Identify and Manage Corn Ear Molds

There are several ear mold fungi that can attack corn, reducing yield potential, grain quality, and feed value. Ear mold damage is often associated with kernel damage from insects, birds, or frost. Potential for damage from ear molds is greatest from silking to harvest. Common ear molds are Aspergillus, Gibberella, Diplodia, and Fusarium.

Management

Pathogens that cause ear rots can remain viable in the soil for several years. Fields with a history of ear rots and stalk rots should be carefully scouted, even if management practices have been employed to decrease disease pressure. Some options to help decrease the risk of ear mold infection include crop rotation, heavy tillage, planting corn products with insect protection traits, and proper fertility.1 Planting several different products with varying maturities and growing degree units (GDUs) to flowering, as well as rotating germplasm planted in the same field from year-to-year, are also good practices to help reduce the effect of ear molds.

Proper grain drying and storage are important when these diseases are evident. Here are some tips for harvesting and storing grain from fields with prevalent ear mold infection:

  • Grain should be allowed to dry in the field to 22 to 25% moisture content. If lodging concerns exist, early harvest should be considered since downed corn is more likely to mold.

  • Consider tillage and rotation away from corn.

  • Adjust combines to minimize kernel damage and maximize cleaning.

  • Grain should be dried to less than 15% moisture content within 48 hours of harvest.2

  • Grain should be stored at cool temperatures (35 °F to 45 °F) after drying.

  • Grain should be checked periodically for temperature, wet spots, and insects.

  • Grain should be stirred and aerated during storage to prevent the development of hot spots.

  • Consider application of antifungal treatments to grain.

Testing

Because some molds can be toxic to livestock, proper identification is needed before using contaminated grain for feed. Always send a sample of suspect corn to a toxicology lab for analysis. If concentrations of a mycotoxin are present, a veterinarian or an extension specialist can help determine if it is safe to feed to livestock.

Contact your local extension specialist for information on testing labs in your area.

Figure 1  

Harvest

Prior to harvest, growers should take a close look at roots, stalks, and ears for disease, insect damage, and moisture content. Under extreme weather conditions, crop status in each field should be monitored to help determine a plan for harvest.​