Clubroot
Disease · Commonly affects: cabbages, cauliflowers, broccoli, kale, Brussels sprouts, pak choi, turnips, radishes
Clubroot is a persistent soil-borne disease of brassicas. It causes roots to swell and distort, preventing plants from taking up water and nutrients properly. It is widespread on some UK allotments and gardens, particularly where brassicas have been grown repeatedly in wet, acidic soil. Spores can survive for years, so prevention and planning matter greatly.
How to identify it
Plants may appear stunted, yellowish and permanently short of water, wilting in warm sunshine despite moist soil. The sure sign is below ground: roots are swollen into irregular, club-like galls, often 10-50 mm or more across, instead of having fine white roots. Young plants may have one enlarged root; older plants can have several knobbly, distorted masses. Later, these galls may rot and release more resting spores into the soil.
Damage
Damaged roots cannot supply enough water or nutrients, so plants grow poorly, wilt repeatedly and may fail to form proper heads, curds or sprouts. Young brassicas can die. Infected plants leave the soil contaminated for future brassica crops, turning a single disappointing season into a longer-term crop-rotation problem if no action is taken.
Prevention
Grow brassicas in a long rotation and avoid moving soil from an affected bed to clean ground on boots, tools or roots. Improve drainage and add lime where a soil test shows that acidity needs correcting. Raise plants in clean modules using fresh peat-free compost, then plant out sturdy transplants. Choose resistant varieties when available. Keep beds free of brassica weeds such as charlock, and clean tools before working elsewhere.
How to manage it
Lift and bin badly affected plants, including as much root material as possible; do not compost them. Do not replant brassicas in the same bed for several years. Mark affected areas so future rotations are realistic. Improve drainage with organic matter and use raised beds where appropriate. For the next brassica crop, use healthy module-raised plants and resistant varieties. Remove brassica weeds promptly, as they can maintain the disease between crops.
Clubroot: frequently asked questions
How do I identify clubroot?
Plants may appear stunted, yellowish and permanently short of water, wilting in warm sunshine despite moist soil.
How do I prevent clubroot?
Grow brassicas in a long rotation and avoid moving soil from an affected bed to clean ground on boots, tools or roots.
How do I get rid of clubroot?
Lift and bin badly affected plants, including as much root material as possible; do not compost them.
General guidance for UK home gardens and allotments, focused on prevention and non-chemical control. For a confirmed diagnosis, the RHS or a local garden centre can help. Page updated 19 Sep 2026.