ARS | Publication request: Environmental Adaptation of Pichia anomala WRS-076 as an Effective Biocontrol Agent for Pre-harvest Application

Submitted to: IOBC/WPRS Bulletin (Abstract for Conference Proceedings)
Publication Type: Other
Publication Acceptance Date: September 8, 2006
Publication Date: N/A

Interpretive Summary: The saprophytic fungus, A. flavus, is air-born and infects plants through wounds. Aflatoxin contamination is well documented to be associated with wounding in corn, peanuts, cotton and tree-nuts before harvest. In general antagonists applied on crops for control of foliar diseases are exposed to environmental stress such as temperature fluctuations, water availability and UV-irradiation. A laboratory experiment was designed by using PEG (polyethylene glycol) 8000 to adjust medium aw to 0.96, which mimicked a water stress condition of –5.62 MPa.. P. anomala WRL-076 can grow at this low water activity (aw) and inhibited the growth of A. flavus.

Technical Abstract: In laboratory experiments, PEG (polyethylene glycol) 8000 was used to adjust medium aw to 0.96, which mimicked a water stress condition of –5.62 MPa.. P. anomala WRL-076 can grow at this low water activity (aw). The yeast cells formed a film and inhibited the growth of A. flavus inoculated to the medium. Two experiments were conducted in a commercial orchard in the summer of 2005. 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.