DISEASES OF SPECIAL CROPS 



85 



lar to those upon the bark soon develop in concentric 

 circles. 



Lawrence notes the Baldwin, Blue Pearmain, Grav- 

 enstein, Newton Pippin, 

 Wagener, \\'oalthy, and 

 Yellow Bellflower as espe- 

 cially susceptible; the 

 Hubbardston, Nonesuch, 

 Imperial Pippin, King of 

 Tompkins County, Maiden 

 Blush, Olympic, Red As- 

 trachan, Rhode Island 

 Greening, Spitzenburg, 

 Striped Astrachan, Twcnij-- 

 ounce Pippin, and Yellow 

 Transparent as less suscep- 

 tible, while the Northern 

 Spy, Waxen, and Ben 

 Davis are comparatively 

 free from the disease ; but 

 these generalizations are 

 largely modified by a great 

 variation in resistance 

 among individual trees. 



Wlien the cankers are 

 few, on small trees, excision 

 may be practiced to advan- 

 tage; when, liowever, there are hundreds of canliers upon 

 each tree, this treatment is manifestly impractical)le. 

 Spraying witli strong Bordeaux mixture, 12-8-50, in the 

 fall after the crop is gathered is valuable to prevent the 



Fig. 32. — Black spot on fruit. 

 After Lawrence. 



