Present, emerging or re-emerging plant diseases due to infection by bacteria of the Lysobacteraceae (syn: Xanthomonadaceae) family are continually challenging food security and cause significant losses to the economies of European countries each year. To address this challenge, concerted R&D actions at the international level were supported by the COST Action networking instruments. COST (European Cooperation in Science and Technology) is a pan-European intergovernmental framework with the mission of enabling break- through scientific and technological developments leading to new concepts and products, thereby contributing to strengthening Europe’s research and innovation capacities.