IDENTITY AND HOST ALTERNATION OF SOME WILLOW RUSTS (MELAMPSORA SPP) IN ENGLAND

Six species of Melampsora: M. salicis-albae, M. larici-pentandrae, M. amygdalinae, M. capraearum, M. ribesii-viminalis and M. epitea, were i dentified among 26 willow leaf samples collected mainly in SW England. Identification of species was based on the morphology of the uredinia l and telial stages as well as on the results of inoculations of the a ecial hosts. M. epitea occurred alone in 18 leaf samples, and together with M. ribesii-viminalis in one further sample. Basidiospores produc ed from teliospores of the autoecious M amygdalinae infected Salix tri andra (a species of tree willows). All other species were heteroecious , with M. laricipentandrae, M capraearum and M epitea producing spermo gonia and aecia on Larix decidua (European larch), and less readily on L. kaempferi (Japanese larch). M. ribesii-viminalis and a form of M. epitea from S. purpurea, occasionally formed spermogonia but not aecia on Ribes spp. M. epitea, M. capraearum, and M. ribesii-viminalis occu rred on cultivars of shrub willows which are favoured for short-rotati on, coppiced energy cropping in the U.K.