The broad-host range plant pathogen Ralstonia solanacearum is a treat for Swiss agriculture and therefore classified as quarantine organism. The current detection methods are, however, cumbersome. Testing surface water at strategic sites, especially downstream of locations where potential host plants are present, appears as an efficient tactic to assess the presence of R. solanacearum over an extended area. This project thus aims at two main points: 1) development of a sampling method for surface water samples that reliably and efficiently allows pathogen detection, and 2) development of a highly specific, selective and sensitive molecular detection method. We envisage a two-step detection method, which first allows high-throughput species level detection followed by subtyping to detect the most pathogenic phylotypes. The developed method will be validated on a comprehensive number of potentially high-risk surface water samples taken throughout the country allowing thus determining the current situation of the pathogen population in Switzerland. Next to the application of the detection method to different samples, the knowledge base developed in this study will influence the management regulations to protect Swiss agricultural production. The need for a reliable diagnostic tool for R. solanacearum is evident and the main reason for close collaboration with EPSD and Agroscope. Two other partners, EAWAG and WSL, will support this project based on their specific expertise.