U-2 



DISEASES OF ECONOMIC PLANTS 



MAPLE 



Leaf spot, phyllostictose {Phyllosticta acericola C. & E.)- — 

 A large proportion of the leaf may become involved, 

 causing premature defoliation which materially lessens the 



Fig. 193. — Maple tar spot. After Heald. 



value of the tree for ornament or shade. The silver maples 

 are especially susceptible, and their sale has thereby been 

 reduced. The leaf spot was first noted in 1874 and is dis- 

 tributed throughout the United States. The blackish, 

 subcircular spots as they enlarge change to brown and later 



