This past winter, many areas saw days with temperatures above 50° F, creating conditions favorable for mold growth. As a result, the corn stored in bins since the fall harvest may develop harmful toxins. Keep an eye on what’s left of your 2011 corn crop for signs of mold.

Richard Stroshine, a Purdue University agricultural engineer, said he has heard reports of higher-than-normal percentages of moldy, discolored kernels when corn has been removed from storage facilities this year.

Stroshine recommends that you check grain frequently for mold growth. “If found, get that corn out of the bin as soon as possible so that it doesn’t spread to other grain in the bin,” he says.

When mold risks are high, farmers should take steps to evenly cool the grain in the bin. A common practice, known as coring, involves taking one or more truckloads of corn from the bin and leveling the crop that remains. The process removes fine material that often accumulates in the center — or core — of the bin, filling air pockets between kernels and restricting air circulation.

To ensure even airflow distribution, farmers should maintain a level surface at the top of the bin. Without sufficient and uniform air movement in the bin, heat can build up in some areas and promote mold growth.

He points out that farmers who have cored their bins reduced the likelihood of mold problems but should still keep an eye on their leftover crop. Those who didn’t perform coring operations will need to be even more vigilant.

Bins should be visually inspected and grain temperatures monitored weekly. Stroshine recommends running bin fans for 30 minutes before entering the storage facility to conduct an inspection.

Aeration will push musty odors, which are indicative of mold growth, to the bin’s headspace. If the problems are deeper in the bin it will take longer for odors to reach the surface. Run the fans another two to four hours and check again.

Look for signs of condensation on the inside of the bin’s roof. That’s an indication you’ve had moisture generated by mold activity. Crusting on the grain’s surface is another symptom.

Stroshine offers other grain bin tips:

  • Exercise extreme caution when entering a bin. Grain can shift and trap a farmer, leading to potential suffocation. Another person should remain outside the bin to offer assistance, if needed. Shut off and tag-out unloading equipment before entering a bin.
  • Cover bin fans when they are not running to keep warm, humid air and rodents from entering the bin through the fan inlet. Covers can be made from plywood, sheet metal, heavy plastic or canvas.
  • Keep grain as cool as possible for as long as possible. If planning to hold onto corn past June, consider warming it to about 50° F.

For more information about corn storage and mold issues, go to