Research status of clubroot (Plasmodiophora brassicae) on cruciferous crops in China

Clubroot, caused by Plasmodiophora brassicae, has emerged as a serious disease threatening the cruciferous crop production industry in China. The distribution, occurrence, physiological races and transmission routes of P. brassicae are briefly described here, providing a basis for understanding the serious implications of clubroot disease in China. Strategies for managing clubroot in a Chinese context are also discussed. Approximately 3.2–4.0 million ha of cruciferous crops are infected by P. brassicae every year in China, causing yield losses of 20–30%. The identification of physiological races is of fundamental importance for breeding clubroot-resistant cultivars. Race 4 of the pathogen, as classified on the differentials of Williams, has been spreading all over China and is becoming increasingly damaging to cruciferous crops. Dissemination of P. brassicae is mainly via the movement of resting spores on seed or in infected plant material. Spore dispersal over short distances depends on the movement of infested soil, wind, water and livestock manure. Integrated control strategies include the development of resistant cultivars, soil liming, fungicide applications and use of biological control agents.