Corn Disease Management in Ohio

Bulletin 802

Ear and Kernel Rots

Figure 19. Gibberella or pink ear rot is caused by the same fungus that causes Gibberella stalk rot. The pinkish colored mold growth, usually located near the tip of the ear, is characteristic of this ear rot. The Gibberella fungus is responsible for producing several “mycotoxins” that are harmful to livestock if fed moldy grain

Many fungi cause ear and kernel rots on corn especially when rainfall is above normal from silking to harvest or when insects or birds damage developing ears. The most common ear rots are Gibberella (Figure 19), Diplodia (Figure 20), and Fusarium (Figure 21) ear rots. Hybrids differ in their susceptibility to these ear diseases, and environmental conditions play a large role in determining the level of ear rots in the field. Some hybrids may escape infection or have ears that do not favor growth of the fungus. Several fungi, particularly Penicillium and Aspergillus, cause kernel rots that are important once the grain is placed in storage. Very little can be done to prevent infection of ears in the field; however, proper drying of grain and good storage conditions are important when these diseases are evident. Some fungi that cause ear and kernel rots produce mycotoxins that may cause problems when fed to livestock. Visit the web site titled “Moldy Grain, Mycotoxins, and Feeding Problems,” at www.oardc.ohio-state.edu/ohiofieldcropdisease/Mycotoxins/mycopagedefault.htm for more information.

Prevention is the best method to manage mold growth on kernels after harvest. Some preventive practices that will reduce damage from moldy corn are:

1. Allow corn to mature in the field to 23 percent to 25 percent moisture for shelled corn and 20 percent to 25 percent for ear corn.
2. Adjust harvest equipment to minimize damage to kernels and allow maximum cleaning.
3. Clean all bins thoroughly before putting in the new crop.
4. Dry ear corn to 20 percent moisture and shelled corn to 13 percent to 14 percent moisture prior to storage.
5. Store grain at cool temperatures (36°F to 44°F) after drying.
6. Check condition of grain periodically for temperature, wet spots, and insects.
7. Have a mycotoxin analysis performed, if mold is evident, by a competent laboratory to determine if toxins are present.
8. Apply antifungal treatments to grain to reduce mold growth in storage. These products, such as proprionic acid, do not kill the mold already present nor do they reduce toxins already present in the grain. Do not use antifungal agents on stored grain unless you are certain the grain can be marketed after treatment.

Figure 20. Diplodia ear rot occurs most frequently in reduced tillage fields of continuous corn. The ear rot fungus produces a thick layer of mold growth over the kernels and husks. Hybrids vary greatly in their susceptibility to this ear rot.

Figure 21. Fusarium kernel rot is commonly associated with insect damage to ears. Affected kernels are white to pink in color and generally scattered over the ear. The Fusarium fungus is capable of producing a mycotoxin, fumonisin, that is toxic to livestock, particularly horses.

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