Verticillium Wilt
Verticillium Wilt
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A widespread fungus, verticillium is a soil-borne organism that plugs water-conducting vessels. Though it thrives in cool, moist soils, it usually doesn't reveal its presence until the weather turns warm and dry.

Target: More than 200 plant species, including tomatoes, potatoes, strawberries, and Japanese maple.

Damage: One branch or one side of a plant typically wilts. The leaves yellow starting from the edges and progressing inward; then they turn brown and die. The wilt progresses upward or outward from the base of the plant or branch; the tissue inside dead branches is discolored. Often the entire plant dies.

Control: Resistant Plants, soil solarization, new soil, reducing nitrogen fertilizer, pruning.

Notes: Don’t till before solarizing; the fungus is usually in the top 6 inches of soil, and that’s about how far the effects of solarization go. As an alternative to solarization, use clean, new soil in raised beds or containers. Crop rotation is ineffective, since the fungus can survive in the soil for 20 years. Excess nitrogen favors verticillium wilt, so cut back on nitrogen use. Pruning infected limbs may help a stricken tree recover. Maintain adequate soil moisture.