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AF36 Program

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The Problem

Aflatoxins are carcinogenic toxins/by-products produced by various strains of a common fungus (Aspergillus flavus). For over fifty years, 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.


Several Key U.S. trading partners strictly regulate aflotoxins. Crops with even very low aflotoxin content may be at a severe trading disadvantage.


Aflotoxins also contaminate corn, peanuts, and several tree crops including almond, pistachio and fig.

The Opportunity

Pioneering research conducted by Dr. Peter Cotty, USDA ARS, identified certain native strains of Aspergillus Flavus which do not contain aflotoxin. They occur naturally in southwestern deserts at very low levels.


One of these atoxigenic (non-toxin producing) strains, Aspergillus Flavus 36, has been shown to competitively displace aflotoxin-producing strains when applied to cotton fields. This displacement is associated with reduced aflotoxin 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 aflotoxin management suppression program.


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

AF36 Product Registration

In June 1998, USDA ARS granted ACRCP a license to utilize USDA atoxeginic strain patents to control aflotoxin 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.


The current collaborative research effort between Dr. Peter Cotty, 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.