Fusarium Wilt: Soil-Borne Vascular Disease of Tomato, Pepper & Ornamentals

Fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici (tomato), F. o. f. sp. capsici (pepper), and other formae speciales, is a warm-soil vascular fungus. It enters young roots, blocks xylem, and causes progressive yellowing, wilting, and stunting. The pathogen persists indefinitely in soil and debris. Control relies on rotation, sanitation, soil solarization, and resistant varieties.

Symptoms

• Daytime wilting (recovers at night initially).
• Yellowing, fading foliage (bottom up).
• Stunted growth, few flowers/fruit.
• Brown vascular streaks in lower stem (diagnostic).
• Eventual death in susceptible varieties.

Prevention (The Effective Strategy)

1. Rotation & Sanitation

• Never plant same crop in same spot annually. 3–4 year rotation.
• Sterilize pots (10% bleach) + fresh soil when reusing.
• Remove all crop debris annually; burn if diseased—do not compost.
• Clean tools, shoes, equipment between beds.

2. Soil Solarization

• Black or clear plastic over moist soil in full sun, 4–6 weeks summer.
• Heat "cooks" fungus in top 6–12".

3. Resistant Varieties (Most Practical)

• Tomato: 'VFN', 'VFNT', 'VFNTA' labels = Fusarium (race 1, 2, 3), Verticillium, Nematode, Tobacco mosaic, Alternaria resistance.
• Pepper: resistant lines available.
• Ornamentals: select resistant cultivars where known.

Treatment (Limited, For High-Value Plants)

• Fumigants: Metam sodium, chloropicrin—require licensed applicator; read labels carefully.
• Root/bulb soak: Wash soil off roots; soak in fungicide solution (per label) before replanting in clean soil.
• Not curative for established field infections.

Core Principle

Fusarium wilt is a disease of monoculture and dirty practices. Rotation, resistant genetics, clean tools, and solarization break the cycle. The grower who rotates never sees it; the one who doesn't fights it every season.