Fusarium Basal Rot

HOSTS

• Onions
• Garlic
• Leek

DESCRIPTION

Fusarium basal rot is caused by fungi in the genus Fusarium, including F. oxysporum and F. proliferatum.  

BIOLOGY

Fusarium basal rot is usually introduced through the use of infected seeds or soil. It overwinters as specialized spores in the soil. These spores, called chlamydospores, can survive in the soil without a host for long periods. When the temperature warms from 77 °F to 84 °F, the spores reproduce and can infect crops. The spores invade the host plant through wounds on the plant’s roots or basal plate. As the plant begins to rot, nutrients and water are prevented from reaching the leaves, causing more damage to the plant. Rotting can continue when the plant is in storage.

SYMPTOMS

• Foliar chlorosis and dieback. 
• Red or brown bulb discoloration that starts at the basal plate. 
• Soft and watery bulb. 
• White mold growth on the roots and bottom of the bulb. 

GENERAL MANAGEMENT

• Plant resistant cultivars. 
• Rotate alliums with unsusceptible crops for 3-4 years. 
• Avoid planting in fields with a history of Fusarium basal rot. 
• Avoid injuries to the bulbs by managing insect damage and working with the bulbs carefully. 
• Store onion bulbs at 39 °F and relatively low humidity (70%) to prevent losses.