Tomato Wilting: Root Diseases, Nematodes, and Why Crop Rotation Matters

Established tomato wilting in Central CA (mid-80s, breezy). All signs point to root issues. Also asking: how close must marigolds be to repel nematodes?

Marigold Reality Check

• Only French marigolds (Tagetes patula) repel nematodes.
• Must be planted inches from target roots — not a border, but interplanted.
• Common marigolds don't work.

Common Tomato Wilts

• Fusarium / Verticillium wilt — soil-borne fungi, vascular blockage.
• Bacterial wilt (Pseudomonas solanacearum) — warm climates, rapid collapse.
• Rhizoctonia root rot — young and old plants, wilt + collapse.
• Tomato Spotted Wilt Virus (TSWV) — thrips/aphid spread, stunting, ringspots.

How to Check Roots

Gently dig beside plant, expose root crown. Look for brown/black lesions, rot, galls (nematodes). Healthy roots = white, firm.

The Real Fix: Rotate Crops

Tomatoes in same spot yearly = disease buildup. Rotate to non-solanaceae (beans, corn, brassicas) every 2–3 years. It's the single most effective prevention.

Describe wilt pattern (top/bottom, old/new leaves, insects) for finer diagnosis.