Clubroot
A soil-borne disease of cabbage-family plants that causes swollen, distorted roots, wilting and stunted growth.
Also known as: Club root of brassicas
Symptoms and identification
Plants wilt on warm days and recover at night, look stunted, and have yellowish or purplish leaves. When lifted, the roots are swollen into club-shaped lumps that rot.
Causes
The organism Plasmodiophora brassicae lives in the soil for many years and thrives in acidic, wet soils. It spreads in infected soil, transplants and water.
Organic treatment
Lift and bin affected plants with their roots; do not compost them. Lime the soil before replanting and grow brassicas in containers with fresh mix.
Prevention
Raise seedlings in clean potting mix, improve drainage, and raise the soil pH above 7 with garden lime. Rotate brassicas with other crops for several years.
Chemical treatment (use with care)
No home-garden chemical cures clubroot. Rely on liming, rotation and resistant varieties.