Agriculture & Natural Resources, University of Wisconsin-Extension

By: Tim Jergenson, 715-537-6250, tim.jergenson@ces.uwex.edu

December 2006

The recent warm weather has lead to concerns about stored corn grain beginning to mold in storage.  Temperatures in Barron County have been above average for 31 of the last 52 days. These warm temperatures have caused some stored corn to begin to go out of condition.     

Symptoms of corn going out of condition include crusting of the top layer due to sprouting and molding, soggy surface corn due to condensation and moisture absorption and hot spots within the top few feet of the bin.

Farmers have only a limited number of options to counteract corn storage problems.  The primary one is to check the bins twice a week. To check grain, follow these steps:

• Look for signs of moisture accumulation.  Grain moisture can increase during storage, especially near the exposed top surface.  Look for signs of crusted grain; wet, slimy grain; and heating.
• Smell the grain. A musty or moldy odor indicates the beginning of a storage problem; a fermented or sour odor indicates a serious problem.
• Use a long, slender rod to pinpoint problems. Poke into the corn in several places to find hard, compacted, or moist areas.
• Measure grain temperature. Attach a grain thermometer to the end of a metal rod to detect hot spots, or record temperature of the first air that comes through the grain. The thermometer can be left at an 8-ft. depth to get a weekly temperature check. A rise of only 3-4 degrees indicates a possible problem; monitor temperature daily.

If the moisture content of the corn is higher than 14.5-15%, or if crusting or rewetting has occurred, producers should remove the affected grain immediately by drawing out the core of the stored grain. The corn removed can be recirculated back on top of the pile or marketed.  If corn is going out of condition, marketing the corn may be the best option because it probably will not store well into the spring.

If temperatures in stored grain begin to rise noticeably, a hot spot may be developing. The aeration fans should be turned on immediately. On bins with corn of questionable keeping quality, it may also be advisable to operate the aeration fans for a few hours every week during cold weather periods.  Four to five days of freezing temperatures with aeration will be needed to stop the spoilage process in a typical corn storage set-up.

Farm safety studies have shown an increase in grain-entrapment fatalities when farmers are working with spoiled grain. To avoid farm accidents when handling grain follow these precautions:

• Watch for falls off ladders, and never enter a bin while grain is being unloaded. It only takes 3 or 4 seconds to become helpless in flowing grain.
• Before entering the bin, lock out the unloading augers.
• Bridged grain and cavities may collapse and trap a person quickly. Beware of plugged unloading spouts and steep grain piles; dislodge either of them carefully with a long pole.
• Because mold spores are airborne, they can be inhaled, causing irritation and severe illness. A dust mask capable of filtering fine particles should be worn while inside the bin.

For more information about managing stored grain and minimizing the risk of storage losses, contact Tim Jergenson, Agricultural/Natural Resources/Horticultural Agent at the Barron County UW-Extension Office in Barron at 715-537-6250.