954 Popular Editions of Station Bulletins of the 



The fungus producing this disease has two fruiting 



Development of forms, but one of them has not been found in New 



the disease. York State and apparently is not essential to the 



indefinite continuation of the life of the parasite. 

 The pycnidia, or spore-containers, of the fungus stage found in this 

 State are minute flask-shaped bodies, occurring usually in the bark of 

 one or two previous seasons' growth, which raise the corky layer of 

 the bark, and form the tiny pustule-like spots shown in Plate VIII. 

 A drawing of one of these pycnidia, greatly magnified, is shown on 

 the title page. These are found in greatest abundance in early 

 spring, and each ruptures and pours out its accumulation of spores 

 shortly after the bursting of the grape buds. The spores seem to be 

 embedded in a mucilaginous material which swells greatly when it 

 absorbs moisture and forces itself and the spores from the pycnidium 

 in a striking, reddish yellow ball or curl. These spores may be carried 

 to young shoots a few feet away by spattering drops of rain, or may 

 be washed to shoots immediately below, but most of them pass to 

 the ground and perish. 



The spores find favorable conditions for germination in the 

 clinging drops of water which persist on the shoots for many hours 

 during continued fog and rain, such as often prevail in both the 

 Chautauqua and Central Lakes regions late in May. After the 

 germ tube enters the interior of the shoot, about a month usually 

 elapses before the disease shows externally, but by the first of July 

 lesions appear. These are generally found only at the bases of the 

 shoots, indicating that but one period of infection occurs each year. 

 This spore infection of the new shoots was formerly thought to be 

 of minor importance in the spread of the disease, as compared with 

 inoculation from the saw and other pruning tools previously used 

 on diseased vines, since these agencies may transfer the parasite 

 directly to the arm which it will destroy, while infection of the arm 

 from the shoots is indirect. If only a few spots are produced on 

 the shoot, the resulting cane may bear a crop the succeeding year 

 and be removed before the fungus has had an opportunity to grow 

 down into the more permanent part . On the other hand, if the 

 infections are numerous there is a possibility in case the cane is 

 saved for bearing wood that marked symptoms of the disease will 

 develop during the bearing period of the cane, and at all events the 

 probability of the fungus gaining entrance into the arm is greatly 

 increased. Infection through tools used in pruning has been 

 proved possible by many successful inoculations made in this way, 

 and is probably a common means of spreading the disease. Spread 

 through purchase of infected nursery stock is possible, but tests 

 made indicate that under most conditions vines started from infected 

 cuttings will not survive to reach the grower. If the cuttings are 

 made from canes only slightly infected, though, it is quite prob- 

 able that the cuttings would make vines that could be sold and 



