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Ecology and Epidemiology

Colonization of Bean Flowers by Epicoccum purpurascens. Ting Zhou, Graduate student, Department of Plant Science, Macdonald College of McGill University, Ste-Anne-de-Bellevue, Quebec, Canada, H9X 1C0; R. D. Reeleder, adjunct professor, McGill University, and Plant Pathologist, Agriculture Canada, Research Station, Delhi, Ontario, Canada, N4B 2W9. Phytopathology 81:774-778. Accepted for publication 7 March 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-774.

Emerging flowers, newly opened flowers, and senescent flowers of bean were sprayed with conidial suspensions of Epicoccum purpurascens, then sampled at 4, 8, 12, 24, and 96 h. The number of conidia per square millimeter of tissue surface was greater on newly opened or senescent flowers than on emerging flowers. Germination of conidia was greater on senescent petals than on younger tissue. However, conidia applied to emerging flowers germinated sufficiently such that resultant hyphae were able to completely colonize flowers as they senesced. The addition of malt extract to conidial suspensions improved germination on flowers and increased mycelial coverage on emerging flowers. Application of E. purpurascens did not accelerate senescence or affect chlorophyll content of bean leaves, nor did it affect yield or percentage of abscised flowers or pods. E. purpurascens did not penetrate leaves until they were in an advanced state of senescence, although the fungus readily colonized dead leaf tissue.

Additional keywords: biological control, Phaseolus vulgaris, Sclerotinia sclerotiorum, white mold.