Crown Rot (Soil-Borne Fungus): Identification, Rescue Attempt & Prevention

Crown rot, caused by soil-borne fungi (Phytophthora, Pythium, Rhizoctonia, Fusarium, Sclerotium), attacks at the soil line in wet, heavy soils. Dry rotting at crown, wilting, yellow/red/purple foliage, stunting, dark bark/sap on trees. Often fatal, especially in young plants. Prevention via drainage is key; fungicides (captan, Aliette) only preventive.

Symptoms

• Dry rot at/near soil line (one side or lateral branches first).
• Discolored tissue: tan/dark = dead.
• Rapid wilt, death (young plants most vulnerable).
• Foliage: yellow, red, purple.
• Stunted but may still bloom sparsely.
• Trees: dark bark at crown, oozing dark sap.

Rescue (Early, Valuable Plants Only)

• Pull infected plants; destroy promptly.
• Sanitize area/soil.
• Trees: excavate to main roots, remove oozing/dark bark, expose crown to dry.

Prevention

• Drainage: Amend clay; raised beds; plant on mounds.
• Watering: Only when top 1–2" dry; deep, infrequent.
• Rotation: Vegetables (tomato, etc.) every 2–3 years.
• Fungicide drench (preventive): Captan or Aliette (2 Tbsp/gal) on somewhat dry soil; repeat 2× at 30-day intervals.

Crown rot is a wet-soil disease. Fix the drainage, water wisely, and rotate—and the fungi stay dormant. Let the soil stay soggy, and they'll rot the crown out from under every plant.