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Xanthomonas campestris pv. campestris (Xcc) is a vascular pathogen that invades the xylem of Brassica crops. Current chemical and antibiotics-based control measures for this bacterium are unsustainable and inefficient. After establishing a representative collection of Xcc strains, we isolated and characterized bacteriophages from two clades of phages to assess their potential in phage-based biocontrol. The most promising phages, FoX2 and FoX6, specifically recognize (lipo) polysaccharides, associated with the wxc gene cluster, on the surface of the bacterial cell wall. Next, we determined and optimized the applicability of FoX2 and FoX6 in an array of complementary bioassays, ranging from seed decontamination to irrigation- and spray-based applications. Here, an irrigation-based application showed promising results. In a final proof-of-concept, a CaCl2-formulated phage cocktail was shown to control the outbreak of Xcc in the open field. This comprehensive approach illustrates the potential of phage biocontrol of black rot disease in Brassica and serves as a reference for the broader implementation of phage biocontrol in integrated pest management strategies. The authors thank A. Volckaert for her input, Dr. L. van der Heijden (Bejo Zaden B.V.), Ms. K. Sereti (Rijk Zwaan Zaadteelt en zaadhandel B.V.) for providing seed material and Prof. L. Cruz for providing us with a wellcharacterized Xcc collection. They further thank Miss Y. Busschots for her technical assistance. This research was supported by the ‘Vlaams Agentschap Innoveren en Ondernemen’ (VLAIO) agriculture programme (LA) grant IWT.150914 and by the European Union’s Horizon H2020 Research and Innovation Programme (grant agreement N. 773567). DH holds a predoctoral scholarship from the ‘Fonds voor Wetenschappelijk Onderzoek Vlaanderen’ (FWO) strategic basic research grant 1S02520N.