Problem Identifier Unit Screen//v.w/ RR Template

Problem Identifier Unit Screen//v.w/ RR Template Verticillium Wilt

Problem
Leaves yellow, wilt, and die, starting with the lower leaves and progressing up the plant. Older plants may be stunted. Yellowing and wilting often affect only one side of the plant. Flowering is poor. There may be dark brown areas on the infected stems. When the stem is sliced open near the base of the plant, dark streaks and discolorations of the inner water-conducting stem tissue are seen.

Analysis
This wilt disease is caused by a soil-inhabiting fungus (Verticillium species) that persists indefinitely on plant debris or in the soil. The disease is spread by contaminated seeds, plants, soil, and equipment. The fungus enters the plant through the roots and spreads up into the stems and leaves through the water-conducting vessels in the stems. The vessels become discolored and plugged. This plugging cuts off the flow of water to the leaves, causing leaf yellowing and wilting. For more information about verticillium wilt, see Verticillium or Fusarium Wilt.

Solution
No chemical control is available. It is best to destroy infected plants. Verticillium can be removed from the soil only by fumigation techniques. (For more information about soil fumigation, see Soil Fumigation and Solarization.) However, the best solution is usually to use plants that are resistant to verticillium. For a list of verticillium-resistant plants, see Plants Resistant to Verticillium Wilt.

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