212 



BuLL::-riN 253. 



Stages of infection. 



In Fig. 181 are shown the spots formed by the first infection of 1907 

 on stem, leaf, leaf petiole and tendril. These spots are frequently over- 

 looked by the grower. To many, the first signs of the black-rot is the 

 blackening of the pedicel of the berry. This, however, is only one of the 

 many points of first infection. The little berry is protected by the calyx 



Fig. 181 — Black-rot fungus on the canes, showing as pits and blotches. 



which falls off at blooming time while its pedicel is not so protected; but 

 as the source of sap is cut off the berry fails to develop. 



In the vineyards at Romulus in 1907, the first infection from winter- 

 spores took place with the rain of June 22nd and 23rd, which was followed 

 by showers and cloudy weather. The first spots appeared July loth. 

 The period of incubation was thus from 16 to 18 days. The second 



