Winter testing for mycotoxins

By Pat Frasco

Sales director, milling and grain


Harvest is over and crops such as corn are out of the fields and stored, but this doesn’t mean it’s time to drop our guard when it comes to mycotoxins.

It’s been a rough year for producers throughout the U.S., who have been plagued by drought and outbreaks of the mycotoxin aflatoxin in some areas. Farmers in other areas of the world, such as Europe, also have faced tough growing season and outbreak of other toxins, such as deoxynivalenol (DON). Given this, good management practices and a solid testing plan are crucial to protect stored grains from proliferation of the toxin-producing molds and to prevent the increased impact of toxins during storage.

Prevention of these toxins is crucial as they can have severe impacts on human and animal health as well as cause significant economic losses for producers and processors.

Proper drying and aeration

Storing grain at the proper moisture is a key to preventing the growth of molds.  Fusarium, which produces DON and aspergillus flavus causes aflatoxin are major risk toxins. The critical number to remember is 14%, meaning grain that is stored at 14 percent or less moisture will help minimize mold growth and toxin production.

The proper storage of grain is the best way to prevent fungal growth and thereby toxin production, according to the Food and Agriculture Organization of the United Nations (FAO).  In order to obtain the best results, grain should be dried as soon as possible post-harvest.

Additionally, the correct amount of aeration is needed to maintain grain temperature during storage. This also will help maintain good ventilation to prevent high humidity, which contributes to the growth of molds. Reduce excess chaff and foreign material prior to putting grain in the bin.

Be sure to check storage facilities for proper seals and for leaks. Excess water entering the storage unit or facility can increase the chance that mold growth – and therefore toxin production – will occur.

Damaged grain

The risk of toxins are even higher in grain damaged by drought, for example. Unlike undamaged grain, it will not store through spring and onto summer and should be shipped to market as soon as possible. Grain that is damaged is more susceptible to “fungal invasion”, according to FAO.

Insect control in grain storage also is crucial as they not only damage the grain, but the additional moisture from their presence can promote fungal growth, FAO notes.

Testing stored grain

Grain in storage should be regularly tested for the presence of toxins. To get the most accurate results, it is crucial to obtain a representative sample of the grain. This can be difficult in large containers but using the appropriate probe size and the right number of probes from each container can help mitigate that difficulty (for more on probes, the number of samples and other testing techniques, check out this previous post).

Grain also should be tested for toxins when purchased from a third party, as storage conditions are unknown. Again, the importance of obtaining representative samples cannot be overemphasized.


It is important to note the U.S. Food and Drug Administration (FDA) allowed the blending of grain containing high aflatoxin levels (higher than the limit of 20 parts per billion, or ppb, but lower than 500 ppb) with higher quality, “clean” grain in seven Midwest states this past year. In this grain, proper sampling to monitor the even distribution of aflatoxin-positive grain is key to prevent “hot spots”. This blended grain was allowed to be used for animal feed under strict guidelines.

For Neogen’s mycotoxin test kits, click here.

To view Neogen’s Mycotoxin Handbook, click here.

Want some light reading? Check out the Grain Fungal Diseases and Mycotoxin Reference from the U.S. Department of Agriculture’s Grain Inspection, Packers and Stockyards Administration here.

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