How to Manage Pests

Pests in Gardens and Landscapes

Verticillium wilt on cucurbits—Verticillium dahliae

Verticillium wilt can affect all cucurbits. The first symptoms are wilting and yellowing of crown leaves, which eventually dry up. Wilting gradually progresses out toward the runner tips; in severe cases, the plant dies. Death may take weeks. A light brown vascular discoloration in roots is sometimes seen in cross section. Aboveground vascular tissue is also discolored and can be seen by cutting through a node near the base of the plant.

Life cycle

Verticillium dahliae survives for years in soil as tiny, dormant sclerotia. The pathogen has a wide host range including many vegetable crops, weeds, and trees. When roots of susceptible crops grow in close proximity, sclerotia germinate and infect the roots. Verticillium wilt is most severe during relatively cool periods and subsides during the hottest part of the summer, but wilting is usually seen during warm dry periods when the plant is under stress, such as after fruit set. The pathogen grows in the water-conducting tissue, causing plugging and interference with water transport.

Solutions

Avoid planting where potatoes, peppers, eggplants, tomatoes, or cucurbits have previously been planted. Some resistant varieties are available.

Wilting of cucumber plant
Wilting of cucumber plant

Tomato leaf affected by Verticillium
Tomato leaf affected by Verticillium wilt


Statewide IPM Program, Agriculture and Natural Resources, University of California
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