Corn Growers-Don't Let Aflatoxin Ruin Your 2006 Corn Harvest
By Allen Wrather, Professor, University of Missouri-Delta Center

This is a warning. Corn harvest will soon begin in Missouri, and producers should take precautions to avoid aflatoxin contamination. Aflatoxin is a poison to humans and animals and is produced by a mold which grows on corn kernels in the field and on high moisture kernels stored in a truck or trailer or in a grain tank for a few days, especially drought-stressed corn damaged by earworms. Because of the toxicity of aflatoxin, grain buyers will reject truck loads of corn containing 20 parts per billion. Aflatoxin contaminated corn has not yet been found in any of this year's deep south harvested corn, but Missouri producers should not relax. Corn producers can reduce the risk of aflatoxin by properly irrigating corn and by drying wet, freshly harvested corn to 15 percent moisture within 24 hours. Producers that planted Bt varieties may have fewer problems with aflatoxin because these varieties often have less damage due to earworms than non- Bt varieties.

Yes, you did see this story in the newspaper last year, the year before that, and the year before that. I publish something about aflatoxin each year before corn harvest starts to warn producers about it because most problems due to this potent toxin can be reduced.

To reduce the risk of aflatoxin, producers should irrigate properly and dry wet, freshly harvested corn to 15 percent moisture within 24 hours. Some aflatoxin may be produced by this mold on kernels in the field, but much more will be produced by this mold growing on wet, warm corn kernels stored on a truck or in a grain tank for several days. The mold grows best when 18 percent moisture corn is stored at 86 degrees. Never store wet corn (greater than 15 percent moisture) for more than one day.

Many producers in south Missouri experienced problems with aflatoxin contaminated corn in 1993 and in 1998. Drought and earworms damaged the corn these years, and that damage enhanced growth of the mold that produced the toxin on corn kernels in the field and in especially on wet corn kernels in storage.

Corn producers that irrigated their corn this year and planted Bt varieties will experience fewer problems with aflatoxin than others. But, all producers should still beware of this problem and always dry their corn to 15 percent moisture within 24 hours of harvest. Yes, I already stated four times in this article that corn should be dried quickly after harvest, and I did that because it is very important to avoid this problem. Following these suggested procedures will give corn producers a better chance of producing aflatoxin-free corn. This has been brought to you by University of Missouri Extension through the College of Agriculture, Food, and Natural Resources. More information about aflatoxin is available at http://aes.missouri.edu/delta/croppest/aflacorn.stm.

Allen Wrather
573-379-5431