Ear infected with Aspergillus (green area) and Fusarium (white area)Entering harvest, farmers have a lot to think about, and mitigating risk at every growth stage of the crop is a challenge. One concern you may not consider until harvest is the potential impact of mycotoxins in harvested grain. Fields suffering from
ear rot caused by fungi may produce mycotoxins.
Types of mycotoxinsMycotoxins are a group of toxins produced by specific molds or fungi. Not all fungi produce toxins, and most fungi only produce toxins under certain environmental conditions. Mycotoxins can be present without the visible presence of a mold, and they can also remain in the plant after the mold is removed.
There are 300-400 identified mycotoxins, and the most frequent toxins present in corn are fumonisin, aflatoxin and DON. Some are more common than others and vary significantly in acceptable thresholds, as well as their impact on animals consuming contaminated grain.
Aflatoxin:- Produced by Aspergillus flavus, Aspergillus parasiticus.
- Most concerning of the mycotoxins due to the effects on human and animal health.
- Threshold established by the FDA is 20ppb in grain and feed (0.5ppb in milk).
- Most common aflatoxins are B1, B2, G1, and G2.
Fumonisin:- Produced by Fusarium verticillioides (previous name F. moniliforme).
- Most common fungal disease in corn ears.
- Typically identified by white to pink or salmon colored mold.
- Highly correlated with insect damage on corn ears and grain.
- Of particular concern to equine.
Deoxynivalenol (DON): - Produced by Gibberella zeae or Fusarium graminearum.
- Commonly identified by pink or reddish mold.
- Not highly correlated to insect feeding.
- Of particular concern to swine.
Mycotoxin developmentFungi that produce mycotoxins in grain commonly overwinter in plant material as sclerotia. The sclerotia germinates, distributing fungal spores into the air and soil, which move to developing plants and grain. The fungal spores enter the plant through silks or by infecting injured areas, allowing the fungus to grow on developing grain. Early fungal infection through roots can also occur. Insect damage to corn ears can predispose the developing kernels to fungal infection.
Conducive environmental conditions are necessary for fungal development and mycotoxin production. High temperatures (80-100°F), humidity (85% or greater), and grain moisture (18-20% or greater) are necessary for most fungi development. Crop stressors, such as high temperatures, drought stress, flooding or low soil fertility are ideal for mycotoxin production. Aflatoxin is especially high following drought or high heat conditions.
Harvest considerations  |
| Corn earworm damage and developing mold |
The economic impact of mycotoxins is significant. They reduce the crop value by restricting use of contaminated grain and causing rejection of unacceptable DDGs (dried distillers’ grains). Harvest moisture and handling can also influence grain infection. Higher grain moisture, improper storage, and damaged kernels may increase the likelihood of mycotoxins in the kernels.
Mycotoxins can be extremely harmful to humans and animals. They’re known to disrupt DNA, RNA, and protein synthesis. Mycotoxins can impair animal health, cause death, and the metabolites can be passed through animal products such as milk.
Managing mycotoxinsMycotoxin management is possible. There are tools to dramatically reduce mycotoxins, especially aflatoxins. 4 proactive management options include:
- Implementing best agronomic practices to minimize crop stress.
- Timely fungicide application to minimize foliar disease crop stress.
- Consider planting hybrids with Bt and Agrisure Viptera® trait insect control to reduce insect feeding damage.
- Harvest, dry and store grain at appropriate moisture levels to further reduce mycotoxins.
Contact your
Golden Harvest Seed Advisor with questions or for additional agronomic insights.
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