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Ecology and Epidemiology

Effect of Cold Treatment and Drying on Mycelial Germination by Sclerotia of Sclerotinia minor. L. A. Wymore, Graduate research assistant, Department of Plant Pathology, New York State College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853; J. W. Lorbeer, Professor, Department of Plant Pathology, New York State College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853. Phytopathology 77:851-856. Accepted for publication 7 November 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-851.

Mycelial germination by sclerotia of Sclerotinia minor was of two morphological types: eruptive and noneruptive. Cold treatment of hydrated sclerotia at 3 C for as little as 1 day stimulated rapid mycelial germination, whereas cold treatment of hydrated sclerotia at 12 C also stimulated rapid mycelial germination but reduced the proportion of sclerotia that underwent eruptive mycelial germination and increased the proportion that underwent noneruptive mycelial germination. Cold treatment stimulated mycelial germination of field-collected sclerotia as well as those produced in the laboratory. Air-drying (aging) of sclerotia at room temperature stimulated both eruptive mycelial germination and noneruptive mycelial germination but was not as effective as cold treatment. Fluctuating moisture conditions increased the proportion of sclerotia undergoing noneruptive mycelial germination. Hyphae produced during either type of mycelial germination were capable of causing infection of lettuce tissues without prior colonization of a food base.

Additional keywords: Lactuca sativa, lettuce.