250 



GRAPES 



the vine dies or is nearly killed. It is believed that the muscadine 

 group of grapes is not affected by this pest. It has been suggested 

 that these vines be used as stocks for the grafting of other grapes 

 where this enemy is serious. 



Diseases of the Grape.— The black rot is doubtless the worst 

 disease of the grape. Downy mildew (Fig. 177) is also very destruc- 

 tive in some sections. The methods required in preventing black 

 rot disease will effectively control several other diseases which may 

 otherwise occur. Spraying with Bordeaux mixture in the early 



Fig. 178. — Grapes affected with rot disease. Courtesy Mel. J. Cook. 



stages of fruit formation is recommended. This spray may be 

 combined with arsenical poisons so as to control the disease and 

 the leaf-eating insects at the same time. The first spraying should 

 take place about the time the blossoming is over. It should be 

 repeated every ten days or two weeks according to the weather 

 conditions. With frequent rains and rapid growth, the spraying 

 must be more frequent. 



Figure 178 shows the first effects of rot disease. If the attacks of 

 rot and mildew occur before Bordeaux mixture has been applied it 

 may be impossible to control the diseases. However, unaffected 

 parts of the vine may be saved if the work is done promptly. After 



