The occurence and economic impact of Plasmodiophora brassicae and clubroot disease

\ud The significance of Plasmodiophora brassicae Woronin and the disease which it incites in members of the family Brassicaceae are reviewed as the focus for this Special Edition of the Journal of Plant Growth Regulation. Naming of the disease in vernacular terms indicates a well established importance in agriculture and horticulture from the Middle Ages onwards in Europe. Subsequent spread probably resulted from transfer on and in fodder used by colonists’ livestock. Symptoms, worldwide distribution and economic impact are described. Clubroot disease devastates infected vegetable and agricultural crops. Particular importance is placed on the most recent reports of crop losses in tropical countries, albeit where the crops are grown in cooler altitudes and in the Canadian prairie land canola crops. This latter is of enormous importance since this crop is the single most importance source of vegetable oils used in human food and industrial lubrication.