Cover Crops for Nematode Suppression in Sugar Beet Systems: Practical Strategies from Idaho Producers

Sugar beet producers in southern Idaho are facing an age-old pest with modern solutions. After more than a century of continuous sugar beet production near the Paul Sugar Factory, nematode pressure, specifically sugar beet cyst nematode, has intensified, threatening yields and soil health. But instead of relying solely on chemical controls, innovative growers are turning to a time-tested, regenerative solution: cover crops.

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In this segment from our How to Soil Health video series, Idaho farmers Luke and Brian share how they’ve embraced cover crops not only to build soil health, but also as a targeted biological tool for pest suppression. Their approach offers an adaptable blueprint for producers dealing with pest pressures in monoculture rotations.

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Beginning with Due Diligence: Avoiding Future Weeds

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Before diving into cover cropping, Luke and Brian teamed up with the University of Idaho to answer a critical question: What exactly are we bringing into our fields?

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Being cautious about the species they introduced into their system, the growers were determined not to trade one problem for another. “We wanted to make sure nothing we planted would become a weed or host pest pressure for our main crops,” Luke explained. This led them to carefully evaluate each potential species, not just for biomass or nutrient value, but for pest and disease implications.

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A Targeted Pest Management Strategy

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With sugar beets and potatoes forming the core rotation of their operation, the team faced serious pressure from sugar beet cyst nematodes. Their challenge was clear: reduce nematode populations without compromising future crop performance.

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Through guidance from university researchers and industry partners, they explored biological controls; specifically, species with nematode-suppressing potential. Among the top contenders are oilseed radishes and mustards with proven efficacy.

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These weren’t random cover crops. Many of the cultivars they tested originated from German research during the 1980s. As Europe phased out many chemical fumigants, scientists began looking for natural, plant-based alternatives to control nematodes. That same research is now informing regenerative strategies in Idaho.

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Learn more about building pest-resistant systems using the soil health principles, including maximizing diversity and keeping living roots in the soil.

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Neutral Crops: Breaking the Host Cycle

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One critical insight from their approach is the importance of selecting species that are neutral hosts. That is, crops that neither suppress nor increase nematode populations. “If it doesn’t help, at least it won’t make things worse,” Luke said.

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Over time, they’ve developed a go-to mix of nematode-suppressive and neutral cover crops. Their strategy now includes:

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• Oilseed radish – chosen over daikon for its strong lateral rooting and tillage effect

• White mustard – noted for its pest-suppressing compounds

• Flax, phacelia, and berseem clover – neutral species that increase diversity without hosting pests

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These species not only offer biological pest control, but also contribute to long-term improvements in soil structure, fertility, and microbial activity.

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The Value of a Disease Break

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Another powerful benefit of these carefully selected cover crops? They're not grown commercially in the region. That means the fields get a much-needed break from common pests and diseases that target beets, potatoes, and small grains.

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“It’s a total shift,” Luke said. “We’re moving away from crops we normally grow, and that’s giving us a real disease break.”

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This practice aligns directly with core regenerative principles: introducing plant diversity, reducing chemical inputs, and disrupting pest and disease cycles through rotation and biodiversity.

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Practical Considerations for Other Producers

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While their approach is tailored to sugar beet rotations in southern Idaho, the principles apply widely to any system struggling with pest pressure and soil degradation. Key takeaways include:

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1. Do your homework. Consult with university extension offices, research partners, and seed providers to understand the biological roles of different cover crops.

2. Target your pest. Use species that are known to suppress or avoid hosting specific pests like nematodes.

3. Prioritize diversity. Include both suppressive and neutral species to maintain biodiversity without compromising your goals.

4. Avoid cash crop hosts. Choose species that aren’t part of your normal rotation to maximize disease and pest breaks.

5. Measure results. Track nematode pressure and crop performance over time to see how your mix is working.

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Why This Matters

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The use of cover crops for nematode suppression isn’t just about pest control; it’s about building soil health from the ground up. These practices promote more resilient systems that are less reliant on chemical inputs and better able to support productive, profitable crops over the long term.

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And while the work isn’t without its challenges, these Idaho producers have shown that with careful selection and an eye toward ecology, cover crops can be a powerful ally in the battle against pests. To hear this story from Brian and Luke, be sure to check out our How to Use Covers for Nematode Suppression video.

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