Conditioning Sclerotia of Sclerotinia sclerotiorum for Carpogenic Germination. H. R. Dillard, Cornell University, New York State Agricultural Experiment Station, Department of Plant Pathology, Geneva 14456. J. W. Ludwig, and J. E. Hunter, Cornell University, New York State Agricultural Experiment Station, Department of Plant Pathology, Geneva 14456. Plant Dis. 79:411-415. Accepted for publication 1 February 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0411.

Sclerotia from one isolate of Sclerotinia sclerotiorum produced on cornmeal/vermiculite me-dium were subjected to seven different treatments at 8 C over an 8-wk period to overcome dormancy and promote carpogenic germination. The conditioning treatments of the sclerotia included 1) none (immediate use), 2) incubating dry in petri plates, 3) incubating on moistened filter paper in petri plates, 4) burying in masonry sand in clay pots and leaching with water 2-3 times per week, 5) suspending in bags of fiberglass screen in a pipette washer and constantly rinsing, 6) placing in flasks of water under constant aeration, and 7) placing in flasks of water with no aeration. Following treatment, the sclerotia were incubated on moist sand at 20 C for 4-6 wk. Sclerotia that were not conditioned or conditioned dry in glass petri plates did not germinate. Carpogenic germination increased as the conditioning duration increased, and was greatest after 8 wk of conditioning in a constant rinsing environment. Carpogenic germination of an additional 24 isolates was subsequently examined at conditioning temperatures of 4, 8, 16, and 24 C in flasks of water under constant aeration. Germination of New York isolates was almost eliminated at 24 C, but isolates from other locations varied in their response to condi-tioning at high temperature. The optimal temperature range for conditioning of all isolates was 8-16 C. As sclerotial size increased, the number of germinating sclerotia and apothecia pro-duced per sclerotium also increased.