Beneficial nematodes in turf pest management: how they target soil-dwelling pests

Beneficial nematodes: the tiny, soil-dwelling allies in Ohio turf care

If you’re responsible for a municipal field, a golf course, or a lush turf at a business park in Ohio, you’ve got an underground problem under your feet. The real fight happens below the grass blades, where soil-dwelling pests quietly take shelter. Enter beneficial nematodes—micro heroes that can help you manage those pests without piling on chemical sprays. Here’s what you need to know to use them effectively and keep turf healthy from the roots down.

What are beneficial nematodes, exactly?

Beneficial nematodes are tiny roundworms, so small you need a microscope to see them clearly. They’re not pests themselves. In fact, they’re used as biological control agents to tackle pests living in the soil. Two common players are Steinernema and Heterorhabditis species. They’re naturally occurring in many soils, and when applied correctly, they seek out certain soil-dwelling pests and infect them. Inside the host, they release bacteria that help kill the pest, giving the nematodes a chance to reproduce and continue the pest-control cycle.

Let me explain why this matters for turf. The pests nematodes target—grubs, cutworms, and other larvae that hide beneath the surface—can damage roots, weaken turf, and invite secondary problems like disease or drought stress. By focusing on the soil, nematodes hit the problem where it begins, rather than spraying broad-spectrum chemicals that can disrupt beneficial critters and ecosystems.

The correct use: soil, not foliage

Here’s the thing: beneficial nematodes are designed for the soil. Spraying them onto leaves or the crown of the grass doesn’t do much for pests that live underground. The most effective approach is to introduce them into the soil where the target pests spend their time. When you place nematodes in the root zone, they can hunt for grub larvae and other soil-inhabiting pests, enter the hosts, and start the infection cycle.

Think of it as releasing a tiny, well-trained search-and-destroy team into the soil. They don’t swarm the foliage; they go straight to the underground harbor where the pests hide. That’s why soil application—often followed by gentle irrigation to keep the soil moist—is key to success.

Pests they’re known to curb

• Grubs (the larvae of beetles like Japanese beetles, June beetles, and skippers common in Ohio). Grubs chew on grass roots, causing thinning patches and turf diseases.

• Cutworms, which nick turf at night and can quickly devastate freshly mowed areas.

• Some root-feeding larvae that tunnel through the root zone, leaving you with weak turf that’s easy to pull up.

There are caveats, of course. Nematodes target specific pests, and performance can vary with soil type, moisture, and temperature. They’re not a magic wand for every turf ailment, but when aligned with the right pest and right conditions, they’re a powerful part of an integrated pest management plan.

Why soil conditions and timing matter in Ohio

Ohio’s climate is kind of a Goldilocks situation for nematodes. If the soil is not moist enough or if temperatures swing too far, the nematodes don’t move well, or they dry out quickly and die. The sweet spot tends to be cool to warm soils with consistent moisture—conditions you often find in Ohio from spring through early fall.

• Temperature: Many beneficial nematodes prefer soil temperatures roughly in the 50s to 70s Fahrenheit (around 10–21°C). When soils get too hot, desiccation and heat stress can cut their activity.

• Moisture: Soil moisture is king. Dry soils blunt nematode movement and reduce infection rates. After application, a light, even irrigation helps keep the soil hospitable for the nematodes to hunt.

• Soil type: Sandy soils drain quickly and can be challenging for keeping nematodes in the root zone, while heavy clay soils can hold moisture longer but may slow movement. In Ohio, you’ll see a spectrum, so it’s wise to align expectations with your site conditions.

Practical steps to apply nematodes in turf (Ohio-ready tips)

• Plan your timing: Target periods when pests are active beneath the surface. Early spring or late summer to early fall can work, depending on turf type and pest pressure. Avoid application during droughty spells or when the ground is frozen.

• Choose the right nematodes: Use commercially available formulations labeled for the pests you’re dealing with, and make sure the product is appropriate for soil use. The two main players you’ll see in labels are Steinernema and Heterorhabditis species. The exact species may differ in what pests they control best.

• Storage matters: Most beneficial nematodes come in a living-state form. They’re usually sold refrigerated and should be used before the label’s expiration date. Don’t thaw and re-freeze them, and handle them gently during mixing and loading.

• Apply with soil contact: Use a sprayer, hose-end applicator, or irrigation system to apply the nematodes as a soil drench. The goal is even distribution in the root zone rather than a heavy splash on the surface.

• Irrigate after application: Light irrigation after application helps move nematodes into the rooting zone and keeps the soil moist enough for their activity. Don’t overwater to the point of ponding; just a gentle soak is ideal.

• Monitor and adapt: After treatment, monitor turf areas for improvements in root health and pest pressure. If outcomes aren’t knocking down pest levels, you may need to repeat applications in a few weeks or combine with other IPM tactics.

OSU Extension and real-world soil science

In Ohio, extension resources from land-grant universities like Ohio State University are invaluable. They provide practical guidance tailored to our climate, grass species, and local pests. If you’re curious about timing windows, compatible irrigation practices, or how to integrate nematodes with other control methods (like cultural practices or selective insecticides that are gentle on beneficials), OSU Extension can be a reliable reference.

Who benefits most from nematodes in turf?

• Managed turf on sports fields, parks, and commercial properties where maintaining root vigor is essential for playability and appearance.

• Scenarios with ongoing grub pressure or recurring soil-dwelling pests that aren’t fully controlled by soil-applied insecticides.

• Sites seeking to reduce chemical inputs and improve sustainability without compromising turf performance.

What about the other options people sometimes consider?

A quick reality check helps, especially if someone suggests spraying nematodes on foliage, planting them with the turf, or tossing them into compost. Here’s why those aren’t the best fit for nematodes’ strengths:

• Spraying on foliage: Nematoids aren’t designed to hunt pests in the canopy. They’ll dry out in the sun and wind, reducing their effectiveness.

• Planting them alongside turf: It’s a nice idea, but nematodes need direct access to the soil where their target pests live. If they’re not in contact with soil, they won’t have the chance to locate or infect pests.

• In compost piles: Compost piles are microbial-rich environments, but nematodes aren’t directed to pest larvae that are living in the root zone of turf. The compost setting doesn’t utilize their pest-control potential in the same way soil applications do.

Real-world wins and caveats

• Sustainability angle: When used correctly, beneficial nematodes cut down on chemical pesticide use, supporting pollinators, soil life, and water quality. That’s a win for the turf ecosystem and for Ohio’s broader environmental goals.

• Compatibility: Nematodes work best as part of an integrated approach. They pair well with good cultural practices—proper mowing, irrigation, thatch management, and timely aeration. They don’t replace the need for soil diagnostics or pest scouting; they complement them.

• Limits to expect: They won’t solve widespread, non-soil pests, and performance can vary by site. If you’re fighting a heavy grub outbreak in hot, dry soils, nematodes might be less effective, and you’d adapt with moisture management and targeted treatments.

A concise, Ohio-focused takeaway

• Use nematodes for soil-dwelling pests by introducing them into the soil—not on foliage or into compost, not as a turf planting companion.

• Favor cool to warm, consistently moist soils; timing should align with pest life cycles and local weather patterns.

• Apply with care, following label directions, and water in to move nematodes into the root zone.

• View this approach as part of an integrated strategy that emphasizes sustainable, targeted pest control alongside good turf management practices.

A final note from the field

Turf managers in Ohio know this: the best lawns aren’t just about what you can see above ground. It’s the quiet, underground work—the root zone health, the soil biology, the gentle balance of life—that determines color, density, and resilience. Beneficial nematodes are a practical reminder that nature offers potent tools, when we use them wisely. They are not a magic cure, but a thoughtful option that, when integrated with sound cultural practices, helps you maintain healthy, vibrant turf across our diverse Ohio landscapes.

If you’re curious to learn more, reach out to your local extension office or a reputable turf supplier. They can help you pick the right nematode species for your pest profile, guide you through soil-testing steps, and share the best timing for your specific turf species and site conditions. Happy soil, happy turf, and a healthier outdoor space for everyone in Ohio.