Root-Knot Nematode Control: How to Identify, Prevent and Get Rid of Root-Knot Nematodes

Nematodes have the reputation of being beneficial in the garden because they kill some of the most common pests that can cause significant damage to your plants. However, it is important to note that not all nematodes do good. For instance, root-knot nematode can be destructive for both perennial and annual plants. To prevent suffering from a heavy infestation of this pest, it is important to know how to get rid of root-knot nematodes.

Root-knot nematodes are parthenogenic, which means that it is possible for females to reproduce even without males. Their eggs are usually yellow or white and deposited in a protective material that looks like a jelly. Upon hatching from an egg, most of them become females with a spherical body. They are tiny worms, usually microscopic, which is why it is difficult to spot their presence in the garden.

Root-Knot Nematode

Microscopic Root-Knot Nematode

Root-Knot Nematode’s Habitat

This type of nematode lives all over the world, although it prefers places with tropical and subtropical climate. Warmer regions are more attractive for root-knot nematodes. Their eggs are found on the root surfaces of their host plants. When the juveniles emerge from the egg, they will penetrate the tip of the root of their host. These larvae will stay on the same site for a long time, even if the weather condition is unfavorable. In the warm summer months, it takes approximately 28 days for the root-knot nematodes to complete its life cycle from an egg into an adult laying eggs.

Identifying Root-Knot Nematodes

Plants Affected

With the different species of root-knot nematodes, they can affect a wide array of plants. In most instances, however, one plant will only host a single type of nematode. Their common hosts include fruits, vegetables, ornamental plants, landscape plants, perennials, and annuals, among others. To be specific, its hosts include okra, banana, carnation, grape, chrysanthemum, pineapple, nectarine, papaya, lettuce, ginger, celery, carrot, peach, rose, juniper, cactus, cedar, hibiscus, oak, palm, and mulberry, among others.


The following are some of the most common signs that will give you a hint of the presence of root-knot nematodes:

  • Most of the symptoms will be on the roots. Galls will appear, which are distinctive swellings. The biggest gall can have a diameter of at least one inch, although most of them are smaller. These galls can also serve as entry point for pathogens, which will worsen the damages in the host plant.
  • Above the roots, there are also different symptoms. One of the most common is wilting of the plant, despite having moist soil. The leaves will also turn yellow and the plant will show loss of vigor. All of these will happen as it is no longer able to receive the nutrients that are necessary for its healthy growth.

Results of Infestation

Most of the damages from root-knot nematodes are evident on the roots. However, as noted earlier, there are also above-ground symptoms that will be apparent. The infestation will inhibit the transport of the nutrients to the other parts of the plant. The host will wilt, dry, and eventually die. For commercial growers, this will lead to economic loss as the crops will end up not being marketable at all.

Root Knot Nematode Damage

Galls Caused by Root-Knot Nematodes in Parsnip

How to Get Rid of Root-Knot Nematode

Natural and Organic Solutions

The following are some of the best ways to control and eliminate root-knot nematodes in a natural manner:

  • Among others, one thing that you can do is to add healthy soil in the garden or where the host plants are. This will improve the defense of the plant, making it more of a preventive than an elimination procedure. An organic compost, for instance, will help to improve moisture and kill root-knot nematodes that are already living in the ground.
  • Chitin, which is a popular choice for soil amendment, will also do the trick. This fibrous substance from crustacean shells will be effective in the reduction of the population of root-knot nematodes.
  • Plant isolation or the complete removal of the plant showing signs of an infestation is also another excellent way to eliminate root-knot nematodes. By doing this, the healthy plants in the garden will not have to suffer the same fate as the one that has already been infested.
  • You might also want to consider planting cover crops, such as annual ryegrass, oats, and African marigolds. Their roots have a substance that will deter the presence of root-knot nematodes, and hence, making it easy for their population to diminish.
  • Soil solarization is another method that you might want to give a shot. It is an eco-friendly solution that can be an excellent addition to your integrated pest management. This will capture the radiant heat from the sun, and in turn, this will kill the pest. With this, a clear plastic will heat the surface to get rid of root-knot nematodes.

Chemical Solutions

For home gardeners, chemical control is not an ideal solution. However, it is common for commercial growers who have to deal with a massive infestation. Because of their microscopic size, it is hard to detect their presence. The latter will only be possible once the symptoms appear, and in most cases, it might be too late to apply chemicals. If you will resort to the use of chemicals, nematicides are effective. Aldicarb is one of the most popular brands that fall under this category of pesticides.

How to Prevent Root-Knot Nematodes

On the top of the preventive measures is sanitation. Keeping the environment clean will discourage the presence of root-knot nematodes as there will be no suitable breeding ground for them. Also, they usually enter the garden if you introduce a plant or soil that has already been infested. When using tools in the garden, see to it that they are clean as nematodes can cling on the surface and transfer to a different location depending on where you will use the tools.

Another excellent method of prevention is planting resistant varieties. Intelligent choice for plants will make sure that these nematodes will not wreak havoc in the garden. In the same way, crop rotation will also be a promising solution.

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