Producers concerned about moldy grains and vomitoxin development in storage shouldn’t rely on chemical treatments to prevent any further contamination, according to an Ohio State University Extension plant pathologist.

“I’ve fielded questions from growers as to whether or not vomitoxin will increase in storage over time, if vomitoxin levels can be reduced and if treatments they are looking at are authentic and effective against vomitoxin development,” reports Pierce Paul. “In answer to those questions, yes, vomitoxin can increase in storage if environmental conditions are suitable; vomitoxin won’t be reduced because it’s stable; and I know of no fungicide or other chemical treatment that has been used effectively to reduce vomitoxin in stored grain.”

No scientific data exists to suggest that such treatments work, specifically for vomitoxin control.

“I don’t recall seeing a single recommendation for fungicide applications for ear mold control in the field or in storage,” Paul says. “This is largely because the problem is not common enough to allow for adequate testing of fungicides and adequate application timing will likely be a big concern.”

Cool, wet weather late in the growing season and during harvest combined to produce moldy corn and mycotoxins, especially vomitoxin. That toxin is harmful to humans and animals if ingested. As a result, some feedmills have been rejecting grain with vomitoxin levels above 3 parts per million.

The wet harvest forced farmers to harvest grain at moisture levels above recommendations, creating situations for moldy grain development and vomitoxin contamination in storage.

“I know that some farmers may be desperate to reduce vomitoxin levels in stored grain, but they should avoid buying into the strategies that these chemical treatments work,” says Paul.

Mycotoxin binders are being used to bind the toxin, render it inactive and minimize grain rejection and the health impacts on animals. But these options should be carefully explored.

“Some of the binders have been tested for vomitoxin, but they seem to work better for aflatoxin and don’t seem to work as well for vomitoxin,” Paul says. “I’m not sure why that is. It could be that the elements of vomitoxin are different than that of aflatoxin and they just react differently to the chemical.

“Bottom line is don’t treat all toxins the same. Binders that work for one toxin may not work for another. The ideal thing to prevent an increase of vomitoxin is to do a good job of storing grain and keeping it in cool, dry conditions. Don’t do a bad job of storing in the hopes that these binders or chemical treatments will work,” he says.

Moldy corn can develop in storage when bin temperatures exceed 40 degrees F and grain moisture exceeds 15-20%. Moldy grain increases the chances of vomitoxin. To take a representative sample of grain for testing, pull multiple samples from multiple locations.

To learn more, visit the Ohio State University Extension Agronomic Crops Team Crop Observation and Recommendation Network newsletter at