Fusarium is an important phytopathogenic fungi, can affect tubers all the way through the production cycle, causing seed piece decay, wilt during the growing season, and dry rot in storage. Fusarium species are capable of living saprophytically, in the absence of a host plant, and usually persist in the soil for many years. Fusarium can be introduced to new plots by moving soil with mechanical tools, in infected seed potatoes, or even on the surface of uninfected tubers. Fusarium dry rot of seed tubers can reduce crop establishment by killing developing potato sprouts. Dry rot would not develop without an initial wound. Infection occurs during harvesting and handling (grading) and is favoured by warm weather
The vascular wilt appears first as premature yellowing or other discoloration of the leaves, while the stems and leaf petioles remain green. Leaf tissue between veins turns yellow then brown. Wilting and yellowing of foliage progresses up the stems of affected plants.
Upon cutting a cross-section of the stem, the whole vascular ring (unlike the early symptom of Verticillium wilt) would be discolored, brown to black.
Vine kill before harvest is important, as it will help the skins to set, and form a natural defence against infection.