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Around the County

Dealing with moldy corn issues

November 20, 2009
From Wayne Schoper, Brown/Nicollet Extension Educator

This harvest season has been a very unusual one. We had a very cool month of July that slowed crop development way down to the point that we had to worry about frost damaging the crop before it reached maturity. Fortunately, we managed to avoid that scenario with most of our corn and soybeans and they reached maturity before the first killing frost.

The month of October was a very different story. We had a lot of wet weather that slowed harvest to a standstill. On top of that, the corn and soybeans did not have a chance to go through their normal dry down process so that they went into this cool wet period with very high moisture levels. In recent years we have been very fortunate to have early crop maturation with much of the corn and soybeans mature by the first week of September and dry enough to harvest shortly after. In fact, we have not had to dry soybeans for many years up until this year. In recent years we have not had to dry our corn crops much if any with harvest moisture for the past several years around 16 to 18 percent moisture. Corn moisture at this level will need very little if any dryer gas to drop moisture down to storage levels of 14-15 percent. This year we have had to harvest a lot of corn at moisture levels from 25-30 percent. This means a lot of extra expense, up to 50 cents to a dollar per bushel. Fortunately, we have an excellent corn crop out there with yields from 175 to well over 200 bushels per acre to make up for the extra expense.

The phenomena that we have seen this fall is the formation of mold on corn that has been standing the field too long. The corn samples that I have seen have developed a black/gray mold near the base of the corn ear especially on some of the hybrids that have corn husks that hold the ear in an upright position. This mold has been appearing in corn fields from Ohio to Montana so we are seeing it over a large area of the Corn Belt. Most of the mold seems to come off of the corn kernels during the harvesting process. I addition, we have been recommending that producers screen their corn before putting it into storage. This removes the fines and broken kernels that can harbor mold pathogens.

Article Photos

Wayne Schoper

There is still a concern that corn with high mold spore counts can cause feeding problems, especially to pregnant swine and cattle. Dairyland labs in St. Cloud report that over half of the samples submitted to them have molds that have the potential to produce mycotoxins. A mycotoxin is a highly toxic by-product of mold growth in feed and grain. Myco means fungus and toxin means poison. They represent a broad spectrum of acute and chronic diseases in livestock. Mycotoxins can remain as a residue in meat and milk, posing a possible threat to human health. They are poisons generated from the secondary metabolic processes which can occur naturally in a variety of molds. Temperature and humidity, such as we experienced in October, play a big role in their development. Mycotoxins at high enough levels can cause spontaneous abortions and other metabolic problems.

So what does all this mean? If you suspect that your corn has a high mold level and you will be feeding it to livestock, it would be worth it to have a sample checked. Dairyland Labs and Stearns DHIA labs out of St. Cloud will run samples checking for any three mycotoxins for $79. Compare this to losing an animal or having other health problems and it seems like a good investment.



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