Lesion nematodes

Pratylenchus scribneri

Aboveground symptoms of severe root knot infestation include patches of chlorotic, stunted, necrotic, or wilted plants. Infested plants that are also under moisture or temperature stress may wilt earlier than other plants. Feeding by root knot nematode incites cell enlargement and proliferation resulting in swellings, called galls, on roots. These galls are diagnostic for root knot nematode, however, some bean types do not gall much. An example is the blackeye CB3, which is susceptible to root knot nematode and can support high populations of this nematode but shows little galling. Severely galled roots may be shortened and thickened. Galls caused by root knot nematodes may be confused with nodules of nitrogen-fixing Rhizobium bacteria. Rhizobium nodules, however, are pink inside and come off the root easily when rubbed. Root knot galls cannot be separated from the root.

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