“It’s the Achilles heel of aflatoxin,” Michailides said, adding that early splitting is a problem for 2 percent to 5 percent of the Kerman pistachio crop. He said ways to combat the splitting include applying sufficient irrigation in the spring to avoid tree stress and using the right rootstocks that include UCB-1 that keep early splits low.  Avoiding late harvests can cut down on damage from navel orange worm.

AF36 was used on 73,000 acres of pistachio in 2012. It has been approved for use in pistachios in California, Arizona, Texas and New Mexico.

AF36 was developed in Arizona in a collaborative effort between the Arizona Cotton Research and Protection Council and USDA-ARS scientist Dr. Peter Cotty.

Aflatoxins are carcinogenic toxins/by-products produced by various strains of a common fungus (Aspergillus flavus). For more than 30 years, aflatoxins have cost Arizona’s cotton producers annual losses of over $5 million. Cottonseed containing over 20 parts per billion of aflatoxin cannot be fed to dairy cows, and results in $20-$50 per acre loss in revenue.

Aflatoxins also contaminate corn and peanuts, along with several tree crops including almonds, pistachios and figs.

Pioneering research conducted by Cotty and supported by Arizona cotton producers identified certain native strains of Aspergillus flavus which do not produce aflatoxin, occur naturally in the Southwestern deserts but at very 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.

AF36 was evaluated in commercial fields in Yuma, Ariz., 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 area wide aflatoxin management or suppression program.

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