Verticillium Wilt of Potato: A Diagnostic Guide

Verticillium wilt of potatoes is an important soil-borne disease of potatoes, with reported yield losses exceeding 40%. It is caused by Verticillium species, most notably Verticillium dahliae. Symptoms include leaf chlorosis, limp and flaccid leaves, stunted growth, vascular discoloration towards the stem base, and discoloration of the vascular ring of the tuber. Infection may lead to premature plant decline 4-6 weeks before natural senescence, a condition known as potato early dying. While early dying can occur due to Verticillium alone, symptom severity may increase with co-infection by Pectobacterium spp. or plant-parasitic nematodes. Early dying can also be caused by Colletotrichum coccodes and nutritional deficiencies in the absence of Verticillium. The objective of this guide is to provide detailed information on methods related to disease diagnosis, including isolation, morphological and molecular identification, pathogen detection, isolate storage, and pathogenicity testing for verticillium wilt of potatoes.