Nematode Control and Management

Learning nematode control strategies is essential for the enthusiastic home gardener. Nematodes are tiny roundworms that resemble eels. They feed on the roots of plants and lower the capacity of the plant to absorb water and nutrients, leading to a general decline in plant health and reduced yields. Quite often, signs of nematodes will include stunted growth, falling yields, wilting during moisture stress and leaves turning to a pale green color. Within the ground, the roots may swell into knots or galls. The most effective strategy in controlling nematodes is prevention. This is because once nematodes penetrate into a plant, you cannot kill them without destroying the host as well. Below are some strategies worth trying.

Organic Matter

Adding organic matter to your soil is believed to reduce the presence and activities of nematodes. Manure and peat moss, for instance, contains substances that are detrimental to nematodes. When applying organic matter, you need to ensure that you dig deeply enough because nematodes occur deeply in the soil.

Use Nematode Resistant Plant Varieties

Prevention is better than cure and some vegetable and trees are able to withstand nematodes. Select varieties that are known for their root stock resistance to nemotodes.

Crop Rotation

You can grow crops that will not let certain nematodes such as the cyst variety to reproduce in the soil. Ideal annual crops you can plant to help in reducing root knot nematode, which is one of the more prevalent garden nematodes are sudangrass, barley, wheat, and varieties of beans and tomatoes that are resistant to the parasite.


Practice solarization to reduce the occurrence of nematodes in the first 12 inches of top soil. It will also enable you to grow crops with a shallow root system. Solarization is best undertaken during the hottest part of the summer in July to August. Moisten the soil thoroughly and cover the surface with a clear plastic tarp. Leave the soil covered for 4 to 6 weeks. The high soil temperatures will effectively destroy root knot nematodes including eggs.


Leaving the soil fallow for one or more seasons can reduce the nematode population in your garden. When undertaking fallowing it is vital that you ensure there are absolutely no weeds on the garden that would encourage parasitic nematodes to thrive. You must also make sure the soil is moist to encourage hatching of the nematode eggs. Since the garden will have no plant cover, the pests will starve to death due to the absence of roots to feed on. A one year fallow period should suffice before you plant a crop of your choice although a two year period would reduce even further on the root nematode population.

Chemical Control

Fumigants or nematicides can be used as an alternative to the above cultural methods in controlling nematodes. Fumigants occur in gas or liquid form and diffuse gas during the volatilization process which kills nematodes in the soil. When applying fumigants you need to ensure that the soil contains minimal organic matter as this de-activates the toxicant in the fumigant. Also, soils should be warm to encourage the diffusion process.