Phytophthora spp. are devastating plant pathogens in both agricultural and natural environments. Since little is known about the occurrence and spread of Phytophthora spp. in Sardinia, a survey was carried out in various forest ecosystems. Overall two chestnut groves, one oak stand, two riparian ecosystems and three forest nurseries were surveyed. Isolations were made directly from symptomatic plant tissues and using Rhododendron leaves and apples as bait. Molecular and morphological characterizations were used to identify the isolates. Aggressiveness of the Phytophthora isolates was assayed by different methods: soil infestation and stem inoculation of seedlings and by inoculating living logs. It was also evaluated the ability of some species to produce in vitro phytotoxic metabolites. The survey revealed the presence of 12 species of Phytophthora: P. cambivora, P. cinnamomi, P. cinnamomi var. parvispora, P. cryptogea, P. gonapodyides, P. ilicis, P. nicotianae, P. pseudosyryngae, P. taxon niederhauserii, P. taxon salixsoil, Phytophthora sp. 1 e Phytophthora sp. 2. In particular: P. cinnamomi var. parvispora, P. pseudosyringae and P. taxon niederhauserii were recorded in a new association host-pathogen in Italy. Another species, P. ilcis is here reported for the first time in a natural ecosystem in the Mediterranean basin
