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Agronomy Corner - Aflatoxin

Aflatoxin | Asian Soybean Rust

Aflatoxin is a naturally occurring toxin produced by the fungus Aspergillus flavus. The fungus can be recognized by a gray-green or yellow-green mold growing on corn kernels in the field or in storage. Plant stress due to drought, heat or insect damage during fungus growth usually increases aflatoxin levels. Aflatoxin contamination will reduce feeding value and hinder sales. Because it is extremely poisonous to warm-blooded animals even at relatively low levels, grain handling facilities often check for the presence of the toxin before purchasing corn.

Aspergillus flavus is a common fungus found in soil and debris. Since it occurs so frequently in nature, particularly as airborne spores, it can be found on most grain in the field and in storage. Moisture and heat stress is commonly associated with most aflatoxin outbreaks. Sound agronomic practices and post-harvest practices must be followed to reduce or prevent contamination or buildup once the crop is harvested and stored. When temperatures are below 65 degrees F and the moisture of the corn is below 12 to 13 percent, development of the fungus usually stops.

Suppression of Potential Aflatoxin Prior to Harvest

Aflatoxin contamination problems are minimized with management such as thoroughly grain cleaning, proper combine adjustment to reduce kernel damage, matching drying capacity to wet corn holding capacity, proper drying, removal of fines and broken kernels, proper grain cooling after drying, and sound storage practices.

Sanitation of equipment is the first step in preventing post-harvest aflatoxin contamination. Clean out all harvesting, handling and drying equipment and storage bins prior to harvest. Remove all broken corn, dust and foreign material that can provide a source of contamination. Check and repair storage bins to prevent moisture leaks from faulty joints or other problems. Clean bins and remove debris to reduce contamination. Use an approved insecticide to treat the bin before filling. Mow around storage bins to discourage insect/rodent activity.

What to do:

Contact your agent if you suspect Aflatoxin will be present. You will need to either leave test strips in the field or get an adjuster to grab a sample before the unit is harvested and put in the bin. Please handle with care. We recommend using gloves and wearing a dust mask when handling the infected grain.

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