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STATE BOARD OF AGRICULTURE. 



DISEASES OF THE GRAPE. 



BLACK ROT OF THE GRAPE. 



(Guignardia Bidwellii (Ell.) V. & R.) 



Fig. 26. — A bunch of grapes, many of which have rotted with the black rot fungus. (Original.) 



Among the numerous fungous diseases to which the grape is subject no other 

 is so destructive to the fruit in this country as the one known as black rot. Thus 

 the labor and fruit of a season may be swept away in a few days when the 

 conditions are favorable. In some places grape growing, once a profitable in- 

 dustry, has been almost entirely abandoned on account of the ravages of this 

 fungous parasite. 



The disease attacks all parts of the vine except the roots. The leaves and 

 young shoots first show its effects by the appearance of brownish spots of dead 

 tissue. The fruit is often attacked when only half grown although the greatest 

 destruction usually follows a warm, moist period of weather a little before 

 ripening. Affected berries first show brown or dark colored spots which rapidly 



