Influence of Field Application of an Atoxigenic Strain ofAspergillus flavuson the Populations ofA. flavusInfecting Cotton Bolls and on the Aflatoxin Content of Cottonseed

An atoxigenic strain of Aspergillus flavus was applied to soils planted with cotton in Yuma, Arizona, to assess the ability of the atoxigenic strain to competitively exclude aflatoxin-producing strains during cotton boll infection and thereby prevent aflatoxin contamination of cottonseed. In both 1989 and 1990, the atoxigenic strain displaced other infecting strains during cotton boll development. Displacement was associated with significant reductions in the quantity of aflatoxins contaminating the crop at maturity. Although frequency of infected locules differed between years (1% versus 25%), in both years displacement occurred without increases in the amount of infection as measured by the quantity of locules with bright-green-yellow-fluorescence (BGYF)