Main symptoms

On the lower leaves of the crown of diseased lettuce, Verticillium dahliae produces yellowing that begins at the periphery of the leaf blade and becomes more or less sectoral. The leaves eventually wilt partially or completely and necrode. At this stage, they remain strongly adherent to the apple. Microsclerotia of the fungus are sometimes visible along a few veins.

A longitudinal section of the roots, taproot and stem shows that the vascular system is affected. It reveals a brownish green tint that can be confusing with damage Fusarium .