Guide To Identify, Prevent & Control Nematodes On Tomato Plants?

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In this guide, I will highlight everything you need to identify and control nematodes from attacking tomato plants.

Let’s get started!

What Are Nematodes And How Do They Harm Tomato Plants?

Nematodes are microscopic roundworms. Tomato plants are susceptible to root-knot nematodes that are parasitic and live in the soil.

They may directly damage the plants or increase the susceptibility to other infections.

How To Confirm That Nematodes Is Troubling Your Tomato Plants?

Check the tomato plants for damage. The different characteristics to confirm that nematodes are troubling your tomato plants are yellowing plants, stunted or wilted growth, and the general decline in the plant’s health.

If you suspect a root-knot nematode infestation, pull the weak plants and you will observe numerous galls or swelling on the roots.

It confirms that root-knot nematodes cause the aboveground symptoms.

Natural Ways To Control Nematodes On Tomato Plants

The different organic methods to control the nematode population on tomato plants are the application of chitin products, neem oil, and molasses.

1. Amend The Soil With Chitin Products

The crushed chitin has been shown to reduce the nematode numbers in the soil. It may increase the beneficial microbes in the soil that feed on chitin.

  • Amend the soil– Regularly amend the soil with chitin-containing materials, including seafood meal, eggshells, or shrimp hulls.
  • Reapply– You may require a waiting period of at least two weeks after applying chitin for planting tomatoes.

2. Apply Neem oil

Neem cake and neem seed oil have shown the ability to reduce the root-knot nematode populations.

  • Prepare neem oil spray– Mix 1ml of neem seed oil with 100 ml of water. Shake well and transfer to a spray bottle
  • Apply on the ground-Apply soil with neem seed oil spray to control root-knot nematodes.

Check out this video on how to use neem oil to control root-knot nematodes:

3. Use Molasses Spray

Molasses has been shown to manage root-knot nematodes and increase the fertility of the soil. They are environmentally friendly and do not pose any threat to beneficial insects.

  • Prepare molasses spray– Mix two tablespoons of molasses, and one teaspoon of soap in a liter of water.
  • Apply on the soil– Apply them on the soil to control root-knot nematodes.

4. Add Organic Matter To The Soil

Organic soil amendments can be added to improve plant health and vigor. It will help in the management of nematodes in infested gardens.

  • Add organic matter– Add soil amendments, including compost according to the manufacturer’s instructions.
  • Apply pine bark– If using a thin layer of pine bark, crush them into small pieces before applying. If the area is prone to root-knot nematodes, add organic matter a month before planting.

Physical Ways To Control Nematodes On Tomato Plants

Soil solarization will help in managing the nematodes on tomato plants during mid-summer. It will help in preventing future pest outbreaks.

Method 1- Solarize The Soil

Soil solarisation is an effective method to control damaging root-knot nematodes. It involves the use of plastic sheets on moist soil during high ambient temperatures.

  • Till the soil– Till the moist soil to remove the debris and weeds.
  • Place the clear sheet– Use a clear, UV-stabilized plastic sheet about one to four mils thick. Place the bricks on the ends to prevent them from blowing away. Let it remain in the sun for three to five days.

Check out this video on how to use soil solarisation to kill nematodes:

Chemical Ways To Control Nematodes On Tomato Plants

The chemical control of the nematodes in the soil is expensive. Always wear protective clothing while using a pesticide. It has to be used as a last resort.

Method 1- Apply Metam Sodium Disinfectant

Metam sodium works as a fumigant and soil disinfectant to control nematodes and soil diseases. It does not damage the planted crop. Only licensed pesticide applicators can use it in home gardens.

  • Prepare metam sodium– Read the manufacturer’s label and prepare the solution.
  • Apply the solution– Apply the solution with water to penetrate the soil about 18-24 inches. You may apply with the irrigation system if possible.

How To Prevent Nematodes In Tomato Plants?

Prevention is the best cure for nematodes. Remove the garden debris, practice crop rotation, fallowing, and plant nematode-resistant tomato varieties.

Change The Garden Environment

Remove the nematode-infected plants, including the roots of the crop, after the harvest is completed and eradicate them. TIl the soil two to three times in reducing nematode levels.

Practice Crop Rotation

Practice crop rotation to prevent nematode infestation. Also, solarise the soil to prevent the spread of infection.

Biocontrol With Marigold

The cultivars of marigolds, including African and French marigolds are effective in reducing root-knot nematodes. The roots of these flowering plants contain chemicals that will suppress nematodes.

Plant marigolds from tomato plants are about seven inches apart. One disadvantage is that you may not reap benefits until the following year.

Here is a useful video on treating root-knot nematodes with marigolds:

Method 4- Plant Nematode-Resistant Tomatoes

If your area is prone to nematodes, you may choose nematode-resistant tomatoes denoted by the letter N. The different tomato varieties that may withstand nematode attacks are Carnival, Celebrity, Early Girl, Lemon Boy, President, and Quick Pick.

Fallow The Soil

Practice fallowing leaving the soil without sowing for one to two vegetative cycles. This will starve the nematode population and kill them. Roto-till the soil every two weeks to expose the nematodes and reduce the weeds.

Here is a useful video on preventing nematode attacks on vegetables:

What Causes Nematodes Attacks In Tomato Plants?

Nematodes prefer hot conditions and sandy soils. Also, nutrient deficiencies and soil compaction will increase the sensitivity of tomato plants to nematode damage.

The water-stressed plants are also prone to nematode attacks. It can also be spread with infected soil, equipment, and plants.

Frequently Asked Questions

Can you add black walnut leaves to kill nematodes on tomatoes?

No, you can not add black walnut leaves to kill nematodes on tomatoes. Black walnut releases juglone which is an extreme killer of root-knot nematodes. But, it has an extremely adverse effect on tomatoes and kills them.

How long do root-knot nematodes live?

The length of root-knot nematode life varies depending on the species. It can be as short as two weeks. In cooler regions, they may survive longer. Some species may survive for at least one year in the soil.


I hope this guide has provided many great ways to control and prevent root-knot nematodes on your tomato plants.

Let me know if you had tackled the root-knot nematodes in your tomato garden, and share your experiences.

Do share the guide with your friends and family to help them out too!

Check out other issues associated with tomatoes and how to identify and tackle them here>