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Clubroot
Plasmodiophora brassicae
Fungal diseaseHigh impact
A severe soil-borne disease causing grotesque swelling and distortion of brassica roots. Infected plants cannot take up water or nutrients effectively and typically collapse or die back. Spores survive in soil for up to 20 years. One of the most serious diseases affecting the brassica family.
Currently in peak season - extra vigilance worthwhile.
Key facts
- Type
- Fungal disease
- Affects
- Kale · Cabbage · Broccoli · Cauliflower · Brussels-sprouts · Turnip · Pak-choi · Radish
- Active season
- Apr - Sep
- Peak season
- Jun - Aug
- Vulnerable stages
- Growing
- Spread rate
- slow
- If confirmed
- Act now
Signs & symptoms
- -plants wilting badly in warm weather despite adequate watering
- -swollen, distorted, club-like root growths when plants are lifted
- -stunted growth and pale or yellowing leaves
- -plants failing to establish or dying back unexpectedly
Management
Do now
- -Remove and bin all infected plants including as much root material as possible - do not compost
- -Do not move soil from the affected area to other parts of the garden
- -Mark the affected bed and avoid growing any brassica there for as long as possible
Prevention
- -Raise soil pH to 7.0-7.5 with lime - clubroot is inhibited in alkaline conditions
- -Raise transplants in modules and transplant with a large plug of clean compost to give roots a disease-free start
- -Rotate brassicas - minimum 4 years between crops on the same ground
Further reading
- -Clubroot spores can survive in soil for up to 20 years - once a bed is infected, brassica growing there is long-term compromised
- -The disease is favoured by acidic, poorly drained soils