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Isolation of yeasts from buds, shoots, fruits, and leaves of pistachio and screen for efficacy against A. flavus. 2. evaluation of yeasts collected annually for their biocontrol activities on detached flowers, fruits and leaves. 3. Production of yeast, Pichia anomala, in sufficient quantity for field application. 4. Field test of effective yeasts in pistachio orchards.
Yeasts will be collected periodically from samples of buds, cuts, shoots and fruits from the orchards. The yeasts will be extracted from the plant materials and transferred to selective nutrient agar by a spiral plate system. Isolated yeast colonies will be identified and stored in 30% glycerol at -800C. The yeasts will be evaluated for their effectiveness against A. flavus by a bioassay developed in our lab. The mechanisms of biocontrol will be analyzed using biochemical, microbiological and microscopic techniques to provide information on potentially effective combinations of yeast strains for field application. The effective yeast, Pichia anomala, will be grown in Fernbach culture flasks on a incubatorshaker. The yeast cells will be harvested by centrifugation and stored at 40C. Yeast suspensions will be prepared in water and sprayed on ten pistachio trees in the orchards. Ten trees sprayed with water will serve as control. Sprays will be applied to male flowers in early and late bloom. Experiments will also include the spraying of a non-toxigenic strain of A. flavus alone and also co-inoculation of yeast and A. flavus. Biocontrol efficacy will be analyzed by determining the CFU (colony forming unit) of A. flavus and yeast on the male flowers. (Formerly 5325-42000-032-02T - 09/04)