64 Journal of Agricultural Research voi. v. No. a 



PERONOSPORA FICARIAE 



On ]\Iay 10, 1 91 1 , Peronospora ficariae was very prevalent on Ranunculus 

 fascicularis in the vicinity of Madison. This fact, coupled with De Bary's 

 (3) statement in connection with his discussion of the perennial nature 

 of mycelium of Phytophthora infesians, that Peronospora ficariae is peren- 

 nial in the tissues of Ranunculus ficaria, led the writer to determine whether 

 it sur\dves the winter in the mycelial stage on Ranunculus fascicularis also. 

 Eighteen plants, very generally infected with the disease, were staked on 

 the date above mentioned so that they could be readily located through- 

 out the winter and following spring. On February 2, 191 2, five of the 

 plants were chopped out of the frozen ground and carried into the 

 greenhouse, where the adhering soil was allowed to thaw out and was 

 removed from the fascicled roots, after which the roots were carefully 

 washed until free from soil and then transplanted in greenhouse soil. The 

 plants, two of which refused to grow, started very slowly, the first one 

 coming up on March 3, and two others the following day. The young 

 plants were chlorotic, distorted, and yellowish green, but there was no 

 evidence of Peronospora ficariae present until they had been held under 

 small bell jars for 24 hours, after which the fungus present on the 

 deformed leaves fruited profusely, showing plainly that the fungus was 

 alive in the host tissues during the winter. 



The 13 plants that were left in the marked space from which the 5 

 were taken were also watched carefully after they began to come up. 

 On April 5 five appeared, and these were covered with small bell jars. 

 On the following day conidiophores and spores of Peronospora ficariae 

 were collected from the underside of the leaves, showing that in this 

 case also the plants were infected before they reached the surface of the 

 soil. The results of these experiments confirm De Bary's (3) statement 

 and also show that Peronospora ficariae is perennial not only in Ranun- 

 culus ficaria but also in Ranunculus fascicularis. 



PERONOSPORA VICIAE 



Peronospora viciae occurs on several of the legumes. On May n, 

 1 91 3, the writer found it to be quite abundant on Vicia sepium, a peren- 

 nial common in the District of Columbia. At that time about 25 per 

 cent of the plants, which were from 4 to 6 inches high, were infected with 

 the disease, the fungus sporulating profusely and the plants giving every 

 evidence of systemic infection. The location of these plants was staked 

 off on the date above mentioned and the patch kept under observation. 

 On April 5 the following spring the plants started to come up, the tallest 

 being only 2 inches, and at this early stage nine were found to be system- 

 ically infected. It was not uncommon to find a healthy and a diseased 

 plant within 2 inches of each other. If infection was caused by oospores 

 or conidia, it is difficult to understand why the infection was not general 



