Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/20/2005
Publication Date: 3/1/2006
Citation: Dorner, J.W. 2006. Commercial production and use of afla-guard® for biological control of aflatoxin contamination in peanuts. American Peanut Research and Education Society Abstracts.
Interpretive Summary: None required.
Technical Abstract: Prior research has led to development of a product that effectively reduces aflatoxin contamination of peanuts. The active ingredient is a nontoxigenic strain of Aspergillus flavus that competitively excludes toxigenic strains present in soil in the infection and colonization of peanuts. Spores of the nontoxigenic strain are coated onto the surface of hulled barley, which is applied to peanut fields at a rate of 22.4 kg/ha. After application, the nontoxigenic strain grows and sporulates on the surface of the barley, thus inoculating the soil. The coated barley formulation was given the trade name, afla-guard®, and it received EPA Section 3 registration as a biopesticide in May, 2004. Approximately 50 tons of afla-guard® was produced by Circle One Global, Inc., in 2004, and growers in Georgia and Alabama applied it to approximately 5000 acres of peanuts. Soil samples were collected from representative treated and untreated fields prior to digging to determine the establishment of the nontoxigenic strain in the soil. In addition, grade samples (1.5-2.0 kg) of harvested peanuts were collected at various buying points from 178 and 404 loads of untreated and treated peanuts, respectively. Samples were shelled, ground in a vertical cutter mill, and analyzed for aflatoxin by liquid chromatography. Application of afla-guard® resulted in an average change in the ratio of toxigenic to nontoxigenic strains of A. flavus in soil from 2.5:1 to 1:24. Aflatoxin in farmers’ stock peanuts from all locations was reduced from a mean of 78.9 µg/kg in untreated peanuts to a mean of 11.7 µg/kg in treated peanuts (85.2% reduction). Not only was the mean aflatoxin reduced, but the percentage of loads containing high levels of aflatoxin also was reduced similarly. Sixteen percent of loads from untreated fields contained > 100 µg/kg of aflatoxin compared with only 2% of loads from treated fields (87.5% reduction). The study demonstrated that commercial use of the biological control technology was as effective in reducing aflatoxin as has been demonstrated experimentally.