How one can Determine and Deal with root-knot Nematodes


Whereas many backyard pests are seen to the bare eye, root-knot nematodes lurk beneath the soil floor. These tiny worm-like creatures are sufficiently small that gardeners usually spot their harm earlier than they find the pests themselves.

And boy, is their harm distinctive! As their identify suggests, this group of nematodes causes knotty development on plant roots. Whereas these sci-fi-esque growths are fascinating to have a look at, they’re synonymous with weak and stunted crops. If left untreated, these pests can destroy most of your backyard.

Earlier than you elevate your fingers and declare the root-knot nematodes the victors, take word that there are methods to handle and management these pests. I’ll cowl methods to find out in the event you’re coping with root-knot nematodes, then share some prevention and management methods.

What Are Nematodes?

Close-up of a variety of Nematodes through a microscope. Nematodes are microscopic, worm-like organisms with a cylindrical body and a tapered, pointed head. They lack appendages and have a transparent or translucent appearance, making them difficult to detect without magnification.
The Nematoda phylum contains each useful and dangerous species.

Nematodes are a phylum of small worms that accommodates about 25,000 particular person species. Whilst you might not see nematodes, tons of them are current on the planet—some scientists suppose there are about 60 billion nematodes for every human on Earth! However don’t fear, not all these critters are dangerous root-knot nematodes.

Nematodes can survive in various situations and many various meals sources. Some nematodes eat fungi, micro organism, or different microscopic creatures. Different nematodes feed on insect eggs or larvae, making them a welcome backyard addition in the event you’re coping with pests like cutworms and root maggots.

One other group of nematodes, together with the root-knot nematode, feed on plant tissue and hurt the focused crops. This group of nematodes causes severe crop harm worldwide.

What Are Root-Knot Nematodes?

Close-up of plant roots affected by nematodes against a blurred background. Root-knot nematodes, microscopic roundworms, induce distinctive symptoms on plant roots characterized by the formation of small, knot-like swellings or galls. The affected roots exhibit a swollen, distorted appearance with the development of knotty, tumor-like structures.
These dangerous nematodes trigger gall-like swellings on roots.

Root-knot nematodes all belong to the Meloidogyne genus. Though the species’ look and best habitat fluctuate, all of them dine on plant roots. Because the pests feed, they trigger the roots to develop small, rounded swellings generally known as galls. These “knots” are what give these nematodes their identify.

This dangerous microscopic pest impacts numerous crops, together with edibles and ornamentals. The contaminated crops fluctuate relying on the precise species of nematode. Some crops are prone to assault from a number of species. Others act as host crops for some species however not others.

Some greens prone to root-knot nematode harm embrace:

  • Tomatoes
  • Peppers
  • Eggplant
  • Beans
  • Peas
  • Onions
  • Carrots
  • Beets
  • Broccoli
  • Zucchini
  • Cucumbers

These pests may also hurt decorative crops, together with lilacs, snapdragons, and roses.

Life Cycle

Close-up of a Nematode under a microscope against a brownish-pinkish background. Nematodes are slender, unsegmented roundworms with a simple, tube-like body structure. It is translucent.
These soil-dwelling pests have six life phases.

All species of root-knot nematodes undergo six life phases: egg, 4 juvenile levels, and grownup. Most of those nematodes overwinter within the cool soil as eggs. When the soil warms above 65°F (18°C), the eggs hatch and second-stage juveniles emerge. These tiny nematodes hunt down plant roots, burrow in, and start feeding.

The juveniles proceed to feed on the plant roots, the place they molt via the remaining juvenile levels and finally flip into adults. Females then lay a whole lot or 1000’s of eggs in a jelly-like mass exterior the roots, and the method resumes.

Though eggs can overwinter within the soil, they will full their life cycle in as little as a couple of weeks in the course of the summer season. These future generations of nematodes received’t journey very far on their very own, however they will infect new areas as people inadvertently transfer them with soil or plant materials. Heavy rainfall and runoff may also assist the nematodes journey throughout the land into new areas.

Widespread Species

Microscopic photograph of a nematode colored under a phase contrast microscope. The nematode is a microscopic, unsegmented roundworm with an elongated, cylindrical body tapered at both ends. It has a pinkish tint.
4 species trigger most plant harm in the USA.

Whereas there are near 100 totally different species of root-knot nematodes, 4 species trigger the overwhelming majority of plant harm in the USA. These species have totally different host crops and best situations for development and replica. Understanding which species are current in your backyard might help you identify which crops you possibly can develop with out hurt.

The 4 commonest species are:

  • Southern root-knot nematode (Meloidogyne incognita)
  • Northern root-knot nematode (Meloidogyne hapla)
  • Javanese root-knot nematode (Meloidogyne javanica)
  • Peanut root-knot nematode (Meloidogyne arenaria)

How one can Determine Root-Knot Nematodes

Since root-knot nematodes are solely a couple of millimeters lengthy, you received’t be capable to spot the pests except you seize a magnifying glass and take an in depth look. As an alternative, it’s best to look out for numerous signs that sign the presence of those pesky pests.

Lots of the above-ground signs carefully resemble these current with different root points like Fusarium wilt or root rot, so trying on the roots is usually one of the best ways to test for these parasites.

Stunted Development

Close-up of a corn plantation with stunted growth due to root-knot Nematodes. Plants with stunted growth presents a visibly compromised appearance characterized by shorter-than-expected plant height, reduced leaf size, and overall diminished vigor.
These pests restrict root well being, inflicting stunted development in crops.

When root-knot nematodes chew on plant roots, they restrict the well being of your complete root system. Impacted crops can’t correctly take up water and vitamins, which may result in stunted development. Should you discover that a couple of crops or your whole backyard are smaller than regular, these pests may very well be the trigger.

Nevertheless, don’t assume that stunted crops imply your soil is teeming with these dangerous worms. Many different components can result in stunted development, together with underwatering, improper temperature, and lack of correct vitamins. It’s a good suggestion to test in on the general well being of your backyard earlier than utilizing root-knot nematodes because the scapegoat for all of your crops’ issues.

Wilted Tissue

Close-up of wilted cucumber plants attacked by nematodes in the garden. Cucumber plants are characterized by vining stems with large, lobed leaves that are dark green in color. The plants climb using tendrils to grasp onto support structures. The leaves are drooping, wilted, and some are brown in color with a crispy texture.
Wilting leaves and stems might point out infestation.

One other potential signal of root rot nematodes is wilted leaves and stems. Contaminated roots have a tricky time taking over water and vitamins, which may lead crops to lose turgidity and appear like they’ve had all of the moisture sucked out of them. Even when your plant appears wholesome and inflexible within the morning, sizzling afternoon temperatures might trigger them to wilt.

As with stunted development, wilting crops aren’t a positive signal of nematode harm. Underwatering, overwatering, root rot, and different components may also result in wilting leaves. So be sure you study your watering practices and the crops’ root well being earlier than you determine you’re coping with root-knot nematodes.

Spherical Galls on Roots

Close-up of soybean roots affected by nematodes in a garden against a blurred green background. Soybean roots affected by nematodes display distinct symptoms characterized by the presence of small, swollen nodules or galls along the root surface. These galls are caused by the penetration and feeding activity of nematodes. The affected roots appear swollen, distorted, and discolored, with a knotty or bumpy texture.
They trigger tell-tale knots on plant roots.

The most tell-tale signal of root-knot nematodes is the namesake knots they kind on plant roots. These tiny swellings are true galls which are a part of the plant tissue. In contrast to with the nodules fashioned by nitrogen-fixing micro organism, you can’t rub these galls off of the roots.

The galls fluctuate in measurement from a couple of millimeters to as much as an inch. Nevertheless, many of the knots are on the smaller facet.

Whereas it’s in all probability apparent, you want to have the ability to study the plant’s roots to examine them for knots. To test a row of carrots or beans, pull up a single plant and search for indicators of harm. If this plant is contaminated, the opposite crops are additionally in peril.

Should you don’t wish to pull up a bigger plant like a tomato or hibiscus, you possibly can pull up smaller surrounding crops (together with weeds) and test their roots for harm. Nevertheless, since not all root-knot nematode species feed on all kinds of crops, this will not result in an correct prognosis. Another choice is to fastidiously dig across the fringe of the plant’s root system till you discover a piece of root you possibly can examine.

Nematode Take a look at

Close-up of a farmer collecting soil samples in the garden. A farmer's hand holds a transparent glass beaker with soil mixture inside. A small sprout growing in the soil.
Ship soil and plant root samples for nematode testing to determine species.

Should you suppose you’re coping with nematodes however aren’t optimistic, you possibly can ship a pattern of the soil and plant roots to a lab for a nematode take a look at. This take a look at will inform you what nematodes are current and provide you with a warning to the presence of different dangerous nematodes like dagger nematodes and lesion nematodes.

How one can Stop Root-Knot Nematodes

Stopping root-knot nematode harm entails avoiding the pest’s introduction to your backyard and creating an unfavorable setting. Listed below are some methods you possibly can stop an infection and harm.

Examine All Transplants

Close-up of a gardener checking the roots of a young tomato seedling in a sunny garden. The gardener is wearing black rubber boots, jeans and a brown sweater. He is holding a black plastic pot and a tomato seedling in his hands. A tomato seedling has a root ball, an upright, slightly hairy stem, and compound leaves with slightly serrated edges.
Prevention entails inspecting crops for knots earlier than planting.

One of the simplest ways to stop an infestation is to maintain this pest out of your backyard within the first place. However since these pests are so small, that is simpler mentioned than performed. Understanding how they enter your backyard is step one to preserving them out.

Probably the most widespread methods these soil-dwelling pests enter a brand new space is by way of new crops. So earlier than you plant the ‘Cherokee Purple’ tomato seedlings you bought on the native backyard heart or transplant that catnip plant your good friend divided for you, give the roots once-over. Should you seed any small knots on the roots, keep away from including these crops to your backyard.

Fastidiously Clear All Instruments Earlier than and After Use

Close-up of a gardener's hands cleaning a shovel from soil residues in the garden against a blurred background of a flower bed. The shovel has a wide metal blade covered with wet soil.
Utilizing instruments throughout totally different areas spreads nematodes.

Whilst you might not suppose a lot of grabbing a shovel to dig a gap in your yard vegetable backyard, after which utilizing the identical shovel to plant a rose bush in entrance of your own home, this seemingly innocent process can unfold detrimental nematodes. Shifting soil by shovels, rakes, hoes, and different instruments additionally strikes the nematodes residing within the soil. 

I’m not saying it’s best to sanitize your shovel after every use. Slightly, be aware of how a lot soil your instruments are transferring. If you recognize one space of your land is closely infested with root-knot nematodes, attempt to keep away from carrying soil from this space to a different space of your property.

How one can Handle

Root-knot nematodes are troublesome to take away, however useful nematodes might help deal with infestations.

Should you decide you’re coping with root-knot nematodes, there’s not a straightforward approach to take away them out of your soil. Nevertheless, you possibly can take steps to restrict their unfold in addition to the hurt they trigger to crops.

The best approach to deal with root-knot nematodes is to use useful nematodes to the areas they’ve infested. These are simple to seek out at your native backyard heart or ironmongery store. What issues most is your timing in making use of them.

You’ll need to deal with soil with useful nematodes twice for them to be efficient. Apply two remedies two weeks aside in temperate seasons. Hit that candy spot after the time root-knot eggs have hatched however earlier than the warmth of summer season units in. Should you do that, you received’t have to fret about root-knot nematodes for a while.

Solarize the Soil

The soil is covered with a translucent sheet of plastic to warm the soil. Sheets of plastic are pressed down with wooden blocks.
Solarizing soil with clear plastic will kill adults and eggs.

Each mature root-knot nematodes and their eggs can not face up to temperatures above 130°F (54°C), so heating the soil above this vary kills off the pests. Solarization is one approach to warmth the soil to this degree. This apply entails moistening the contaminated soil after which laying a sheet of clear plastic over the bottom for a couple of weeks in the summertime. The plastic will entice warmth and trigger the soil temperature to rise.

Since solarization will solely warmth the highest 6-12 inches of soil, it’s not a long-term resolution for controlling root-knot nematodes. Nevertheless, it’s going to will let you develop wholesome annual greens and flowers.

Take Benefit of Cool Rising Seasons

Close-up of lettuce growing in a garden bed. Lettuce plants have a compact, rosette-like appearance with crisp, leafy foliage arranged in loose heads. The leaves are broad, bright green in color with curly edges and a wrinkled texture.
Chilly-tolerant crops develop earlier than the pest turns into lively in spring.

Since root-knot nematodes are inactive when the soil temperature is under 65°F (18°C), they received’t hurt crops in early spring and late fall. Getting cold-tolerant crops like peas, lettuce, and kale within the floor within the early spring will enable the crops to develop earlier than the dangerous nematodes turn out to be lively.

When the soil rises above 65°F, the nematodes will come out of their winter slumber and begin to feed on crops. Nevertheless, your early spring crops could also be prepared to reap by this level.

Select Resistant Crops

Close-up of ripe tomatoes in the garden. The tomato plant has a sturdy central stem with sprawling branches that support a lush canopy of dark green, serrated leaves. The plant produces a cluster of medium round fruits of bright red-orange color with thin shiny skin.
Plant resistant species and varieties.

Since root-knot nematodes could be troublesome to regulate and stop, it’s at all times a good suggestion to select resistant species or varieties. Though these pests influence all kinds of crops, some species are proof against assault. Some kinds of floss flowers, salvia, and marigolds are proof against quite a few root-knot nematode species. These could be nice companion crops or elements of your crop rotations.

Together with planting resistant species, you may also look out for varieties which are proof against assault. Let’s take a look at tomatoes, for instance. Whereas varieties like ‘Brandywine’ and ‘Sungold’ are prone to nematode assault, hybrids like ‘Sakura’ and ‘Mountain Advantage’ can face up to these microscopic worms.

Take away Roots and Weeds

Close-up of a gardener's hands pulling out weeds and roots in a garden bed. The gardener's hands are dressed in white gloves. A gardener uses a metal garden tool with a fork on the end.
Pull roots from the soil to sluggish the unfold.

Since these nematodes feed on plant roots, limiting the variety of roots within the soil helps sluggish their development and unfold. Whereas I typically suggest leaving roots within the soil to extend the quantity of natural matter, pull up any roots contaminated with root-knot nematodes. When you’ve got an lively compost pile that heats as much as above 130°F (54°C), you possibly can toss the crops within the pile. In any other case, it’s greatest to place the contaminated roots within the trash.

Together with eradicating contaminated roots, maintain weeds down. Many weed species are appropriate hosts for these nematodes, so typically extra weeds equals extra nematodes.

Depart the Floor Fallow

Close-up of a growing rye cover crop in a garden bed. The Winter rye cover crop presents a dense and lush appearance characterized by its tall, slender stems and abundant foliage. The foliage consists of long, narrow leaves that form a dense canopy.
Let contaminated areas relaxation or plant nematode-resistant cowl crops as a substitute.

Since root-knot nematodes feed on plant roots, they received’t survive in the event that they don’t have any appropriate roots to feed on. When you’ve got the time and talent to let an contaminated space of your backyard relaxation for a yr, the nematode numbers will drop.

One possibility is to let your backyard go utterly fallow. This implies you received’t develop something on this space for a couple of months or perhaps a yr. Since nematode eggs can survive as much as a yr within the soil, an extended fallow interval could have an even bigger influence than a shorter interval. Should you determine to let a bit of floor go fallow, I like to recommend protecting it with a bit of silage tarp to stop soil erosion.

Another choice is to keep away from planting prone decorative and edible crops for a yr and plant nematode-resistant cowl crops as a substitute. I choose this technique over fallowing since these crops will proceed to feed useful soil microbes and stop erosion with out supporting the dangerous nematodes.

Some cowl crop choices for coping with root-knot nematodes embrace cowpea, sorghum-sudangrass, and rye. Since these crops develop greatest at totally different instances of the yr, you possibly can develop a number of rounds of nematode-resistant cowl crops in a single yr.

Rotating your crops is one approach to stop root-knot nematodes as effectively. You’ll be able to select to go away an space fallow after planting one thing that might entice nematodes, or you possibly can plant nematode-resistant crops. By planting one thing totally different in an space, you stop their buildup.

Plant French Marigolds

Close-up of blooming French Marigolds against a blurred green background. French Marigolds present a vibrant appearance characterized by compact, bushy plants adorned with an abundance of small, daisy-like flowers. The flowers come in various shades of yellow, orange, and red. The petals are a rich red-orange color with thin yellow edges. The foliage is finely divided with a dark green color.
French marigolds assist restrict root-knot nematodes within the backyard.

Should you’ve been across the plant world for any time frame, you’ve in all probability heard individuals tout marigolds for his or her potential to repel all the things from mosquitos to deer. Whereas not all of those claims are rooted in reality, French marigolds are confirmed to assist sluggish the unfold of root-knot nematodes.

Planting French marigolds within the backyard can assist suppress these parasitic nematodes. The marigolds received’t utterly eradicate the pests, however they’ll assist restrict harm and sluggish their unfold. This prevention, nevertheless, happens within the season after you plant marigolds. Which means subsequent yr’s tomatoes get the profit.

Keep Correct Irrigation and Fertilization

Watering vegetable garden. Close-up of a gardener with a large pink watering can watering onions, strawberries and other crops. Strawberries bloom with small white flowers.
Common irrigation and fertilization enhance plant resistance.

Identical to consuming a nutritious diet and getting sufficient sleep might help people struggle off infections, correct irrigation and fertilization might help crops chase away root-knot nematodes. We’re not saying that wholesome crops will repel these parasites, however they’ll obtain much less harm.

Root-knot nematodes trigger extra harm to drought-stressed crops than they do to non-stressed crops. Irrigating your crops frequently is one approach to restrict drought stress. You too can combine in compost to enhance a soil’s water-holding capability and mulch the highest of the soil to restrict evaporation and preserve moisture.

Incessantly Requested Questions

Some micro organism and fungi species feed on root-knot nematodes. Many Trichoderma species of fungi might help management nematodes. Useful nematodes feed on root knot nematodes as effectively.

Root-knot nematodes develop and reproduce most quickly when the soil is moist and heat. Subsequently, they’re essentially the most lively throughout moist intervals in the course of the spring via fall.

Whereas people might ingest root-knot nematodes when consuming root crops like beets, carrots, and potatoes, the nematodes received’t infect people. As an alternative, they’ll journey via the digestive tract and are available out on the opposite facet.

Ultimate Ideas

Root-knot nematodes may cause severe harm to many crops, however staying on prime of those pests might help restrict their antagonistic results. Keep in mind that solarizing the soil and planting resistant cowl crops might help remove these pests, and planting resistant crops might help you develop wholesome crops even when the nematodes are current.

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