Dry growing conditions raise concerns about aflatoxins, which are mycotoxins produced by the fungal pathogens that cause Aspergillus ear rot (Aspergillus flavus and Aspergillus parasiticus)1. Aflatoxins can be produced in the field or while the grain is stored in a bin. Due to health risks for humans and livestock associated with aflatoxins, the FDA has guidelines for acceptable aflatoxin levels for various potential uses. Sampling and testing grain, as well as taking preventative measures to help reduce the production of aflatoxin, can help reduce risks associated with grain contaminated by aflatoxin.

Understanding and Managing Aflatoxins in Corn - IL

Risks Associated with Aflatoxins

Feed efficiency, reproductivity, and the ability to fight infectious diseases can be reduced when livestock consume grain contaminated with aflatoxins1. A less common risk is death of livestock. Human health risks are also a potential concern since aflatoxin can be found in milk produced by dairy cows that have consumed aflatoxin contaminated grain. The most prevalent aflatoxin is carcinogenic. Due to these risks, the FDA has set guidelines for acceptable aflatoxin levels depending on how the grain is to be used (Table 1). An elevator can reject a load of grain if aflatoxin levels exceed 20 parts per billion (ppb) and there is not an alternative use for the grain1.

Identification of Aspergillus Ear Rot

Proper identification of ear rots can help more accurately assess the risk for aflatoxins or other mycotoxins, as not all ear molds produce mycotoxins and only Aspergillus produces aflatoxins. Aspergillus ear rot appears as a gray-green or olive, powdery mold, starting at the tip of the ear and spreading along damage from insects such as Japanese beetle, corn rootworm adults, and

corn earworm (Figure 1). The fungus infects through silks or kernels damaged by insects, hail, or birds. Infection can occur from the time of silking through harvest. Aspergillus is common in drought years and the fungus can grow on ears at grain moistures down to 15%2.

Testing for Aflatoxins

The black light test, which detects kojic acid, a secondary by-product rather than aflatoxins themselves, is not a reliable assay for aflatoxins. For reliable results, consult a lab approved for aflatoxin testing by the Grain Inspection, Packers and Stockyard Administration (GIPSA). If a field is suspected of having aflatoxins, it is important to communicate with the insurance provider. Crop insurance may not cover aflatoxin losses if the sample is taken

after the grain has been stored. A sample should be a composite of several subsamples as the distribution of aflatoxin in a field is not uniform. When sampling during harvest, subsamples can be collected at 30 second intervals while the combine is unloading5. A 10 pound sample is recommended when submitting a sample to a GIPSA approved testing facility. Samples are commonly shipped in gallon freezer bags when samples are taken during harvest, grain is under 20% moisture, and samples delivered to the lab in a few days or less. Removing as much air as possible from the bag and sealing the top of the bag with additional tape can help maintain the integrity of the bag during shipping4. Proper

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Monsanto Technology Development & Agronomy

Use Af latoxin

level (ppb)

Corn o f unknown des t inat ion < 20

Corn for Young Animals < 20

Corn for Dai ry Cat t le < 20

Corn for F in ish ing Swine < 200

Corn for F in ish ing Cat t le < 300

Corn for Breed ing Beef , Cat t le ,

Swine, and Mature Poul t r y < 100

Table 1. FDA guidelines for acceptable aflatoxin levels in corn based on intended use1.

Aspergillus (L); Penicillium (R)

Fusarium

Figure 1. Examples of different ear molds.

Aspergillus Trichoderma Diplodia Gibberella

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Individual results may vary, and performance may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible. Leaf Design℠ is a servicemark of Monsanto Company. All other trademarks are the property of their respective owners. ©2012 Monsanto Company.07242012EJP

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Understanding and Managing Aflatoxin in Corn– IL

Monsanto Technology Development & Agronomy

Figure 2. A partial list of labs approved by the GIPSA for aflatoxin testing. ————————–—— Cairo Grain Inspection Agency, Inc. 4007 Sycamore Street Cairo, IL 62914-1037 618-734-0689

Central Illinois Grain Inspection, Inc. P.O. Box 3631 Bloomington, IL 61702-3631 115 S. Euclid Bloomington, IL 61701-4785 309-827-7121

Domestic Inspection Operations Office USDA, GIPSA, FGIS P.O. Box 74855 Cedar Rapids, IA 52406-4855 319-841-9210

Champaign-Danville Grain Inspection Departments, Inc. 2002 N Linview Urbana, IL 61801 217-344-9306

Decatur Grain Inspection, Inc. 3460 E. William, Suite 1 Decatur, IL 62521-1649 217-429-2466

Kankakee Grain Inspection, Inc. P.O. Box 328 Essex, IL 60935-0328 702 North East Street Essex, IL 60935 815-365-2268

Keokuk Grain Inspection Service 500 S. Water St. Havana, IL 62644 309-543-3557

Mid-Iowa Grain Inspection 29400 S Rt. 53 3350 N. 27th St. Elwood IL. 60421 or Decatur, IL 62526 (319) 363-0239

Titus Grain Inspection, Inc. 1111 East County Road 800 North West Lafayette, IN 47906-9006 765-497-2202

labeling of the samples is critical to utilize the lab results effectively. Labs often have forms that can be filled out electronically or on hard copy, so be certain to contact the lab prior to shipping to help assure that all paperwork is filled out properly. A partial list of labs approved for aflatoxin testing by GIPSA is included in Figure 2.

Reducing Risk of Aflatoxin in Corn

Utilizing best management practices, such as using hybrids and planting dates adapted to the area, maintaining balanced fertility, and taking steps to minimize insect damage, can help reduce the risk of aflatoxins5. If available, appropriate irrigation from silking through the late dough stages can help manage aflatoxin risk. Closer to harvest, consider the following management options5:

• Combine ground and cylinder speed should be adjusted to minimize trash and broken kernels in the hopper, as aflatoxin is commonly linked with lightweight or broken kernels.

• High yielding fields can be harvested separately from poor yielding fields, especially if a late season drought has occurred.

• Harvest should begin when grain is around 24% moisture. Grain should then be dried to 15% within 24 hours or as soon as possible.

• Between different lots of grain, clean auger wells and other areas where grain can collect.

Reducing Risk of Aflatoxins During Storage

The following are tips to reduce risk of aflatoxin issues while corn is in storage5:

• Bins and grain handling equipment should be thoroughly cleaned prior to putting grain in storage.

• Grain should be cleaned prior to storage, with lightweight and broken kernels, fines, and foreign materials removed.

• Grain should be dried to 15% moisture within 24 hours, unless it is going into long term storage and then it should be dried to 13%, as moisture is critical for growth of microorganisms in corn.

• Grain should be aerated to safe and equalized temperatures throughout the grain mass.

• Insects should be controlled.

• Stored grain should be checked on a regular basis and maintained at proper temperature and moisture with aeration.

Handling Corn Infected with Aflatoxins

If grain has aflatoxin levels greater than 20 ppb it can be considered for other uses that are allowed for the level of aflatoxin detected (Table 1). Screening can effectively remove much of the aflatoxins, but should be done with care5. Blending or detoxifying through ammoniation is not recommended.

Sources: 1 Munkvold, G. et. al. 2009. Aflatoxins in Corn. Iowa State University Extension. Publication Number PM 1800.

2 Bradley, C. and M. Hutjens. 2009. Dealing with moldy corn and mycotoxin risks. University of Illinois Extension. The Bulletin. Issue 24. Article 6. http://bulletin.ipm.illinois.edu/article.php?id=1244 (verified 7/20/2012).

3 Corn ear and kernel rots. 1991. University of Illinois Extension. RPD No. 205.

4 Titus, Doug. 2012. Personal communication.

5 Sweets, L. and J. A. Wrather. 2009. Aflatoxin in corn. University of Missouri. http://aes.missouri.edu/delta/croppest/aflacorn.stm (verified 7/21/2012).

Aspergillus ear rot, which is associated with aflatoxin, is

gray or olive green and is more

prevalent in dry years.