Myrtle rust update from Australia

It has been twelve years since myrtle rust established along the east coast of Australia. Australia is home to more than 2,500 species of Myrtaceae, and myrtle rust has had a devastating impact on this iconic Australian flora. Four native species have been listed as Critically Endangered due to myrtle rust, including once-ubiquitous rainforest trees. Another dozen or more species are believed to be in a similar precarious state but have not had sufficient assessments to be able to be classified under Australia’s threatened species listing processes. Repeated, severe damage from myrtle rust has seen local extinctions of these species across eastern Australia, with only a handful of locations having any semblance of individuals that could be classed as “surviving”. The reproductive capacity of these species is virtually non-existent, and they are on the brink of extinction. Conservation efforts are underway to try and stave-off extinction. The knock-on impacts of the loss of these species, such as co-dependant flora and fauna and ecological systems, are not known and yet to be investigated. Early signs point to a change in composition of flora, with non-Myrtaceae starting to dominate forests once dominated by Myrtaceae. Compounding the impact of myrtle rust is fire in the landscape, including the Black Summer wildfires of 2019‒2020 that burnt 8.5 million ha (21 million acres) of forest. Vast stands of regenerating Myrtaceae are at threat of damage with new shoots and leaves ideal for infection by myrtle rust. Monitoring of burnt stands has seen a loss of Myrtaceae, replacement by non-Myrtaceae, and in some cases a dominance of weedy species. Managing myrtle rust in a native landscape shaped by fire is no simple task. Partnerships have been developed with Indigenous Australians to understand the cultural impact of myrtle rust on country, using cross-cultural learning to increase our knowledge of how to manage biosecurity threats to native ecosystems.