DETAILED ACCOUNT OF SPECIFIC PLANT DISEASES 



535 



open out, the curling and arching of the blades become manifest. 

 The curling may be confined to a small portion of a leaf, or it may be 

 general and all of the leaves of a tree may be affected, as well as the 

 young stem on which \hey are found. The green, or reddish, color of 



Fig. 192. — Peach leaves deformed by leaf curl {Exoascus deformans). (After Heald, 

 F. D., Bull. 135 (Set. Ser. 14), Univ. of Tex., Nov. 15, igoQ-) 



the leaves is lost as they mature, and they become pale, or slightly 

 discolored. Diseased shoots may grow to twice their normal diameter 

 and assume a characteristic paleness. The diseased leaves finally 

 turn brown and drop off the tree, and if this defoliation is excessive 



