Disease Note

Leaf Blight (Didymosporina aceris) of Norway Maple in Connecticut and Pennsylvania. C. W. Ellett, ChemLawn Diagnostic Laboratories, Columbus, OH 43085. Plant Dis. 69:451. Accepted for publication 25 January 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-451a.

Didymosporina aceris (Lib.) Hohn. (syn.: Marssonina trunculata (Sacc.) Magn.) was identified as the cause of a leaf blight of Norway maple (Acer platanoides L. ‘Crimson King’) in Rocky Hill, CT, and of a green leaf cultivar near York, PA. Spots were circular to irregular and coalesced to form extensive necrotic areas. Acervuli were epiphyllous and abundant and were also present on the wings of the samaras. The conidia were unequally two-celled and pale brown. From the Connecticut location, considerable leaf drop in early August was reported on several trees. Previous reports of this disease in the United States have been from New York on Norway maple and from Oregon on bigleaf maple (A. macrophyllum Pursh.); reports from Europe have been numerous. A. Y. Rossman of the Plant Protection Institute, USDA, Beltsville, MD, confirmed identification of the fungus.