All Brassicas, Stocks and Wallflowers can be affected. Foliage is pale pinkish in colour and wilts in sunny weather. Roots are swollen and distorted and plants grow slowly or die. Affected roots have an unpleasant smell. Affected plants can fail completely or produce a poor crop.
Cultural measures: Ensure land is adequately drained and well limed. Plant resistant varieties. Practice crop rotation - rotate your brassica crops annually to avoid disease. Don't grow brassicas on the same plot more often than one year in three, as moving the crop helps avoid the build up of soil pests and diseases. Clubroot can remain viable in the soil for up to 20 yrs.
Raise plants in clean compost in individual pots of at least 5cm diameter. Plant out when plent of roots have formed. Choose reistant vegetable cultivars such as Calabrese 'Trixie', Chinese cabbage 'Harmony', Kale 'Tall Green Curled' and Swede 'Marian'
There are currently no chemical registered for the control of this problem.