The Growing Threat of Tar Spot in Corn: What Farmers Need to Know
The Growing Threat of Tar Spot in Corn: What Farmers Need to Know
What Is Tar Spot, and Why Should You Be Concerned?
Tar spot, caused by the fungus Phyllachora maydis, is an increasingly prevalent disease affecting corn crops. Characterized by raised black lesions on corn leaves, this disease can significantly reduce photosynthesis, leading to lower yields and poor-quality grain. In severe cases, tar spot can cause yield losses of up to 50%, making it a critical concern for farmers.
GOLD = TAR SPOT REPORTED, GRAY = FOUND IN PREVIOUS YEARS
Why Tar Spot Could Be Worse This Year
Several factors suggest tar spot could be more problematic, and expanding further west into central and western Nebraska this growing season:
Weather Conditions:
Tar spot thrives in cool, humid environments. This year, weather patterns in Nebraska have brought more frequent rain and cooler nighttime temperatures, creating ideal conditions for the fungus to flourish.
Increased Inoculum Levels:
Spores from infected plant debris can survive over the winter. With tar spot’s expansion in recent years, there is likely a higher baseline of fungal spores in the region.
Crop Stress:
Drought-stressed corn followed by late-season rains creates a perfect storm for tar spot infections, as weakened plants are less capable of resisting fungal attacks.
Tar Spot Symptoms and Detection
Early detection is critical to managing tar spot effectively. Symptoms include:
Small, raised black spots (ascomata) on leaves, resembling specks of tar.
Chlorosis or yellowing of the leaves around the lesions.
Premature leaf death, leading to early lodging and reduced grain fill.
Tar Spot's Increasing Impact in the U.S.
Tar spot has rapidly spread across the Corn Belt, with reports indicating significant yield losses where the disease remains unmanaged. According to Farm Progress, the disease’s impact has grown due to limited hybrid resistance and weather conditions that support its proliferation. With its ability to develop quickly, tar spot poses a challenge for farmers relying solely on fungicides.
Tar spot infection presence on a corn leaf during 2022 (Photo Credit: Dan Quinn)
Defending Against Tar Spot
Farmers have several tools at their disposal to mitigate the effects of tar spot:
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Crop Rotation: Avoid planting corn back-to-back to reduce inoculum levels.
Residue Management: Tilling or removing infected residue can help break the disease cycle.
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Choose disease-resistant hybrids whenever possible. Consult with seed providers to identify varieties with proven tar spot tolerance.
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Protecting your crop from the start is crucial. Seed treatments like UAS N-Compass Corn Blends offer targeted protection against fungal pathogens, including tar spot.
These blends combine fungicidal and insecticidal properties to safeguard seedlings during critical growth stages. Visit our corn seed treatment blends to learn more about how N-Compass can help shield your crop from tar spot.
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Timely fungicide applications can be effective in controlling tar spot. Scout fields regularly, and apply fungicides during VT to R3 growth stages if symptoms appear or weather conditions favor disease development.
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Reduce leaf wetness by timing irrigation to avoid evening and nighttime watering when humidity is naturally higher.
The Role of UAS N-Compass in Tar Spot Prevention
Unified Ag Solutions’ N-Compass Corn Blends are designed to give your crop a strong start against tar spot and other fungal diseases. With a combination of:
High-quality fungicides for broad-spectrum disease control.
Plant growth regulators to improve root development and stress tolerance.
Insecticides to fend off early pest pressure.
These blends ensure your corn has the best defense against environmental and biological stresses.