Discovery of a fourth evolutionary lineage of Phytophthora ramorum: EU2

► We identified Phytophthora ramorum isolates of a new, fourth lineage, designated EU2. ► All P. ramorum EU2 isolates tested are of A1 mating type. ► Limited distribution and no SSR-based diversity suggest a recent introduction. ► Fast discrimination of EU2 lineage isolates is demonstrated with PCR-RFLP assays.