In April 2010 a new pathogen that is profoundly changing Australia’s ecology was detected in NSW.
Known as ‘myrtle rust’, the pathogen slipped through national biosecurity borders and has since spread from NSW to Victoria and to far north Queensland and north-western Australia. Climatic modelling suggests it will spread further, with south-western Australia at grave risk.
Myrtle rust attacks many plants in family Myrtaceae, which is Australia’s dominant plant family. It targets young, soft plant tissues, often leading to severe disease or even death of the plant.
This fast-spreading disease has begun reshaping our forests, heathlands, and wetlands, and has the potential to decimate entire ecosystems. It’s one of the worst biosecurity threats Australia has faced, putting already endangered species at further risk.
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.
Myrtle rust (Austropuccinia psidii), previously called ‘eucalyptus rust’ and ‘guava rust’ is a fungus that affects trees and shrubs in family Myrtaceae.
It infects leaves, stems, buds, and fruits, potentially leading to severe impacts that vary from species to species. Some species experience only mild symptoms, such as leaf spots, while others, such as native guava, face mass deaths and near extinction. Within some species there is great variation in susceptibility.
Myrtle rust spreads through wind, water, insects and other animals. Its spores can travel far and infect plants many kilometers away. These can also be carried on infected plants and on tools, vehicles, and clothing.
Since its detection in 2010 at a nursery near Gosford, NSW, myrtle rust has spread rapidly, establishing itself across eastern and northern Australia, from Tasmania to Torres Strait islands, and west to the Kimberley. It thrives in the rainforests of eastern Queensland and NSW, but colder climates and dry regions may limit its spread in Victoria and Tasmania. South Australia remains rust-free, although conditions in its southeast could become suitable.
Melaleuca quinquinervia (top), Agonis flexuosa cv Afterdark (bottom left) and turpentine (Syncarpia glomulifera) infected with myrtle rust. Photos: NSW Department of Industry & Innovation
Myrtle rust poses a serious threat to Australian ecosystems, given the dominance of Myrtaceae plants. Described by plant pathologist Geoff Pegg as the ‘pinnacle of pathogens’, the disease has caused significant damage globally and could have catastrophic consequences for Australia if its spread continues and new strains arrive.
A Myrtle Rust Action Plan published in 2020 identified five plant species as critically endangered, requiring emergency germplasm collection, including the Blackall Range myrtle, smooth scrub turpentine, and native guava. A team of botanists recently expanded that list, declaring that 16 species face imminent extinction.
Myrtle rust may exacerbate the effects of climate change by reducing vegetation recovery after intense bushfires and droughts. A highly flammable weed, lantana, has replaced some rainforest plants killed by myrtle rust.
By killing kanuka box trees lining tropical streams, myrtle rust is believed to be increasing erosion along streams and sediment loads reaching the Great Barrier Reef.
Ecosystem-level impacts will be massive if eucalypt-killing strains reach Australia. Threatened species that could be affected include the koala, greater gliders and swift parrot.
Myrtle rust has imposed costs on nurseries and lemon myrtle and tea tree growers. Nurseries must now use costly fungicides and have abandoned some susceptible plant species, while the lemon myrtle industry faces increased costs from fungicide use, which has derailed plans to achieve organic status. If myrtle rust spreads to Western Australia it could devastate farms growing Geraldton wax, which is highly susceptible. New eucalypt-killing strains pose a threat to Australia’s native hardwood industry.
For more than a decade before it arrived, myrtle rust was considered a serious risk to Australia. The Office of the Chief Plant Protection Officer was said to be investigating costs and options for early detection. As far as we are aware, 5 years after it reached Hawaii, no early detection systems or specific surveillance programs had been established.
The Office of the Chief Plant Protection Officer released a national response plan in 2007 and Plant Health Australia published a contingency plan for the nursery and garden industry in 2009. We are uncertain how many of the recommendations were implemented. Quarantine restrictions were introduced to reduce the risk of infected Myrtaceae material from countries known to host the rust.
Plant Health Australia assessed myrtle rust as having:
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.
On 23 April 2010, presence of the rust was confirmed at a nursery in NSW. One week later, on 30 April 2010, the National Management Group decided against an eradication attempt, deeming it not feasible even though the rust had been detected on only 2 properties and not in bushland.
Under pressure from key groups, including Plant Health Australia and Nursery and Garden Industry Australia, an eradication program was launched in July, involving up to 380 staff. This ceased in late December after advice that eradication was no longer feasible because the rust was spreading in bushland, facilitated by wet summer weather.
This response to the arrival of myrtle rust was heavily criticised by environmental, industry and government stakeholders, including the Invasive Species Council.
Australia’s missed chance to detect and stop myrtle rust early, due to poor surveillance and poor decision-making, has had serious consequences.
Myrtle rust is one of the most threatening invaders of the natural environment, yet there has been minimal engagement of the environment sector and community in preparing for and responding to the incursion.
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 in the response to myrtle rust to highlight weaknesses in Australia’s preparedness for environmental invasive species.
A national action plan to address plant conservation was not published until July 2020 – a decade after the rust arrived.
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.
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.
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.
The seeds and tissues of some newly endangered plants have been preserved at the Australian PlantBank of The Royal Botanic Gardens in Sydney. The seeds of the most threatened species are no longer produced in the wild, and they do not remain viable in seed banks anyway, requiring a focus on difficult and costly tissue culture cryopreservation.
Resistant individuals of some rare species have been located, and their seeds will be used in restoration projects, or to grow plants in gardens in regions too dry for myrtle rust.
The plants threatened by myrtle rust need more attention and better funding. Endangered mammals and birds attract far more conservation funding in Australia than plants.
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 a national response to myrtle rust that involves cost-sharing for high-priority actions that are primarily in the public interest.
The story of myrtle rust incursion is symbolic of a biosecurity system that struggles to protect Australia’s environment. Without significant reform, Australia risks losing a large part of its unique ecological heritage. The Invasive Species Council continues to push for changes in biosecurity preparedness, research, and management.
A short documentary prepared by the Australian Network for Plant Conservation summarising Australia’s myrtle rust problem.
The Invasive Species Council was formed in 2002 to seek stronger laws, policies and programs to protect nature from harmful pests, weeds and diseases.
The Invasive Species Council acknowledges the Traditional Custodians throughout Australia and their connections to land and sea. We pay our respect to their Elders past and present and extend that respect to all Aboriginal and Torres Strait Islander peoples today.
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.
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.
