The Black-rot of the Grape, and its Control. 22'j 



III. RECOMMENDATIONS FOR CONTROL OF BLACK-ROT 



The most vulnerable point of attack is against the old mummies. 

 If it is practicable, these should be gathered at picking time along with 

 the gleaning, and after the separation in the packing house the whole 

 rotted mass burned. In this way, great quantities of rot are removed 

 and sources of infection for the next year destroyed. 



In the spring, plow just as deeply as possible without disturbing the 

 roots too seriously. Turn the ground completely over, thus burying the 

 rotted berries three to six inches under the surface. Plow as near the 

 vines as possible with a two-horse plow, and then use a one-horse plow to 

 get nearer. Use a horse-hoe to turn the remaining debris and soil from 

 under the rows into the furrow. Some mummies will remain on the sur- 

 face even after such treatment, but each cultivation will cover up a few 

 of these or at least disturb them and reduce their chances for maturing 

 spores. Keep all weeds and grass down. 



After trimming, there will be a few mummies left on the arms. The 

 trimmers should be instructed to gather these and as opportunity affords 

 burn them. All brush should be burned clean. 



Never allow basal water-sprouts to spread out over the ground ; they 

 are prime centers of infection. Keep the vines off the ground. 



A cover-crop of crimson clover, vetch or buckwheat, planted about 

 the middle of July or earlier, is desirable. 



Spray thoroughly: first, with Bordeaux mixture, 5-5-50, at the 

 time when third or fourth leaf is showing; second, with the same mixture 

 just when blossoms are swelling; third, with the same mixture soon after 

 flowers have fallen. 



The remaining applications will depend upon the weather. If the 

 season is rainy, the applications should be made at intervals of ten days 

 to two weeks; if dry, fewer applications will be necessary. Until July 20th 

 use Bordeaux, 5-5-50; after this time use ammoniacal copper carbonate, 

 5-3-50. The latter solution will not discolor the grapes as Bordeaux 

 mixture would. It is nearly as efficient as Bordeaux and perfectly harm- 

 less to the berries. 



The spray should be put on at the rate of eighty to one 

 hundred gallons to the acre, and under a pressure of at least one 

 hundred pounds. The hole in the disc of the nozzle should be 

 one-sixteenth inch. 



Stationary nozzles may be used for the first two applications. When 

 the fruit begins to form, use trailers and apply the spray directly on the 

 berries. 



