46 THE FUNGI WHICH CAUSE PLANT DISEASE 



artificially produced knot with unchanged characters. E. F. 

 Smith's results *' do not agree with those of C. O. Smith. (See 

 Pseudomonas savanastoi.) 



B. oleraceae Harr. (Group number 221.1113022.) ^^^^^ 



This organism was studied by Harrison in 1901 in Canada where 

 it was foimd associated with a soft rot of cauliflower, cabbages and 

 turnips. In the rotting tissue it was always present; it was iso- 

 lated, and upon inoculation and cross inoculation characteristic 

 infection followed. The organism was reisolated in unchanged 

 character. The chemical products of the bacillus, secured by 

 filtration, also produced the characteristic tissue changes. Sec- 

 tions of diseased tissue showed the bacteria in the intercellular 

 spaces, occupying the i>osition of the middle lamella which was 

 softened and eventually dissolved by the bacterial enzymes. 



Harding and Morse '^ from their extensive studies conclude 

 that this form is identical with B. carotovorus. See p. 42. 



B. omnivorus v. Hall is described by van Hall ^^' as the cause of 

 a soft rot of iris shoots and rhizomes. According to Harding & 

 Morse '' it does not present characters sufficient to distinguish it 

 from B. carotovorus. See p. 42. 



A species closely related to B. onmivorus is described by Uyeda ^^* 

 as the cause of a disease of Zingiber. The organism was isolated and 

 studied and the disease produced by inoculation with pure culture. 



B. oncidii (Pegl.) Stev. is mentioned ^^^ as the cause of an 

 orchid leaf spot. 



B. oryzse Vogl. has been mentioned as the possible cause of 

 brusone ^^* of rice. 



B. phytophthorus Appel. (Group number 221.21230 — .) A 

 non-sporiferous rod, 0.6-0.8 x 1.5-2.5 n, actively motile by per- 

 itrichiate fiagella. Gram negative. It rots potatoes, cucumbers, 

 etc.; is aerobic or a facultative anaerobe; grayish white on agar; 

 surface colonies round, smooth; gelatine liquefaction moderate; 

 bouillon clouded; no indol; no gas. Nitrate changed to nitrite. 

 Milk coagulated and casein precipitated. Opt. 28-30°. T.D.P.47°. 



It was described by Appel ^" of Berlin as the chief cause of 

 potato black-leg. The description given above is by E. F. Smith '^ 

 and was made from Appel's organism. Smith also isolated it from 

 potatoes grown in Maine and in Virginia. 



