Armor Against Mycotoxins in Corn Silage

January 30, 2026

Armor Against Mycotoxins in Corn Silage for Cleaner Feed

Mycotoxins in corn silage present a complex challenge. When growing corn for grain, a producer only needs to consider the risk of ear-sourced mycotoxins. Dairies growing corn silage need to consider risk for the whole-plant: ear and stalk-sourced mycotoxins.

Fungus, mold, disease, rot, toxins — these are all terms often used interchangeably when describing mycotoxins in corn silage from seed to bunk. Regardless of the name given to this invisible threat, once mycotoxins are present at high levels in feed, they are impossible to remove and result in costly losses.

This is a guide to armoring your corn-for-silage plants from Fusarium, a toxin-producing organism known by two names: Fusarium and Gibberella (the name given to Fusarium in its sexual stage). The two-name organism, Fusarium/Gibberella, produces two of the most problematic mycotoxins in silage corn:

1. deoxynivalenol (DON - vomitoxin)
2. zearalenone (ZEA)

All soils contain Fusarium fungal inoculum, as it is hosted by most grass species, including corn, cereal crops, forage grasses and grass weeds. Fusarium can enter the plant through the roots and wounds and persist inside the stalk throughout the season. Spores from soil or infested residue splashing into the whorl or leaf axils can colonize the stalk base, predisposing the plant to stalk rot and eventual mycotoxin formation in lower tissues. 

Environmental Factors

Silking: Cool, wet weather occurs during silking, allowing Fusarium graminearum to thrive and producing ideal conditions for ear rot.

Stubble residue: Fusarium spores from corn residue or infected wheat stubble can move to silks, which are most susceptible in the first 2–6 days after emergence.

Insect injuries, hail, and bird damage: Pests like the western bean cutworm or corn borers, hail, or bird damage also exacerbate ear rot by giving fungi entry points.

Soil, roots, and early stalk: Fusarium can enter the plant through the roots and wounds and reside inside the stalk throughout the season. Spores from soil or infested residue splashing into the whorl or leaf axils can colonize the stalk base, predisposing the plant to stalk rot and eventual mycotoxin formation in lower tissues.

Agronomic Armor

• Select hybrids with disease tolerance and insect protection traits.
  • While there is no formal mycotoxin resistance rating for silage hybrids, seek good ratings for Gibberella ear rot and stalk integrity.
• Plant at optimal population. Stalk and ear health correlates directly with potassium fertility.
  • High populations require higher potassium levels and often fail to receive adequate fertility. Dense canopies increase stress and humidity, making plants more susceptible to disease and DON and ZEA accumulation.
  • Low potassium combined with high plant populations is a deadly combination that favors mycotoxin-causing disease.
  • Timely planting and harvest.
• Late planting of full-season hybrids leads to plants maturing late into fall, when conditions favor stalk and ear mold development. Harvesting silage at the correct moisture (~65%) reduces the time fungi have to grow and produce toxins.
• Fusarium and Gibberella fungi overwinter on crop residue. Avoid grass-on-grass rotations (corn, wheat, triticale, grass hay, etc.) and/or employ tillage to bury disease-harboring residue.
• Control insects. Wounds from insect feeding above and below ground invite fungal invasion.
• Bt corn hybrids that control root- and ear-feeding caterpillars indirectly reduce fungal infection risk.
• Bt traits can reduce ear damage and subsequent DON and ZEA levels in silage corn.
• Additionally, soil-applied insecticides can extend root protection into mid-summer beyond seed treatment windows (21–28 days). Root-feeding insects create entry points for stalk-rotting fungi, which can move upward as the plant shifts resources to reproduction and ear development.
• Monitor crop maturity and overall plant health. 

The First and Last Line of Defense: Fungicides

Even with proper seed selection, soil preparation, and pest control, high-disease-pressure years can still lead to mycotoxin contamination. This is where fungicide use becomes crucial.

Stalk and ear vulnerability to mycotoxins born from Fusarium/Gibberella can be addressed as early as planting and tasseling with fungicide application. Here’s what Vive Crop Protection suggests:

1. Armor the roots:
   • Incorporate an in-furrow fungicide such as AZteroid® FC 3.3 at 4.2 oz/ac to protect root-rotting fungi from becoming stalk-rotting fungi.
   • An in-furrow application of Vive's Bifender® FC insecticide protects roots against wireworms and grubs such as the Japanese beetle larva. The current landscape of root protection is broad-spectrum seed treatments and Bt traits for corn rootworm only. Bifender FC extends protection into the summer months, preventing wounds caused by grubs and wireworms.
2. Armor the seed: AZteroid FC 3.3 is a seed-safe, systemic, in-furrow or 2x2 fungicide, providing two-fold protection against stalk diseases.
3. Armor the ear: Applying a fungicide at the tassel/green silk window is the best timing for protecting the ear from invasion of Fusarium/Giberella at pollination. Vive’s Phobos® FC fungicide, containing Prothioconizole, delivers a strong drying solution for improved leaf and silk coverage and serves as a valuable resistance-management tool. If your crop protection program relies heavily on Group 7 strobilurins, adding Phobos FC helps counterbalance the increased risk of mycotoxins in wheat and corn. 

Conclusion

Test your silage regularly for mycotoxins so you can design a corn silage program that mitigates risk to herd health. Dairy producers can greatly reduce exposure by protecting the crop from seed to silage. As you plan your next corn silage crop, Vive is here to help you make strong agronomic decisions to fight the invisible threat of mycotoxins.

Learn more about Vive’s solutions: https://www.vivecrop.com/products.

Important:  Always read and follow label instructions. Check state registrations before use. AVERLAND FC AND BIFENDER FC ARE RESTRICTED USE PESTICIDES. Allosperse®, Averland®, AZterknot®, AZteroid®, Bifender®, Phobos®, Viloprid®, and Precision Chemistry™ are trademarks of Vive Crop Protection Inc. ©2026 Vive Crop Protection Inc.