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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 (photo: Nancy Keller).

Why scouting stored grain is a good idea

I have not been willingly neglecting the Hill and Furrow Blog. Since the holidays, many weeks have been spent traveling around the state participating in University of Illinois Extension winter meetings.

My topic for the Crop Management Conference series was corn ear molds and mycotoxins. I did write a blog article about scouting for ear molds last summer, but I would like to revisit the topic here as this may still a pertinent issue for some people.

Ear molds not only reduce grain test weights and storage life, but many of the fungi that cause ear molds can also produce mycotoxins. Mycotoxins are a diverse group of molecules that have several things in common: 1) they are all produced by fungi, 2) they cause disease when ingested by humans and animals.

Three things must come together for ear mold disease to occur: 1) a susceptible plant, 2) the pathogen, and 3) an environment that favors the interaction between the plant and the pathogen. We have the first two to a certain extent each year: Many of the corn hybrids that we plant are susceptible to corn ear mold pathogens. AND The pathogens that cause corn ear molds survive in corn residue and sometimes directly in the soil.

Fusarium ear mold is the most commonly occurring ear mold disease in Illinois. Consequently, fumonisin, a mycotoxin produced by the Fusarium species that cause the ear mold, is the most commonly occurring mycotoxin in Illinois. The Illinois Department of Agriculture has a yearly mycotoxin survey in which they collect and test grain samples from four grain elevators per county (400 samples total). In 2010, 2011, and 2012, approximately 1/3 of all samples collected in the survey tested positive for fumonisin contamination.

Aspergillus ear mold and associated mycotoxins called aflatoxins are much less common in Illinois than Fusarium ear mold. This is because, although there is no hybrid resistance to Aspergillus and the fungus survives both in the soil and in crop residue, environmental conditions typically don't favor disease. However, the drought conditions in 2012 favored the interaction between the plant and pathogen: Not only are corn hybrids under drought stress more susceptible to infection, but the pathogen produces large numbers of spores in droughty soils.

Aflatoxin is a potent carcinogen and the US Food and Drug Administration allows very low levels of contamination (in the parts per billion) in food and feed. The Illinois Department of Agriculture survey showed that in 2010 and 2011, fewer than 5% of samples tested positive for aflatoxin contamination, while 29% tested positive in 2012. In 2012, aflatoxin was detected in samples collected from all regions of the state, from as far north as Stephenson and De Kalb Counties, to Hancock and Warren in the west, Vermillion and Champaign in the east, and many southern counties.

Harvest is complete, the damage has been done, why am I still talking about this issue?

Knowing the risk of aflatoxin contamination, many producers in the southern half of Illinois took action to market and deliver their corn right after harvest. Producers in the northern half of the state may not have been as aware of the wide-spread risk of aflatoxin contamination.

The species of Aspergillus that cause ear mold can cause infection both in the field and in storage. Regardless of when infection takes place, warm and moist grain can allow continued fungal growth and mycotoxin contamination. During the winter months we recommend scouting your grain at least once every other week looking for crusting, hot spots, moisture, visible mold {Aspergillus produces grayish-green powdery mold (Figure)}, or even a moldy smell.  If you notice any of these things it may be time to take action to break up hot spots, aerate the bin, remove spoiled grain, or even market the gain before more fungal growth and aflatoxin contamination takes place.

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