378 



STATE BOARD OF AGRICULTURE. 



all trimmings and burning all rliseased fruit as fast as it appears has served 

 in some cases to hold this disease in check. Spraying with Bordeaux at the first 

 appearance of the disease if thorough and persistently followed will in most 

 cases serve to control the black rot. One spraying with copper sulphate 

 solution before growth begins should be made, and after leaves are out Bordeaux 

 mixture should be applied at intervals of two or three weeks until grapes are 

 about half grown. After this some clear fungicide may be used, such as weak 

 copper sulphate solution, ammoniacal copper carbonate or soda Bordeaux which 

 will not stain the fruit. Sprayings, in many cases, will not need to be continued 

 after August first. 



DOWNY MILDEW. 



(Plasmopara viticola B. & C.) 



J^.-iA 



^ 



vt 



Fig. 28. — Leaves and younp growth of 'grape attacked by the downy "mildew. The upper 

 surface of the leaves shows brownish spots, while the lower side gives rise to^ajwhitish, 

 downy growth. 



As a destructive disease of the grape the downy mildew probably holds the 

 highest rank. It affects all tender growing parts of the vine. On the leaves 

 it first produces pale spots on the upper surface. These spots soon become 

 brownish while on the lower side of the leaf a whitish downy outgrowth appears 

 suggestive of the common name. This appearance is due to the formation of 



