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Techniques

Isolation of Ceratocystis wageneri from Forest Soil with a Selective Medium. B. R. Hicks, Staff research associate, Department of Plant Pathology, University of California, Berkeley 94720; F. W. Cobb, Jr.,(2), and P. L. Gersper(3). (2)Associate professor, Department of Plant Pathology, University of California, Berkeley 94720; (3)Associate professor, Department of Soils and Plant Nutrition, University of California, Berkeley 94720. Phytopathology 70:880-883. Accepted for publication 4 March 1980. Copyright The American Phytopathological Society. DOI: 10.1094/Phyto-70-880.

A selective medium containing 800 μg/ml cycloheximide was developed for the isolation of Ceratocystis wageneri from soil. Fifty-nine soil samples were collected from around roots of infected ponderosa pines and assayed. In 11 cases, C. wageneri was isolated in quantities of up to 12,000 propagules per gram of soil and, in one case, was found 4–6 cm from the infected root. Most propagules apparently were conidia but several bits of mycelium removed from soil also proved to be C. wageneri. Mycelial growth through soil for short distances may be an important means of spread of the pathogen. Other species of Ceratocystis were isolated from soil and were tolerant of high concentrations of cycloheximide.