Location: Food and Feed Safety Research2009 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.
3. Progress Report
The primary goals of this project seek to evaluate the use of atoxigenic strains of Aspergillus flavus to manage aflatoxin contamination 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 order to follow the experimental plan, field tests were set up with collaborating corn producers in San Patricio, Grayson, Jackson, Hidalgo, Ellis, Medina, and Victoria counties in Texas. Soil samples were taken prior to treatment in most test areas in order to determine the fungal community structure prior to treatment. The atoxigenic strain material arrived on most farms late, and applications were made after optimal periods. In over half the locations, applications were made several weeks after tasseling (i.e. formation of male flowers in corn). Only in Grayson County did applications appear to be close to the target application timing, and in those cases, near the end of the target period. Excellent displacement and reductions to aflatoxin content of maize were achieved in Grayson and Ellis counties. Significant efficacy was also achieved in other treatment areas, although the late treatments resulted in levels of displacement of aflatoxin-producing strains, lower than our target of 80% displacement. Data on the aflatoxin analyses and fungal community genetic analyses are currently being put together for the EPA. In 2009, collaborators received material earlier and a greater proportion of treatments were conducted on time (i.e. before tassel formation in corn). However, even earlier treatments in some areas may still be advantageous. An additional goal of the project is to determine Aspergillus flavus populations in Texas associated with the maize crop in regions where aflatoxin contamination is common. Ten elevators, wholesalers, and processors collaborated with this study in 2008. These include Dorchester Grain (Grayson County), Boyce Grain (Ellis County), Keller Grain (Medina County), Bee Agricultural (Hidalgo County), Vic-Cal Grain (Victoria County), El Campo Cooperative (Wharton County), Willianson County Grain, Premier Grain (Jackson County), Bee County Cooperative, and Azteca Milling (Hidalgo County). We hope to perform a second sampling in 2009. Research progress was monitored through routine teleconferencing, meetings, emails, and reports.