Myrtle rust (Austropuccinia psidii) was first detected in Australia in 2010. Fifteen years on, it has done what every plant pathologist working on it warned it would do: spread further than initial containment efforts could hold, and threaten species that the early surveys had not flagged as susceptible.

The latest aggregated survey data from the state plant health authorities, combined with the Plant Biosecurity Research Initiative reporting cycle, paints a sobering picture for May 2026.

Geographic spread continues south

The pathogen is now confirmed established in pockets of southern New South Wales coastal and ranges environments where it was not present three years ago. The northeastern Victorian detections that were treated as isolated incursions in 2023 have continued to expand, and several new finds in the Gippsland region during late 2025 suggest the southern containment line is no longer holding.

Tasmania remains free of confirmed established populations, but the surveillance burden on that boundary has increased significantly. The biosecurity arrangements at the Bass Strait crossing - particularly for nursery stock, cut foliage, and recreational visitors carrying plant material - continue to be the front line for protecting Tasmanian Myrtaceae.

Western Australia remains free, though the increase in incursion attempts on east-west freight has been notable through 2025. Each of the major freight pathways has had at least one interception event over the past twelve months that required tracing and follow-up surveillance.

The species impact picture has worsened

The list of native Myrtaceae species showing severe susceptibility has continued to grow. Several Rhodamnia and Rhodomyrtus species are now considered functionally extinct in significant parts of their natural ranges, with seed banking and ex-situ conservation now the principal management tools.

The expansion into native eucalypts remains the most worrying medium-term concern. Most eucalypt species have shown low to moderate susceptibility under field conditions, but the variability between individuals within a single species has been higher than the early modelling suggested. The implication is that the population-level impact over decadal timescales remains genuinely uncertain, and the precautionary management posture from the Department of Agriculture, Fisheries and Forestry is appropriate.

Several commercial production species - particularly in the cut foliage and ornamental sectors - have been hit hard enough that the industry composition has shifted. Some growers have exited Myrtaceae production entirely; others have moved to varieties with demonstrated resistance.

Surveillance technology is catching up

The encouraging development in the past eighteen months has been the maturation of remote sensing tools for myrtle rust surveillance. Several state agencies are now running operational programmes using drone-mounted multispectral imaging combined with AI-based detection models to identify symptomatic foliage in canopy environments where ground-based surveillance is impractical.

The detection sensitivity is genuinely useful - early-stage rust pustules show distinctive spectral signatures that the trained models can pick up before symptoms are visible to ground observers. The technology doesn’t replace ground confirmation, but it dramatically improves the efficiency of survey deployments by directing inspectors to the right canopy positions.

The infrastructure to scale this work is still patchy. Different states are using different platforms, the data standards aren’t harmonised, and the cost per hectare surveyed varies considerably. National coordination on the technology stack would produce better outcomes than the current fragmented approach.

Nursery and production sector adaptation

The nursery and production sector has had to adapt extensively. Hygiene protocols at production facilities have tightened significantly since 2020, and the verified-rust-free production schemes operated through industry programmes have grown in importance. For commercial buyers - landscape architects, council operations, native restoration projects - sourcing from accredited rust-managed suppliers is now the operational norm.

The cost of this hygiene infrastructure has fallen disproportionately on small producers. Several heritage and specialist Myrtaceae nurseries have closed over the past three years, and the genetic diversity available in commercial supply has narrowed as a result. The conservation implications of this narrowing are getting more attention than they did a few years ago.

Restoration programme implications

For revegetation and ecological restoration programmes, myrtle rust has reshaped species selection in affected regions. Several commonly used Myrtaceae species are no longer recommended for new plantings in higher-risk environments, and the substitute species lists maintained by the major restoration programme operators have expanded.

The hard question for long-term restoration planning is whether the affected species will eventually develop resistance through natural selection at meaningful rates, or whether the planting decisions made now should assume permanent loss of those species in the affected ranges. The science suggests that some natural resistance development is occurring but at rates that probably won’t restore species to their former ecological roles within human planning horizons.

Border and quarantine implications

For the biosecurity community, myrtle rust remains one of the clearer examples of why the precautionary principle matters. The original incursion came through pathways that were not fully controlled, and the subsequent spread has cost orders of magnitude more in management and ecological terms than tightening the original controls would have cost.

The relevance for current biosecurity work is that several other rust pathogens with similar spread potential remain on the watch lists. The lessons from the myrtle rust experience should inform the assessment of pathway risks for those organisms - particularly the recognition that detection and response capability needs to be in place before the incursion arrives, not stood up after the first finds.

What to watch in 2026

Three things are worth watching over the next twelve months. The southern spread trajectory will tell us whether the pathogen is approaching its climatic limit in cooler parts of southeast Australia. The eucalypt impact data, particularly from long-term monitoring plots, will help refine the medium-term risk assessment. And the operational deployment of remote sensing surveillance at scale will determine whether the detection-to-response timeline can shorten enough to give containment a fighting chance in the more peripheral incursions.

Fifteen years in, myrtle rust is a continuing case study in why biosecurity matters before the pest arrives, not after.