Keep Mold-Affected Corn Separate and Test Before Choosing Its Destination

Keep your handling options open

When mold-affected corn arrives, keep it separate from sound grain while you evaluate it. A representative sample and mycotoxin test can guide the next sale or feeding decision without mixing the suspect lot into better corn. Keep confirmed toxin-contaminated corn separate, too—do not blend it with clean grain.

Separate poor-quality corn before loads meet

Hold suspect, mold-affected and other poor-quality corn apart from better grain. Visible ear rot is a warning to investigate mycotoxins—toxic substances produced by some fungi—not a measurement of contamination.

Iowa State Extension’s October 5, 2026 guidance on wet-weather grain quality in Iowa says mycotoxin-contaminated grain must remain separate from non-contaminated grain and should not be blended with clean grain.

Its damaged-grain handling guidance also recommends keeping the poorest-quality grain separate from better grain. If differing qualities have already been mixed, manage the mixture according to the worst condition present.

Sample the lot, not just the worst-looking kernels

A composite sample combines grain collected from several points in the lot. For corn mycotoxin testing, Iowa State’s 2026 hail-damaged corn guidance recommends either:

– A composite sample of at least 10 pounds collected from a moving grain stream.
– Multiple probes in a grain cart or truck, combined into a 10-pound sample.

Those quantities describe the collected composite, not necessarily the amount to ship. Before submission, ask the testing laboratory how to prepare the sample and how much to send. University of Minnesota Extension likewise recommends contacting the laboratory for its specific sampling requirements.

Use the laboratory results to identify the toxin and its concentration rather than routing corn by appearance alone.

Dry wet corn while you evaluate its use

Keep the drying decision moving alongside testing. Iowa State’s October 2026 guidance recommends drying harvested corn to 15% moisture or below as rapidly as feasible. Drying may prevent further fungal growth, but it does not remove existing toxins or mold. Reaching that moisture level therefore does not settle the corn’s destination.

Match the results to the proposed destination

For sale, share the results with the intended buyer and confirm its requirements before dispatch. For severely damaged grain, Iowa State recommends finding out whether a buyer exists and what discount applies. The buyer determines acceptance and pricing.

For feed, review the specific toxin, measured concentration and intended livestock species with a veterinarian or Extension specialist. Iowa State notes that some toxin-positive corn may be usable for a less-sensitive species, such as beef cattle, depending on the toxin and concentration. That is a decision based on results—not a reason to automatically route moldy corn to cattle.

Your next step at receiving is simple: keep the suspect lot separate, arrange representative testing, and bring the results to the buyer or livestock adviser who can help determine its use.

Discuss a grain sample test

Not sure how to prepare your grain for storage?
Send Metra a sample for a free grain cleaning test. Our team can evaluate your grain, demonstrate how different fractions can be separated and recommend suitable cleaning equipment and settings to help prepare your grain for storage.

Contact info@graincleaner.com to arrange your free sample test.