Fusarium wilt

Worst in warm soils through summer, December to March.

Fusarium wilt is a soil fungus that blocks the water-carrying vessels inside the stem, so plants wilt and die even in moist soil. It hits tomatoes, cucurbits, peas and beans, often striking one side of a plant first, and it lingers in the soil for years.

How to identify

• Plants wilting in the heat, often one side or one branch first
• Lower leaves yellowing and dying upward from the base
• Brown streaks in the stem tissue when a stem is sliced lengthwise
• Gradual collapse despite adequate watering

How to prevent

• Grow resistant varieties, often marked F or FF on the label
• Rotate crops on a long cycle and avoid replanting hosts in the same bed
• Improve drainage and avoid waterlogging, which favours the fungus
• Keep tools and trays clean and start with disease-free seedlings

How to control organically

• Pull out and dispose of infected plants whole, never composting them
• Avoid replanting susceptible crops in the affected bed for several years
• Build soil biology with compost to suppress the fungus
• Solarise badly affected beds over summer before replanting
• Switch the bed to resistant or non-host crops