Tomato Stem Rot: Causes, Treatment & Prevention Guide (2026)

Tomato stem rot_ What Causes It and how to treat your plant

Tomato stem rot is caused by soil-borne fungi — most commonly Fusarium, Pythium, or Rhizoctonia — that attack the stem at or just below the soil line. The stem turns brown or black and the plant wilts even when soil is moist. It cannot be cured once established — the plant must be removed. This guide covers identification, treatment of early cases, and how to prevent it next season.