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Germination of Fusarium oxysporum Chlamydospores in Soils Favorable and Unfavorable to Wilt Establishment. Shirley N. Smith, Assistant Research Plant Pathologist, Department of Plant Pathology, University of California, Berkeley 94720; W. C. Snyder, Professor, Department of Plant Pathology, University of California, Berkeley 94720. Phytopathology 62:273-277. Accepted for publication 13 September 1971. DOI: 10.1094/Phyto-62-273.

Chlamydospores of Fusarium oxysporum f. sp. batatas, cubense, and lycopersici, and three common soil saprophytic F. oxysporum, isolates which resemble each of the three pathogenic clones culturally, were compared for their ability to germinate in soil when small concentrations of glucose and asparagine were added to the premoistened soil. A higher percentage of saprophyte chlamydospores germinated in soil known to be wilt-suppressive than did chlamydospores of the tested pathogens. In soil where wilt has been known to occur, little difference was observed in percentage germination between pathogens and saprophytes. Increasing the nutrient level increased the percentage germination in both soils and decreased the differential between pathogen and saprophyte, indicating that competition with common soil flora for small amounts of nutrients may be involved. Bacterial numbers (determined by plate counts) increased more rapidly in the wilt-suppressive soil than in the wilt-conducive soil.

Additional keywords: nutrition of soil-borne fungi, saprophytic and pathogenic Fusarium oxysporum compared.