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Field Trial for the Competitive Suppression of Aspergillus Flavus on Pistachio Nuts by a Biological Yeast in the Orchard


This proposal is a continuation of a project funded in 2003 to test the field efficacy of a biocontrol yeast for control of Aspergillus flavus. <P>Three questions need to be answered. 1) Are the yeasts durable enough to survive field conditions, 2) is the applied yeast phytotoxic (eg. does it adversely impact nut production, shape etc. and 3) will the yeasts be effective at inhibiting the growth of A. flavus in the field and at what concentration.

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Approach: A pistachio plot containing appx. 65 mature Kerman pistachio trees will be used for the study. They are located at the UC Dept. of Pomology research farm at Winters CA (Wolfskill Experimental orchard. The 20 trees will be used for the experiment with the remaining trees serving as borders. A single strain will be used for this initial trial. This strain has been shown to be effective for control of A. flavus. Three concentrations will be used for the study. The inoculum will be sprayed on nut clusters by Dr. Parfitt at concentrations, 107/ml, 5x107/ml and 108/ml. Two applications of yeast, applied one week apart at the end of July. Leaves and developing nut clusters of 'Kerman' pistachio will be sprayed with yeast cells and subsequently assayed for yeast and fungal populations on the nuts and any evidence of pytotoxicity. Documents SCA with UC Davis.

Hua, Sui
University of California - Davis
USDA - Agricultural Research Service
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