Occurrence of Phytophthora species in riparian stands of black alder (Alnus glutinosa) in Slovakia

During the monitoring period of alder decline phenomenon in Slovakia, indicative symptoms of Phytophthora diseases were observed in riverside stands in Slovakia. The study aimed to test the presence and diversity of Phytophthora species in declining alder stands. The samples were collected from six stands situated by rivers/streams in the central and eastern parts of Slovakia. Phytophthora plurivora and P. cactorum were detected in soil, root and water samples. The most isolated species was P. plurivora. Both Phytophthora species have been recognized in the literature as the perpetrators of black alder dieback together with other species, such as P. alni or P. polonica. To our knowledge, this is the first report of P. plurivora and P. cactorum in riverside stands with the main share of black alder in Slovakia.