Clubroot
Risk near you, next 48h
See whether your local forecast favours this disease right now.
When it strikes
Fix the cause, not the leaf
No spray will help here. The trigger is soil, water supply, nutrition or temperature, so change the growing condition and judge the result on new growth, not on damaged leaves.
Soil and crop debris
It waits in the ground or in last season's debris, so removing the plant does not clear the bed. Rotation and debris removal are the working controls.
It carries over to next season in soil, debris or seed — which is why rotation matters here, not just treatment.
Keep out of the compost
This survives a garden heap. Bag it for municipal green waste, which is composted industrially at temperatures a garden heap cannot reach, or burn it where that is permitted.
When and where to look
Scout the planting while temperatures hold between 12°C and 27°C, with humidity above 70%, after rain or heavy dew, while the leaves are still wet.
Rule these out first
Same category, and at least one host crop in common — so they are genuinely confusable in the same part of the garden.
The signs that lead here
Full problem lists for these crops
About
Clubroot (Plasmodiophora brassicae) is a soil-borne disease of cabbage, broccoli, kale and other brassicas that swells the roots into useless galls and persists in soil for up to 20 years.
Symptoms
Stunting, wilting in midday heat, and yellowing of older leaves above ground; swollen, distorted club-shaped roots below ground that rot and smell.
Organic Treatment
Raise soil pH to 7.2 with lime to suppress the pathogen, improve drainage, and remove and destroy infected roots. Rest beds from brassicas for years.
Chemical Treatment
No effective chemical control in the garden; commercial growers rely on resistant varieties and liming.
Prevention
Plant resistant cultivars, lime acidic soils, rotate brassicas on a long cycle, improve drainage, and avoid spreading infested soil on tools.
Crops at risk
Related problems
Clubroot risk by location
Each location has a month-by-month profile computed from the weather archive: how many hours a year actually meet this disease’s thresholds.