Powdery Mildew on Soybean in Delaware. S. Leath, Graduate Assistant, Department of Plant Science, University of Delaware, Newark 19711. R. B. Carroll, Associate Professor, Department of Plant Science, University of Delaware, Newark 19711. Plant Dis. 66:70-71. Accepted for publication 5 April 1981. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-70.

This is the first report on the occurrence of Microsphaera diffusa infection of soybeans in Delaware and the northeast region. Powdery mildew was observed on field-grown soybeans in September 1980; of 38 lines observed at four locations, nine were susceptible to natural infection by M. diffusa. Susceptible varieties were Ag DSR 232 and 532, AP 350, Essex, Falcon, and Md 71-583; Emerald, V76-438, and Ware were very susceptible.

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