Solarization helps reduce nematodes in vegetable gardens

By Larry Williams, UF/IFAS Extension Agent, Okaloosa County

Plant-parasitic nematodes can be among the most damaging and hard-to-control pests in a vegetable garden.

In today’s article, Theresa Friday, Santa Rosa County Extension Agent, describes these microscopic pests and shares methods used to control them.

Nematodes are non-segmented roundworms that live in the soil. Most can only be seen using a microscope. Most are beneficial because they feed on bacteria, fungi and insect pests. Unfortunately, there is a group of nematodes that damage plants.

Plant-parasitic nematodes feed upon a plant’s root system and reduce the plant’s ability to obtain water and nutrients from the soil. When there is a high population of nematodes in the soil or when the plant is stressed, the plant begins to show symptoms.

Mild symptoms include stunting, loss of vigor, wilting and reduced yields. Severe symptoms include early plant death and complete loss of production. 

Root-knot nematodes are the most well-known and most destructive of the plant-parasitic nematodes. Galls produced by root-knot nematodes are a distinctive symptom. Galls are small to large swelling of the roots in the areas where nematodes have entered the root.

Okra, tomato, cucumber, butterbeans, squash and melons are some of the most vulnerable vegetable plants. Greatest damage occurs on plants that are grown during summer months when soil temperatures are warm.

Managing nematodes may involve using one or more techniques that reduce nematode populations.

Plant resistant varieties: Some vegetable varieties are marketed as “nematode resistant.” Contact your local Extension Office for recommendations on resistant varieties.

Crop rotation: Most problems with nematodes arise because susceptible crops are grown in the same area each year. Gardeners need to rotate crops within the garden and never plant very susceptible crops consecutively. Another alternative is to grow vegetables in containers using a soilless potting media.

Solarization: This is a process of using the sun’s heat to kill nematodes and other pests. Use a hoe or rototiller to break up clods of soil. Remove debris such as sticks and roots. The soil should be moist but not soggy wet. Cover the soil with a clear plastic tarp and bury the edges of the plastic. Leave the plastic on the soil for at least 4 to 6 weeks.

Sunlight goes through the clear plastic and heats the soil underneath. Long-term exposure to high temperature kills nematodes, as well as many weeds, fungi and insect pests. Solarization works best during the summer months when the soil will receive maximum direct sunlight.

While these recommendations can help avoid or reduce problems with plant-parasitic nematodes in the vegetable garden, they are not guarantees of success.

Originally published July, 2007