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Techniques

A Method for Estimating Numbers of Viable Sclerotia of Sclerotium rolfsii in Soil. R. Rodriguez -Kábana, Department of Botany, Plant Pathology, and Microbiology, Auburn University, Auburn, AL 36830; M. K. Beute(2), and P. A. Backman(3). (2)Department of Plant Pathology, North Carolina State University, Raleigh 27650; (3)Department of Botany, Plant Pathology, and Microbiology, Auburn University, Auburn, AL 36830. Phytopathology 70:917-919. Accepted for publication 17 March 1980. Copyright The American Phytopathological Society. DOI: 10.1094/Phyto-70-917.

Sclerotia of Sclerotium rolfsii germinate when stimulated by certain volatile components of the host plant. Methanol was used as a stimulant to develop a method for determination of numbers of sclerotia in field soil. Air-dried soil was allowed to imbibe a 1% (v/v) aqueous methanol solution until it was evenly moist. After 4 days incubation in a closed chamber, the number of white colonies of S. rolfsii on the soil surface was counted. The method is at least 75% effective for detecting viable sclerotia. This method is as accurate and simpler than the soil-sieving and flotation methods currently used for determining numbers of viable sclerotia in soil.