If you live in a coastal area or along the Southern U.S., you’ve probably heard of nematodes in local lawns. These nematodes aren’t the beneficial kind; these are plant-parasitic worms that love to munch on grass roots in warm, sandy soils. So, how do you get rid of nematodes in your lawn? With a correct diagnosis, there are simple maintenance practices you can DIY (or hire out) to help your lawn recover.
In this article, we’ll cover:
- What are nematodes?
- How to identify nematode damage in your lawn
- How to get rid of nematodes in your lawn
- How to prevent nematode damage in your lawn
What are nematodes?
Nematodes are a type of roundworm. Unlike earthworms, they’re unsegmented and microscopic, so you can’t see them with the unaided eye.
There are two broad types of nematodes: beneficial nematodes and plant-parasitic nematodes.
- Beneficial nematodes are an effective means of biological control in the home lawn. They help control common lawn pests, such as grubs, sod webworms, fleas, ticks, thrips, and many others. Other types of “good” nematodes eat other microorganisms, such as fungi and bacteria.
- Plant-parasitic nematodes (PPN), on the other hand, eat plant tissues, such as turfgrass roots. This makes it difficult for the plant to absorb water or uptake fertilizer or nutrients and leaves the grass less resilient and more prone to death or disease.
Here are a few of the common types of plant-parasitic nematode species you may hear about:
- Awl nematode
- Lance nematode
- Lesion nematode
- Ring nematode
- Root-knot nematode
- Sheathoid nematode
- Spiral nematode
- Sting nematode
- Stubby-root nematode
We’ll learn about the plant-parasitic nematodes in this article.
Nematode life cycle
Nematodes thrive in lawns with sandy soils, warm climates, and warm soil temperatures (60-85 degrees Fahrenheit). Their life cycle consists of the egg phase, four juvenile or larval stages, and the adult phase. Treatment recommendations are the same for all stages of life.
Feeding behavior
Plant-parasitic nematodes puncture plant roots with their sharp, piercing mouthpart or “mouth spear” called a stylet. This damages the root and, consequently, weakens the entire plant. (FYI: Beneficial nematodes, in contrast, do not have this needle-like spear and cannot eat plant tissue.)
Size and appearance
Plant-parasitic nematodes range from one-fiftieth to one-sixteenth of an inch long and most species are transparent. Even on the high-end of the range, it’s unlikely that you’d be able to spot these wrigglers without the help of a microscope.
How to identify nematode damage in your lawn
Signs and symptoms
As with many other lawn pests, nematode damage mimics other turf problems, including fungus and disease, drought, or insects. Here are a few signs and symptoms to look for:
- Lawn has yellow or brown patches
- Lawn is thinning
- Unhealthy root system — rotted, shallow (less than 1 inch), and with few or no small side roots
- Lawn has difficulty thriving during hot or dry weather (wilting), even with sufficient water
- Weeds start to encroach as grass weakens and dies
- Galls or knots appear on plant roots (These are characteristic of a few different species of nematode, including the root knot nematode, Meloidogyne graminis. These galls are usually more apparent on crops but may be visible in grass roots in some cases.)
Remember that nematode infestations vary in degree. The degree of damage you’ll see depends on how many nematodes you have in the lawn, environmental stresses, and your grass type.
Soil test
Since nematodes aren’t visible without a microscope, the only way to know if nematodes are the problem is to test the soil in a lab. Ask your local Extension Office whether they have a state or local lab that tests for nematodes.
Also, ask them how to take a sample since nematode sampling is slightly different from regular soil sampling. Most of the time the lab results will include:
- Types of nematodes in your lawn
- How many nematodes are present (this can vary from lab to lab)
- Recommendations for how to control the nematode population in your lawn
FYI: You can get samples of nematodes in lawns any time of the year.
If you have very sandy soil, you may be predisposed to certain types of nematodes, so keep this in mind as you heed the recommendations from the soil test. If the problem is extensive, you may want to consider a grass alternative.
How to get rid of nematodes in your lawn
As with all lawn pests, it’s not possible to get rid of nematodes completely. (There are 57 billion for each person on Earth!) However, nematode control — or at least control of their symptoms — is possible in most cases.
Build a healthy lawn
A healthy, resilient lawn can withstand some nematode feeding without showing any or too much discoloration, thinning, or weed encroachment.
- After you aerate, topdress the lawn with rich compost to increase the organic matter, drainage, and microbial activity in the soil.
- Fertilize and water well, but don’t overdo it. Too much fertilizer and water don’t help the lawn. Some grasses tend to produce too much thatch when they are overfertilized.
Overwatering leads to short grass roots, which is not ideal. You want to water deeply but infrequently (about 1-1 ½ inches once per week). This encourages the roots to grow deep into the soil searching for water and strengthens the turf in times of drought and stress.
- If a lawn is in too much shade and is struggling, nematodes may be the thing that takes it out completely. No grass thrives in too much shade. Consider a shade garden or a grass alternative instead.
Grass type
Although turfgrass breeders have made great strides in developing grass cultivars with resistance to certain diseases, insects, and fungi, there are no turfgrasses that are resistant to nematodes.
However, ask your local Cooperative Extension office if bahiagrass is an option, as it is relatively resistant to nematode damage.
Chemical and natural products
So, what about chemical pest control products? Unfortunately, nematicides (products that kill nematodes) are not available for homeowners to buy. Since they are highly toxic and/or persist in the soil for a long time, only those with pesticide training and certifications can purchase and apply these chemicals.
No bio-based products are recommended by universities at this time.
Consult with a professional
If you’re at your wits’ end, contact a pro. Lawn Love pros and local Cooperative Extension agents are there to help. Extension departments might even put you in touch with an entomologist if they don’t have the answer themselves. If nematodes are a problem in your lawn, they are likely a problem in your area, so a local expert will be able to give sound advice.
Go with a grass alternative
If you’ve tried all of the curative measures and have exhausted those options, you may want to consider a grass alternative. Here are a few lawn alternatives that may suit your landscape:
- Hardscaping: Add a patio, walkway, deck, or gravel patio to create a grass-free area that enhances your outdoor living space.
- Go artificial: Artificial turf may not be right for everyone, but if you haven’t considered it, know that today’s synthetic grass is miles from first-generation products and is embraced by a growing number of homeowners.
Wait it out
Believe it or not, nematode populations in the lawn may vary from year to year. If you can stand a less-than-perfect lawn, it may be worth it to embrace it, keep on with good root-strengthening lawn maintenance, and see what next year brings.
Paint your lawn
If you want the lawn to look beautiful while you wait, why not paint your lawn? Lawn paint is completely non-toxic and a great way to “keep up appearances” until next year.
How to prevent nematode damage in your lawn
Here are a few ways to prevent or manage nematode damage in your lawn:
Seed over sod
If you buy sod, you have no control over its growing conditions or whether it will come with nematodes, larvae, or other critters who hitch a ride. Consider using seed over sod to establish a lawn and reduce the chance that you’ll introduce unwanted pests to your lawn.
Proper lawn care
As we’ve mentioned, this should be the first step you take to try to control the nematode damage in your lawn. A stronger lawn will not show as much damage as one that is stressed or weak.
Build healthy roots
The stronger the roots, the more they’ll be able to withstand nematodes munching on them. Here are a few simple ways to strengthen the grass roots in your lawn:
Mow tall: Taller mowing heights help the grass grow deeper roots.
Aerate the lawn: Aeration reduces compaction around the root zone. This opens up the soil and helps oxygen, fertilizer, and water reach and strengthen the roots, especially in heavy or compacted soils.
Dethatch if the grass feels spongy: If you have too much thatch (over ½ inch as a general rule), air, fertilizer, and water are also restricted and won’t be able to reach the soil level. Dethatch your lawn to allow these substances to reach and strengthen the plant’s roots.
Pro Tip: A common sign of too much thatch is that portions of the lawn will feel spongy underfoot.
Pay attention to your grass type
There are a few grass types that nematodes favor more than others.
- Bahiagrass is the grass that is least likely to suffer damage from nematodes, with one exception: It has recently been noted to suffer damage from root-knot nematodes.
- Seashore paspalum is also fairly resistant to nematode damage except for the spiral nematode, which can do a lot of damage. Lance and sting nematodes rarely cause damage.
- Bermudagrass, centipedegrass, St. Augustinegrass, and Zoysiagrass are all susceptible to various types of nematode damage. Cultivars with vigorously growing roots or naturally thick roots tended to show less damage than cultivars with fine root systems.
If microscopic wrigglers aren’t your cup of tea, let one of our local Lawn Love pros strengthen your lawn through regular maintenance and care to minimize any lawn stresses that come your way.
Main photo credit: Curtis Adams | Pexels
