PLANT STRESS DUE to drought, heat or insect damage during fungus growth usually increases aflatoxin levels in corn.
As the interest in corn production in the Southeast continues to grow, so does the need to reduce aflatoxin contamination and increase the value of the grain.
“We always stress planting early as a means of avoiding aflatoxin in corn, especially in dryland conditions,” says Austin Hagan, Auburn University Extension plant pathologist.
“You want the corn to mature before the temperature hits a sustained 95 degrees F. in the afternoon. Temperatures must get really high for the fungus to produce toxins.”
More corn varieties are coming onto the market that will have some drought tolerance, says Hagan.
“The ones we have now have been incrementally getting better as far as drought tolerance, but in a few years, that trait will be much stronger in the varieties coming down the line.”
Irrigation, however, is not 100-percent effective against aflatoxin, he warns.
“In the aflatoxin trials we conduct in the Wiregrass in southeast Alabama, we routinely see aflatoxin in our irrigated corn. Levels are not as high as they would be in dryland corn, so irrigation is not 100-percent effective, but it comes pretty close,” he says.
Harvesting early at high moisture and then drying the grain might be a strategy for reducing aflatoxin, especially in dryland fields where you’re more likely to have problems, says Hagan.
“Just blowing the lighter seed out of the back of the combine can help since that’s the seed that has been damaged by insects or rotted by the fungus.
“If it goes out the back, then a lot of your aflatoxin will go out the back,” he says.
The same concentration of aflatoxin will not be found in all of the kernels in a load, he says.
“Most of the kernels won’t have any aflatoxin or very little in them, but a few of them might have up to 14,000 to 15,000 parts per million in one kernel, and if it goes out the back of the combine, you can save yourself a lot of lot of trouble.”
In field trials, Hagan and other researchers have been looking at Afla-Guard and some of the advanced Bt traits.
One seed company is promoting its advanced Bt traits as a means of reducing aflatoxin in corn, he says.