Verticillium Wilt of Potato

The primary pathogen of the disease is the fungus Verticillium dahliae, with V. albo-atrum and other species occurring less frequently. The pathogen enters the plant through the roots and colonizes the vascular system, blocking the transport of water and nutrients, which leads to the development of early dying syndrome.

The first signs of infection appear during the flowering period as yellowing of the lower leaves, the appearance of spots with yellow margins, and subsequent curling of the leaflet edges. In hot weather, plants take on a scorched appearance, and darkening of the vascular bundles is clearly visible in cross-sections of stems and in the stolon end of tubers.

Breeding for resistance is complicated by the absence of simple monogenic sources of resistance. In modern practice, varietal resistance is more often classified as tolerance, and breeding efforts are focused on identifying quantitative trait loci (QTLs) that reduce the intensity of infection development.