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Aquaculture Division Home
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NematodesNematodes are microscopic roundworms. Although most nematode species either have no effect on agriculture or are actually beneficial, some types can be harmful to livestock and pets, and other types, the plant-parasitic nematodes, pose a major threat to Arkansas' row crop, horticulture, and ornamental industries. Most of the plant-parasitic types of nematodes that are of concern in our state are found in the soil and feed on the roots of plants. They damage the roots which leads to a range of problems, including poor plant growth, poor fruit, seed, or fiber production, or in extreme cases, plant death. Unfortunately, because nematodes are microscopic, they may not be identified as the cause of these problems. Many nematode problems each year are mistakenly attributed to poor fertility, insect problems, or weather. In Arkansas, three major groups of nematodes are of the most economic concern, although several other types can be damaging in certain situations. The most widespread is the root-knot nematode which is found in all Arkansas counties. Root-knot nematodes get their name because they cause small galls or swellings to form on the roots of infected plants. This nematode species can feed on over 5,000 different plant species. In Arkansas, cotton, soybean, corn, most vegetables, many tree and small fruits, most turfgrass types, and many ornamentals can be affected. A second major economic nematode species is the soybean cyst nematode. As its name implies, soybean is the preferred host for this species, and in contrast to root-knot, the soybean cyst nematode has only a limited number of hosts. These include soybean, green bean, lespedeza, and certain common weeds. Soybean cyst nematodes do not cause visible galls to form on roots of infected plants, but tiny, white, yellow, or brown adult nematodes (cysts) can be seen with the aid of a magnifying glass attached to the roots of the plants. A third type of nematode that is of serious concern in cotton and to a lesser extent in soybean is the reniform nematode. This nematode species is a relative newcomer to the state, and has been expanding throughout eastern and southern Arkansas for the past 10 years. Reniform nematodes, like soybean cyst nematodes, do not cause galls to form on roots. Unfortunately, while reniform nematodes are also attached to the roots, they are not generally visible even with a magnifying glass. Other nematode species that may be a problem on certain plant species under specific conditions include lesion nematodes, lance nematodes, ring nematodes, dagger nematodes, and stubby-root nematodes. Because of their microscopic nature and the fact that nematodes live in the soil, the only practical means of determining whether nematodes are present in a field, lawn, orchard, or nursery is by collecting a soil sample and having the soil assayed by a nematology laboratory. The laboratory will process the sample through several steps to separate the nematodes from the soil, and then all nematodes will be identified using a microscope. The Cooperative Extension Service provides this service to all citizens of the state of Arkansas, for a nominal fee, through the Arkansas Nematode Diagnostic Laboratory located in Hope. Details and suggestions for the proper procedures for collecting and handling samples, and forms for submitting samples to the laboratory can be obtained from this web site.
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