Corn With Mold on Ears in the Field Should Be Tested for Mycotoxin

More feed mills, grain elevators and ethanol plants are checking the corn they buy from farmers for the presence of mycotoxin.

Published on: Nov 24, 2009
There are a lot of reports about mold in corn grain this year, and some of it, especially in the eastern Corn Belt, is producing mycotoxins that can be harmful when the corn is fed to livestock. Likewise, if the corn is sold to ethanol plants, the distillers grains concentrate the vomitoxin in the distillers grains that are fed to livestock.

In Iowa and other states in the western Corn Belt, grain elevators, grain processors and others who buy corn are keeping a wary eye on the situation. Will this mold issue on corn, the longer we go with the corn standing unharvested in the field, become a bigger and bigger problem? "Yes it will. The longer the corn sits in the field, particularly as wet as it is east of Iowa, the more likely it will be to find vomitoxin in the grain," says Charlie Hurburgh, an Iowa State University grain quality expert.

Farmers are concerned that they will get a lower price for their corn if it has vomitoxin, because grain buyers are checking even more closely for it now. "The vomitoxin is a feed issue," says Hurburgh. "Ethanol plants and feed mills are starting to check more rigorously for both mold and the toxin itself, where it is feasible to do this checking and testing."

Mycotoxin becomes more concentrated in distillers grains

If an ethanol plant takes in corn with a toxin in it, and the grain goes through the extreme heat and other processes that it is subject to in the alcohol manufacturing process, how can you still wind up with toxins in the distillers grains? That's a question many farmers are asking.

"The toxin stays with the rest of the corn kernel, the portion of the corn that is not starch," explains Hurburgh. "So when that is filtered off at the end of the fermentation process, the toxin is still there and it is stable in the presence of alcohol. Thus, the toxin doesn't break down and it ends up in the distillers grains. It concentrates there at about three times the percentage level that it was when it came in with the corn." So the mycotoxin is more concentrated in the DDGs than it is in the corn, notes Hurburgh, who is director of the Iowa Grain Quality Initiative at ISU.

If you have mold on your corn, how can you tell whether or not it is going to produce mycotoxins? By scouting the corn before you harvest the field and looking for mold on the ears. And afterward, by having the corn tested. "If you see mold on the ears of corn in your field, or if you saw it while harvesting the corn, it would be wise to talk with your crop insurance agent or adjuster and see if they would like for you to leave some strips of unharvested corn in the field," he says. You may be able to get an adjustment. You can use ISU Extension publications to identify which molds are likely present.

Farmers who feed livestock are running the greatest risk

If you are a farmer feeding your own livestock, it would be wise to at least segregate the grain that is visibly moldy from the grain that doesn't have visible mold, says Hurburgh. Send a good sample of each, through your veterinarian, to a good testing lab like the veterinary diagnostic lab at Iowa State University. That way you will find out what you have in your feed ingredients and will get a plan as to how to use the corn safely.

"Farmers who are feeding corn or distillers grains to livestock are as much at risk as anyone," says Hurburgh. What if you get a lower price on this mycotoxin contaminated corn, and you blend it with clean corn to get the mycotoxin down to an allowable level, can you cut your feed cost by using this cheaper corn? Can you still get the weight gain on the cattle?

"That's right, and that's what is going to happen, particularly in the case with feedlot cattle, which are much more tolerant to vomitoxin than swine or poultry," says Hurburgh. "So this is a blending issue with corn, and you are going to have to send the sample to a testing facility to see if it is below the allowable limit."

Mycotoxin in corn is both a blending issue and a segregation issue

Also, buyers of grain can use a little strip-test kit that will tell you whether the mycotoxin is present. Five parts per million of vomitoxin is the guideline that the federal Food and Drug Administration has set for feed ingredients for swine. Those ingredients need to be no more than 20% of the total ration. So it is a segregation issue, too -- in order to keep the corn separate from corn that doesn't have the vomitoxin -- so you can blend the two types of corn correctly.

"Food safety issues like this are really complicated for the grain handling system," says Hurburgh. For more information, go to the Iowa Grain Quality Initiative Web site at