EN
In 1987-1991 a dramatic genetic shift occurred in P. infestans populations in Poland. This shift was expressed in electrophoretic pattems for gluco-6-phosphate isomerase (Gpi), peptidase (Pep), DNA fingerprints, specific virulence and sensitivity to metalaxyl. There was also a parallel breakdown in the resistance of the Polish potato cultivars Bronka and Bzura and some breeding lines of the Department of Genetics of the Potato Research Institute in Młochów caused by new migrating genotypes. This paper discusses the possible impacts of genetic changes in fungal populations on selected elements of late blight management, in particular on breeding potatoes durably resistant to late blight and chemical control. It postulates changes in breeding and management strategies that could enable obtaining durable resistance in potato cultivars and improve late blight management efficiency in Poland.