Clubroot

Plasmodiophora brassicae

also called Finger and toe

A soil disease that swells and distorts brassica roots; plants wilt and stunt. Lime the soil toward pH 7, improve drainage, and rest infected ground from brassicas for years.

Fungus No cure Soil-borneSpread in waterSpread on tools & hands Spreads to neighbors

What you'll see

Lifted roots are swollen into knobbly clubs and fused fingers instead of a normal fibrous system.
Plants wilt in sunshine and pick up overnight, then stop recovering as the season goes on.
Growth is stunted and pale, often with a purple or reddish cast to the older leaves.
Swellings eventually rot to a foul-smelling slimy mush, releasing spores back into the soil.
Unlike gall weevil damage, the swellings are solid throughout with no grub or hollow chamber inside.

Why it happens

Not a true fungus but a soil-dwelling slime mold, which is why fungicides do nothing against it. Its resting spores survive in the soil for up to twenty years and germinate when a brassica root grows near them. It usually arrives on the roots of bought-in plants, on muddy boots and tools, or in imported soil and manure.

Acid, wet, poorly drained soils in a warm summer favor it most. Repeated brassica cropping on the same ground builds the spore load until even a short rotation cannot outrun it.

Treating it

There is no cure for an affected plant. Lift it whole, with as much root as possible, and bin or burn it — never compost it.
Lime the ground to bring the pH toward 7.0 to 7.5, which does not kill the organism but slows infection considerably.
Improve drainage with organic matter and raised beds so the swimming spores cannot move freely.
Where you must grow brassicas, raise them in large pots of clean compost so they go out with a big established root system, and earth them up.
Rest the ground from all brassicas, including radish, rocket, swede and wallflowers, for as long as you can manage.

Keeping it away

Raise your own plants from seed rather than buying in brassica plugs of unknown origin.
Grow clubroot-resistant cultivars such as the Clapton and Kilaton types where the disease is established.
Keep a strict rotation and never follow brassicas with brassicas.
Clean soil off boots, tools and barrow wheels before moving between beds.
Weed out charlock, shepherd’s purse and other brassica weeds, which host it quietly.

Who gets it

All brassicas — cabbage, kale, sprouts, cauliflower, broccoli, swede, turnip and radish — plus wallflowers, stocks and brassica weeds.

and 9 more in the catalog