WOOSTER, Ohio – Ohio growers may be concerned about moldy grain and vomitoxin development in storage, but they shouldn't rely on chemical treatments to prevent any further contamination, says 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," said 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."
Paul, who also holds an appointment with the Ohio Agricultural Research and Development Center, said that he has not seen any scientific data to suggest that such treatments work, specifically for controlling vomitoxin.
"I don't recall seeing a single recommendation for fungicide applications for ear mold control in the field or in storage," said Paul. "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 production season and during harvest created conditions ripe for ear rot development, most notably Gibberella ear rot. The fungal pathogen not only produces moldy kernels, affecting grain quality, but it also produces mycotoxins, especially vomitoxin. Vomitoxin is harmful to humans and animals if ingested. As a result, some grain elevators have been rejecting grain with vomitoxin levels higher than 3 parts per million.
In addition, due to the weather conditions, growers harvested their grain at moisture levels higher than recommended, 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," said Paul.
Paul said that some treatment methods are used by those who ration feed for livestock to bind the toxin, rendering it inactive and minimizing grain rejection and the health impacts on animals. However, he urges farmers to be careful when exploring such options.
"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. 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," said Paul. "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."
Moldy corn can develop in storage when bin temperatures are above 40 degrees Fahrenheit and grain moisture is above 15 to 20 percent. Moldy grain increases the chances of vomitoxin. To avoid high variations of vomitoxin levels during testing, growers should pull multiple samples from multiple locations.
For the latest on ear rots and vomitoxin, refer to the OSU Extension Agronomic Crops Team Crop Observation and Recommendation Network (C.O.R.N.) newsletter at http://agcrops.osu.edu.