Root knot nematodes are damaging to cotton as a single pest problem and as part of the Fusarium wilt disease complex on cotton. A given nematode population is relatively more damaging to cotton in the presence of Fusarium than when it occurs alone. Fusarium wilt damage is consistently associated with root knot nematode infection. Their feeding stimulates the production of galls.
Crop rotation is also useful for reducing root knot nematode populations.
For successful control of nematodes in a rotation program, susceptible weeds or grasses must be controlled completely during the non-cotton parts of the rotation. Rotation crops that help to reduce cotton root knot nematodes include alfalfa, winter small grains, resistant cowpea cvs. California Blackeye CB 5, CB 27, and CB 46, and root knot resistant cultivars of processing tomatoes. A resistant variety of Acala cotton, NemX, developed in the San Joaquin Valley of California, suppresses initial infection by cotton root knot nematode and thus reduces yield loss of cotton plants grown in infested soil. The use of NemX is especially effective for managing root knot nematode in rotations with other nematode susceptible crops.