Fusarium Wilt

Fusarium oxysporum

Fusarium wilt is a collection of pathogenic fungi that attacks the xylem of host plants. It is most common in warm, moist soils but has been found to survive in most soils worldwide. Once the fungus reaches the xylem, water and nutrient uptake become increasingly limited leaving plants highly susceptible to other stressors. This combination of vascular damage and increased vulnerability reduces growth rates and may lead to crop failure. If left unchecked, Fusarium wilt leaves plants losing more water than they can transport. Stomata close, leaves wilt and the plants die in turn.

What to Look For:

  • Recently infected plants wilt during the hottest part of the day, but will recover at night.
  • One side of the plant will yellow. Sometimes this occurs on one half of a compound leaf.
  • Yellowing progresses to the whole plant and the plant wilts with occasional leaf browning.
  • Vascular tissue in the lower stem will be dark red to brown.
You can reduce the spread of Fusarium wilt by limiting overhead watering, sanitizing equipment and planting resistant cultivars. Infected seeds and transplants are also common vectors of the disease, so know your sources or take proactive measures to sterilize plants before introducing them into the growing area. If you grow in a humid climate where temperatures exceed 85°F, plan to take preventive action (biofungicides, sanitation) to avoid infection.