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Cotton and Corn Brochure

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Pistachio Brochure

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EPA labels for traditional AF36 and AF36 Prevail



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OBJECTIVES          PURITY          USDA ARS          2006 REPORT         2020 REPORT

The Problem

Aflatoxins are carcinogenic poisons produced by some strains of the common fungus (Aspergillus flavus) that contaminate crops throughout the world. Cotton, corn, peanuts, and several tree crops including almonds, pistachios and figs are just some of the crops susceptible to aflatoxin contamination.

Crops with aflatoxin content exceeding regulatory limits set by the FDA and several key U.S trading partners prevent these crops from entering premium markets and are at a severe trading disadvantage.

In Arizona alone, aflatoxins have cost Arizona’s cotton producers annual losses of over $10 million. Cottonseed containing over 20 parts per billion of aflatoxin cannot be fed to dairy cows, and results in at least $20-$50 per acre loss in revenue per season.


The Opportunity

Pioneering research conducted by the University of Arizona, USDA ARS, identified certain native strains of Aspergillus flavus which do not contain aflatoxin. They occur naturally in the southwest at low levels.

One of these atoxigenic (non-toxin producing) strains, Aspergillus flavus AF36, has been shown to competitively displace aflatoxin-producing strains when applied to cotton fields. This displacement is associated with reduced aflatoxin levels in Arizona cottonseed.

Aspergillus flavus AF36 was evaluated in commercial fields in Yuma, Arizona, during the period of 1996-1998. The results suggested a high potential for reducing the vulnerability of all crops grown in a treated region to aflatoxin contamination. This provided the opportunity for an areawide aflatoxin management suppression program.

The Arizona Cotton Research & Protection Council (ACRPC) established a working partnership with USDA ARS to both manufacture AF36 and advance atoxigenic strain technology. 


The Solution

The biological control Aspergillus flavus AF36 Prevail has established itself as an effective tool in managing aflatoxins by using a native strain of the fungus that naturally does not produce aflatoxins.

The beneficial fungus, AF36, is coated onto a carrier grain that is sterilized (will not germinate) and serves as a food source for the fungus. By applying AF36 Prevail to crops at the appropriate time, the fungus grows on the carrier grain in the field, and moves to the desired crop before the aflatoxin-producing strains have an opportunity to infect the crops.

Using AF36 actually changes the composition of the fungi in the environment, shifting the majority of the population from aflatoxin producers to the safe non-toxin producing strain of Aspergillus flavus.

  • AF36 PRODUCT REGISTRATION - In June 1998, USDA ARS granted ACRCP a license to utilize USDA atoxeginic strain patents to control aflatoxin in Arizona cotton.
  • MANUFACTURING FACILITY DEVELOPMENT - In September 1998, the ACRCP leased 15,000 square feet of building/warehouse space to house a prototype AF36 production facility plus associated labs and offices. Facility development has progresed to its current state which is capable of supplying commecial scale quantities of AF36 capable of treating more than 200,000 crop acres per season. This represents a multi-million dollar investment on the part of the Arizona cotton industry.
  • PROGRAM IMPLEMENTATION - Since its inception in 1998, the USDA ARS / ACRCP partnership has led to the treatment and evaluation of AF36 applications on more than 200,000 cumulative acres of cotton in Arizona and Texas. This, in turn, has resulted in the progressive displacement and hence reduction of aflatoxin producing fungi by AF36 throughout treatment regions. Refinements continue in the production, distribution and utilization of atoxigenic strain technology. This process is accelerated through coordinated basic and applied research involving the Arizona Cotton Research & Protection Council and USDA ARS.
  • THE FUTURE - The expansion of atoxigenic strain technology to a wide variety of agricultural commodities holds great potential for the future. Current label expansions for corn and pistachios coupled with existing registrations for cotton in the West offer hope for a bio-control technology which may significantly enhance the agricultural export market for the United States while concurrently addressing critical issues of public health and safety.
  • CONCLUSION - The current collaborative research effort between the University of Arizona, USDA ARS, and the Arizona Cotton Research and Protection Council represents a model for cooperative development of public sector technology which has multiple applications across agricultural commodity lines. Continued USDA ARS support of this mutually beneficial working relationship is strongly encouraged by cotton industry groups in both Arizona and Texas.

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