In February, a vigilant citizen scientist photographing flowering shrubs in the gardens of the National Museum of Australia spotted conspicuous yellow pustules on the leaves of a Geraldton wax plant (Chamelaucium uncinatum). The report, submitted via iNaturalist Australia, alerted the ACT government’s biosecurity officers. On confirmation by the Environmental Protection Authority in March, two infected wax bushes were removed in April, and the site was subject to sanitation protocols. The discovery marks the first known case of myrtle rust (Austropuccinia psidii) in the museum grounds and has prompted renewed surveillance across the Australian Capital Territory (ACT).
What Is Myrtle Rust and Why Is It Dangerous?
Myrtle rust is a fungal pathogen native to South America that produces bright yellow to orange spores on young shoots, buds and fruits of Myrtaceae family members—among them eucalypts, bottlebrushes, tea-trees and lilly pilly. The fungus can severely distort leaf and shoot growth, impair flowering and fruiting, and in extreme cases, kill susceptible species outright. In its wake, entire understory communities can collapse, undermining habitat for native animals and disrupting bushfire resilience.
Historical Footprint in Australia
First detected on Weeping Lilly Pily near Brisbane in 2010, myrtle rust has since spread along the eastern seaboard and into northern Australia, causing dieback in several rainforest and woodland species. Emergency responses, including mass pruning of infected foliage and fungicide treatment, have slowed—but not halted—its march. In the ACT, trace detections occurred in a commercial nursery in 2022 and intermittently at the Australian National Botanic Gardens in Canberra, but each previous outbreak was successfully eradicated before becoming established.
The National Museum Incursion: A Cause for Concern
Unlike earlier detections confined to greenhouse and nursery settings, the National Museum infections occurred on open ground, where wind and insect vectors can disperse spores across wide areas. Renowned mycology researcher Dr Benjamin Schwessinger of ANU warns that “if rust has taken hold in a public, heavily trafficked area like the Museum grounds, it may already be present on wild eucalypts and tea-trees nearby.” His team will conduct follow-up surveys in spring—when new growth provides fresh infection sites—to determine whether the pathogen has overwintered and formed a self-sustaining population.
Vulnerable Species and Ecological Risks
Founder of the Invasive Species Council Tim Low highlights the particular vulnerability of Canberra’s iconic prickly tea-tree (Leptospermum continentale) and the planted Geraldton wax, used extensively in urban landscaping. “If left unchecked, myrtle rust could decimate local tea-tree understories and threaten the regeneration of native eucalypts after fire,” Low warns. He estimates that at least 16 rainforest-dependent Myrtaceae species face extinction without emergency intervention, though many are not found in the ACT.
Government and Community Mobilization
Following the museum detection, the ACT Environment, Planning and Sustainable Development Directorate (EPSDD) has intensified inspections of parks, streetscapes and private gardens, deploying trained officers and citizen volunteers to report suspect symptoms. Fungicide trials on potted specimens are underway, and waste-water runoff from the museum site has been tested to ensure spores are not carried offsite. EPSDD Director of Biosecurity Mark McCabe assures that “resources will be in place for repeated spring and summer sweeps to nip any nascent rust colonies in the bud.”
Challenges of Control in Wild Settings
While fungicidal sprays—typically copper- or triazole-based—can protect high-value ornamental or heritage trees, treating large tracts of public bushland is neither practical nor ecologically benign. McCabe notes that “blanket chemical treatment risks harming non-target species and aquatic invertebrates.” Instead, the agency is exploring biological controls, such as hyperparasitic fungi that attack rust spores, though these remain experimental.
The Climate Factor: Canberra’s Advantage—and Risk
Myrtle rust thrives in warm, humid climates. Canberra’s cool, dry winters have historically limited the pathogen’s southern spread. “The Australian Capital Territory enjoys a natural climatic buffer,” says Tim Low, “but increasingly erratic rainfall and warmer winters could erode that advantage.” As climate change raises average annual temperatures and summer humidity, the risk of establishment on wild Myrtaceae communities in the ACT will grow.
Regional Coordination and Indigenous Knowledge
EPSDD is collaborating with the NSW Department of Primary Industries, CSIRO and local Landcare groups to share data and coordinate responses across the NSW–ACT border. Aboriginal elders from Ngunnawal Country have been invited to guide the team on culturally significant stands of eucalypt and melaleuca, ensuring that surveillance priorities respect sacred sites and traditional ecological knowledge.
Looking Ahead: Prevention, Preparedness and Public Engagement
As the ACT braces for another spring of heightened rust activity, authorities stress the importance of public vigilance. Gardeners are urged to inspect new Myrtaceae plantings for yellow lesions, sterilize pruning tools between sites and source nursery stock from rust-free suppliers. The Nursery and Garden Industry Association has distributed rust-monitoring kits to its members and is exploring certification schemes to guarantee rust-tested plants.
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In the long term, breeding programs led by the Australian National Botanic Gardens and CSIRO aim to develop rust-resistant cultivars of key species—including the prickly tea-tree and lilly pilly—through conventional selection and genomic screening. Meanwhile, the detection at a national institution underscores the need for rigorous biosecurity controls at all public venues.
Conclusion: A Call to Unified Action
The discovery of myrtle rust at the National Museum of Australia is a stark reminder that invasive plant diseases can breach botanical sanctuaries and urban landscapes alike. While the ACT’s cooler climate and swift removal of infected specimens have thus far prevented establishment, the window for eradication narrows with each warmer winter and rainy season. By combining government surveillance, community reporting, cultural partnerships and scientific innovation, Canberra can stand a fighting chance to protect its treasured Myrtaceae species—and the ecosystems that depend on them—from this relentless fungal invader.
