Verticillium Wilt

The first symptoms of verticillium wilt are blotchy yellow lesions on the lower leaves, rather than a wilting plant as the name implies.

The verticillium fungus thrives in moist, cool soil. It affects many vegetable and plant varieties including cucumber, radish, and beet to name a few.

How to Identify Verticillium Wilt

• Yellow, blotchy lesions first develop on lower leaves.
• Tan-colored V-shaped lesions on leaf tips.
• Wilting of the entire plant may occur during the hottest part of the day.
• Split open a stem lengthwise to diagnose. Tissues will be brown, especially near the soil line, but can extend upward 10- to 12-inches.

Causes

• Fungi are present in garden and greenhouse soils where they can persist for many years.
• Caused by the fungi Verticillium albo-atrum and V. dahliae.
• The disease survives between seasons on dead plant debris remaining in the soil.
• Can multiply in common weeds, including cocklebur and ragweed.
• Infection occurs at moderate temperatures (13˚C to 30˚C/55˚F to 86˚F) in saturated soil.

Preventative Measures

• Plant disease resistant varieties (labeled V for Verticillium).
• Plant tomatoes only in well-drained soil.
• Practice crop rotation on a long four-year cycle with nonrelated-hosts (no peppers, potatoes or eggplant).
• Fumigate the soil.
• Don't saturate the soil by over-watering.

Treatments

Natural remedies

• By far the best remedy is to avoid the disease by planting Verticillium-tolerant tomato varieties.

Chemical treatments

• Soil fumigation may be your best option if soils are severely infested.

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Credits for technical content

1. Ontario Ministry of Agriculture & Rural Affairs
2. The Ohio State University Extension