Technical Abstract: Historically, methods to control aflatoxins in peanuts have focused on postharvest measures to reduce existing contamination. Recently, a biopesticide was developed and shown in plot studies to prevent much of the preharvest contamination that normally occurs under late-season drought conditions. The biopesticide, afla-guard®, establishes in soil a dominant population of a nontoxigenic strain of Aspergillus flavus, which competitively excludes toxigenic strains from invading peanuts. Studies were carried out to monitor the efficacy of afla-guard® in its first year of commercial use. Results from seven buying points in Georgia and Alabama showed that mean aflatoxin in treated vs. untreated farmers’ stock peanuts was reduced by 85.7%. Official analyses of shelled lots at two plants showed that mean aflatoxin in treated peanuts was reduced by 78.2% and 97.5%. All treated lots met the 15 ppb USDA cut-off necessary for sale while 16.7% and 48.4% of untreated lots at the respective locations failed.