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Fusarium wilt

Quick facts

  • Host plants include tomato, eggplant and pepper.
  • The entire plant turns and yellow and wilts, with browning of leaves occurring rarely.
  • The fungus can be introduced on infected transplants or spread on equipment contaminated with infested soil.
  • There are many varieties of host plants with resistance to Fusarium wilt. 
  • Different cultural control strategies are recommended for managing the fungus.

Pathogen

The fungus Fusarium oxysporum f. sp. lycopersici

Host range

Tomato, eggplant and pepper. Can also survive on weeds such as pigweed, mallow, and crabgrass.

Identification

Signs and symptoms

Tomato plant with yellowing of leaves and some browning on lower leaves
Yellowing leaves due to Fusarium wilt
  • Initially, plants wilt during the hottest part of the day and recover at night.
  • Leaflets turn yellow on one side of the plant, or even just leaflets on one half of a compound leaf.
  • The entire plant soon turns yellow and wilts. Browning of leaves occurs rarely.
  • Peel the epidermis off the lower stem to see dark red and brown discolored vascular tissue.
    Tomato stems with brown vein streaks running up the stem
    Discolored veins due to Fusarium wilt
  • Confirm diagnosis by sending a plant sample to the University of Minnesota Plant Diagnostic Clinic, as this disease is easily confused with Verticillium wilt.

Environment

  • Disease of warmer weather (optimal soil temp 82°F).
  • More severe in acidic soil.

Biology and disease cycle

  • The fungus can survive as chlamydospores (fungal resting structure) for many years in the soil or in plant debris.
  • Can be seed borne, but rare in commercial seed.
  • The fungus can be introduced on infected transplants or spread on equipment contaminated with infested soil.
  • Long distance dispersal by air borne spores only occurs very rarely.
  • The pathogen most often enters through root wounds caused by cultivation or by nematode feeding.
  • The pathogen moves up the plant through the vascular system.
  • Only one infection cycle occurs each growing season; once a plant is infected, it usually will not spread to another plant in the same growing season.

Management

 | 

Anna Johnson; Michelle Grabowski, Extension educator and Angela Orshinsky, Extension plant pathologist

Reviewed in 2016

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