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