1a.Objectives (from AD-416)
1) Follow Experimental Use Program for Corn once approved by U.S. Environmental Protection Agency.. 2)Experimental course initiated in 2006 will continue. . 3)The natural distribution of the atoxigenic strain within each treatment area in Texas will be determined as well as incidence of the high aflatoxin producing S strain. . 4)In new treatment areas, the behavior of soil applied wheat seed colonized by an atoxigenic strain of A. flavus will be determined.
1b.Approach (from AD-416)
1) Follow Experimental Use Program for Corn once approved by U.S. Environmental Protection Agency. . 2)Treatment of cotton in several Texas areas and monitoring fungal communities on the treated cotton crop as well as on corn rotated to the cotton. . 3)The potential importance of the S strain to aflatoxin contamination of corn in Texas will be assessed. . 4)Influences of timing of application on efficacy of treatments will be sought. Producers will be asked about preferred application methods and timing and the practicality of atoxigenic strain use in the test areas will be assessed.
Research is carried out in the Agricultural Research Service (ARS) laboratory at the University of Arizona and in commercial fields in Texas. The Texas corn industry participates in the trials and in sampling the commercial crop. The experimental use program previously approved by the United States Environmental Protection Agency (EPA) for initiation in 2008 was continued in 2010. This program is intended to allow collection of information from commercial corn fields supportive of a corn registration for the atoxigenic strain AF36 for use in Texas. Currently this biocontrol fungus is only fully registered in Texas for use on cotton and treatments to corn are limited to 5,000 acres. The 2009 crop was analyzed for both aflatoxins and fungal community structure during the 2010/11 project year. The results indicate that applications of AF36 achieved both excellent displacement of aflatoxin producing fungi and good reductions in the aflatoxin content of corn in both the 2008 and 2009 tests. Reports on efficacy of AF36 based on the 2008 and 2009 crop year treatments have been submitted to EPA. During 2010 approximately 5,000 acres of corn were treated with AF36. Treatments in 2010 were by collaborating farmers in Grayson, Ellis, Jackson, Wharton, and San Patricio counties. Over 6,000 isolates of Aspergillus flavus were collected from 437 maize samples from 8 elevators, wholesalers, and processors that assisted with sampling the 2009 crop. Laboratory studies comparing the strains for ability to inhibit contamination in corn are underway. Coordination among parties is maintained primarily by phone contacts, emails, and on site visits by ARS.