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Disease Increase and the Dynamics of Spread of Canker Caused by Anisogramma anomala in European Filbert in the Pacific Northwest. T. R. Gottwald, Research plant pathologist, USDA-SEA-AR, Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; H. R. Cameron, professor of plant pathology, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. Phytopathology 70:1087-1092. Accepted for publication 15 May 1980. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-1087.

In southwestern Washington, eastern filbert blight, which is caused by Anisogramma anomala (Diaporthaceae), was first discovered in 1973. The rate of disease increase and the geographical pattern of spread from the original focus of infection were studied. Increase in length of individual cankers averaged 31.72 cm/yr. Regression analyses of disease progress curves gave disease increase values of r = 1.085 and r = 1.236 unit per year within single trees (treated as independent epidemics) and disease increase within orchards, respectively. Within the area presently affected the original focus was determined to be a group of five orchards in the northeast quadrant from which the disease spread south and west to 44 additional orchards. Inoculum dispersal over long distances is infrequent; therefore, the southernmost diseased plantings pose the greatest threat of disease spread into orchards farther south in the main filbert-growing areas of Oregon.

Additional keywords: disease survey, Corylus avellana.