Symptoms and Signs
Symptoms of Verticillium wilt include wilting, chlorosis, and stunting of plants. Leaves often have a marginal necrosis. Vascular discoloration, which is characteristic of this disease on other hosts, may not be always present in artichoke plants. Diseased plants produce smaller buds, and in severe cases, buds become discolored and dried, and the plant collapses. Roots exhibit the characteristic vascular discoloration of this disease.
Comments on the Disease
Some infected artichoke plants may not exhibit any symptoms of disease. It is possible that stressed plants will show the most severe symptoms. In severe cases, yields can be reduced by as much as 50%. Verticillium dahliae produces microsclerotia that can survive for many years in the soil without host plants present. Research indicates that V. dahliae isolates from artichoke, lettuce, and strawberry can each infect these three crops and perhaps other plants as well.
Practice proper cultural practices in order to avoid stressing plants. Do not take crowns to be used for propagation from fields where the disease has occurred. Do not plant annual artichokes in fields with a history of V. dahliae. Rotate Verticillium-infected fields into broccoli. Because lettuce and strawberry are commonly planted in the artichoke-producing region, before planting artichoke note whether previous lettuce or strawberry plantings were affected by Verticillium wilt. All annual artichoke varieties have been found to be more susceptible to V. dahliae than the perennial Green Globe variety.