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Myrtle rust

Our Work  |  Pathogens

In April 2010 a new pathogen that could fundamentally alter Australia’s ecology was detected in NSW.

Myrtle rust infecting a Western Australian peppermint. Photo: NSW Department of Industry & Innovation

The pathogen, myrtle rust, had slipped through national biosecurity borders and has since spread to far north Queensland and Victoria. Climatic modelling suggests it will spread much further.

There are more than 2000 plants in family Myrtaceae, Australia’s dominant plant family, including eucalypts, bottlebrushes and tea trees – most are susceptible to the disease.

Myrtle rust could alter the composition and function of forest, woodland, heath and wetland ecosystems. This incursion is about as bad as it can get for biosecurity in Australia – a new disease attacking our dominant plants, including species already on threatened lists.

What is myrtle rust?

Myrtle rust (Puccinia psidii) is a fungus that causes disease in plants in family Myrtaceae. It is one of a complex of fungal pathogens known as eucalyptus or guava rusts.

Australian scientists have been greatly alarmed by these rusts since they were first reported causing serious disease in eucalypt plantations overseas.

Early on, it was recognised that the list of Australian plant species that might fall prey to these pathogens could be very long and have potentially dire results for our ecosystems.

Myrtle rust pictures

Melaleuca quinquinervia (top), Agonis flexuosa cv Afterdark (bottom left) and turpentine (Syncarpia glomulifera) infected with myrtle rust. Photos: NSW Department of Industry & Innovation

Potential impacts

It is not possible to accurately predict the ecological impacts of myrtle rust in Australia but Geoff Pegg, plant pathologist with Biosecurity Queensland called it “…(t)he pinnacle of pathogens we wanted to keep out of Australia.”

Eucalyptus rust disease is highly variable depending on rust strain, susceptibility of host species, and environmental factors.

That eucalyptus rust has caused severe damage to plants elsewhere, and that Myrtaceae plants dominate many Australian ecosystems and are naïve to the pathogen, suggest the impacts could be severe and change over time as the rust adapts to Australian conditions.

There are no control options (fungicides) in bushland.

NSW has already made a preliminary determination to list myrtle and eucalyptus rusts as key threatening processes. They note that the area of highest risk in NSW – the coastal zone from Illawarra to the Queensland border – includes a large proportion of the state’s conservation reserve system, many Myrtaceae-dominated ecological communities, and most of NSW’s World Heritage-listed rainforest.

How was Australia caught off-guard

Contingency plans against the possible incursion of these rusts were drawn up by government and industry.

Plant Health Australia assessed myrtle rust as having:

  • High potential for entry to Australia.
  • High potential for establishment.
  • High-to-extreme potential for spread.
  • High environmental impact.
  • High-to-extreme economic impact.

The Invasive Species Council highlighted the dangers in our submission to the government’s review of biosecurity arrangements in 2008:

Australia is at grave risk of importing Eucalyptus rust (also known as guava rust) from South America, where it is an endemic pathogen of Myrtaceae plants and infects eucalypt plantations. Its arrival in Australia would likely be devastating in its consequences for woodlands and forests. But as yet there is no strategy in place to prevent its incursion – a strategy that would prioritise working with countries of origin to prevent its export.”

Despite government recognition of the high threat level, Australia was poorly prepared for an incursion.

How did Australia respond to the incursion?

In April 2010, the rust was discovered at a commercial property in NSW.

Inexplicably, after just one week of searching and finding the rust in only one other nearby facility and none in surrounding bushland, the national response was stood down by a federal committee, to the consternation of scientists, conservationists and affected industry sectors.

A letter sent to federal environment minister Tony Burke by the Institute of Foresters of Australia clearly expresses this concern, warning that myrtle rust is a ‘major bio-security incursion and the consequences to our native flora and plant industries are unknown but potentially enormous’.

This concern resulted in the reinstatement of the national shared-cost response in June 2010. Finally, in December, after the disease was found in bushland at multiple sites, the rust was again deemed ineradicable.

Would Australia have been able to detect and eradicate myrtle rust if it had been better prepared and the contingency plan was immediately implemented?

That the rust may have been in Australia up to two years before it was detected suggests that eradication opportunities were lost because of a lack of surveillance. The failure to immediately dedicate national resources to eradicate the disease may cost our environment and industries that use Myrtaceae dearly.

What did we learn?

In May 2011 the Invasive Species Council proposed a Senate inquiry into the myrtle rust response so that policies and procedures can be improved by learning from its successes and failures. In 2014, the Senate held a broad-ranging inquiry to look at the failures in quarantine since 2000, including the incursion of myrtle rust in 2010. The Invasive Species Council prepared a detailed myrtle rust case study as part of its submission to the Senate inquiry.

The final report of the Senate inquiry documented deficiencies with the response to myrtle rust to highlight weaknesses in Australia’s preparedness for environmental invasive species.

Myrtle rust continues to spread across Australia. By late 2015 is was widespread in Queensland, NSW and Victoria. It has reached Tasmania where it was detected in garden plants in the NE in February 2015 and  Northern Territory where it was detected on Melville Island in May 2015, The Tasmanian government is seeking to contain and eradicate myrtle rust from the state while the Northern Territory government has determined it is not possible to contain or eradicate the pathogen.

What should be done now

Review biosecurity arrangements

Conduct an independent review to consider how national and state/territory biosecurity regimes could be improved to reduce the risk of further incursions and detection/eradication of the rust should further incursions occur.

Aim to keep further strains out of Australia

High priority should be given to keeping further biotypes of eucalyptus or myrtle rust out of Australia; new strains could considerably exacerbate the disease and the number of species affected.

Conduct research to assess ecological impacts

Develop a comprehensive ecological research program to assess the likely ecological impacts of the disease and management options. A scientific panel should be established to advise on the research program and management options.

Involve environmental NGOs and agencies in response management

Ensure that environment NGOs are accorded equality with industry groups in all government processes to respond to the disease and biosecurity arrangements. Environmental agencies should be involved in all relevant government decision making. Develop cost-sharing arrangements for priority actions in the national interest: Develop a national response to myrtle rust that involves cost-sharing for high-priority actions that are primarily in the public interest.

The bigger picture

The story of myrtle rust incursion is perhaps indicative of a biosecurity system that cannot adequately protect our environment.

It appears to the Invasive Species Council that, through our national biosecurity system, the protection of Australia’s environment is undervalued in contrast to the protection of commerce and trade. Serious environmental threats are not being accorded sufficient priority.

Community participation in policy and decision-making around environmental threat should be a routine part of our national biosecurity architecture.

We have taken up these issues with government and we hope proposed improvements will be implemented.

Find out more

A short documentary prepared by the Australian Network for Plant Conservation summarising Australia’s myrtle rust problem.

Dear Project Team,

[YOUR PERSONALISED MESSAGE WILL APPEAR HERE.] 

I support the amendment to the Kosciuszko National Park Wild Horse Heritage Management Plan to allow our incredible National Parks staff to use aerial shooting as one method to rapidly reduce feral horse numbers. I want to see feral horse numbers urgently reduced in order to save the national park and our native wildlife that live there.

The current approach is not solving the problem. Feral horse numbers have rapidly increased in Kosciuszko National Park to around 18,000, a 30% jump in just the past 2 years. With the population so high, thousands of feral horses need to be removed annually to reduce numbers and stop our National Park becoming a horse paddock. Aerial shooting, undertaken humanely and safely by professionals using standard protocols, is the only way this can happen.

The government’s own management plan for feral horses states that ‘if undertaken in accordance with best practice, aerial shooting can have the lowest negative animal welfare impacts of all lethal control methods’.

This humane and effective practice is already used across Australia to manage hundreds of thousands of feral animals like horses, deer, pigs, and goats.

Trapping and rehoming of feral horses has been used in Kosciuszko National Park for well over a decade but has consistently failed to reduce the population, has delayed meaningful action and is expensive. There are too many feral horses in the Alps and not enough demand for rehoming for it to be relied upon for the reduction of the population.

Fertility control as a management tool is only effective for a small, geographically isolated, and accessible population of feral horses where the management outcome sought is to maintain the population at its current size. It is not a viable option to reduce the large and growing feral horse population in the vast and rugged terrain of Kosciuszko National Park.

Feral horses are trashing and trampling our sensitive alpine ecosystems and streams, causing the decline and extinction of native animals. The federal government’s Threatened Species Scientific Committee has stated that feral horses ‘may be the crucial factor that causes final extinction’ for 12 alpine species.

I recognise the sad reality that urgent and humane measures are necessary to urgently remove the horses or they will destroy the Snowies and the native wildlife that call the mountains home. I support a healthy national park where native species like the Corroboree Frog and Mountain Pygmy Possum can thrive.

Kind regards,
[Your name]
[Your email address]
[Your postcode]


Dear Project Team,

[YOUR PERSONALISED MESSAGE WILL APPEAR HERE.] 

I support the amendment to the Kosciuszko National Park Wild Horse Heritage Management Plan to allow our incredible National Parks staff to use aerial shooting as one method to rapidly reduce feral horse numbers. I want to see feral horse numbers urgently reduced in order to save the national park and our native wildlife that live there.

The current approach is not solving the problem. Feral horse numbers have rapidly increased in Kosciuszko National Park to around 18,000, a 30% jump in just the past 2 years. With the population so high, thousands of feral horses need to be removed annually to reduce numbers and stop our National Park becoming a horse paddock. Aerial shooting, undertaken humanely and safely by professionals using standard protocols, is the only way this can happen.

The government’s own management plan for feral horses states that ‘if undertaken in accordance with best practice, aerial shooting can have the lowest negative animal welfare impacts of all lethal control methods’.

This humane and effective practice is already used across Australia to manage hundreds of thousands of feral animals like horses, deer, pigs, and goats.

Trapping and rehoming of feral horses has been used in Kosciuszko National Park for well over a decade but has consistently failed to reduce the population, has delayed meaningful action and is expensive. There are too many feral horses in the Alps and not enough demand for rehoming for it to be relied upon for the reduction of the population.

Fertility control as a management tool is only effective for a small, geographically isolated, and accessible population of feral horses where the management outcome sought is to maintain the population at its current size. It is not a viable option to reduce the large and growing feral horse population in the vast and rugged terrain of Kosciuszko National Park.

Feral horses are trashing and trampling our sensitive alpine ecosystems and streams, causing the decline and extinction of native animals. The federal government’s Threatened Species Scientific Committee has stated that feral horses ‘may be the crucial factor that causes final extinction’ for 12 alpine species.

I recognise the sad reality that urgent and humane measures are necessary to urgently remove the horses or they will destroy the Snowies and the native wildlife that call the mountains home. I support a healthy national park where native species like the Corroboree Frog and Mountain Pygmy Possum can thrive.

Kind regards,
[Your name]
[Your email address]
[Your postcode]