64 



ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 46 



are similar, except in color, to the green streaks that the disease 

 produces in maple. General symptoms and control measures are 

 those given for maple. 



MAPLE 



Most species of maple grown in Illinois are subject to leaf, 

 stem, and vascular diseases. 



Anthracnose. — Anthracnose or leaf blight, caused by the 

 fungus Gloeosporium apocryptufn, develops in maple as small to 

 large, circular to irregular or indefinite, light brown areas of 

 dead tissues (Fig. 60). As the diseased areas of a leaf enlarge, 

 they may merge with one another until the entire leaf is killed. 

 Severely affected leaves may drop prematurely. However, leaves 

 that have only limited diseased areas may appear as leaves af- 

 fected with scorch, a noninfectious disease. Anthracnose may ap- 

 pear from late May to early August. Trees affected by this dis- 

 ease for a single year usually are not damaged sufficiently to re- 

 quire treatment. However, trees affected for several successive 



Fig. 60. — The anthracnose fungus in maple kills large areas of leaves 

 or occasionally entire leaves. 



