Phytophthora in the Gondwana Rainforests of Australia World Heritage Area

Abstract

The Gondwana Rainforests of Australia World Heritage Area (GRWHA) covers approximately 370,000 ha, extending along Australia’s east coast from southeast Queensland to central eastern New South Wales (NSW). The rainforests include cool temperate and subtropical ecosystems supporting a high biodiversity of plant and animal species. More than 200 plant species found in the GRWHA are rare or threatened, and invasion by pest species, including Phytophthora, is a significant concern. The current study used a sample design based on GIS layers representing conditions conducive to Phytophthora, including the presence of human disturbance, rainfall, temperature, elevation and slope, to determine the probability of Phytophthora occurring at a particular location and to identify sampling locations within the GRWHA. Sampling at these sites revealed eight Phytophthora species; P. cinnamomi, P. cryptogea, P. multivora, P. heveae, P. frigida, P. macrochlamydospora, two isolates referred to as Phytophthora gondwanense prov. nom. and one isolate referred to Phytophthora sp. (clade 4). Species were identified based on internal transcribed spacer (ITS) and cytochrome oxidase subunit II (cox II) data. The greatest diversity of Phytophthora species was found in the Oxley Wild Rivers National Park. This is the first report of P. frigida in Australia and is the first study to detect P. multivora within the GRWHA. Identification of these Phytophthora species within the GRWHA is concerning due to the unknown susceptibility of endemic native flora.