-infection 158 a. Materials ar.d methods 158 b. Results 159 (2) Experiments verifying several factors related to stigma· infection 167 a. Relation to age of blossoms 167 b. Relation to pollination c. Relation to fungicides ... d. Relation to ringing and defoliation e. Relation to varieties f. Inoculation experiments with ascospores g. Relation to other fruit-trees IV. Behaviour of Monilia-hyphae and poUen·tubes in the tissues of pistil (I) Materials and methods (2) Experimental results a. Anatomical survey of fixed materials b. General characters and behaviours of the apple pollen· tube and the causal fungus 2 0 3 V. Discussion 209 (I) Inoculation experiments 209 [Jour. Facul. Agr. Hokkaido Imp. Univ., Sappo~o, Vol. XXXIX, Pt. 3, November, 1936] 144 YOSHICHIKA SHIMA (2) Anatomical studies ... •.• •.. •.• 216 a. Behaviour of pollen-tuLes 216 L. Behaviour of hyphae ... 217 c_ Relation between hyphae and pollen-tubes 21 9 VI. Theoretical and experimental considerations on prevention of young fruit-rot and axis-blight •.• ... •.. ..• ..• ... ... ... ... 225 (I) Factors related to outbreak of the disease 226 a. Blooming period 226 b. Weather •.. 231 c. Tree vigour . 233 d. Varietal resistance 234 (2) Mode of infection of the causal fungus 235 (3) Prophylaxis for the leaf and blossom-blight 245 a. The treatment of sclerotia ..• ..• 245 b. The spraying of fungicides... ..• 246 (4) Prophylaxis for the young fruit· rot and the axis-blight •.• 249 VII. Conclusion and summary •.• 259 Literature cited 262 Explanation of Plates 268 Plates INTRODUCTION The young fruit-rot as well as the blossom-blight is one of the most serious diseases of apple-tree in our country. Several cases of its epidemic outbreaks have been reported during the past four decades from the north­ eastern parts of Honshu and from Hokkaido. The epidemics which happened recently (in 193 I and in 1933) are thought indeed to be the most disastrous considering the large acreage damaged. Although a great number of researches concerning the Monilia-diseases of apple and other fruit-trees have hitherto been published, they have leaned toward the mycological field of the study or, in other words, have rather neglected the phytopathological considerations, particularly in respect to prophylaxis. It is self-evident that the principle of the prevention of parasitic diseases shall be established by clearing up the life history and physiological charac­ ters of the causal fungus and the host-parasite relations especially such as the mode of infection and varietal resistance of the host-plant. Notwith­ standing that the Monilia-diseases are common through the pomaceous STUDIES ON THE YOUNG FRUIT-ROT OF APPLE-TREE 145 and drupaceous fruit-trees, and their occurrence is extended over various organs of these host-plants, rather a few researches on the mode of infection of the fungus have been published except by WORONIN (49) on Vaccinia­ berries and by SCHELLENBERG on quince (106) and medlar (108). Besides them \VORMALD (142, 144, 145, 146 and, 147) published many valuable works on Monilia, having his interest focused upon the comparison of species or strains of the fungi. He stated in one of his papers (144) that MOllilta-fungus cease~ the development of the blossom or checks the pollen­ tubes growing into the style, but he did not show how it occurs. Investi­ gators in our country have studied mostly on the blossom-blight of apple­ tree and their opinions concerning the mode of infection seem to have been inconsistent. Although the application of Bordeaux-mixture has been recommended as the most effective method for the control of these diseases, but it has not necessarily been so in all cases. The results for many years have shown that it is only effective for the blossom-blight, but not for the young fruit-rot no matter what kind of fungicide may be used. It is greatly interesting from the phytopathological point of view to study the reason why spraying is only effective for the blossom-blight, but not for the young fruit-rot, in spite of the same causal fungus, and also it is greatly important to find out the effective controlling measures for the latter case of the disease. This is a motive actuating the present author in undertaking this research work. The present thesis deals whth some characteristics of the MJllilia-diseases and their mode of infection, especially stigma-infection as well as an anatomical survey of the relation between pollination and infection. In particular, the relation between the results of this research work and practical observation has been considered from the standpoint of apple growing for the purpose of throwing some light upon the control measure. The field observations and experiments were done at the Aomori Agricultural Experiment Station in Aomori Province and the University orchard in Sapporo since 1924, and the anatomical studies have been executed in the laboratory of the Department of Horticulture, the Hokkaido Imperial University. The author wishes to express his heartiest gratitude to Profs. Y. HasHINo, J. HANZAWA, S. ITO and Y. TacHINAI of the University for their valuable advice and encouragement throughout the course of the work. Thanks are due also to Emeritus Pro£ K. MIYABE for the courtesy of allowing the use of his library. Further the author is indebted to Messrs_ 146 YOSHICHIKA SHIMA A. TOSHIMA, E. SAWADA and other members of the staffs of Horticulture, Applied Mycology and Plant Pathology of the University for help in both field and laboratory work. I. HISTORICAL REVIEW Among the Monilia-diseases of fruit-trees, the Brown Rot of ripe fruits has been known in Europe and America for a considerably long time, It was, however, at the end of the 19th century that mycologists and pathologists called attention to the disease since it seriously attacked blos­ soms and young shoots of cherry trees in the Continent. Consequently a good many researches have been published of which 170 have been enumerated by WORMALD (144), The first recorder PERSOON (96) discoverd lIifonilia spores on Pints cOJJlmltlZis, Prumts domestica, and Amygdalus Persica, and named the fungus Torula frllctigma. In 1801 he established the genus 1I1011ilia and named it lIifonilia fructigena. EHRENBERG (34) found a form on the almond tree and named it Oidium laxum. BONORDE?\: (15) described Monilia cillerea in 1851. SCHROTER (108) anticipated that Monilia fmctigena must be the conidial stage of .Sderotinia fructigena. W ORONIN (15 I, 152) claimed in his noted papers that Jr[uJlilia jrltctigen:l can be distinguished from MOllilia cinerea clearly and that the former attacks the pomes whereas the latter the drupes. SCHELLENBERG (105) described Sclerotinia Cydolliae which attacks the quince tree. NORTON (91) proved SCHROTER'S anticipation by finding apothecia on peaches and p~ars. ADERHOLD (2) also succeeded in obtaining apothecia of JVlonitia fructigena and JVlunitia cinerea, and pointed O:1t that Sclerotillia fructigena (PERS.) SCHROTER of NORTON must be S,-lerotinia cincrea (BON.) SCHROTER newly describing the latter. After that he and RUHLAND (4) described Sderotinia taxa (EHI<ENBERG) ADERHOLD and RUHLAND by the discovery of the apothecia, and here three different species of Sclerotinia which attack fruit-trees have been established. Al­ though there were many researches or contentions about the taxonomy of the fungi published up to the present time, it is not necessary to go over them again since former writers have already reviewed them rep~atedly. BJt, since the reports which concern the pathology of MJnilia-disease on leaves, blossoms, shoots or young fruits especially the stigma-infection, have close connection to the present study, the following citations may be worth while. In Europe, von THihmN (129, 131) for the first time has pointed out STUDIES ON THE YOUNG FRUIT-ROT OF APPLE-TREE the economical importance of Monilia which attacks not only fruits but also blossoms and shoots. HALLlER (47), too, stated this, and thereafter many reports concerning the blossom-blight of cherries and pomes have been published by various authors as follows:- SORAUER (Ill, cherry), DRATEN (32, cherry), WITMACK (140, cherry), SORAUER (Il8, cherry), WITMACK and FRANK (14I, cherry), WORonin (153, cherry), ADERHOLD (I, cherry and pear), WEHMER (135 , cherry), FRANK (4I, cherry, almond and apple), BEl-IRENS (13, apple· and pear), WORONIN (I5 I, cherry and apple), SCHELLENBERG ( 106, quince), FRANK and KRUGER (42, cherry), MULLER-THURGAU (85, apple), SORAUER (120, apple), WORONIN (I52, apple and cherry), WEISS (136, pear and apple), MOLLlARD (83, almond), ADERHOLD (2, apple), OSTERWALDER (93, quince), SCHELLENBERG (106, medlar), EWERT (35, cherry, apple etc.), VOGES (133, cherry, apple), SORAUER (122, cherry), BROZ (I9, fruit-trees), ERIKSSON (37, cherry, apple), CHIFFLOT (23, apricot), ANON (5, pear). In England there is a'note of the apple blossom-blight in the textbook of MASSEE (76). SALMON (103, 104) reported that blossoms or stems of plum, cherry, peach, pear, apple and medlar are damaged by the fungus: ever since then the Monilia-disease has been noticed as one" of the important apple diseases in that country, especially in Kent. WORMALD (I46) has turned his attention to the so-called biologic forms and collected many strains of Sclerotillia fructigena and Sclerotinia cinerea from several parts of the world.