Clubroot

Worst in warm, wet, acid soils through the main brassica season, spring through autumn.

Clubroot is a soil disease of brassicas that swells the roots into useless clubs, blocking water and nutrients. It thrives in acid, wet soils and survives many years in the ground, so once a bed is infected the focus shifts to lime, drainage and long rotations.

How to identify

• Brassicas wilting in the heat and recovering overnight
• Stunted, yellow, sickly plants that never get going
• Swollen, distorted, club-like roots when a plant is lifted
• Rotting, foul-smelling galls late in the season

How to prevent

• Lime the soil to raise the pH towards 7, since clubroot hates alkaline soil
• Improve drainage with raised beds and compost
• Rotate brassicas on the longest cycle you can manage, ideally 4 years or more
• Only plant clean, certified seedlings and never move infected soil around

How to control organically

• Lift and bin infected plants whole, roots and all, never composting them
• Lime the bed heavily and improve drainage before any replanting
• Rest infected beds from brassicas for several years
• Raise brassica seedlings in clean mix so they go in strong
• Grow clubroot-resistant varieties where available