Fusarium Crown Rot

Fusarium crown rot disease in tomatoes causes the leaves to turn brown or black and eventually wilt.

Fusarium crown and root rot is caused by the fungus Fusarium oxysporum radicis-lycopersici (FORL). Infected plants may be stunted, and as they begin to bear fruit, their lower leaves turn yellow and wilt. Plants appear to recover at night after wilting during the warmest part of the day. Infected plants may either totally wilt and die, or survive in a weakened state, producing reduced quantities of inferior fruit.

How to Identify Fusarium Crown Rot

Tomato crown rot
Wilted tomato plants infected with Fusarium crown rot fungus
Courtesy of University of Florida
Institute of Food and Agricultural Sciences
Fusarium crown rot
Fusarium crown rot disease spreading
Courtesy of University of Florida
Institute of Food and Agricultural Sciences
  • Early symptoms caused by crown rot in tomato seedlings include stunting, yellowing, and premature loss of cotyledons (first sprout) and lower leaves.
  • Late symptoms include a brown lesion surrounding the stem next to the roots, root rot, wilting, and dying plants.
  • During the growing season, lower leaves turn yellow and wilt.
  • Plants either die or persist in a weakened state, producing inferior fruits.

Causes

  • The disease is worsened by cool temperatures (10˚C to 20˚C/50˚F to 68˚F).
  • Other factors that encourage the disease are soil with poor drainage, low soil pH, and ammoniacal nitrogen.

Preventative Measures

  • Sterilize the soil and avoid use of wooden stakes, as the fungus can survive between seasons, or disinfect or use new stakes each season.
  • Plant only disease-free transplants.
  • Disinfect transplant trays by steaming before reusing.
  • Avoid over-watering.
  • Rotate crops each year.

Treatments

Natural remedies

  • Remove and destroy infected plants.
  • Add more organic matter to your soil for tomatoes before planting.

Chemical treatments

  • Fumigate the soil before planting and immediately cover with a plastic mulch.

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Credits for technical content

  1. Colorado State University Extension
  2. Florida Plant Disease Management Guide



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