The data set provides information on the incidence, prevalence and severity of a rust fungus Triphragmium ulmariae occurring in populations of the herbaceous perennial Filipendula ulmaria growing on a range of islands in the Skeppsvik archipelago, northern Sweden. These data, together with information on the size of individual host populations, has been used to monitor the impact of the disease on host population growth rates and temporal and spatial dynamics in a natural plant pathogen - host metapopulation system. See Zhan, J., Ericson, L., González-Jiménez, J. & Burdon, J.J. (202*). Disease affecting host population growth rates in a natural wild plant-pathogen association over a 30-year period. Journal of Ecology, accepted. And Smith, David L., Ericson, Lars & Burdon, Jeremy J. (2003) Epidemiological patterns at multiple spatial scales: an 11-year study of a Triphragmium ulmariae– Filipendula ulmaria metapopulation. Journal of Ecology 91 (5), 890-903. for further details.