Grainnet

Controlling Aflatoxin Biologically Proves Effective in Parts of the Southern United States

Peoria, IL--Benign strains of Aspergillus flavus (A. flavus) have been found to control aflatoxin-producing strains of A. flavus, according to research conducted by Dr. Peter J. Cotty, USDA-ARS, University of Arizona, Tucson.

Cotty presented his research at the North American Millers’ Association (NAMA) and the U.S. Department of Agriculture’s National Center for Agricultural Utilization Research’s (NCAUR) 48th Annual Corn Dry Milling Conference, May 31 and June 1 in Peoria, IL.

The conference was split into two sessions. The first session dealt with mycotoxins and their effect on corn quality.

The second session covered the ethanol industry’s effect on various aspects of the corn market.

During the first session, Cotty spoke about biologically controlling aflatoxin-producing fungi in corn.

According to Cotty, in some southern growing regions of the United States, aflatoxin is often found in more than half of the season’s corn crop in amounts of more than 100 parts per billion.

Cotton and peanuts are also greatly affected by aflatoxin.

While several members of the Aspergillus genus of mold produce aflatoxin, the most common producer is the species A. flavus.

Although A. flavus is the most common aflatoxin-producing species, not all A. flavus strains produce aflatoxins.

Strains that do not produce aflatoxins are commonly referred to as atoxigenic strains.

Cotty’s presentation dealt with utilizing atoxigenic strains of A. flavus to biologically reduce the presence of aflatoxin.

"If you co-inoculate corn with both toxigenic strains and atoxigenic strains, the amount of aflatoxin is reduced," Cotty said.

In 1996, development of atoxigenic strain technology in commercial cotton began.

After 10 years of testing, Cotty was able to get AF36, an atoxigenic strain of A. flavus, approved by the U.S. Environmental Protection Agency (EPA) for use as a biopesticide for aflatoxin management.

Currently, AF36 is approved for use on cotton crops.

In field applications, wheat seed inoculated with AF36 is spread over a cotton field, just before the cotton flower blooms.

From there, the atoxigenic strain begins to take over toxic strains of A. flavus, thereby reducing the level of aflatoxin produced in the field.

In his research, Cotty said the effects have been shown to last for approximately three years.

One year after application, atoxigenic strain incidences are greater than prior to the initial application.

In parts of Texas, AF36 is administered during the cotton growing season.

Cotty said Texas farmers primarily apply atoxigenic strains to cotton in order to reduce aflatoxin in corn, which is rotated with cotton.

Experimental Use Permits have been requested from EPA to directly treat corn and pistachios, Cotty said.

How Well Does It Work?

"Normally, we see an 80% reduction in aflatoxin in the treated crop, once the atoxigenic strain is introduced," Cotty said.

"This is normal, but there haven’t been any area-wide treatments; therefore, aflatoxin producing strains can blow in from adjacent fields."

Cotty added that he hopes to begin trials in which an entire farm is treated with AF36, not just several acres.

Although AF36 reduces the amount of aflatoxin, Cotty said it does not raise the amount of A. flavus in the soil overall.

Cotty added that AF36 should not be used in areas that do not contain the strain naturally.

Cotty estimates the cost for AF36 is approximately $5 per acre.

For more information on AF36, call the Arizona Cotton Research and Protection Council at 602-438-0059.

Circle One Global Inc., Cuthbert, GA, manufactures a product called Afla-Guard, which works in the same way as AF36 but is approved for use on peanuts.

For more information on Afla-Guard, call Circle One Global at 229-732-3101.

Josh Flint, Milling Journal editor