The plants affected by Verticillium dahliae frequently show a discreet wilting of lower leaflets at the hottest times of the day. At first, this wilting is reversible overnight. Subsequently, as the disease develops, it can be observed that certain sectors of the leaf blade, often interveinal and in the shape of a “V”, gradually soften and turn yellow (figures 1 to 5). Large portions of the leaflets eventually turn beige to brown and then necrose. Leaflets and leaves thus affected die prematurely, which can lead to exposure of the fruits to solar radiation and therefore the risk of solar burns .

A longitudinal or transverse cut in the vessels of the lower part of the stem or of a branch shows that they show a slight browning , much less marked than in the case of fusarium (figures 6 and 7).

The symptoms of verticillium wilt tend to be expressed in spring and autumn in France; the spread of the disease can stop during the summer period. Unlike fusarium, they do not lead to the death of plants but contribute to their weakening and reduced yields.