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Angie Peltier


Angie Peltier
Former Extension Educator, Commercial Agriculture



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Hill and Furrow

Current topics about crop production in Western Illinois, including field crops research at the NWIARDC in Monmouth.
Figure. Aspergillus ear mold is abundant in southern and central Illinois (photo - Robert Bellm).
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Watch for ear molds in late planted corn


Severe to extreme drought conditions throughout Illinois have stressed both corn producers and corn plants. Late planted corn at the Northwestern Illinois Agricultural Research and Demonstration Center in Monmouth has experienced many stresses this season - from heavy insect feeding which increases susceptibility to many ear rot diseases, to a wide range of weather conditions from severe drought and above normal temperatures to the more recent cooler, wetter weather. Both Penicillium and Fusarium ear molds are abundant.

Although fungi that cause ear rots can reduce yield by consuming grain dry matter and reducing test weight, of far greater importance is that many ear mold fungi produce chemicals called mycotoxins. Mycotoxins are by-products of fungal growth that are toxic when consumed by humans and other animals. The fungi that cause Penicillium, Aspergillus, Fusarium and Gibberella ear rots also produce mycotoxins.

Know your risk. Scouting your fields for ear rot is critical. Scouting at physiological maturity (black layer) can help you to make important insurance, harvest, post-harvest handling, and storage decisions. From multiple locations within each field, peel the husk back from several (10) ears and look for mold. If you observe mold, proper diagnosis can help you to determine your risk of mycotoxin contamination. Consider early harvest (as soon as possible) when more than 10 percent of the grain on more than 10 percent of the ears you scouted within a field is affected by ear mold. The University of Illinois Plant Clinic and your local Extension Office can help in ear mold diagnosis.

Aspergillus ear rot. Signs of Aspergillus should be easy to see and most often develop near the ear tip due to insect feeding or anywhere else kernels have been damaged. Aspergillus produces a very powdery, grey-green mold growth on and around kernels (Figure). Aspergillus ear rot has been observed at University of Illinois Research Centers throughout the state from Dixon Springs and Brownstown in southern Illinois, to Champaign and Perry in central Illinois.

The presence of Aspergillus ear rot indicates that there is the potential for contamination by aflatoxin, a mycotoxin produced by certain Aspergillus species and a potent carcinogen. Aspergillus fluoresces when illuminated under a black light and most grain elevators have blacklights to check grain for Aspergillus infection. However, this method is neither quantitative nor very accurate as some strains of the fungus fluoresce but do not produce mycotoxins. A positive black light test triggers further chemical analysis to determine whether your corn contains aflatoxin and if so, at what concentration. The U.S. Food and Drug Administration has strict guidelines for aflatoxins in food and feed and grain for interstate sale.

Penicillium ear rot. Insect-damaged kernels can become infected with Penicillium ear rot. Signs of the fungus include green to blue-green fungal growth on and between kernels (Figure). Penicillium fungi can also infect the kernel embryo causing a blue discoloration known as "blue eye." The fungi that cause Penicillium ear rot can produce ochratoxin mycotoxins which can cause serious intestinal, kidney, and liver problems in humans and animals.

Fusarium ear rot. Symptoms of Fusarium ear rot, the most common ear mold in Illinois, can include a distinct 'starburst' pattern of streaks radiating from the silk attachment point on top of kernels or pink-to-reddish brown discoloration of individual or small groups of kernels. Signs of the fungus include cottony fungal growth that ranges from white to pink in color. Signs and symptoms can be scattered throughout the ear (Figure). Some Fusarium species produce mycotoxins called fumonisins, which can be toxic or fatal to livestock.

Insurance and post-harvest considerations. The USDA Risk Management Agency (RMA) has very specific guidelines for those wishing to make insurance claims for aflatoxin contaminated grain. Because aflatoxin concentrations can increase in storage or during transport, if you suspect that your grain may be contaminated, be sure to contact your insurance agent BEFORE harvest, storage, or sale delivery.

Once mycotoxins are present in grain, they are not broken down by the drying process. However, there are several actions that you can take to decrease your risk for increasing mycotoxin concentrations in stored corn. Start with clean grain bins and store contaminated grain separately from uncontaminated grain. Set your combine to kick out light weight kernels and minimize kernel damage during harvest. Clean your grain using a rotary cleaner if possible before storage. All of the mycotoxin-producing fungi can continue to grow and produce mycotoxins in grain with more than 21 percent moisture. If you anticipate large-scale infections, harvest at higher moisture (up to 25%) levels and dry at high temperatures to 18% for short term storage and 15% for long-term storage as soon as possible to stop fungal growth and the potential for additional mycotoxin production. Aflatoxin can continue to accumulate in grain with moisture levels above 15 percent, so contaminated grain should be dried to 15 percent or lower. Cool all grain after heat drying as soon as possible. Long-term storage of aflatoxin contaminated grain is generally not recommended.

Further information. For further information on specific ear rotting fungi and aflatoxin testing, visit the University of Illinois Drought Resources website.




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