Nematodes are underground pests that eat the roots of lawns, vegetables, ornamental plants, and trees. It is difficult to detect the presence of nematodes in the soil. The only way to know if nematodes are in the soil is to have the soil tested by the local extension office.Testing the soil will not only provide proof of nematodes but it will also state what type of nematode is present in the soil. There is no chemical treatment currently available for residential use. However, there are methods to control the severity of the nematode infestation, but there is no known treatment, chemical or otherwise, that will totally eradicate the nematodes infesting residential soils.
What are Nematodes
Nematodes are microscopic, eel-like roundworms with needle-like mouth parts. They are dormant in soils under 65 degrees and perish in soils above 130 degrees. However, they thrive in the late spring and summer months. Nematodes prefer sandy soil, but live in all types of soil. They are easily spread from one area to another by run-off water and dirt.
Nematode damage may cause plants or grass to appear yellow, weak and slow to grow. In lawns, the grass may start to thin. In other plants, wilting during the heat of the day, even with adequate water, would be a reason to suspect nematodes in the soil. Plants will be smaller and produce less fruit and blooms when infected by nematodes.
Preventing the Spread of Nematodes
The first line of defense in nematode treatment is only to buy plants from reputable nurseries that can provide nematode-free plants. If nematodes are already present in the soil, avoid moving the plants or soil from one area to another. Clean all tools used in the infected area thoroughly before using them in an uninfected area. Use deep watering and infrequent watering to encourage deep root systems. Keep the infected area well watered, so the infected plants will be healthy enough to survive any nematode damage. Try to keep excess water or dirt in an infected area from running off into an uninfected area.
Plants as Treatment
Another type of nematode treatment is to rid the lawn of nematode-susceptible plants and replace them with plants that are resistant to nematodes. Planting plants while temperatures are 64 degrees or lower will allow the plants to develop deep roots before the nematodes become active. Marigolds are also useful for nematode treatment. The favorite varieties to suppress nematodes are the French marigolds, such as Queen Sophia, Tangerine,and Petite Blanc. Marigolds have been a popular treatment for nematodes in India for hundreds of years.
Soil solarization or heating of the soil is a more drastic form of nematode treatment. It takes about four to six weeks and very hot weather for soil solarization to achieve results. Soil solarization involves watering the soil well and covering the soil with a clear plastic tarp. The plastic will heat the soil up to 130 degrees on a hot summer day, thus killing the nematodes and eggs. Unfortunately, soil solarization only kills the nematodes that are in the top 6 to 12 inches of the soil.