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Survival of Whetzelinia sclerotiorum and Initial Infection of Dry Edible Beans in Western Nebraska. G. E. Cook, Former Graduate Research Assistant, University of Nebraska, Lincoln, 68503, Present address of senior author: Dept. of State, Ibaden (ID), Washington, D. C. 20521; J. R. Steadman(2), and M. G. Boosalis(3). (2)(3)Assistant Professor, and Professor of Plant Pathology, University of Nebraska, Lincoln, 68503. Phytopathology 65:250-255. Accepted for publication 24 September 1974. DOI: 10.1094/Phyto-65-250.

Sclerotia were the primary survival structures of Whetzelinia sclerotiorum in the North Platte Valley of western Nebraska. The fungus also overwintered as mycelium in bean seeds, but this was not an important source of initial inoculum. Nearly 75% of the sclerotia recovered after 3 years' burial at 5, 12.5, and 20 cm below the soil surface germinated and formed apothecia in culture. The majority of sclerotia that formed apothecial initials in soil were recovered at 5- and 10-cm depths. Sclerotial survival was not always correlated with carpogenic germination, but was adversely affected by high soil temperature and moisture. The capacity of sclerotia to form secondary sclerotia and their longevity in soil insures that inoculum will be present in a 3-year crop rotation. Ascospores were the primary source of initial inoculum and infected beans in the field and greenhouse after germination and colonization of senescent flowers, adhering to or in contact with other plant organs. Mycelium from sclerotia initiated less than 10% of the initial infections. Bean plants became infected when exposed to mature apothecia or ascospore suspensions. Initial infection in the field was correlated with senescence of flowers and apothecial production.