Abstract
Phytophthora alticola was first isolated and described from plantation eucalypts in South Africa (RSA), and has more recently been found in Western Australia (WA), where it has only been isolated from nurseries and urban tree plantings, predominantly from eucalypts. Phytophthora arenaria has been isolated from vegetation occurring on the northern sandplains of southwest WA, predominantly from Banksia spp. A number of isolates with similar morphological characters to P. arenaria have been isolated, but with some variation in ITS region sequences, and have been referred to as P. aff arenaria type I (with the vast majority of isolates coming from nurseries and urban tree plantings) and type II (predominantly from the northern sandplains). A re-evaluation of these species suggests that type I isolates are P. alticola, while type II isolates are P. arenaria. A detailed overview of how this taxonomical evaluation has been undertaken will be discussed. While it is thought that P. arenaria is endemic, we are still to ascertain whether P. alticola is endemic or has been introduced to Western Australia.