Since its introduction to Australia in 2010, the invasive rust fungus Austropuccinia psidii (myrtle rust, formerly Puccinia) has caused severe declines in several previously common Myrtaceous species. While there have been diligent efforts of a few research groups to understand the extent and impact of myrtle rust, there are still many unknowns. To facilitate a more co-ordinated effort on managing the threat from myrtle rust, this study builds on previous work by: 1) compiling an updated Australian host list; 2) collating known occurrences of myrtle rust in Australia using records gathered from researchers, government departments and natural resource managers; 3) using this updated occurrence data to model climate suitability for myrtle rust in Australia under current and future climatic conditions with MaxENT software; 4) identifying species at risk based on range overlaps with myrtle rust, susceptibility data and current threat status.
So far, 380 native Australian Myrtaceae species have been tested for susceptibility to myrtle rust, with 366 found to be susceptible. Presently, myrtle rust appears in coastal areas of QLD, NSW, VIC, TAS and the Tiwi Islands. The models suggest that under current climatic conditions, the known occurrence data aligns well to the expected areas of climatic suitability. While previous bioclimatic modelling has shown high climate suitability for myrtle rust in south-west Western Australia, our modelling found only low climatic suitability for this region. We found 867 Myrtaceae species had ranges within the area of current climate suitability for myrtle rust and 1207 Myrtaceae species had ranges within the area of future climate suitability. The majority (65 to 73%) of these species are untested for susceptibility. Three categories of actions were created for species expected to be exposed to myrtle rust, giving priority to species with at least 90% of their range overlapping climatically suitable areas for myrtle rust.