Ear and kernel rots of corn
An additional concern with ear and kernel rots of corn is the possibility of mycotoxin production. Mycotoxins are naturally produced chemicals that in small amounts may be deleterious to animal or human health. Aspergillus and Gibberella are most frequently involved in cases of mycotoxin contamination in Missouri corn. The presence of molds or their spores does not necessarily mean that mycotoxins will be produced. Circumstances that favor mold growth may allow production of mycotoxins in some situations, but frequently mold growth occurs with little or no mycotoxin production. Once formed, mycotoxins are stable and may remain in grain long after the fungus has died. In general, swine and poultry are more susceptible than ruminants to mycotoxin-induced health problems. In cases where mycotoxin problems are suspected, a sample should be submitted to a qualified laboratory for mycotoxin analysis. Table 1 below gives the acceptable levels of aflatoxin in corn intended for various uses as established by the United States Food and Drug Administration.
Table 1. Present acceptable levels of aflatoxin in corn used for food and feed as established by the United States Food and Drug Administration (FDA) are as follows:
- Corn containing no more than 20 ppb of aflatoxin when destined for food use by humans, for feed use by immature animals (including immature poultry) and by dairy animals, or when the intended use is unknown.
- Corn containing no more than 100 ppb aflatoxin when destined for breeding beef cattle, breeding swine or mature poultry (e.g. laying hens).
- Corn containing no more than 200 ppb aflatoxin when destined for finishing swine (e.g. 100 lbs. or greater).
- Corn containing no more than 300 ppb aflatoxin when destined for finishing (i.e. feedlot) beef cattle.
Little can be done to prevent or reduce the invasion of corn by fungi in the field. These ear and kernel rots tend to be more severe on ears with insect, bird, hail or other physical damage. Ears well covered by husks and maturing in a downward position usually have less rot than ears with open husks or ears maturing in an upright position. However, if ear and kernel rots developed in the field, it is important to harvest the field in a timely manner and to store the grain under the best possible conditions. Both Penicillium and Aspergillus can continue to develop on corn in storage if the grain is not stored at proper moisture content and temperatures. These two fungi can cause serious storage mold problems.
Adjust harvest equipment for minimum kernel damage and maximum cleaning. Before storing grain, clean bins thoroughly to remove dirt, dust and any grain left in or around bins. Thoroughly clean grain going into storage to remove chaff, other foreign material and cracked or broken kernels. Dry grain to 15% moisture as quickly as possible and monitor grain on a regular basis throughout storage life to insure moisture and temperature are maintained at correct levels. Protect grain from insects.