Clubroot
Clubroot is a soil-borne organism that infects the roots of cabbages, cauliflowers, broccoli, kale and radishes, turning them into swollen, distorted clubs. Its spores survive in the soil for up to 20 years.
Fungal diseases
What it looks like
Lift a plant to be sure.
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Warm-day wilt Leaves flag in sun and recover overnight. -
Stunted plants Plants stay small with discoloured leaves. -
Swollen roots Roots are thickened into knobbly clubs. -
Rotting clubs The clubs rot and smell later in the season.
How to confirm it
Dig up a struggling plant.
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Club-shaped roots
Swollen, distorted roots confirm it.
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Acid, wet soil
Worse on acid, badly drained ground.
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Brassicas only
Only the cabbage family is affected.
What to do
Manage the soil for years.
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Remove plants and roots
Lift and bin infected plants before the clubs rot.
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Lime the soil
Raise pH to about 7.5 to reduce infection.
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Raise plants in pots
Grow transplants to a good size in clean compost before planting.
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Grow resistant varieties
Clubroot-resistant brassicas are widely available.
Prevent it next time
- Improve drainage.
- Never bring in soil or plants from infected ground.
- Clean boots and tools.
What not to do
Do not compost infected roots, or move soil from an infected bed.
In the growing guides
Where the guides mention it, with plant-specific advice.
Sources
- Club root, Royal Horticultural Society