Fusarium crown and root rot

Pathogen

The fungus Fusarium oxysporum f. sp. radicis-lycopersici (FORL)

Host range

Tomato, pepper, eggplant, and a number of common weeds. The complete host range is not known.

Identification

Signs and symptoms

• Stunted, yellowed seedlings

  

• Lower leaves turn yellow and drop prematurely
• Plant wilts and may die

  

• Chocolate brown lesion girdles the main stem just above the soil line
• Reddish to brown discoloration of the stem cortex when sliced lengthwise

  

• Rotted, discolored, and stunted roots

Environment

• Cool temperatures (50 to 70°F optimum)
• Low soil pH
• Areas of poor drainage, waterlogged soil

Biology and disease cycle

• Spores produced on stem lesions can spread through the air and infect above ground plant parts.
• The fungus can spread by root-to-root contact, resulting in clusters of diseased plants.
• Spread through movement of soil and roots on equipment, plants, and workers.
• The fungus survives as thick walled spores (Chlamydospores) in soil, wooden stakes, and other high tunnel surfaces.

Management

Resistant varieties

There are some tomato varieties with resistance to FORL. In addition, susceptible varieties can be protected by grafting onto resistant varieties.

Cultural control

• Maintain a soil pH of 6 to 7.
• Promptly bag and remove infected plants, including roots to prevent spread.
• Remove and/or plow in remaining plant debris immediately after harvest to encourage decomposition.
• Reduce transmission year-to-year by using new stakes or new strings each year.
• Avoid wounding young transplants during planting.
• Use booties or disinfest boots by washing them between high tunnels. Begin working in cleanest tunnels first.

Chemical control

There are no fungicides that are effective for managing Fusarium crown and root rot.