PRODUCTION, DELIVERY SYSTEMS, AND SURVIVAL IN SOIL OF 4 FUNGI WITH DISEASE BIOCONTROL POTENTIAL

Fermenter biomass, wheat-bran and peat preparations of Gliocladium virens, and three Trichoderma isolates antagonistic to Sclerotium cepivorum were examined as candidate production and delivery systems. Production of chlamydospores and conidia differed between isolates and with growth medium. Conidial germination was more rapid at 25-degrees-C compared with that at 15-degrees-C. Changes in water potential (range -7.75 to -1.93 MPa), pH, and addition of nutrients to growth media had variable effects on the colony-forming units per gram substrate produced for each fungal isolate, but in general these were small. The shelf life of the preparations in the laboratory was improved in some cases by storage at 4-degrees-C compared with that at 20-degrees-C. Following incorporation into soil, fungal numbers either transiently increased, remained stable, or declined.