Above-ground symptoms depend on the level of infestation. At high levels there may be stunting, yellowing and an unthrifty appearance. Plants may wilt in the heat of the day and recover at night. Yields are reduced. Symptoms may be confused with mineral deficiency, drought, herbicide injury or other soilborne diseases.
Symptoms occur in oval patches or spaced erratically through the field.
Roots have small to large galls and may be branched excessively. Roots are usually discolored. Root-knot nematodes are involved in diseases complexes with wilts and seedling diseases. Rotation with small grains or other grasses and some soybean varieties may reduce nematode numbers. Other rotations depend on the species present.