Xanthomonas campestris pv. campestris: Current Knowledge and Emerging Biological Control Strategies Using Phyllosphere- and Rhizosphere-Associated Bacillus spp.

Xanthomonas campestris pv. campestris, the causal agent of black rot, is one of the most important bacterial pathogens affecting Brassicaceae crops worldwide. Its seed-borne nature, multiple routes of dissemination, and limited availability of resistant cultivars make black rot difficult to manage and underscore the importance of early and reliable pathogen detection. This review summarizes current knowledge on the epidemiology of X. campestris pv. campestris, with emphasis on advances in conventional and molecular approaches used for its detection and characterization, as well as on the currently used disease management strategies. Particular attention is given to biological control as a promising and sustainable alternative to conventional approaches. Recent studies on the use of Bacillus spp. for black rot control are discussed, with emphasis on their secondary metabolites and antimicrobial potential. Despite promising results including disease suppression, comparable to that achieved with chemical control, the translation of laboratory findings into reliable field applications remains challenging, particularly with regard to formulation and consistent efficacy under variable environmental conditions. Future research should focus on integrating current knowledge of pathogen epidemiology, diagnostics, and biological control to facilitate the development of sustainable and practically applicable strategies for black rot management in Brassica crops.