Dryland corn producers know that you can't assume the 2012 corn in the bin has not been contaminated by molds, including mold species capable of producing mycotoxins. The only defense against mycotoxin contamination in corn is to manage the grain moisture content and grain temperature to minimize mold growth in the grain.
Tom Dorn, University of Nebraska-Lincoln Extension educator, makes the following recommendations to help you protect your stored grain:
•Dry dryland corn down to 13% moisture if it's to be stored for more than a month.
•Run aeration fans whenever the air temperature was 10 degrees cooler than the grain temperature since the rate of mold growth is slower at cooler temperatures.
•Cool stored grain down to 30 degrees (plus or minus 5 degrees) to stop mold growth. If you have not cooled the grain to the recommended temperature for late fall and winter, do so soon, especially if you plan to keep the grain into the new year.
In fall and winter, grain next to the bin wall will be cooled while grain in the center of the bin will stay warmer, Dorn says. The difference in temperature can result in convection air currents migrating through the grain. The warmer air in the center of the bin rises and the grain next to the cold bin wall sinks. When the warm rising air encounters the colder air at the top of the bin, the escaping air can go below the dew point temperature of the rising air and deposit moisture on the grain. This can create a wet spot in the top-center of the bin, he adds.
If the grain is warm enough for microbial activity, a hot spot can form and molds can grow, even in winter. This includes molds that can produce mycotoxins.
Run the aeration fans at least once a month when the humidity is low and the ambient air temperature is 30 to 35 degrees, Dorn recommends.
To conduct a preliminary check on grain quality, start the aeration fans, then climb up and lean into the access hatch. If the air coming out of the hatch is warmer than you expected, has a musty order or if condensation forms on the underside of the bin roof on a cold day, continue to run the fans long enough to push a temperature front completely through the grain.