Shoots and leaves may wilt during the day but regain turgidity at night. As the infection progresses, stems become bleached. The xylem eventually becomes plugged, causing death. Fusarium wilt can be identified by the dark reddish brown discoloration in the stele, or center, of the taproot. Fusarium oxysporum may persist in soil for several years.
Fusarium wilt is more sever when plants are infested with root-knot nematodes.
Soil moisture does not affect the severity of the disease, but high soil temperatures favor infection. Cultivars with resistance to both fusarium wilt and root-knot nematodes offer the best control when both organisms are present. Verticillium Wilt Verticillium albo-strum, a fungus that causes Verticillium wilt is a potentially serious problem over seasons and years rather than a devastation in a single year. Therefore, the fungus could exist in a field that appears healthy. Also, the disease is apparently more serious in irrigated fields than in dryland fields.