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Preservation of Ascospores of Sclerotinia sclerotiorum on Membrane Filters. J. E. Hunter, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva 14456; J. R. Steadman(2), and J. A. Cigna(3). (2)Department of Plant Pathology, University of Nebraska, Lincoln 68583-0722; (3)Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva 14456. Phytopathology 72:650-652. Accepted for publication 7 September 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-650.

More than 90% of the ascospores of Sclerotinia sclerotiorum collected from laboratory-produced apothecia, dried on Millipore membrane filters, and stored over calcium chloride desiccant in a closed vessel survived for 24 mo when refrigerated or frozen. A higher percentage of spores also survived without a desiccant in a freezer. With a desiccant, survival of freshly collected spores at 25 C was adequate for ascosporic inoculum to be shipped to workers who lack the facilities or experience to germinate sclerotia carpogenically. Isolates from different hosts and geographical locations survived similarly. Stored ascospores that were still germinable were as effective as freshly collected ascospores in inducing disease on beans (Phaseolus vulgaris). Germinability of stored ascospores was greater on a nutrient-rich medium, such as potato-dextrose agar, than in water.