Fusarium foot rot causes varying degrees o … Fusarium foot rot causes varying degrees of interveinal chlorosis and necrotic spotting on young foliage. Foliar symptoms may be similar to certain viruses (tomato spotted wilt or alfalfa mosaic). Flowers are often necrotic. Aboveground symptoms may be restricted to single branches. In severe cases, plants die. A dark brown lesion, about 0.5 to 1 inch (1?2.5 cm) long, is visible on the tap root or a main lateral root. Often the lesion completely girdles the root. The lesion usually occurs on the roots within the top 12 inches (30 cm) of soil. Internally, a brown discoloration of the vascular system extends 1 to 4 inches (2.5?10 cm) from the lesion. 1 to 4 inches (2.5?10 cm) from the lesion.