GRAPE DISEASES 235 



in the leaves, canes and other attacked organs. Soon there 

 follows the development of fruit-bodies, the pycnidia. The 

 mycelium forms a gnarl just beneath the epidermis, and in a 

 few hours a crop of pycnospores is matured. These are 

 imbedded in a mass of gelatinous matter, and when moistened 

 a marked swelling of the mass occurs and the pycnospores are 

 forced out in a coil. They are subsequently scattered to other 

 leaves, fruits and woody parts, where new lesions are developed. 

 This process is repeated many times through the summer. 

 With the advent of autumn the fungus ceases vegetative ac- 

 tivities and prepares for winter. Some of the pycnidia live 

 over until spring, as already stated. In other cases, generally 

 in August, sporeless pycnidia appear on mummies ; in place of 

 spores the cavity of this body is filled with a whitish cellular 

 tissue. In such a state the structure is sometimes referred to 

 as a pycnosclerotium, and as such the fungus passes the winter. 

 In the spring the solid interior of the pycnosclerotium is re- 

 placed by asci which eject most of their spores in June. Some 

 of the ascospores are not discharged until later, and may even 

 be found as late as October. With two kinds of spores always 

 present in a vineyard of affected plants it is not difficult to 

 understand how unsprayed, susceptible varieties may be ruined 

 in a favorable season of considerable rain. 



Control. 



Black-rot has long been kept in check by the application 

 of bordeaux mixture. It is essential to successful protection 

 of the vines that the spraying should be made before rains and 

 that the work be thoroughly done. Apply bordeaux mixture 

 5-5-50 as follows : (1) when the second or third leaf is showing ; 

 (2) before the blossoms open ; (3) after the blossoms have 

 fallen ; (4) about 10 to 14 days later ; (5) again in 10 to 14 days. 



In spraying and in the employment of other measures against 

 black-rot the following matters should be kept clearly in 

 mind : 



