Club Root

Plasmodiophora brassicae is a parasitic protist in the class Phytomyxea that causes clubroot disease, one of the most economically damaging soilborne diseases of Brassica crops worldwide. Despite being historically classified as a slime mold, molecular studies place it within the Rhizaria. P. brassicae infects the roots of plants in the family Brassicaceae, including economically important crops such as cabbage, broccoli, cauliflower, canola, and mustard. Infected roots develop characteristic swollen, club-shaped galls from which the common name derives. These galls disrupt water and nutrient uptake, causing wilting, stunted growth, and yield losses. The pathogen produces environmentally resistant resting spores that persist in soil for decades, making eradication practically impossible once a field is infested. P. brassicae is distributed globally wherever brassicaceous plants are grown, facilitated by movement of infested soil and plant material. The disease is managed through crop rotation, liming to raise soil pH, use of resistant cultivars, and fungicide treatments. The species has not been evaluated for IUCN conservation status, as it is considered a harmful plant pathogen rather than a species of conservation concern.