398 



Diseases of Economic Plants 



lines which extend lengthwise of the leaves arfe produced by 

 the ascus-bearing organs. 



Premature defoliation results. 



Fig. 210. — Cronartium ribicola on pine showing general aspect of 

 disease. After CoUey. 



Leaf-blight, twig-blight (Lophodermium brachysporum 

 Rostr.). — In Maine the leaf-blight has been noted as de- 

 structive to a considerable number of small trees and in- 



