First Report of Dollar Spot, Caused by Sclerotinia homoeocarpa, on Turfgrass in Washington. G. K. Stahnke, Department of Agronomy Washington State University, Puyallup 98371. C. R. Foss, Department of Plant Pathology, Washington State University, Puyallup 98371. Plant Dis. 78:100. Accepted for publication 31 August 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0100B.
Dollar spot is a persistent disease that occurs commonly in low-fertility turfgrass throughout North America but has not been reported previously in Washington. The disease, which occurs on several grass species, was reported during 1991 in Oregon. In October 1992, symptoms of bleached spots less than 2.5 cm in diameter were observed on a low-fertility bentgrass (Agrostis sp.) and annual bluegrass (Poa annua L.) area at a golf course located in western Washington. The appearance of symptoms coincided with fall precipitation and 18 C day temperatures following a dry summer. Sclerotinia homoeocarpa FT. Bennett was isolated on PDA from bleached bands delimited by reddish brown margins on leaf tissue. Bentgrass was inoculated with the pure culture in the greenhouse, and dollar spot symptoms were evident after 5 days. S. homoeocarpa was then reisolated. Both infected leaf tissue and the S. homoeocarpa culture tested positive with an immunoassay test (Agri-Diagnostics Associates, Moorestown, NJ). The S. homoeocarpa culture has been deposited at Washington State Pathology