Frequently Asked Questions about Aflatoxin in Corn:
(September 14, 2012)
Q: What is aflatoxin?
A: Fungi in the genus Aspergillus produce aflatoxins. These Aspergillus fungi can colonize corn
kernels causing an ear mold or ear rot. The most common Aspergillus species that affect
corn are Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are carcinogens (cancercausing agents) in animals and humans.
Q: What does the Aspergillus ear rot look like?
A: Aspergillus ear rot appears as an olive-green colored mold growing on and between corn
kernels on an ear.
Q: What conditions favor aflatoxin contamination of grain?
A: Drought and high temperatures during the corn grain fill stages are the most favorable for the
development of aflatoxin in grain. Pictures of Aspergillus ear rot are available on-line at:
http://bulletin.ipm.illinois.edu/article.php?id=1699.
Q: What can I do to prevent Aspergillus ear rot and aflatoxin contamination of grain in my
fields?
A: When conditions are very favorable for Aspergillus ear rot and contamination (hot
temperatures and droughty conditions), prevention of the disease and the toxin development
can be difficult. Any practices that minimize stress from heat and drought may limit
development of Aspergillus ear rot and aflatoxin. Planting hybrids adapted to local soil types
and conditions, maintaining good fertility and soil conditions may help alleviate heat and
drought stress. Managing insects that feed on silks and ears also will reduce exposure of
kernels to Aspergillus fungi. A product known as “Aflaguard” from Syngenta Crop
Protection is registered for use on corn to help prevent high aflatoxin contamination levels.
This product has not been tested by the University of Illinois, but has been tested by
scientists at Texas A&M University. Some results from Texas A&M field studies have
indicated that alfatoxin levels were reduced compared to non-treated controls. The
Aflaguard product contains a strain of the Aspergillus fungus that does not produce aflatoxin.
Aflaguard must be applied prior to tasselling and silking to achieve the best efficacy.
Q: Should fields that are at the highest risk for aflatoxin be harvested differently than other
fields?
A: Fields that have suffered the most from drought and heat stress would be at a higher risk of
having higher levels of aflatoxin contamination. These fields should be harvested first and
immediately dried to below 15% moisture. Drying the corn to below 15% moisture will
prevent additional mold development and aflatoxin production. For long-term storage, grain
should be dried to below 13% moisture. Adjusting the combine settings to limit the number
of broken kernels and amount of trash in the hopper may reduce aflatoxin levels in the
harvested corn, as broken kernels tend to have the highest level of aflatoxin contamination.
Q: What crop insurance implications are there for aflatoxin contaminated grain?
A: Aflatoxin contamination is considered a quality-loss, and is covered by crop insurance. If
aflatoxin is suspected, the crop insurance agent should be contacted immediately. An
independent test for aflatoxin must be done before the field is harvested, so it is imperative
that the crop insurance agent be contacted immediately if aflatoxin is suspected or detected.
For more information about crop insurance implications of aflatoxin in corn, go to:
http://www.farmdocdaily.illinois.edu/2011/08/crop_insurance_implications_of.html.
Q: I have aflatoxin contamination in my grain, is there anything I can do to lower the aflatoxin
level?
A: Running the grain through a rotary screen to take out fines may reduce the level of aflatoxin
contamination. Damaged and broken corn kernels tend to have the highest level of aflatoxin
contamination. Cleaning out these broken and damaged kernels should reduce the level of
aflatoxin. It is important that the screenings from the cleaning process not be used for animal
feed; however, as the aflatoxin levels may be very high in this material.
The process of ammoniation has been shown to reduce aflatoxin contamination levels in
corn. The ammoniation process detoxifies the grain. This process generally can be done
only for on-farm livestock feeding use, as the FDA does not allow ammoniated corn to be
shipped in interstate commerce. The ammoniation process may discolor corn and will leave
a temporary off-odor on the corn, which could result in feed refusal by animals. Because the
ammoniation process is somewhat dangerous, it should be conducted only by trained
professionals. Ammonia:corn dry matter ratios for treatment range from 0.5% to 1.5%
depending on the level of contamination, so the per-bushel cost of ammonia treatment is
considerable even before adding the treatment apparatus and labor.
Q: What can I do with loads of corn that have been rejected at the elevator because of high
aflatoxin contamination levels?
A: Depending on the level of contamination, aflatoxin contaminated corn may still be used as
livestock feed. Aflatoxin can also be diluted at feeding by blending with non-contaminated
feed, but such blending needs to be done with care to ensure the resulting mixture is below
the target action level. The U.S. Food & Drug Administration (FDA) has guidelines for
feeding aflatoxin contaminated corn (below; also online at: www.fda.gov).
Animal Feeds
Action level (parts per billion)
Corn products intended for finishing beef
300
cattle
Corn products intended for finishing swine of 200
100 lb or greater
Corn products intended for breeding beef and 100
dairy cattle, breeding swine, or mature
poultry
Corn products intended for lactating dairy
20
animals
Q: Can a mycotoxin binder be added to the ration to reduce risk of alfatoxin?
A: FDA has not approved mycotoxin binders, but classifies these feed additives as flow agents
or anti-caking additives. For aflatoxin, the addition of clay based additives (such as
aluminosilicates and benetonite products) can tie up some of the toxin, reducing its negative
impact on cattle. For mycotoxins such as zearolene or T-2, the use of yeast cell wall
products (called MOS) and enzymatic products can be effective.
Q: Can corn with high levels of aflatoxin contamination be used to make ethanol?
A: Aflatoxin does not interfere with ethanol production; however, aflatoxin may become even
more concentrated in the distillers grains. Because these distillers grains are intended for
animal feed, ethanol plants may reject corn with high levels of aflatoxin contamination.
Q: How is aflatoxin detected in corn?
A: Different tests are available that can detect and quantify the level of aflatoxin contamination
in corn. The use of a black light may detect the presence of kojic acid, a precursor to
aflatoxin, in corn, where the kojic acid will fluoresce (glow) in the presence of black light.
This black light test is considered somewhat rudimentary, because it is not directly detecting
aflatoxin, and may lead to a false positive or negative result. Some commercial kits are
available that rely on immunoassays to detect aflatoxin. Analytical laboratories may use
different techniques that are highly accurate, such as gas chromatography, mass
spectroscopy, or thin-layer chromatography.
Q: Where can I have my grain tested for aflatoxin?
A: There are a number of laboratories and approved facilities that can test for aflatoxin. A list of
certified testing facilities for aflatoxin in Illinois, Indiana, Ohio, and Michigan is available
on-line at: http://www.rma.usda.gov/fields/il_rso/2012/aflatoxin.pdf.
Prepared by:
Carl Bradley, Department of Crop Sciences, University of Illinois (carlbrad@illinois.edu)
Ted Funk, Department of Agricultural and Biological Engineering (funkt@illinois.edu)
Michael Hutjens, Department of Animal Sciences (hutjensm@illinois.edu)
Gary Schnitkey, Department of Agricultural and Consumer Economics (schnitke@illinois.edu)