New York Agricultural Experiment Station. 357 



3. Just after tlie blossoming. 



4. From ten to fourteen days after the third treatment. 



5. If a iifth treatment is necessary let it follow the fourth after 

 an interval of from ten to fourteen days. 



6. If a later treatment than the dfth is needed ammoniacal solu- 

 tion of copper carbonate should be used as that is less liable to stain 

 the fruit than the Bordeaux mixture. Directions for preparing it 

 are found in article 4 on Fungicides and Insecticides. 



The number of the treatments will be governed by the weather 

 conditions and the severity of the disease. If the vineyard is not 

 badly diseased, and if there is not an excessive amount of hot, wet 

 weather, four treatments may be found suthcient for all practical 

 purposes. 



The early treatments are extremely important. 



Thorough treatment is essential to success. 



Downy Mildew. — In some grape growing sections of the State 

 this is a very serious disease. It attacks nearly every portion of the 

 vine. Its first appearance on the leaves, that will be noticed by a 

 casual observer, is in dry, brick red spots on the upper surface. On 

 the under side of the leaf the diseased area will be covered with 

 the interlaced threads of the fungus. The red spots increase in 

 size until in many instances the entire leaf dies and falls to the 

 ground. It frequently causes the berries to turn dull brown and 

 become soft and shrivelled. This appearance of it has been com- 

 monly called " brown rot." The spores are found on the threads 

 which issue from the under side of the leaves or from the stems or 

 fruit, the whole giving when fresh a glistening white downy ap- 

 pearance from which the disease takes its most common and prefer- 

 able name of "downy mildew.'" Later these parts of the fungus 

 exposed on the surface assume a gray hue and so the disease has 

 also been known as " gray rot." Some varieties, like Delaware, 

 appear to be quite susceptible to the attacks of the disease and none 

 of the cultivated varieties are known to be exempt. 



Remedy. — It may be successfully treated in the manner just de- 

 scribed for Black Rot. See p. 356. 



Powdery Mildew. — Unlike many of our fungous diseases, the pow- 

 dery mildew flourishes best during the dry weather of mid-summer. 

 It usually begins its attack in June, though it may appear earlier 

 and destroy many of the grape blossoms. Its name is descriptive of 



