Researchers begin new aflatoxin project

Steve Moore of the LSU AgCenter's Dean Lee Research Station in Alexandria, La., and Rick Mascagni of the AgCenter's Northeast Research Station in St. Joseph hope their latest research project aimed at that goal bears significant fruit.

The goal is to use non-toxic strains of the A. flavus mold – a naturally occurring mold that produces aflatoxin as a dangerous byproduct – to protect corn from serious damage, especially during dry, hot growing seasons.

South Louisiana's hot, droughty conditions help aflatoxin spread. That resulted in a lethal combination of factors that led to millions of dollars in damages to the state's corn crop five years ago when 70 percent or more of the state's corn crop was infected.

Now, LSU AgCenter researchers and scientists in other states are hoping they may be working toward the magic bullet to protect corn. The latest advances were among topics discussed during he LSU AgCenter's Northeast Research Station Field Day here Thursday.

Topics covered during the field day included irrigation tips, advances in pest management and advice on the best-yielding corn hybrids on the market.

In corn research, the possible salvation for growers could be one or more non-toxic cousins of the aflatoxin fungus, according to researchers.

Moore and Mascagni, working in cooperation with USDA, began the latest project just three weeks ago. They have taken wheat seed inoculated with non-toxic A. flavus mold and spread it in test plots at both the Dean Lee Research Station and in St. Joseph.

Other similar tests with various strains of non-toxic A. flavus mold are taking place in other states, including Georgia, Moore said.

Here's what happens:

First, wheat seed laced with non-toxic A. flavus mold is spread by hand in a corn field at a rate of 10 pounds per acre, Moore said. Researchers suggest introducing the wheat seed when young corn plants are roughly 30 inches tall. The non-toxic fungus then spreads and, if all goes well, squeezes the toxic aflatoxin out of the corn plant.

"Some of the non-toxic strains of A. flavus are very aggressive fungi and they out-compete the aflatoxin on the corn ear. They occupy all the infection points," said Moore, a corn specialist with the LSU AgCenter. The cost of the treated wheat seed is likely in the $5-$6 per acre range, Moore said.

Typical infection points are cracks in a corn ear caused by drought and high temperatures or openings caused by insect damage.

Moore and Mascagni are using sterilized wheat seed treated with two separate non-toxic strains of the A. flavus mold. The non-toxic mold produces spores, which are wind blown or rain splattered onto the corn.

"We have to see to what extent this reduces aflatoxin in corn. It's a promising technology, and if it works, it could become almost immediately available," Moore said after a presentation at the LSU AgCenter Northeast Research Station's Crop Production and Pest Management Field Day.

Aflatoxin is considered potentially harmful in food at rates as low as 20 parts per billion. But researchers in Arizona have reported reducing the rate of aflatoxin in cotton by as much as 90 percent in recent related studies.

The aflatoxin fungus differs from many other fungi in that it doesn't need cool, wet weather to grow. Instead, it thrives in high temperatures that shut down most other fungi, Moore said.

"Drought stress also aids the spread of aflatoxin, because dry weather puts stress on the corn kernel itself, and causes little fissures and cracks. Those become infection points," Moore said.

Randy McClain is a writer for the LSU AgCenter.

e-mail: [email protected]

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