The most numerous multicellular animals on the planet, nematodes are simple organisms which are parasites of insects, plants and animals. Plant nematodes are colorless and range from .25 mm to 3 mm long. They are tiny and nearly invisible, but nematodes can ravage a vegetable garden or lawn if left untreated.
In field and vegetable crops, this parasitic disease is most easily recognizable as root knot nematodes. This makes the roots look knotty and deformed. You can dig up a plant you suspect of having nematodes and look at the smaller roots.
Infestation can cause retardation of growth as plants lag behind healthier specimens early in the season. Later in the season when fruiting occurs, a greater demand is placed on the plant for nutrients and water. You may find smaller fruit, lower overall plant height and a greatly reduced canopy as compared to healthy plants. At this point, the infested plants may soon die.
If you are in the business of agriculture, you should take root and soil samples to a lab to have them professionally analyzed. Nematodes can wreak havoc in agriculture, especially on corn, potatoes, soybeans, sugar beets, turf, vegetables of all types, and trees, orchards and vineyards.
Pesticides for Nematodes
According to Cornell University, Basamid G will kill nematodes and plants that are infected with nematodes. It can be applied according to package directions to fumigate soil prior to planting beds.
Home Remedies for Nematodes
Sugar is often given as an organic method to control nematodes. It won't kill them directly, however. Ground up sesame is often used for the same purpose. Just mix a few teaspoons of sugar, molasses or ground sesame into the soil around infected plants. This encourages beneficial microorganisms to take over, and it deters the nematodes.
Another home remedy or organic method of control is simply to add as much new organic material to your garden beds as possible every year to build up the soil away from the infestation below.
Mulching also helps keep plants healthier in general, and strong, healthy plants are the best deterrent to all pests and diseases.
When soil is infected in a large area, you may want to take more drastic measures such as solarization. Both heat and infrared light will kill nematodes. To solarize soil, place plastic over the area for an extended period of time. The soil underneath will be heated to high temperatures by the sun. Be aware that this may kill anything in the soil--even beneficial insects and bacteria.
Organic Methods for Preventing Nematodes
Prevent nematodes by keeping your soil in top condition with fresh applications of rich compost and mulch. Rich soil and healthy plants are the best deterrent. Insects and other pests are attracted to dying plants and rotting fruits.
It may also help not to dig too deeply in infected areas, because this action may bring the nematodes up near the plant's roots. Amend the soil with rich compost and add mulch after planting. Just lay the compost on top of the soil to build it up--don't mix it in with the existing dirt.
Be careful digging deeply in and around infected plants as you may also transfer the parasites to other areas on your shovel or hoe.
Any infested plants or roots you dig up should be disposed of far away from your garden and away from any other areas where you intend for plants, trees, vines or shrubs to grow.
Sometimes gardeners unknowingly transfer nematodes to other areas by transplanting an infected specimen. Examine the roots of any plants you receive from friends and neighbors prior to planting them in your yard. By the same token, don't give away plants from your infected soil.
Other Methods for Preventing Nematodes
As mentioned previously, when you know there is an infestation of nematodes in your soil, you may fumigate the soil with Basamid G prior to creating your beds. Other methods to prevent nematodes destroying your plants include: solarize the soil prior to preparing your garden beds; create your beds in a new location; destroy and dispose of all infected plants and plant roots from the prior year and remove them from the garden plot; and use raised beds that are filled with a mixture of rich top soil, compost and dirt from an area that is not infected with nematodes.