Clubroot, a destructive disease of Brassicaceae, is caused by the soilborne, biotrophic protist Plasmodiophora brassicae. The pathogen was first identified by Mikhail Woronin in 1875 and named turnip disease in England. This pathogen has a unique, multiphase life cycle that takes place largely within a living host; however, it can also persist as resting spores in the soil for several years. P. brassicae pathotypes have strong adaptability, enabling them to overcome host resistance. Sustainable control requires an integrated approach, combining resistant cultivars, crop rotations, and soil amendment to optimize soil pH. The complexity and severity of clubroot have led to research efforts over the past 145 years, yielding significant advances in integrated disease management. Here, we discuss recent discoveries in the pathogenesis of P. brassicae, focusing on pathogen distribution, genetic diversity, trends in host-pathogen interactions, and advancements in genomics and effector biology as well as approaches to disease management.