SUMMARY: Suppression of germination of conidia of Cochliobolus victoriae was similar during incubation on sand being leached with water and on sand leached with salt solutions. Conidia of C. victoriae, Thielaviopsis basicola and Curvularia lunata, and sclerotia of Sclerotium cepivorum, exuded more 14C label during leaching with phosphate buffer than on buffer-saturated sand without leaching. Conidia of C. victoriae and Cochliobolus sativus became dependent upon exogenous nutrients after 7 days’ incubation on soil or leached sand. Decreased viability followed the loss of nutrient independence. Germination of C. victoriae and Cu. lunata was stimulated when they were leached with exudate from spores of either fungus, or by a dilute nutrient solution simulating natural exudate. Conidia rendered nutrient-dependent by leaching, germinated and accumulated radioactivity when incubated on exudate from 14C-labelled spores. Nutrient-independent spores exude non-specific energy-rich nutrients which may be rendered unavailable to the spores by microbial activity in soil, resulting in fungistasis.
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