44^ Bulletin 76. 



essential for the satisfactory control of the black rot that the early 

 application be made as thoroughly as possible and upon the same 

 dates as given for the first treatments of the powdery mildew. If 

 the rot is feared, the last applications should be made more fre- 

 quently, and as long as there is no danger of a permanent staining 

 of the fruit the clusters should be thoroughly treated. The ammo- 

 niacal carbonate of copper should be used after the middle of July, 

 or the first of August at the latest. It is better to use the Bor- 

 deaux mixture early in the season. The total number of applica- 

 tions necessary to control the black rot varies from three to seven, 

 depending upon the dampness and temperature of the summer 

 months. In warm weather, when the air and soil are kept moist 

 by frequent showers, the disease often spreads with extreme rapidity, 

 and under such conditions the treatment must be repeated every 

 seven to ten days. Among some Seneca lake vineyardists there 

 has arisen the impression that the more they spray the worse tlie 

 rot becomes. Such a state of affairs is of course impossible. 

 The applications made were probably not followed by as good re- 

 sults as was expected but that must be the fault of the operator 

 and not of the mixture. One cause of this trouble was quite 

 evident. The vines were a mass of foliage, so that it seemed im- 

 possible to reach the individual clusters in spraying. The land 

 was also very rich in nitrogen so that the conditions were favora- 

 ble to fungous growths. The absolute necessity of thorough 

 work cannot be to strongly emphasized. Figure 5 represents 

 two clusters of Catawbas, the one on the left not treated, the one 

 on the right treated according to the above directions. la this 

 case absolute protection was afforded by the spray. 



E. Brown Rot, Gray Rot. 

 {Peronospora viticola.') 



This disease is also caused by a fungus which thrives upon all 

 the green portions of the grape. 



It may attack the berries any time during the growing season 

 but is as a rule more serious early in the summer. Diseased 

 berries stop growing and soon becomes covered with a mealy sub- 

 stance which gives them a gray appearance. This has caused 

 the disease to be called a gray rot. When the berries are more 



