|Hua, Sui Sheng - Sylvia|
Submitted to: Biological Control Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/15/2006
Publication Date: 7/25/2006
Citation: Hua, S.T., Parfitt, D.E., Brent, H.A. Evaluation of a biopesticide, pichia anomala wrl-076 to control aspergillus flavus in a commercial orchard. Biological Control Symposium Proceedings. Interpretive Summary: There is no conventional fungicide to control A. flavus. Aflatoxin continues to be a regulatory deterrent to the pistachio industry. Grower and processor are looking for effective means to control Aspergillus infestations and subsequent contamination of edible nuts with aflatoxin. Pichia anomala WRL-076 is not known to produce any toxic compounds or causes disease in plants and animals and humans. The cost of spraying yeast in orchards should be comparable with most other biopesticide. Pichia anomala WRL-076 has been tested as a biopesticide to control A. flavus and aflatoxin on corn in Texas. Researchers in California are testing this biopesticide to control Alternaria disease in pistachio. Once field efficacy of the yeast has been demonstrated, growers will most likely use it because for control of A. flavus and possibly other fungal pathogens. Application of this pesticide to pistachio will result in economic gain to the grower and industry
Technical Abstract: Existing literatures indicate that wounds in plant tissues provide the entry to A. flavus. By mechanically wounding pistachio nut-fruits, sufficient number of nut-fruits conducive to A. flavus and fungal infection are generated. The wounded nut-fruits are easily recognized for sampling. Two experiments were conducted in a commercial orchard in the summer of 2005. Nut-fruits of pistachio were individually wounded with a dissecting needle. Four treatments were applied. Nut clusters were sprayed with water; sprayed with an aqueous suspension of yeasts at 5x107 cells/ml; sprayed with an aqueous suspension of yeasts at 5x107 cells/ml and two hours later sprayed with spore suspension of A. flavus at 1x103 cells/ml; or sprayed with a spore suspension of A. flavus at 1x103 cells/ml. The biopesticide, P. anomala WRL-076 reduced the frequency of A. flavus colonization by 4 to 10 times and decreased the total propagules of A. flavus by 80 to 99% in comparison to nut-fruits not sprayed with the yeast.