Corn rootworm pressure isn’t letting up, and if you thought traited corn alone would solve the problem, recent seasons have likely proved otherwise.
Dr. John Murphy, Director of Agronomy at AgXplore, has spent time traveling across the Corn Belt, and what he’s seen is clear: despite widespread use of traited hybrids and insecticide programs, severe rootworm damage continues to show up in fields. His takeaway?
“We’re no longer in a one-tool world when it comes to CRW. It’s going to take layers, smart ones.”
Why Corn Rootworm Remains a Top Threat
Corn rootworm isn’t just a mid-summer headache. It’s a persistent, soil-level challenge that starts long before planting season and can quietly undermine yield even when plants appear healthy above ground.
Here’s what makes it so difficult to manage:
Resistance is real and spreading. But traits that once provided reliable protection are losing effectiveness in many regions. Relying on a single trait is no longer a safe bet.
Root damage has ripple effects. Feeding by rootworm larvae weakens root systems, leading to lodging, uneven grain fill, and delayed harvest. Even if your corn stays standing, compromised roots can limit nutrient uptake and water efficiency during critical growth stages.
Adult beetles are adapting. Traditional rotation strategies and chemical timing windows are becoming less predictable as beetles adjust their behavior. Some populations have even developed extended diapause, allowing them to survive rotation in certain areas.
Yield loss isn’t always visible. You might not see every plant tip over, but inconsistent root development can cost bushels without obvious symptoms until it’s too late.
Dr. Murphy emphasizes that corn rootworm management has fundamentally changed. What worked in the past may not be enough today, and growers need to think differently about how they protect their fields.
A Multi-Layered Approach to Corn Rootworm Control
There’s no silver bullet for corn rootworm control. But there is a framework, one built on multiple tactics working together to reduce pressure and protect yield potential.
1. Crop Rotation
Rotation remains one of the most effective tools against corn rootworm, particularly for Western corn rootworm populations. Breaking the corn-on-corn cycle disrupts the pest’s lifecycle and can dramatically reduce larval feeding damage.
But rotation isn’t fool proof. In some regions, extended diapause variants allow rootworm eggs to remain dormant for more than one season, surviving even a year of soybeans. That’s why Dr. Murphy stresses the importance of tracking field history and conducting beetle scouting as part of your rotation planning. Know what you’re dealing with before you assume rotation will solve the problem.
2. Trait Selection
Traits still have a role to play, but only when used strategically. Stacking multiple modes of action is essential in areas with confirmed resistance or heavy historical pressure.
Dr. Murphy warns against relying on marketing names alone. Dig into the actual proteins expressed in your hybrid and understand how they’ve performed under real-world pressure in your area. Not all “rootworm packages” are created equal, and matching trait stacks to your specific field history is critical.
3. Soil-Applied Insecticides
In-furrow or banded insecticides can provide an additional layer of protection, especially on traited corn in high-pressure environments. They’re not a replacement for other tactics, but they can serve as a valuable companion when beetle populations are elevated.
Timing and placement matter. An insecticide won’t compensate for poor root architecture or weak hybrid genetics, but when applied correctly, it can help reduce early-season feeding and give roots a better start.
4. Biological Tools: GroPak® CT CoPak System
Every spring, corn rootworm larvae go to work before you ever see the damage — feeding on root systems, robbing your crop of the foundation it needs to perform. And by the time you notice, it’s too late. That’s exactly why getting a biological defense in the planter box has become one of the smartest layers in a corn rootworm management plan.
The GroPak CT CoPak System is a three-part biological planter box seed treatment built around this challenge. At the center is GroPak CTX — an EPA-registered biological specifically formulated to defend against corn rootworm damage at the root level, right from planting. One bucket covers 125 acres, and its talc and clay base keeps seed flowing freely whether you’re running a traditional row unit planter or a central fill system.
If you’re farming in central Illinois, Ohio, Wisconsin, northern Indiana, Iowa, Nebraska, or southern Minnesota (or anywhere with significant corn rootworm pressure) this is the layer your operation may be missing.
As Dr. Murphy puts it: “We’re not replacing tools. We’re adding smarter ones to the toolbox.” GroPak CT CoPak System is exactly that — a smarter biological tool that goes to work the moment seed hits the ground.
What Growers Should Be Doing Now
Planning for corn rootworm doesn’t start at planting. It starts during the off-season. Dr. Murphy recommends a straightforward checklist to help you build a stronger management plan:
Review your recent planting and pressure notes. Where did you see damage? Which hybrids or management practices performed well, or fell short?
Pull out beetle trap counts or late-season field observations. Adult beetle activity is a key indicator of future larval pressure.
Talk with your seed provider about exact trait stacks. Don’t settle for vague descriptions. Know what’s protecting your crop and whether it’s appropriate for your field history.
Evaluate rotation options and check for extended diapause risk. Not all fields are good candidates for rotation alone.
Look at your yield maps. Was lodging a factor? Did you see uneven grain fill or areas that underperformed despite good growing conditions?
The best corn rootworm plans involve collaboration with agronomists, seed advisors, and crop consultants who know your fields and can help you layer tools effectively.
Questions to Ask as You Plan
As you think through your strategy, consider these field-level questions:
- Did you see goosenecking or late-season leaning last season?
- Did adult beetles show up earlier or stay longer than expected?
- Was rootworm pressure evenly distributed, or concentrated in certain soil types or zones?
- How many consecutive years has this field been in corn?
- Are you layering enough tools, or relying on hope and a single tactic?
Corn rootworm doesn’t respond to hope. It responds to pressure, planning, and precision.
Put GroPak CT CoPak System in Your Planter Box This Season
Planting season won’t wait, and neither does corn rootworm. The GroPak CT CoPak System is available now through the end of planting season. Once the window closes, this opportunity is gone until next year.
Don’t head into this planting season without a defense plan in the planter box. Contact your AgXplore representative today to secure your supply and add this critical layer to your corn rootworm management strategy.
Join the Conversation
What’s your current corn rootworm strategy? What’s worked well in your operation, and where have you seen weaknesses? Are you using biologicals, layering insecticides with traits, or exploring new approaches?
The fight against corn rootworm is evolving, and so should your management plan. With the right combination of tools and a proactive mindset, you can stay ahead of the pressure and protect your yield potential.
Dr. John Murphy
Director of Agronomy
