Root-knot nematodes cause galls or knots to form on roots. The sheath nematode retains one of its cuticles at molting resulting in the appearance of a sheath surrounding the body. Feeding by stubby-root nematode causes the root tip to stop growing and appear stubby. Paratrichodorus is another important genera found in California. Spiral nematode typically appears to be curled up when viewed microscopically.
Pin nematode is one of the shortest plant parasitic nematodes.
Feeding and migration by lesion nematode can result in visible lesions forming on roots. Stem and bulb nematode typically affects bulb crops such as daffodil , garlic and onion, or is found within the stems of plants such as alfalfa. Foliar nematodes are typically found within leaves of plants rather than within roots. Citrus nematode has a relatively narrow host range and was first found affecting citrus, although it is also a serious problem on other crops such as grapes. The body of adult female cyst nematodes is typically swollen and becomes a cyst to protect eggs laid within it.