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Fusarium wilt

Quick facts

  • Susceptible crops include tomato, eggplant and pepper.
  • The entire plant turns yellow and wilts. Occasionally the leaves will turn brown. 
  • The fungus Fusarium oxysporum f. sp. Lycopersici causes fusarium wilt and infects solanaceous crops and weeds (such as pigweed, mallow, and crabgrass).
  • 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.

How to tell fusarium apart from other plant issues

Tomato plant with yellowing of leaves and some browning on lower leaves
Yellowing leaves due to Fusarium wilt
Tomato stems with brown vein streaks running up the stem
Discolored veins due to Fusarium wilt
  • Initially, plants wilt during the hottest part of the day and recover at night.
  • Leaves turn yellow, but the yellowing is not uniform. Sometimes 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.
  • Peeling the epidermis (outer tissue layer) off the lower stem will reveal dark red and brown discolored vascular tissue.
  • Confirm diagnosis by sending a plant sample to the University of Minnesota Plant Diagnostic Clinic, as this disease is easily confused with Verticillium wilt.

Biology

  • Fusarium wilt is caused by the fungus Fusarium oxysporum f. sp. lycopersici, which has three races; race 1, race 2 and race 3. 
  • Fusarium wilt affects tomato, eggplant and pepper. It can also survive on weeds such as pigweed, mallow and crabgrass.
  • The fungus thrives in warmer weather (optimal soil temp 82°F) and is more severe in acidic soil.
  • The pathogen most often enters through root wounds caused by cultivation or by nematode feeding.
  • Fusarium wilt can be seed borne, but it is rare in commercial seed. The fungus can be introduced on infected transplants or spread on equipment contaminated with infested soil.
  • 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.
  • The fungus can survive as chlamydospores (fungal resting structure) for many years in the soil or in plant debris.
  • Long distance dispersal by air borne spores only occurs very rarely.

Managing fusarium wilt in the home garden

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Managing fusarium wilt on the farm

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Marissa Schuh, horticulture IPM extension educator, Anna Johnson; Michelle Grabowski, and Angela Orshinsky.

Reviewed by Natalie Hoidal, Extension Educator - Local Foods and Vegetable Crops

Reviewed in 2021

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