Small Fruits 105 



nar, glandlike structures, chiefly upon the upper side of the 

 leaf, and present even before the leaves unfold. These 

 structures (pycnia) become more distinct as the leaves 

 enlarge. 



The mycelium of the causal fungus when once established 

 in the cane lives in it from year to year, spreading through- 

 out the plant. Spraying is, therefore, ineffectual. In fact 

 the only successful way to combat the rust is to remove 

 and burn all affected plants. Diseased plants are valueless 

 and are a menace to the healthy plants. Resistant varieties, 

 such as the Snyder, should be used. 



Late-rust ^-^ (Kuehneola albida (Kiihn.) Magn.). — As 

 the name implies, this rust usually appears late in the season, 

 distinguishing it from orange-rust, which is prevalent in the 

 spring. The spores are not so abundant as those of orange- 

 rust, but occur in small, pale-yellow or whitish spots scattered 

 on the under side of the leaf. This disease has not as yet 

 become sufficiently prevalent to be of serious import, al- 

 though its increase at any time under favorable climatic 

 conditions may place it among the important plant enemies. 

 It appears to be limited to blackberries, and is known both 

 in Europe and the eastern United States. 



Cane-blight ^'"^ (Leptosphcpria coniothyrium Sacc. Coniothy- 

 rium). — First mentioned in literature in 1899 by Stewart and 

 Eustace as occurring in the Hudson Valley, this disease seems 

 to be widespread and destructive upon both red and black 

 raspberries. Principal damage occurs to the fruiting canes, 

 the foliage of which suddenly wilts and dries. New canes 

 are frequently killed during the first season's growth. 



Infection usually occurs through wounds, especially 

 pruning wounds or those made by insects, and progresses 

 toward the root. Sometimes the disease remains upon one 

 side, while in other cases it encircles the cane. 



Upon diseased canes the bark is lighter colored and dis- 

 figured by smoke-colored patches of spores extruded from 

 the pycnidia within. The pycnidia appear as very minute 

 pustules. The wood is much discolored and eventually 



