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Chlamydospore Formation in Fusarium in Sterile Salt Solutions. S. C. Hsu, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48823; J. L. Lockwood, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48823. Phytopathology 63:597-602. Accepted for publication 17 November 1972. DOI: 10.1094/Phyto-63-597.

Methods of inducing chlamydospore formation aseptically were developed for Fusarium oxysporum f. sp. lycopersici, F. oxysporum f. sp. melonis, F. solani f. sp. phaseoli, F. solani f. sp. pisi, and F. roseum f. sp. cerealis‘Culmorum’. Chlamydospores were formed readily from washed, nongerminated macroconidia incubated on Nuclepore filters floated on 0.03 M Na₂ SO₄, but not on water. Germlings, obtained by incubating macroconidia on filters placed on potato-dextrose agar, produced chlamydospores readily on acid-washed sterilized sand continually leached with water or 0.025 M phosphate buffer (pH 6.9). Fewer chlamydospores were formed without leaching. Germlings also produced large numbers of chlamydospores when incubated directly in 0.03 M Na₂ SO₄; distilled water was slightly less effective. The results indicate that chlamydospores are produced when the environment is deficient in energy but contains appropriate mineral salts.