310 Agrioultukal Experiment Station, Ithaca, N. Y. 



The turnips did not seem to be very much injured though in several 

 cases large areas of the surface of the leaves were white with the mil- 

 dew. In many cases the Scotch kale leaves were completely covered 

 on both surfaces with the growth, and in such cases must produce con- 

 siderable injury. The Japanese cabbage which was affected was going 

 to " seed," and not only were the leaves affected but sevei al of the 

 fruiting stems were completely covered by the fungus. Several 

 Erysiphe which fruit shyly on the leaves of their hosts frequently do 

 so abundantly on the stems and it was hoped x-hat in this case the per- 

 fect form of this Oidium might be obtained, but thus far no sign of the 

 ascosporous stage has been seen . It would be difficidt to propei'ly cor- 

 rellate the form without the evidence to be derived from this stage, but 

 there is some evidence to be gained which at least suggests relationship 

 to some species. As I have found, the haustcria on the mycelium are 

 lobed. It is quite possible that the form is ultimately to be referred to 

 some of the species of the genus Erysiphe. As DeBary * has pointed 

 out, the haustoria on the mycelium of Erysiphe galeopsidis are 

 lobed and this character is useful in differentiating this species from 

 Erysiphe cichoracearum. No species of Erysiphecie have as yet been 

 recorded upon any of the cruciferous family. If the Oidium on tur- 

 nips has been properly referred to the Oidium halsamii on Verbascum 

 then there would be some probability at least that this was the conidial 

 stage of Erysiphe galeopsidis, since that species has been found upon a 

 genus of the Scrophulariacem {Chelone). In size and form the Conidia 

 of Erysiphe galeopsidis agree very well with those of the turnip mildew. 

 But this evidence can only suggest, not determine, the true relationship. 



GEO. F. ATKINSON. 

 *Morp. und. Phys. d. Pilze, III, p. 49. 



