Species Involved in Decline in Portugal.

Recent field surveys conducted in five common alder ecosystems in Portugal have shown the occurrence of severe canopy dieback, bleeding canker and root rot symptoms indicative of infections. Isolations from symptomatic tissues, rhizosphere and water samples yielded a total of 13 species belonging to 6 phylogenetic clades, including (13 isolates), (10), (9), (6), (6), (4), (4), (3), (2), (2), (2), (1) and (1). Results of the pathogenicity test confirmed the complex aetiology of common alder decline and the additional risk posed by to the riparian habitats in Portugal. At the same time, the diversity of assemblages detected among the investigated sites suggests that different species could contribute to causing the same symptoms on this host. Two species, and are reported here for the first time in natural ecosystems in Europe.