Clubroot
A soil-borne organism that distorts brassica roots into swollen clubs, so the plant cannot take up water and wilts in sunshine while the soil is still wet. Its resting spores survive in soil for around twenty years, which makes it the one brassica problem that permanently changes what a plot can grow.
Caused by: Plasmodiophora brassicae
Nothing available to a home grower will fix this
There is no treatment that removes clubroot from soil. Once a plot has it, brassicas are grown around it — with resistant cultivars, liming, large transplants and long rotations — rather than after clearing it.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Clubroot
Checked 2026-08-13
Described view
Two cabbage plants compared: one uniformly pale from the oldest leaves upward with the plant otherwise upright and the root system normal, and one lifted from the ground beside it with its roots swollen into the knobbled club-shaped galls of clubroot and the lower leaves yellowing and wilting in sunshine
What brings it on
Favoured by acid, wet, poorly drained soil and warm conditions. Spores move in soil water and on boots, tools and the roots of bought-in plants — which is how most clean plots first acquire it.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Clubroot
- University of Minnesota Extension — University of Minnesota: Clubroot of cole crops
Checked 2026-08-13
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Raise your own brassicas from seed rather than buying plants in, and never accept a gift of plants from a plot with clubroot. Introduction on roots is the commonest route in.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Clubroot — avoiding introduction
Checked 2026-08-13
- Lime acid soil to raise the pH towards neutral before planting brassicas. The organism is much less active in alkaline conditions.
Sourced guidanceDepends on conditionshigh confidence
Applies when: Liming suppresses the disease; it does not eradicate it, and it is only appropriate where a soil test shows the pH is genuinely low.
- Royal Horticultural Society: Clubroot — liming
Checked 2026-08-13
- Improve drainage, and rotate brassicas around the plot on the longest cycle the space allows.
source
Sourced guidancehigh confidence
- Garden Organic — Garden Organic (Henry Doubleday Research Association): Clubroot — cultural control
Checked 2026-08-13
Dealing with it once it is there
- On infested ground, raise plants in large modules or pots so they go out with a substantial root system, and choose a clubroot-resistant cultivar. Plants often crop adequately despite infection if they start large enough.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Clubroot — growing on infested soil
Checked 2026-08-13
What it affects
Signs that lead here
Each of these lists the other things that produce the same sign, and how to tell them apart.
On sprays and treatments
GrowingHQ does not tell anyone what to apply, at what rate, or how often. Pesticide approvals differ by country, change without notice, and the product label is legally binding — it is also the document you are holding. What is described here is cultural and physical control, which is what a home grower can act on without a label in front of them.
Plant-specific guides
Where this is one of several causes that look alike on a particular plant, GrowingHQ publishes the differential rather than the general answer.