Verticillium Wilt
Verticillium dahliae, Verticillium albo-atrum
Overview
A widespread soil-borne fungal disease affecting hundreds of plant species. The fungus invades the vascular system through roots, causing progressive wilting, yellowing, and death. Microsclerotia persist in soil for years. Verticillium Wilt spreads mainly by spores on wind, splash, tools, and crop debris. Humid, crowded plantings and overhead watering favor outbreaks in home gardens and food forests. Causal agent: Verticillium dahliae, Verticillium albo-atrum. In regenerative gardens, prioritize sanitation, airflow, and unbroken soil cover over calendar spraying, and intervene early when symptoms appear.
Symptoms
Wilting of leaves and branches, often on one side of the plant initially. Yellowing (chlorosis) between leaf veins. Brown streaking of vascular tissue in stems and roots. Marginal leaf scorch. Gradual decline and death. Compare several plants and note whether symptoms spread after rain, insect feeding, or wet foliage. Photograph undersides of leaves and cut stems when wilt is present to refine the diagnosis. Rule out simple drought, fertilizer burn, and herbicide drift before assuming a pathogen - abiotic injury often mimics disease.
Environmental Conditions
Cool
Prevention
Plant resistant varieties. Avoid planting susceptible crops in infested soil. Rotate with non-host crops (grasses, corn). Solarize soil. Maintain plant vigor with proper nutrition. Mulch to reduce splash, clear season-end debris, and avoid working plants when wet. Design beds for airflow and diverse plantings that support beneficial insects without creating permanent humid pockets around susceptible crops.
Management
No chemical cure available. Remove and destroy infected plants. Prune out affected branches on trees. Improve soil drainage. Add compost to promote beneficial soil microbes. Avoid excess nitrogen. Prefer drip irrigation, morning watering, and open spacing so leaves dry quickly. Disinfect pruners between cuts on woody plants. Use copper, sulfur, or biological products only as labeled protectants when pressure is high - they rarely reverse advanced infections alone. Destroy (do not casually compost) highly infectious debris.