Bins should be visually inspected and grain temperatures monitored weekly, Stroshine said. He recommended 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 headspace of the bin," he said. "If the problems are deeper in the bin it will take longer for odors to reach the surface. So you could run the fans another 2-4 hours and check again.

"While you're in the bin, 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. Also, look for crusting on the grain's surface, which is symptomatic of mold growth."

Farmers also should check grain temperatures for mold-generated hot spots at numerous places in the grain mass, Stroshine said. If a producer does not have a temperature probe, a metal rod will do. Stroshine advised sliding the rod into the grain and pulling it out after about 15 minutes. If the rod is warm, mold could be present.

Insects that invade stored grain probably will be active earlier this year, he said.

Stroshine offered other grain bin tips:

• Exercise extreme caution when entering a bin. Grain can shift and trap a farmer, leading to potential suffocation. A family member or friend 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 fans 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 the middle of June, consider warming it to about 50 degrees.

More information about corn storage and mold issues is available in the paper "Check Stored Corn for Potential Problems" by Stroshine and fellow agricultural engineer Matt Roberts. The paper can be found on Purdue's Post Harvest Grain Quality website by going to http://www.grainquality.org and then clicking on "News and Information." Related information can be found by clicking on the "Extension Publications" tab.