Incidence and Control of Cytospora Canker and Bacterial Canker in a Young Sweet Cherry Orchard in Oregon. R. A. Spotts, Oregon State University, Mid-Columbia Agricultural Research and Extension Center, Hood River 97031. T. J. Facteau, L. A. Cervantes, and N. E. Chestnut. Oregon State University, Mid-Columbia Agricultural Research and Extension Center, Hood River 97031. Plant Dis. 74:577-580. Accepted for publication 8 January 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0577.

A field study to evaluate control of Cytospora canker was initiated in 1981 by planting sweet cherry trees (cv. Bing). Treatments applied to the trees included white trunk paint, three levels of nitrogen, and application of benomyl (225 mg a.i. per liter) after dormant pruning or at popcorn, petal fall, and shuck split. Trees were evaluated annually from 1982 to 1986 for active trunk cankers, and isolations were made from margins of cankers. One to 5% of the trees were infected with Cytospora cincta each year, and 18% were infected by 1986. Bacterial canker, caused by Pseudomonas syringae, occurred in 13% of the trees in 1982 and in 25% of the trees by 1986. The death rates of trees infected with C. cincta and P. syringae were 16 and 17%, respectively. Disease incidence was highest in trees close to an old cherry orchard. Nitrogen or benomyl did not reduce the incidence of cankers. White trunk paint reduced the incidence of both Cytospora and bacterial trunk cankers.