Verticillium Wilt
Verticillium dahliae
181 host plants · Fungal
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
Verticillium wilt strikes from the ground up, often catching you by surprise. You'll notice leaves on just one side of a maple, cherry, or blueberry beginning to yellow and wilt, sometimes while the opposite side remains vigorous. As the disease progresses, entire branches die back, and the characteristic symptom appears: vascular streaking inside the stem, visible when you cut through wood showing brown or purple discoloration in the water-conducting tissue. This disease commonly emerges in maples and blueberries after the plant has been in the ground for a few years, making established plantings vulnerable when conditions turn wet.
Verticillium wilt is caused by a soilborne fungus that nearly impossible to eradicate once established in your soil. The pathogen persists for years as microsclerotia and can survive in susceptible weeds around your property. Once in the plant's vascular system, it blocks water movement and produces toxins that trigger wilting. There is no cure for infected plants. Your management strategy must center on prevention: plant only healthy, certified stock; avoid planting susceptible crops in previously infested soil; control weeds aggressively; and keep nitrogen fertility at normal levels only, as excessive nitrogen promotes disease severity. If a plant develops symptoms, remove it promptly to reduce spore production in that location.
Quick Reference
Management
Root infection and colonization occur during the active growing season (April–June in Pacific Northwest); symptom expression peaks during warm months (June–September) when heat and moisture stress interact. Newly transplanted susceptible plants are vulnerable immediately upon planting into infested soil. Trees showing symptoms one year may recover partially in cool seasons (especially maritime autumns with consistent moisture), then deteriorate in subsequent hot, dry summers. Once established in a plant, the pathogen is permanent; infected trees decline incrementally over years. BBCH 10–70 (root growth through shoot elongation); high-risk period May–Sept when soil is warm and plants transpire actively.
Infection occurs when fine roots contact microsclerotia-infested soil. Germination of microsclerotia is triggered by root exudates and warm soil. Root colonization is most active when soil temperatures reach 65–75°F (optimal 70–75°F). Symptom expression is accelerated by heat stress (85°F+), drought stress, poor soil drainage, excessive nitrogen fertilization, root injury from cultivation, or infestation with root-knot nematodes. The fungus is soil-persistent and always present in infested soil; once established, the pathogen remains viable for 10+ years without active host tissue. Cool maritime winters in Pacific Northwest slow disease progression; affected trees may decline gradually over several years rather than rapidly.
Cultural Controls
- No curative treatment exists once soil is infested. Management is prevention and site selection.
- Conduct preplant soil assay for Verticillium propagules before planting susceptible species in sites with history of susceptible crops (tomatoes, potatoes, strawberries, raspberries, peppers, peppermint). WSU Extension and private labs offer testing.
- Do not replant susceptible species in the same location where a plant has died from Verticillium wilt. Plant susceptible species at least 20 feet from infested soil.
- Choose resistant species for infested sites: conifers, birch, dogwood, sycamore, oak, holly, juniper.
- Mulch with conifer-based products; conifers do not host the fungus.
- Do not import soil, mulch, or compost from unknown sources. Clean tools and equipment between sites.
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