As farmers gear up for the 2025 growing season, managing corn rootworm remains a critical challenge, particularly in regions with heavy pressure like Iowa, Illinois, and Wisconsin. Insights from our agronomist, Craig, shared during a recent agronomy meeting, highlight the complexities of rootworm behavior and offer practical strategies to protect yields. This blog post dives into effective rootworm management techniques, leveraging biological tools, monitoring, and on-farm trials to stay ahead of this persistent pest.
The Rootworm Challenge
Corn rootworm, both northern and western species, poses a significant threat to corn yields, especially in continuous corn and corn-soybean rotations. Craig’s presentation detailed how rootworm pressure varies by region:
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Illinois: Predominantly western corn rootworm, with some northern presence. The western variant, which lays eggs in soybean fields, creates extreme pressure in corn-soybean rotations.
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Iowa: A mix of both northern and western rootworms, with northern rootworms exhibiting extended diapause—eggs laid in corn remain dormant through the soybean year, hatching when corn returns.
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Wisconsin: Heavy western rootworm presence, with some northern rootworms.
Monitoring data from the Iowa State Extension’s Regional Rootworm Monitoring Network shows thresholds being met in some areas, with two beetles per trap per day indicating moderate pressure and over ten signaling severe infestations. These pressures, combined with variants like the western corn rootworm laying eggs in soybeans, demand a robust management approach.
Strategies for Effective Rootworm Management
To combat rootworm and protect corn roots, consider these integrated strategies:
1. Leverage Biological Tools
Biological products like Tune Up Plus, highlighted in Craig’s upcoming split-planter trials, offer a promising tool for rootworm management. These products contain a wide range of microbes, including bacillus bacteria, which deliver multiple benefits:
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Nutrient Uptake: Trials show bacillus bacteria increase nitrogen uptake by 43%, phosphorus by 30%, and potassium by 100-200% in plants. These endophytes cycle nutrients into root tips, enhancing plant vigor and resilience.
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Stress and Pest Resistance: Tune Up Plus helps plants combat soil-borne fungal diseases, nematodes, and stress factors like drought, which can exacerbate rootworm damage.
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Root Protection: By promoting rapid germination, these biologicals help corn plants establish quickly, outpacing early rootworm feeding.
Craig’s trials, including a large-scale study on his farm and an organic farm in DeKalb, Illinois, will pair Tune Up Plus with FieldView yield data to analyze performance across soil types, fertility practices, and manure applications. These studies build on previous split-planter trials, which showed significant yield improvements with biologicals.
2. Integrate Multiple Approaches
No single solution can handle heavy rootworm pressure. Combine these tactics for maximum impact:
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Traits and Insecticides: Use advanced traits like SmartStax PRO, which prevent adult rootworms from escaping, alongside soil insecticides for high-pressure fields. Products like TS-201, a rootworm bio-capsule, complement traits by reducing larval pressure and promoting root regeneration.
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Beetle Bombing: Target adult beetles the year before to reduce egg-laying, lowering larval populations in the following season.
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Crop Rotation: While corn-soybean rotations help, variants like the western rootworm and extended diapause northern rootworm reduce rotation effectiveness. Monitor fields closely in rotation systems.
3. Monitor and Adapt
Regular monitoring is key to staying ahead of rootworm pressure. The Iowa State Extension’s monitoring network provides real-time data on beetle populations, helping farmers identify high-risk areas. For example:
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Continuous corn fields often show heavy pressure (red dots on monitoring maps, indicating over ten beetles per trap per day).
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Corn-soybean rotation fields in Iowa are seeing threshold-level pressure due to extended diapause, while Illinois fields face risks from the western variant.
Use this data to tailor your management plan, adjusting trait selection, insecticide use, or biological applications based on local pressure.
4. Conduct On-Farm Trials
Craig’s enthusiasm for on-farm studies underscores their value in fine-tuning rootworm management. His 2025 trials with Tune Up Plus will explore how biologicals perform under diverse conditions, including organic systems with minimal seed treatments. Farmers can replicate this approach by:
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Testing biologicals or new traits on small plots.
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Using precision tools like FieldView to collect yield and soil data.
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Partnering with seed reps or agronomists to analyze results and refine strategies.
These trials help identify what works best for your farm, especially in high-pressure rootworm zones.
Why Biologicals Matter
Craig emphasized the “shotgun approach” of biologicals like Tune Up Plus, which combine multiple microbes to address varied soil and pest challenges. While soil tests to pinpoint deficiencies are still evolving, broad-spectrum biologicals ensure benefits across different fields and conditions. Beyond rootworm suppression, these products enhance germination, combat soil-borne diseases, and improve nutrient cycling, making them a versatile tool for 2025.
Final Thoughts
Corn rootworm management requires vigilance, integration, and innovation. By combining biologicals like Tune Up Plus, advanced traits, insecticides, and diligent monitoring, farmers can protect their corn from rootworm damage and boost resilience against stressors like drought. Craig’s on-farm trials offer a blueprint for testing new tools, ensuring your strategies are tailored to your farm’s unique needs.