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Effect of Atoxigenic Strains of Aspergillus flavus on Aflatoxin Contamination of Developing Cottonseed. P. J. Cotty, Research Plant Pathologist, Southern Regional Research Center, U.S. Department of Agriculture, Agricultural Research Service, New Orleans, Louisiana 70179. . Plant Dis. 74:233-235. Accepted for publication 15 September 1989. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1990. DOI: 10.1094/PD-74-0233.

Simultaneous inoculation of wounded 28- to 32-day-old cotton bolls with toxigenic and atoxigenic strains of Aspergillus flavus led to lower levels of aflatoxin B1 (B1) in the cottonseed at maturity than in bolls inoculated with the toxigenic strain alone. Six of seven atoxigenic strains tested reduced the level of contamination produced by toxigenic strains. Less B1 was detected when the atoxigenic strain was introduced into the wound 1 day before inoculation with a toxigenic strain than when atoxigenic and toxigenic strains were coinoculated. In contrast, toxin levels at maturity were not reduced when the atoxigenic strain was introduced 1 day after the toxigenic strain. Use of an atoxigenic strain at 10-fold higher spore concentration led to significant reduction in B1 if the atoxigenic strain was introduced within 16 hr after the toxigenic strain. Atoxigenic strains of A. flavus may be useful in biological control of aflatoxin contamination.