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Comparison of Germination of Pathogenic Fusarium oxysporum Chlamydospores in Host Rhizosphere Soils Conducive and Suppressive to Wilts. Shirley Nash Smith, Department of Plant Pathology, University of California, Berkeley, CA 94720; Phytopathology 67:502-510. Accepted for publication 8 October 1976. Copyright 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-502.

The germination of chlamydospores and subsequent growth of hyphae of Fusarium oxysporum f. sp. vasinfectum and F. oxysporum f. sp. tracheiphilum were less in soils known to be suppressive to Fusarium wilts than in wilt-conducive soils, whether in host rhizospheres or in response to added nutrients (300 μg glucose and 300 μg asparagine per gram of soil). Germination and growth in seedling rhizospheres usually continued longer than germination following a single introduction of nutrients to the soils, but even in these rhizosphere soils, germination often decreased after 24-60 hr. An Arthrobacter sp. was associated with the F. oxysporum germlings in the wilt-suppressive soils, but was rare in the wilt-conducive soils that were studied. This bacterium increased markedly as the chlamydospores germinated and the germlings grew.

Additional keywords: cotton, cowpea.