Rotation of crops is an effective and widely used cultural practice to reduce nematode populations in the soil. To be most effective, crops that are poor hosts or nonhosts of the target nematodes should be included in the rotation sequence. Root-knot and lesion nematodes have such a wide host range that a practical rotation plan to reduce these nematode populations for vegetable crops cannot be recommended at the present time. Some plants commonly used as cover crops are naturally suppressive to certain nematode species, but no single crop is effective against all nematodes. The cover crop plant may be a nonhost and, therefore the nematodes starve, thus reducing their populations as with fallow.
Nematodes invade the roots of certain other cover crop plants, but they fail to reproduce.
Green manures and soil amendments. In general, the incorporation of large amounts of organic matter into the soil reduces populations of plant-feeding nematodes. The decomposition products of some plants kill nematodes. These include butyric acid, which is released during the decomposition of rye and timothy, and isothiocyanates, released during the decomposition of rapeseed and other plants in the genus Brassica . Plant nutrition and general care of the plant.