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Sugar Maple Anthracnose Caused by Discula campestris in Wisconsin. G. R. Stanosz, Departments of Plant Pathology and Forestry, University of Wisconsin, Madison, 53706. Plant Dis. 78:1217. Accepted for publication 9 September 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-1217A.

Anthracnose affected understory sugar maple (Acer saccharum Marsh.) saplings in mixed hardwood forests of Oneida Co. in June 1993, and also was observed on large, open-grown, ornamental sugar maple trees in Oconto Co., WI, in August 1993. Symptoms associated with relatively light damage in each location included irregular, brown to black necrotic areas that occurred both along and between veins and on margins of leaves. A distinct, dark brown margin was sometimes present between dead and healthy tissue on older leaves from the open-grown trees. Acer-vular conidiomata developed in necrotic areas of leaves from both locations. Spores from these conidiomata produced pure cultures of Discula campestris (Pass.) von Arx that fruited abundantly on autoclaved sugar maple leaf pieces. Leaves on newly germinated sugar maple seedlings were punctured with a hot dissecting needle, sprayed with an aqueous suspension of conidia, and incubated at 20 C in the laboratory (2). Necrotic areas developed around wounds, enlarged, and coalesced resulting in leaf death. Acervular conidiomata were produced on these dead leaves and the fungus was reisolated. This is the first report of D. campestris in Wisconsin. The pathogen previously has been identified on sugar maple in the northeastern U.S. (1,2) and Ontario.

Reference: (1) B. L. Nash et al. Plant Dis. 78:285, 1994. (2) G. R. Stanosz. Plant Dis. 77:1022, 1993.