Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: June 1, 2004
Publication Date: July 1, 2004
Citation: Hua, S.T. 2004. Field assessment of an effective yeast strain to control aflatoxin-producing fungus, aspergillus flavus [abstract]. California Conference of Biological Control. p. 154-157. Interpretive Summary: The use of chemical pesticides has caused the development of pest resistance and resurgence as well as environmental pollution and risks to human health. There is a growing interest in the food industry, including retail supermarkets, grower cooperatives and large food companies to consider 'biocontrol' as a means to minimize risk. The results demonstrated that the yeast, P. anomala can modulate spore production of A. flavus on the wounded pistachio nut-fruits. Field spraying of these effective yeasts to pistachio trees may decrease the population of A. flavus in the orchards and prevent further infection by A. flavus as a secondary inocula so that the number of nuts infected by this fungus would be decreased. A reduction of aflatoxin contamination in the edible nuts can be predicted.
Technical Abstract: Aflatoxin contamination is associated with wounding in pistachio nuts. The efficacy of P. anomala was assessed by artificially wounding pistachio nuts in the orchard. Production of A. flavus spores in wounded nuts sprayed with yeast was reduced by 77-99% compared to control. Furthermore colonization of A. flavus on wounded pistachio nuts was prevented by the presence of yeast on wounded nuts by 3-5 fold. Saprophytic yeasts, which can colonize plant surfaces for very long periods under dry conditions, produce extra cellular polysaccharides that enhance their survivability and restrict both colonization sites and nutrient flow to other fungi. The identification of promising biocontrol agents will benefit California orchards.