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Analysis of a Maple Canker Epidemic in Pennsylvania. T. Craig Weidensaul, Formerly Research Assistant, Department of Plant Pathology, currently Head, Laboratory for Environmental Studies and Associate Professor of Plant Pathology, Ohio Agricultural Research and Development Center, Wooster 44691; Francis A. Wood, Formerly Research Associate, Center for Air Environment Studies, and Professor, Department of Plant Pathology, The Pennsylvania State University, University Park 16802, currently Professor and Head, Department of Plant Pathology, University of Minnesota, St. Paul 55121. Phytopathology 64:1024-1027. Accepted for publication 23 February 1974. DOI: 10.1094/Phyto-64-1024.

A sugar maple canker epidemic in Pennsylvania was analyzed in 1967 using van der Plank’s techniques. The disease is induced by several species of Fusarium, primarily F. solani. Data were collected from 30 trees having more than 3,100 cankers. The frequency of cankering for each tree was recorded by tree face, height of occurrence on the stem, and by year of initiation. There was an inverse relationship between frequency of cankering and height of occurrence, but no difference in frequency of cankering among tree faces. Peak periods of cankering were 1950, 1952, 1957, and 1961-63. The frequency of disease began to increase logarithmically in the late 1930’s and to decrease in the early 1960’s. During the period of most rapid rate increase of the epidemic, disease incidence was doubling every 4 yr.