Myrtle rust is a disease limited to plants in the Myrtaceae family. It is a member of the guava rust complex caused by Puccinia psidii, a known significant pathogen of Myrtaceae plants outside Australia. In Australia, infestations are currently limited to New South Wales, Victoria, Queensland and Tasmania. Tasmanian infestations appear to be limited to nursery plant hosts (predominately Lophomyrtus species) in residential gardens i.e. not been found in native bushlands.