This particular Fusarium wilt only affects blackeye beans and other cowpea varieties. Symptoms usually first appear 6 weeks after planting, with diseased plants having pale green, flaccid leaves that turn yellow and drop off. Subsequently, patches of plants in the field will die, whereas surrounding plants that are not infected still retain green leaves and continue to grow and produce pods.
Diagnosis involves slicing the tap root, stem, and branches with a sharp knife.
Susceptible, infected plants will have a brown discoloration in the vascular tissue in the center of the root and stem, reaching the branches in some cases. Resistant varieties may have some brown discoloration in the vascular tissue of the roots, but not in the shoots. Susceptible, infected plants that have not died can exhibit a distinct swelling of the base of the stem and adjoining tap root. This fungus survives in soil indefinitely, and crop rotation has not been shown to be adequately effective in suppressing the disease. Susceptible varieties can exhibit greater damage due to Fusarium wilt in the presence of root knot nematodes.