Symptoms

The disease causes wilting, dwarfism, premature senescence and early death of the plants (photo 1).

Symptoms in growing crops usually start on one side of the plant or the leaf (photo 2) with chlorosis beginning between the leaf veins. This then develops into necrosis and finally foliage dehydration or wilting.

The withered leaves turn brown, fall or remain attached to the stem, which remains green. At the base of the diseased stems, a brownish discolouration of the vessels can usually be observed (photo 3) when sectioning the stems.

On the stems and roots of the withering plants, small black sclerotia or mycelium may be observed, depending on the species of fungus (photo 4).

The infected tubers display brown spots on the vascular ring (photos 5 and 6) and may be of a smaller size. Pinkish-brown necrosis of the eyes may be observed.