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.
This project is a collaboration between the United States Department of Agricultural/Agricultural Research Service (USDA/ARS) laboratory based at the University of Arizona, the University of Arizona, and several farmers that produce corn in Texas. This work is supported in part by the Texas Corn Board. The work is coordinated through the internet, phone calls, and periodic meetings both on farm and in Tucson, AZ. The early portions of this work culminated in sufficient commercial field data on the efficacy and safety of biological control of aflatoxins in corn to allow a Section 3 registration of a second biological control strain of the fungus Aspergillus (A.) flavus. The results and our manner of working with the farmers and allowing them to select which fields to treat have all been received very well and there is broad and strong support in portions of Texas for use of the biological control. Commercial use of biological control (using non-toxigenic strains of the fungus) has resulted in the requirement for considerable advanced discussions with farmers to arrange for fields for experiments that will not be commercially treated with one of the two registered biocontrol strains. In 2011, new tests were initiated in four commercial fields to assess differences among 16 atoxigenic strains of A. flavus endemic to corn in Texas in ability to move to the crop and overwinter between seasons. The fungi are being followed in the field and on the crop with vegetative compatibility analyses. Analyses of the first year’s studies are still underway. The second year’s tests, on a second set of four commercial fields, are currently underway. The results should provide insight on which atoxigenic strains have competitive advantage for aflatoxin mitigation in the regions of Texas with the greatest aflatoxin contamination of corn.