Use of Atoxigenic Strains of A. flavus to Manage Aflatoxin Contamination of Corn in Texas
Food and Feed Safety Research
2010 Annual Report
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.
The primary goals of this project seek to evaluate the use of atoxigenic strains of Aspergillus (A.) flavus to manage aflatoxin (a potent carcinogen) contamination caused by toxigenic strains of this fungus in Texas corn production and develop the use of these strains in Texas with the intent of providing a tool for practical use. An experimental use program was approved by the U.S. Environmental Protection Agency (EPA) for initiation in 2008. 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 registered on cotton. In 2009, we completed analysis of the 2008 crop samples and performed additional testing in collaboration with producers on 5,000 acres in Texas. Samples were collected for analysis of the 2009 efficacy as well. Excellent efficacy was achieved in areas where crops were treated prior to tasseling. A report was submitted to EPA in compliance with the requirements for the Experimental Use Permit (EUP). The results were instrumental in modifying application recommendations for all atoxigenics. Treatments to approximately 5,000 acres were also undertaken in 2010 following the plan laid out in the EUP. An important goal of the project is to determine Aspergillus flavus populations in Texas associated with the maize crop in regions where aflatoxin contamination is common. Elevators distributed from near Oklahoma to those situated in the Rio Grande Valley provided samples of the commercial crop. Fungi associated with this maize were isolated in order to construct a random sampling of maize associated A. flavus. We hope to continue this sampling and analysis of the fungal collections during the next project cycle. Another component of the sampling is collection of atoxigenic strains well adapted to Texas cropping systems that include maize. Research progress was monitored through weekly meetings with investigators, presentations at professional meetings, and trips to research fields.