Corn Ear Molds

Wednesday, July 29, 2015

The weather we have experienced offers many opportunities for disease development. There are at least seven ear mold fungi that can attack corn. Ear mold damage is often associated with kernel damage from insects, bird, or frost. The greatest potential for damage from ear molds is from silking to harvest. Pathogens that cause ear rots can remain viable in soil for several years. Fields with a history of ear rots and stalk rots should be carefully scouted. There are several practices that can reduce the possibility of ear rots before planting but we are past that point now. During the fall and prior to harvest, producers should take a close look at roots, stalks and ears for diseases, insect damage, and moisture content. This information should allow for determining a harvest plan the will reduce losses and obtain better grain quality.

There are several practices that are important when diseases are evident and it is time to harvest.

1. Allow corn to mature in the field to 22-25 percent moisture. If lodging is a concern, early harvest may be justified since down corn is more likely to mold.

2. Adjust combines to minimize kernel damage and maximize cleaning.

3. Corn should be dried to less than 15 percent moisture within 48 hours of harvest.

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

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

6. An application of antifungal treatments to grain may be a consideration.

7. Above all, the grain should be checked periodically for temperatures, wet spots and insects.

Below is a brief description of the possible molds that may show up in our area.

1. Aspergillus -- gray-green or light green, powdery mold starting at tip of ear.

2. Cladosporium -- gray to black or very dark green, streaks scattered over ear.

3. Diplodia -- white to gray, usually begins at base of ear and develops toward the tip.

4. Fusarium -- white to pink, individual kernels with fungi growth scattered across ear.

5. Gibberella -- often bright pink, varies from red to white, usually begins at ear tip and progresses to base.

6.Penicillium -- blue to green on or between kernels, powdery.

7. Trichoderma -- green grows on and between husks and kernels.

Several of these fungi can produce mycotoxin.

1. Aspergillus can produce aflatoxin, which is toxic to livestock and humans.

2. Fusarium can produce Fumonisin, which is toxic to livestock particularly horses.

3. Gibberella can produce vomitoxin, zearalenon, which is harmful to livestock.

4. Diplodia is not previously known to produce mycotoxins, but some association with diplodiosis in cattle and sheep.

5. Cladosporium, Penicillium and Tricoderma are not known to produce mycotoxins.

If you have a sample of grain that is suspect, send it to a toxicology lab for analysis.