VINE DISEASES. 



149 



size appear on the grapes, and after a few days these 

 blotches are studded with minute blackish warts — the 

 fruit of the fungus. Within a short period of time the 

 diseased grapes become dry and much shrivelled, but 

 remain han^inf? for a considerable time. During the 



TINE LEAF SHOWING 'BLACK ROT' FFNGUS. 



winter numerous minute black sclerotia, or hardened 

 masses of fungus mycelium, form in the skin of the fruit, 

 and in the following spring, about the time when the 

 leaves are unfolding, these sclerotia produce two distinct 

 kinds of fruit, either of which is capable of infecting the 

 young leaves, thuts producing a repetition of the disease. 



