. Manual of tree diseases . Trees. MAPLE DISEASES 227 In wet seasons defoliation may result. The illustrations show the effect of these diseases on the leaf (Figs. 37 and 38). Many of the other leaf-spots of maple appear similar to these, however, and no accurate determination can be made without a microscopic ex- amination of the fungus. The leaf-spot caused by Phyllo- sticta minima is characterized by light brown cir- cular spots with numerous black dot-like fruiting- bodies near the center (Fig. 37). The general char- acters of leaf- spots, and the life history of the fungi causing them, ar
. Manual of tree diseases . Trees. MAPLE DISEASES 227 In wet seasons defoliation may result. The illustrations show the effect of these diseases on the leaf (Figs. 37 and 38). Many of the other leaf-spots of maple appear similar to these, however, and no accurate determination can be made without a microscopic ex- amination of the fungus. The leaf-spot caused by Phyllo- sticta minima is characterized by light brown cir- cular spots with numerous black dot-like fruiting- bodies near the center (Fig. 37). The general char- acters of leaf- spots, and the life history of the fungi causing them, are more fully discussed on page Fig. 38. — Leaf-spot of maple caused by Gloeosporium apocryptum. Powdery Mildews Caused by Uncinula drdnata Cooke and Peck and Phyllactinia corylea (Pers.) Karst. Two species of the powdery mildew fungi are known on maple leaves in the United States, Uncinula drdnata and Phyllactinia corylea (see page 35). The former has been reported from northeastern and central United States and the latter, which occurs on all kinds of trees, is distributed throughout the country. These two diseases cannot be dis-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Rankin, W. Howard (William Howard), b. 1888. New York : The Macmillan Company
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