1915] 



DUGOAR RIIIZOCTONIA CROCORUM AND R. SOLANI 449 



vegetative mycelium, which would seem, from his figures, to 

 have little in common with the chain-like, ovoidal, often 

 branched or lobed cells (designated "barrel-shaped" by 

 Balls) of R. Solani (see Atkinson, '92, '95; Balls, '05, '06; 

 Duggar, '99; Duggar and Stewart, '01; and others) ; and (3) 

 in the verrucose or warty, wall markings (Shaw, '13, pi. 8, 

 figs. 2-3), all of which indicate some other fungus. 



Again, the development of sclerotia (Shaw, '13, pi. 8, fig. 4) 

 discloses a type of hyphal cell not characteristic of R. Solani; 

 and the small discrete sclerotia themselves (Shaw, '13, pi. 2, 

 fig. 3, pi. 8, fig. 1) convincingly indicate that another fungus 

 was under consideration. I can find no record of a description 

 of sclerotia resembling these in the literature of Ehizoctonia 

 diseases. I am at a loss to understand how a fungus with such 

 characteristics could be likened to Killings fungus on the 

 potato, even though depending upon Kiilm's imperfect de- 

 scription. On the other hand, neither in general appearance 

 nor in structure (as described and figured by Shaw) am I 

 able to find any resemblance to the " small sclerotia" or in- 

 fection cushions of R. Crocorum (R. violacea). 



In moist situations the sclerotia of Rhizoctonia Solani may 

 occur on aerial organs (as on the pods of beans, Hedgcock, 

 '04, on lettuce leaves, Stone and Smith, '00) but the frequent 

 and apparently normal occurrence of minute sclerotia, fairly 

 regularly arranged, on the dead tips of stems, as described 

 by Shaw, finds no parallel in R. Solani. Again, in regard to 



the hyphae, it may be said that while there is a characteristic 

 location of the septum when a branch is formed in a hypha 

 of Rhizoctonia, this character alone is not sufficient to identify 

 the fungus. It is necessary to take into consideration all of 

 the mycelial characteristics which have been referred to, and 

 if possible also the cultural characters. The writer finds that 

 the "Rhizoctonia type" of branching is more or less similar 

 to that found in the hyphae of certain species of Sclerotinia, 

 Morchella, Pleospora, Rosellinia, and many others. It would 

 be unwise to offer any definite suggestions regarding the 

 fungus described by Shaw and referred to above. What rela- 

 tion it may bear to the fungus of "bangle blight" (Cunning- 



