GUMMOSIS 



FREDERICK A. WOLF 



Alabama Polytechnic Institute, Auburn, Alabama 



The phenomenon of gummosis* has, perhaps, incited more 

 investigation than any other plant pathological problem. This 

 malady, evidenced by a gummous exudate from the fruit, twigs, 

 larger branches, and trunk, has been observed wherever species 

 of Prunus and Citrus are grown. In a recent memoir 1 the most 

 exhaustive that has appeared in America, Butler has brought 

 together the. important facts in the observations of Trecul, Wie- 

 gand, Frank, Aderhold, Beijerinck and Rant, Mikosch, Ruhland 

 and others who have investigated this disease. As a result of the 

 work of these observers, it had been concluded that gummosis 

 may be induced by any manner of traumatism which affects the 

 cambial tissues. It may be brought about, on the one hand, by 

 parasitic fungi among which are Coryneum beijerincki Oud., 

 Clasterosporium carpophilum (Lev.) Aderh., Sclerotinia fruc- 

 tigena (Pers.) Schroet., Cladosporium epiphyllu?n (Pers.) Mart., 

 Valsa leucostoma Pers., Tubercularia vulgaris Tode., Botrytis 

 cinerea Pers., Plowrightia morbosa (Schw.) Sacc, and Exoacus 

 deformans (Berk.) Fkl. Bacteria are also believed to be causal 

 organisms. Again, any wound made by insect larvae, by freez- 

 ing or burning, or by the use of chemicals or implements, may 

 cause the disease in question. Butler's work, a confirmation in 

 part of the views of earlier investigators, includes a distinct addi- 

 tion to our knowledge of the details of the earlier stages in gum- 

 mosis. To the theoretical aspect of the problem he contributes 

 hypotheses which diverge materially from those previously ad- 

 vanced regarding the nature of this malady. It is the present 



1 Butler, O., A study on Gummosis of Prunus and Citrus, etc. Ann. Bot., 25: 

 107-153, pi. VII-X, 1910. Butler's memoir contains a bibliography of other 

 authors referred to in this paper. 



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