THE UNIVERSITY OF ILLINOIS LIBRARY AGRICULTURAL LIBRARY UNIVERSITY OF ILLINOIS Agricultural Experiment Station BULLETIN No. 217 AN APPLE CANKER DUE TO CYTOSPORA BY FEANK LINCOLN STEVENS URBANA, ILLINOIS, MAY, 1919 CONTENTS OF BULLETIN No. 217 PAGE DESCRIPTION OF THE CANKER 367 THE FUNGUS Isolations 368 . 371 - .". SIMILAR FUNGI ON EOSACEOUS TWIGS Valsas on Kosaceous Hosts BIBLIOGRAPHY . 372 372 .' . . 377 AN APPLE CANKER DUE TO CYTOSPORA BY FKANK LINCOLN STEVENS, PROFESSOR OF PLANT PATHOLOGY, UNIVERSITY OF ILLINOIS, IN COOPERATION WITH THE DEPARTMENT OF HORTICULTURE A canker on young apple trees which appears capable of doing to the author for identification in the on noted Tho 1918. of only a few trees, its rapid and comspring of the tree, together with the fact that it does not much damage was submitted plete possession agree closely with other apple-tree cankers previously described, worth while to give rather a complete statement of the present knowledge of it. The apple cankers were sent by Mr. G. P. Callender, of Altona, Illinois. He stated that he had received the trees from a certain nursery company in New York, on April 27, 1918. Requests were made of the company that they send specimens of any cankers they might find in their orchards, but no reply was received. makes it DESCRIPTION OF THE CANKER One specimen was found on the main trunk of a young tree about 2 cm. in diameter. The canker extended a total length of 22 cm., completely encircling the tree thruout most of that distance, altho it extended 2 or 3 cm. farther up and down on one side of the tree than on the other side. There was no abrasion or wound which seemed to mark the place of the original infection. Altho several lateral branches had been cut off from the portion found cankered, the wounds were in all cases nicely healing over with callous. The canker for the most part was of a tan color, similar to that which is frequently exhibited in young cankers of apple blotch. Portions of the canker, toward one end, were of much darker bronzed or purplish color, altho at the other end of the canker this color was absent. The demarcation between the diseased and the healthy tissues was very sharp with a slight breaking away of the diseased from the healthy tissues. On removing the bark, a black transverse line about 1 mm. wide was disclosed, apparently separating the healthy from the diseased tissues. It is quite probable that the canker at this point was in dormant condition, resting, not progressive. The other end of the canker did not show sharp limitations between the diseased and the healthy tissues, which gradually faded, one into the other, and did not show externally the 2-cm., dark, purplish band mentioned above, adjacent to this end of the canker. 367 BULLETIN No. 217 368 [May, The canker was studded thruout its area with black pustules having the appearance of pycnidia or perithecia. These were slightly raised conically above the surrounding surface, were black, about 1 to 2 mm. in diameter, and were so abundant that an unbroken area of 5 square millimeters could scarcely be found. graph of this twig was made June A color photo- 5. THE FUNGUS The fungus is apparent to the eye, externally, as small black pustules under, or erumpent thru, the cuticle. On microscopic examination these prove to be relatively large compound pycnidia made up of numerous irregularly arranged cavities in a mass of dense Strom atic structure. Views of the pycnidia from various sections are shown in Figs. 1 to 11. FIG. 1. CROSS-SECTION OF A PYCNIDIUM Fig. 1 shows a cross-section, i.e., a section in a plane parallel a pycnidium, which represents the condition most frequently found. There is a large number of locules, irregular in size and shape, but arranged in a circular manner around a sterile Another pycnidium area, with their longer axes along the radii. is shown in similar view in Fig. 2, and a section in the same direction but farther from the base, in Fig. 3. Fig. 4 is drawn from a section longitudinal to the twig and parallel to the plane of the to the base of radius of the twig, therefore cutting from the top of the pycnidium The irregular locules are here shown, and the large to its base. ILL. AGR. EXP. STA. AN APPLE CANKER DUE 1919] TO CYTOSPORA OOP Fias. 2-11. 369 11 CROSS AND VERTICAL SECTIONS THRU PYCNIDIA BULLETIN No. 217 370 [May, covering mass of sterile mycelium, all below the cuticle but breaking thru it. Figs. 5 to 10 give similar views showing considerable variation as to the locules and their openings into the ostiole, but a general agreement in that the sporiferous cavities are covered in all cases by a dense stromatic or clypeate structure. (Ectostroma, cf. Ruhland. 32 ) Fig. 11 shows a similar section, but nearly tangential to the edge of a pycnidium. Fig. 12 shows the detail of the portion of the pycnidium marked "a" in Fig. 1. The interlocular material is seen to be a firm pseudoparenchyma, the walls of the outer cells being somewhat thicker than the walls of the inner cells. The entire inner surface of the locules is lined with a close palisade of conidiophores, which are in the main simple and narrow, and about 17 to 20 p. long by .5 to .7 /A thick, tho in some instances they may 10 This conidiophore layer is shown branch, as figured by Aderhold. still more clearly in Fig. 13. Fig. 14 shows the detail of the part marked a " in Fig. 10. It is seen that in certain parts the fungus mycelium is loosely woven and with open interstices. Fig. 15 shows the spores, which are produced in very great number. They are ' ' FIG. 12. DETAIL OF PORTION OP PYCNIDIUM MARKED "A." IN FIG. 1 AN APPLE CAXKER DUE 1919] TO CYTOSPORA 371 hyaline, 1-celled, obtuse, quite uniform in size (7x1.6 /*), and either straight or slightly curved. The mycelium is thin and hyaline and by these two characteristics is easily distinguished from the mycelium of the black-rot fungus. Close search revealed no ascigerous structures. ISOLATIONS The fungus was easily secured in pure culture. Fragments from the interior of a pycnidium were placed in a drop of sterile water and portions of this drop then PORTION OF A CONIDIOPHORE FIG. 13. transferred to tubes of melted LAYER corn-meal agar and poured into Petri dishes. Thousands of pure growths were thus secured. Cornmeal agar was also poured into Petri dishes and allowed to solidify. from below the cortex were placed upon Invariably those bits gave rise to the same fungus secured by the dilution method. The fungus thus secured in pure culture was maintained for several months on various media. Tho the fungus vegetated luxuriantly on various agars it did not bear pycnidia in them, or spores of any kind. The colonies on all media were colorless and with a floccose, aerial mycelium. Inoculations from these pure cultures were made on apple and other twigs (pear, rose, Then its bits of diseased tissue surface. blackberry, and plum, peach) in test tubes with a few cubic centimeters of water to keep the culture These resulted in moist. rapid growth and the development in the bark, in about three weeks, of very numerous pycnidia of com- chambered pound, ture, identical struc- with that found in the natural cankers as described above, tho under these conditions there was always an extensive development of aerial mycelium not found under the less ditions. humid natural On con- all species of FIG. 14. DETAIL OF PORTION OF PYCNIDIUM MARKED "A" IN FIG. 10 BULLETIN No. 217 372 twigs employed, except box-elder, cherry, and 'maple, the fungus grew well, penetrating under the cortex thruout the whole length of the twig, some 8 to 10 cm., and breaking out with its erumpent pycnidia over all parts of the twig. On certain twigs, e. g., those of blackberry, tho growth was abundant and rapid, the pycnidia were much smaller than on apple no difference was noticeable in the Careful search was made in all cultures for an ascigerous stage, but none was found. No attempts to produce the disease on trees in the open were made because it was not thought wise to run any danger of giving it wider introduction in this state. From the laboratory evidence as well as from the statements of Mr. Callender it appears that this canker is one of very rapid development and one that might cause serious loss should it become widespread twigs, yet spores. and suitable conditions for Fio. 15. its development ob- SPORES This fungus eyidently belongs to the form genus Cytospora Ehrenb. Several Cytosporas have been referred, on more Cytispora Fries. ) or less conclusive evidence, to the ascigerous genus Valsa Fries. It is therefore of interest in connection with this canker to note other cankers that have been reported upon related hosts, due either to Valsa or to Cytospora. ( VALSAS ON ROSACEOUS HOSTS There are more than 225 species of the genus Valsa proper noted 5 Lindau, with a broader conception of the genus, says there are about 400 species. The following list, tho not entirely complete, at least contains the names of the most important of these, from the viewpoint of pathology, that occur on Eosaceous hosts. The 8 by Saccardo. synonomy and conidial relations, when stated, are as given in the arti- cle cited. 1 1. Valsa ambiens Fries (1:565) (2:120) conidia=Cytispora carphosperma Fries (2:120) (5)=Cytispora leucosperma Fries (25:826)=C. ambiens Fr. (7:2,729). On apples in Europe (8:1,131) (11:278). On most deciduous 2. Valsa acclinis Fr. on Pyrus (8:1,130) Valsa amphibola Sacc. on Pyrus (8:22,354) Valsa ceuthosporae Cke. on Prunus (8:1,143) trees (5) 3. 4. J The first number given in parentheses r efers to the Bibliography, as does also any number standing alone in parentheses. Numbers following indicate volume and page. AN APPLE CANKER DUE 1919] 5. 6. 7. 8. 9. TO CYTOSPORA 373 (5) (8:1,108) on broad-leaved twigs in Europe and North America Valsa eerasi Feltg. on Prunus (8:17,563) Valsa cincta Fries (10) (8:1,143) (5) on Prunus in Sweden, London, Germany, and France=Cytospora rubescens Fr. (33) Valsa coenobitiea (de Not) Ces. and de Not (5) on broad-leaved trees in Germany and Italy Valsa clypeata Fuck, on Eubus (5) (8) Valsa ceratophora Tul. 15. Valsa coronata (Hoffm.) Fr. on Crataegus (8)=Cytospora Valsa crataegi Allesch. on Crataegus in Europe (5) Valsa cydoniae on Cydonia vulgaris in Portugal (5) Valsa excipienda (5) Karst. on Sorbus (8:1,139) Finland and Lapland Valsa excorians C. and E. on Pyrus (8) Valsa flavovirescens (Hoffm.) Nitz. (5) on various broad-leaved trees in 16. Valsa hoffmanni Nitz. on Crataegus (8:l,118)=Cytospora. 10. 11. 12. 13. 14. Europe 17. 18. 19. On peach, plum, and almond (29:485). On apricot Valsa lauro-cerasi Tul.^Cytospora laufo-cerasi on Prunus (8) Valsa lata (Pers.) Nitz. (5) on various broad-leaved trees in Europe Valsa leucostoma (Pers.) Fries (8:1,139) (10) (22) (2:120) (5) (28) (27:515) (4)=V. personii Nitz. (5)=Cytospora rubescens Fr. (5) (14) On Prunus in Europe (33) (ll:278)=e. leucostoma (10) (6:180). (34) and North America (8) (4:264). On pome and stone fruits in Europe, Australia, and America (11:278). On peach, plum, and almond (29). On peach, plum, apricot, and cherry (14). On cherry in America (9:184). On peach (4:264) (15). On cherry (10) Valsa leucostoma Fr. var. cincta Eolfs, common on stone and pome fruits everywhere (9:180). On peach (9:300) Valsa leucostoma Fr. var. rubescens Eolfs. On apricot and almond On plum (9:360) massariana de Not on Sorbus (8:l,138)=Cytospora macrostoma Eehm. on Prunus (8:1,145) (9:157). 20. 21. 22. 23. Valsa Valsa Valsa Valsa maheleb C. and E. (8:1,137) on Prunus niaura (Fr.) Nitz. (5) on wood of Prunus spinosa in Sweden and Germany 24. 25. Valsa microspora (Crouan) Sacc. on Crataegus (8) Valsa microstoma (P.) Fr.:=(Cytospora microstoma) on Prunus (3) (7) (8:8,111) 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. Valsa Valsa Valsa Valsa monadelpha Fr. on Prunus (8:1,128) opulifolia Pk. on Spirea (8:9,449) prunicola Pk. on Prunus (8:9,452) prunastri (Pers.) Fr. on Prunus in Europe and North America (5) (2:111). On plum, apricot, and pear (4:264) (13:218) (6) pycnidia= Cytospora rubescens (2:111) (12:196). Lindau (4:264) says the connection is doubtful. On apple, plum, etc. in England (11:278). On apricot, peach, and plum (26:77) Valsa rhodophila B. and Br. on Eosa (8:1,136) Valsa rubi Fuck, on Eubus (8:1,109) Valsa sorbi (All. and Schw.) Fries (5) on Sorbus in Europe=Cytospora rubescens (12:196) Valsa siberica Thiim. on Cotoneaster (8) Valsa sorbicola Nitz. on Sorbus (8:1,124) Valsa sepincola Fuck, on Eosa and Eubus (8:1,134) Valsa tumidula Cke. and Pk. (5) on Crataegus and Platanus 374 BULLETIN No. 21i [May, In the accompanying tabulation are given the Cytosporas recorded as such on Rosaceous hosts also the Cytospora-like conidial forms of ; various Valsas on Rosaceae. CYTOSPORAS AND CYTOSPORA-LIKE FORMS ON ROSACEAE Arranged in order of minimum spore length No. (/*) 1919] Nft AN APPLE CANKER DUE TO CYTOSPORA 375 BULLETIN No. 217 376 40 fungus to be secondary, while Frank, - 41 [May, Aderhold, 10 Stewart et al., 18 later several others, 13 20 52 have held that it was Rolfs, the cause of the disease, a view that is now definitely established. 14 15> 16 - and - - The most comprehensive articles bearing on Cytospora and Valsa on drupes are by Aderhold 10 and Eolfs. 16 Aderhold referred the form on drupes to Valsa leucostoma, and by extensive cultural and inoculation studies demonstrated its parasitism. Rolfs studied Valsa on peach, plum, apricot, and cherry, and showed that the forms are interinoculable but on the basis chiefly of slight variations in spore measurements, tho to some extent on variations in growth on media, he distinguished two varieties, V. leucostoma var. cincta on cherry and peach, and V. leucostoma var. rubescens 011 apricot and plum, a varietal distinction that has been 9 That such a varietal segregation recognized in at least one textbook. should exist is somewhat surprising, especially when the biologic relations claimed are considered, and the question naturally arises as to the validity, for taxonomic purposes, of the characters selected. While the literature regarding Valsa and Cytospora on drupes is extensive there are but few references to either as causes of disease on cultivated pomes. Aderhold 10 made inoculations upon apple, but makes no reference ; in later publications to its natural occurrence upon that host, tho in 1900 45 he recorded it as the cause of cankers on pear in Proskau. Von der Byl, 53 also Evans, 56 noted Cytospora leucostoma as the cause of die-back of apple trees in South Africa Darnell-Smith and MacKinnon38 report Valsa and Cytospora on apple in New South Wales Nicholls 54 reports death of apple trees in Tasmania associated with Valsa prunastri and Valsa ambiens and Ideta 23 in his textbook gives Valsa mali as the cause of canker on apple twigs. The illustra; ; ; tions given discussion. by Darnell-Smith agree closely with the canker under 35 Cockayne mentions what is probably a Valsa on apples, pears, and other trees in New Zealand, but with inconclusive evidence as to parasitism and as to the species of fungus involved. To place clearly before the reader the difficulties of classification and the necessity of taxonomic revision of these fungi the preceding tables and lists are presented. Truly Aderhold was justified in concluding that from the conidial forms alone it is impossible to make a specific determination. Tho the fungus here discussed agrees well with the Cytospora of Valsa leucostoma, it is best to defer final judgment as to its specific name. It is to be noted that many similar fungi described on other hosts may in fact also grow on Rosaceae also that Cytosporoid fungi belonging to genera of the Valsaceae other than Valsa may cause cankers on these hosts. ; AN APPLE CANKER DUE 1919] TO CYTOSPORA 377 BIBLIOGRAPHY 1. MASSES, GEORGE. 2. COOKE, M. C. 3. ALLESCHER 6. Diseases of Cultivated Plants and Trees. 1910. Fungoid Pests of Cultivated Plants. 1906. Babenhorst, L. Kryptogamen Flora von Deutschland in 5. LINDAU LINDAU 6. BANT, A. 7. WINTER, G. 8. SACCARDO, P. A. 4. 1. Pt. 1901. in Sorauer, P. Handbuch der Pflanzenkrankheiten, 2. 1908. and Prantl. Die Natiirlichen Pflanzenfamilien, 1. Abt. 1. Die gummosis der Amygdalaceae. Diss. Amsterdam, 1906. In in Engler Ztschr. Pflanzenkrank., 17, 179. 1907. Die Pilze in Babenhorst's Kryptogamen Flora von Deutsch- land, etc. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. Sylloge Fungorum Omnium Hucusque Cognitorum. AND L. HESLER, WHETZEL, H. H. Manual of Fruit Diseases. 1917. E., ADERHOLD, B. Ueber das Kirschbaumsterben am Bhein, seine Ursachen und Kais. seine Behandlung. Arb.a.d. Biol. Abt. fur Land und Forstw. Gsndhtsamt., 3, 309, 363. 1903. An extensive discussion of the morphology, taxonomy, and pathogenieity of the fungus, with studies of pure See also review in Zeit. Pfk., 15, 339. cultures. The Fungi Which Cause Plant Disease. 1913. FUCKEL, L. Symbolae Mycologicae, 196. 1869. DUKE OF BEDFORD AND PICKERING, S. U. Observations on a Disease of Plum Trees. Beport on the working and results of the Woburn Experimental Fruit Farm. Beport II, 218, London, 1900; also review in Zeit. Pfk., 12, 177. Beports Eutypella prunastri Sacc. on plum and almond. EOLFS, F. M. Die Back of Peach Trees. Science, 26, 87, July, 1907. Cytospora rubescens followed by its ascigerous stage Valsa leucostoma is given as the cause of the disease on peach and plum. A Disease of Neglected Peach Trees. Mo. St. Bd. Hort., Ept. 2, 278-83. 1908. Due to Cytospora (Valsa, leucostoma}, which he thinks the same as that reported by Stewart et al. is Winter Killing of Twigs; Cankers and Sunscald of Peach Trees. Mo. St. Fruit Exp. Sta. Bui. 17, 1-101. 1910. An extensive account of the morphology, pure cultures, and inoculations. Two varieties of Valsa leucostoma are erected, var. cincta on cherry and peach, var. rubescens on apricot and plum. WATERS, B. Jour. Agr. N. Zealand, 14, 190-96. 1917. Notes presence of Valsa ambiens (?) and Valsa a/uerswaldia as saprophytes or facultative parasites on apple and other fruit trees. STEWART, F. C., EOLFS, F. M., AND HALL, F. H. A Fruit Disease Survey of Western New York. N. Y. (Geneva) Agr. Exp. Sta. Bui. 191, 304, 318, 323. 1900. Cytospora sp. on apricot, peach, and plum. MCALPINE, D. Fungus Diseases of Stone Fruit Trees in Australia and STEVENS, F. L. their Treatment. 20. Melbourne, 1902. WORMALD, H. The Cytospora Disease of the Cherry. Jour. Southeast Agr. 1912. Col., Wye, Kent., No. 12, 367-80, pi. VII-XXII. Description of canker with plates; studies of morphology, pure cultures, and inocuAttributed to Cytospora leucostoma=Valsa leucostoma. lations. 21. 22. 23. Untersuchungen iiber die Ursache des Bheinischen Kirschbaumsterbens. Ber. d. Konigl. Lehranst. fiir Wein Obst u. Gartenbau, Geisenheim a. Eh. (1907) 307. 1908. EWERT. 1st das Eheinische Kirschensterben auf eine Pilzekrankheit zuriickProskau. Obstbau Ztg., 13, 2-8. 1908. zufiihren. LUSTHER, GUSTAV. IDETA, A. Handbook of Plant Diseases of Japan, 295. maH Miz. and Yam. on apple. 1909. Gives Valsa BULLETIN No. 217 378 24. LAPINE, 25. FRANK N. Zum Krebs [May, der Apfelbaume Landw. Jahrb. 21, 937-49. 26. COOKE, M. C. Handbook of British Fungi. 1871. HAETIG, B. Lehrbuch der Pflanzenkrankheiten. 1900. 27. KIRCHNER, O. 28. schaftlichen Kulturpflanzen. 1906. FRIES, E. Systema Mycologicum, 2, 387. 29. 30. 31. 32. Die Krankheiten und Beschadigungen unserer Landwirt1823. ELLIS, J. B., AND EVERHARDT, B. M. North American Pyrenomycetes. 1892. GOETHE, E. Das Absterben der Kirschenbaume in den Kreisen St. Goar, Deut. Landw. Presse, 26,999, 1111-12. St. Goarshausen und Unterlahn. 1899. The Cytospora is regarded as secondary following frost injury. SCHROETER, in F. Cohn's Kryptogamen-Flora von Schlesien. 3,11,405. 1908. EUHLAND, W. Untersuchungen zu einer Morphologie der Stromabildenden Sphaeriales auf entwicklungsgeschichtlicher Grundlage. Hedwigia, 39,1. 1900. 33. 34. NITSCHKE, TH. Pyrenomycetes germanici, 223,228. Breslau, 1867. LESTER, G. Beabachtungen iiber das Eheinische Kirschbaumsterben, 1906. Lehranst. fiir Wein Obst u. Gartenbau, Geisenheim a. Beview in Zeit. Pfk., 16, 324. A die-back of 1915. COCKAYNE, A. H. Jour. Agr. N. Zealand, 11,504. apples, pears, and other fruit trees is noted. A Valsa may be the cause, Ber. d. Konigl: Eh., 1905. 35. but the evidence Zum is incomplete. am 36. WEHMER. 37. Cites presence of Valsa leucostoma. Kirschenzucht und Kirschbaumkrankheit in ZAPFE. Eathgeber Obst u. Gartenbau, 14,473. 1899. 1080. Kirschbaumsterben Ehein. Deut. Landw. Presse, 26,96, 1899. Camp a. Eh. Prakt. 38. DARNELL-SMrfn, G. P., AND MACKINNON, E. Fungus and Other Diseases of the Apple and Pear. Dept. Agr. New South Wales, Farmers' Bui. 99, 18. 1915. Eeports Cytospora and Valsa on apple. 39. WALTON, E. C., AND BABCOCK, D. C. Abst. Phytopath, 6, 112. FRANK. Das Kirschbaumsterben am Ehein. Deut. Landw. 40. 1899. 41. 42. 43. 44. 1916. Presse, 26,249. .- Gelungene Infektionsversuche mit dem Pilze des Eheinischen Kirschbaumsterbens. Deut. Landw. Presse, 27,1024. 1900. True parasitism of the fungus was proved by inoculations. EOLFS, F. M. Fruit Tree Diseases and Fungicides. Mo. St. Fruit Exp. Sta. Bui. 16, 15-16. Attributes die-back to Valsa leucostoma= 1907. Cytospora rubescens. PERSOON, C. H. Synopsis Methodica Fungorum, 39. 1801. ADERHOLD, E. Unserer Obstbaume Hausarzt. Proskau. Obstbau Ztg., 37. 1899. 45. Arbeiten der botanischen Abteilung der Versuchstation des Pomologischen Instituts zu Proskau. Centbl. Bact., II, 6,620. 1900. Cytospora rubescens noted on pear. LABONTE. Die Krankheit der Kirschbaume am Ehein und ihre verschiedenen Ursachen. Mitt, iiber Obst u. Gartenbau, 102. 1900. EASCHEN. Kirsehbaumsterben und Kalkdiingung. Deut. Landw. Presse, 1900. No mention is made of parasitic fungi. 27,1,7. Kgl. 46. 47. 48. SORAUER, P. 201. 49. 50. 51. Das Kirschbaumsterben am Ehein. Deut. Landw. Holds the fungi to be secondary. Das massenhafte Absterben der Siisskirschen Presse, 27,18, 1900. am Ehein. Naturw. Wchnschr., 15,133. 1900. TASCHENBERG, O. Schutz der Obstbaume gegen feindliche Tiere, III, 108. HEALD, F. D. Beport on Fungous Diseases. Tex. Dept. Agr. Bui. 22,158. 1911. AN APPLE CANKER DUE 1919] 52. 53. TO CYTOSPORA 379 T. On a New Canker Disease of Prunus yeodoensis, P. mume ana Other Species Caused by Valsa japonica n. sp. Jour. Col. Agr. Tohoku Imp. Univ., 7,,257. 1916. These fungi cause disease and gummosis. VON DER BYL, P. A. Die Back of Apple Trees Caused by Cytospora Leucostoma. So. African Jour. Sci., 12,545. 1916. Eeported as serious on apples in many localities; also on drupes. HEMMI, 56. NICHOLLS, H. M. Agr. and Stock Dept. Tasmania, Ept. 1916-18. Valsa prunastri and Valsa ambiens are reported on dying apple trees. Obstbaumsterben und Kartoffelblattrollkrankheit. Jahresb. STO"RMER, K. Discusses Valsa leucostoma as the cause 1909. Ang. Bot., 7,119". of death of cherry trees, and Cytospora piricola of death of apple trees. EVANS, I. B. P. Union So. Africa, Dept. Agr. Ept. 1912-13, 169. Cytospora 57. SPRENGER. 54. 55. leucostoma is reported as causing death of apple trees. Influences Affecting Cherry Culture. Cultura, 27,325. 1915. UNIVERSITY OF ILLINOIS-URBAN*