You have a bumper corn crop that’s sold for $7/bu. and the combines are running. Your high-cost inputs, sweat and toil are rewarded. But testing shows the cream of a crop contains toxins and is illegal to sell. You may even have to bury it.
That scenario – created by aflatoxin contamination – has been real for more growers than you’d think, especially in southern areas, where a dry growing environment or drought stress and high humidity can cause aflatoxin contamination.
Aflatoxin costs U.S. growers over $200 million annually.
“We farm mostly wheat and corn and have faced a lot of aflatoxin issues,” says Bruce Wetzel, who farms with his son Chad in north Texas near Sherman. He and other growers have switched some corn acres to sorghum or cotton primarily to avoid aflatoxin.
However, after years of university research funded partially by the Texas Corn Producers Board (TCPB), the EPA has finally approved the use of a second product that can significantly reduce aflatoxin contamination.
AF36 is the newest atoxigenic tool to fight aflatoxin in corn. It’s a natural fungus that occurs normally at low levels across Texas and the South. It joins Afla-Guard from Syngenta as the only products proven to displace the toxin-producing fungus. AF36 is limited for use in Texas and Arizona on corn but is also registered for cotton.
However, Averhoff, who’s worked with the National Corn Growers Association to fight aflatoxin, says he expects a push by other areas to have access to AF36. “This is a new-use label, but the product’s been around a long time on cotton,” he says.
“Growers in Louisiana and Arkansas are asking us about how the products can help them, and we expect growers in other states to seek its EPA approval,” he says.
Wetzel has been one of several growers who’s had AF36 test plots on his farm. It has worked where aflatoxin has been detected. TCPB has funded research by Peter Cotty with the USDA-ARS at the University of Arizona since 2006.
Cotty says the product had been approved for use on Arizona and Texas cotton, another crop susceptible to aflatoxin. Cottonseed and cottonseed hulls are popular feedstuffs for poultry, swine, beef cattle and dairy cattle – but not if it has aflatoxin contamination.
Aflatoxin can be deadly to humans and animals and is measured in parts per billion (ppb). Corn can contain no more than 20 ppb of aflatoxin for dairy animals or food corn, 300 ppb for beef cattle, 200 ppb for 100-lb. finishing pigs and 100 ppb for poultry.
EPA approved the AF36 bio-control product after its effectiveness and efficacy rates were proven via research by Peter Cotty with the USDA-ARS at the University of Arizona on farms across central and north Texas.
“In field trials, AF36 reduced aflatoxin to less than 20 ppb, while other nearby untreated fields were often in excess of 300 ppb,” says Scott Averhoff, Waxahachie, TX, grower and TCPB chairman. “We’ve seen similar results from Afla-Guard.”
Wetzel applies AF36 at 10 lbs./acre at a cost of about $10/acre, plus aerial application costs of $6,” he says. “Afla-Guard also works and costs about the same.”
Wetzel’s region, which can see dry conditions more often than not, averages about 100 bu./acre. “I have yielded 150 bu., but I’ve also seen below 50,” he says. “If we have an aflatoxin rate above 20 ppb, we’ve lost markets at our regional dairies and have been forced to ship our corn farther to Panhandle feedyards.
“These aflatoxin-control products can hold down the fungus and open up new markets,” he says.
Averhoff adds that the Texas corn group has a proposal with the USDA Risk Management Agency to enable growers who use an approved atoxigenic product to restore their APH without quality loss adjustments due to Aflatoxin for federal crop-insurance purposes.
Wetzel’s farm has additional field tests from Cotty this year. “He’s testing other strains of fungi and blending three or four of the more aggressive strains to improve the good results he’s already getting.”
Syngenta says Afla-Guard contains a naturally occurring, non-toxic fungus that reduces the aflatoxin-producing fungi in grains, nuts and oil seeds.
Both AF36 and Afla-Guard are granules that include grain-based nutrients. (Afla-Guard uses barley and AF36 uses wheat). Granules are applied to initially deploy the non-toxic fungi. Fungi then grow on the granules and produce spores that disperse throughout the field, allowing the atoxigenic fungi to efficiently compete with and displace aflatoxin-producers throughout the treated area.
University and state chemical laboratories offer aflatoxin testing for about $35/sample. You can buy aflatoxin test kits from various laboratory supply retailers, including Envirologix and Romer Labs.