Discula campestris Infection of Sugar Maple Leaves Associated with Pear Thrips Injury. B. L. NASH, Former Research Associate, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. G. R. STANOSZ, Assistant Professor, Department of Plant Pathology, University of Wisconsin, Madison 53706; and G. TAYLOR, Former Research Assistant, and D. D. DAVIS, Professor, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. Plant Dis. 78: 285-289. Accepted for publication 7 October 1993. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source The American Phytopathological Society, 1994. DOI: 10.1094/PD-78-0285.

Acervuli of Discula campestris were frequently observed on necrolic portions of thrips-injured sugar maple leaves in 1989. Necrosis was present on 82 98% of leaves collected at three sites in May, June, and August 1990 in Potter County, Pennsylvania, but symptoms were not severe. Evaluation of necrotic leaves indicated that 82-91% of the leaves were affected on ≤5% of their surface area. Marginal and interveinal necrosis were most common, while veinal necrosis was rare. The study was expanded to five central Pennsylvania counties in 1991. The median incidence and severity of all forms of necrosis were 0.1-1.0%. Twenty-one of 25 trees were rated positive for D. campestris following incubation of symptomatic or asymptomatic leaves in a moist chamber. The fungus was identified on leaves from seven northeastern states: Maine, Massachusetts, New Hampshire, New York, Pennsylvania, Rhode Island, and Vermont.