How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS

Verticillium wilt becomes evident when lower leaves on the vine turn yellow and wither. Symptoms progress upward until the entire plant yellows and wilts. Vascular tissue of stems becomes a light brown, which is best observed near ground level. Some tubers from infected plants may develop a light brown discoloration in the vascular ring near the stem end. Wilt causes early senescence of plants in heavily infested fields.

COMMENTS ON THE DISEASE

The fungus persists in soil for long periods. Infection is favored by cool weather, but symptom development is favored by high temperatures. The fungus interferes with water transport in the stems, so injury is most severe during periods of hot weather when plants are stressed for water.

MANAGEMENT

Some cultivars are more tolerant than others. Rotate out of potatoes and other susceptible crops for 2 to 3 years. Cereals, grasses, and legumes are good rotation crops. Treatment is rarely required for Verticillium wilt in California, but fumigation with 1,3-dichloropropene* may be justified if fields have high levels of lesion nematode, which is known to exacerbate this disease.

PUBLICATION

UC IPM Pest Management Guidelines: Potato
UC ANR Publication 3463
Diseases
R. M. Davis, Plant Pathology, UC Davis
J. Nuñez, UC Cooperative Extension, Kern Co.
B. J. Aegerter, UC Cooperative Extension, San Joaquin Co.
Acknowledgment for contributions to the disease section:
C. Smart, Plant Pathology, UC Davis

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