Clubroot
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When it strikes
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.