An invasive fungus that attacks some of Australia’s most ecologically important tree species has spread to Western Australia while also thriving in wet conditions along the country’s east, triggering a “silent extinction” and urgent calls for a national response.
Experts warn that if the myrtle rust fungus discovered in East Kimberley has reached the state’s biodiversity-rich southwest, the consequences could be dire for those ecosystems.
Since its discovery in a NSW nursery in 2010, the fungus – known for its bright yellow and rust spots on leaves – has settled along the east coast and has been detected in every state except South Australia.
One 2021 study predicted that myrtle rust would claim at least 16 rainforest plants within a generation in an extinction event of “unprecedented magnitude”.
The fungi affect plants in the myrtle family – a diverse group that includes rainforest species, leafy gardeners, eucalyptus, and myrtle. Guava, which was once widespread, has been eradicated by fungi.
A team led by the Department of Primary Industries in Western Australia discovered the fungus in nine broad and narrow leaf gardens in eastern Kimberley in late June. The exact species affected by Melaleuca is not yet known.
The department surveys tourist points and nurseries, with no new discoveries yet. A spokesman for the department said the potential impacts were “not yet determined”, but the disease could cause trees to die, dying, losing species, and putting ecosystems at risk.
Dr Louise Choi, a forester with the Queensland Department of Agriculture and Fisheries, traveled to Kimberley to help with detection efforts.
“Myrtle rust can travel hundreds of kilometers in the wind and that is why it has spread so far,” she said.
The site was investigated after modeling indicated isolated wetlands as a possible site, spreading from affected vegetation in the Northern Territory to the east.
Alyssa Martino, a research scientist at the University of Sydney, began testing 25 types of Melaleuca WA to check for susceptibility to the fungus, which originated in South America. The first three tested showed a high susceptibility to infection.
Martino said rust is driving the extinction of plant species, so understanding how different plants interact will help conservation efforts.
Keeping rust out of Western Australia’s biodiversity hotspot in the southwest will be critical, Shuey said, as it has been the most diverse region on the planet for pest animals — with nearly half of the world’s species.
Conservation botanist Bob McKinson has coordinated a national action plan – developed voluntarily by relevant scientists and wild plant managers – through the Australian Plant Conservation Network.
About 350 Australian species have been identified as hosts of the fungus. The pests found in the state’s southwest, McKinson said, are essential parts of the ecosystem.
“Many of them are part of the wild spring communities that attract tourists from all over Australia and the world,” he said.
“If it settles there, we are likely to see a significant increase in the number of host species and in the number of native species that are threatened with extinction or extinction. It could be a biological disaster.”
Fungi especially love moisture and fresh plants, and therefore thrive on new growth after rain or after a wildfire, which means the humid conditions in the east of the country have provided the perfect environment.
The National Action Plan was completed in 2020 but has not been formally adopted by governments.
“While some agencies and researchers are heroically active in this field, their efforts need to be expanded, linked together, and better resourced,” MacKinson said.
James Trezzis, the Invasive Species Council’s director of conservation, said myrtle rust was driving a “silent extinction” among Australia’s diverse plant life.
“The system for dealing with this major environmental threat is clearly not working,” he said.
“Australia already has a disturbing title as a global leader in the field of mammal extinction. If we do not strengthen our threat reduction and biosecurity systems, we may also find ourselves as a global leader in plant extinction.”
The Federal Environment Minister, Tanya Plibersek, agreed on the need for a coordinated response and said the government was working to implement a national action plan.
“There have been targeted investments to conduct a national inventory of myrtle species susceptible to rust and to provide specific myrtle rust training to indigenous rangers and landowners in New South Wales and Queensland,” she said.