Grape. 305 



fungi and insects, the remedial measures should be directed 

 towards strengthening the plant by means of proper fertil- 

 izers, potash being perhaps the most important element re- 

 quired. See Cornell Bulletin, 76, for a full account of the 

 trouble. 



Ripe Rot; Bitter Rot (Glaeosporium fructigenum, Berk.). 

 Description. The names given this disease are suggestive of 

 the time in which the berries are attacked, and what eifect the 

 fungus has upon the flavor of the fruit. The disease may 

 attack the fruit stems, and cause the berries to wilt on account 

 of the supply of nourishment being cut oif. But more com- 

 monly the berries are directly attacked. Such fruit shows a 

 reddish-brown discoloration at the affected point, and this color 

 soon extends over the entire berry. The surface then becomes 

 dotted with black pimples as in the case of black rot, but here 

 they are not so numerous, and they are also larger but less ele- 

 vated. The berry also shrivels, but the black color is wanting, 

 since those affected with ripe rot remain dark purplish brown, 

 although some assume a red tint. As a rule, they fall to the 

 ground when this stage is reached, while berries destroyed by 

 black rot remain upon the vine even until the following spring. 



Ripe rot will spread after the grapes have been harvested, and 

 care should therefore be exercised in selecting only sound fruit 

 when it is to be stored. See under APPLE, page 240. 



Treatment. The same treatment which serves to check black 

 rot will also control this disease, the later treatments being of 

 special importance. 



INSECT ENEMIES. 



Grape-slug; Grape-sawfly (Selandria Vitis, Harris). Descrip- 

 tion. The adult, a small four-winged fly, lays its eggs in 

 little clusters on the under side of the young leaves. These 

 eggs produce small yellowish-green larvae, which feed in groups, 

 beginning at the margin of the leaf and eating inwards until 

 the leaf is destroyed. Others are then attacked, and it fre- 

 quently occurs that very serious injury to the vineyard is done 

 by this insect. There are two broods, the first appearing in 

 spring, and the second in July or August. The winter is passed 

 in the pupal state. 



