396 



Diseases of Economic Plants 



quantity from Germany, between 1900 and 1909 on diseased 

 pine seedlings, though isolated cases occurred here prior to 

 those dates, even as early as 1892. It is now known in 

 Maine, New Hampshire, Vermont, Massachusetts, Con- 



FiG. 209. — Map showing general location of pine blister infections. 



^ Diseased white pines found in 1816. 



• Diseased currants and gooseberries found in 1916. 



^ Areas of heavily infected currants and gooseberries, 

 i-i. Centers of heavy infection where the principal efforts were made 

 '■"•'^ to eradicate diseased plants. 



(Thiee centers of infection also exist in Wisconsin and Minnesota.) 

 Courtesy of the Office of Forest Pathology. 



necticut, New York, Pennsylvania, Rhode Island, New 

 Jersey, Kansas, Ohio, Indiana, Wisconsin, Minnesota. The 

 alternate host is Ribes (see p. 116), some twenty-one species 

 of which are susceptible. In the spring, sporidia from the 



