A shot hole borer on wood, next to some of the holes it has made.(Supplied: Department of Primary Industries and Regional Development)
It’s smaller than a sesame seed, yet the shot-hole borer has made short work of some of Perth’s most iconic trees.
Now the rest of Australia is being warned to pay attention to avoid a similar fate.
For its size, the polyphagous shot-hole borer wields wildly disproportionate power.
It’s cleared tree canopies and devastated crops across the world in places like California, Hawaii, Brazil, Argentina, Israel and South Africa.
The shot-hole borer has had a devastating impact on Perth’s tree canopy.(ABC News: Kate Forrester)
In 2021, shot-hole borer made its way to Perth, infecting nearly 5,000 trees that were later chopped down.
In June this year, the WA government conceded it had lost the battle to eradicate the highly destructive pest and said it would instead focus on trying to contain it.
The tiny beetle had exposed a glaring hole in the nation’s biosecurity.
A tube with polyphagous shot-hole borer inside, at Curtin University.(ABC News: Grace Burmas)
A shot-hole borer on a tree.(Supplied: Department of Primary Industries and Regional Development)
Some of the damage wrought by the shot-hole borer on a piece of wood.(Supplied: Department of Primary Industries and Regional Development)
The shot-hole borer kills plants and trees by burrowing in and cultivating a fungus that blocks the flow of water through the plant.
The borer can’t fly far, so it gets around hiding in mulch, firewood and garden waste.
Kings Park has been scarred by the borer.(ABC News: Aran Hart)
The fringes of Perth’s Kings Park was one of the earliest high-profile victims.
Some of the damage on Kings Park seen from the air. (ABC News: Aran Hart)
Among the world’s biggest inner-city green spaces, it became the perfect playground for the borer to etch a trail of destruction.
About 42 Moreton Bay figs and coral trees were removed from a riverside embankment that was for decades a popular wedding photo venue.
Hyde Park has also been severely impacted. (ABC News: Nicholas Martyr)
At the smaller Hyde Park, a few kilometres away, the scar is much more noticeable.
Trees have been reduced to bags of wood chips at Hyde Park.(ABC News: Nicholas Martyr)
Many mature tall trees were reduced to plastic bags packed with wood chips in a bid to save the rest of the park’s mature Moreton Bay figs.
While local and state governments decide how to fill their parks’ bald patches, a national task force is drafting a plan to get WA to a stage where it can manage the pest.
What’s at stake?
Until now, both the state and federal governments have pitched in to fund the $57 million effort to kill and control the shot-hole borer.
But amid the onslaught of biosecurity pests the Commonwealth is dealing with, the management of shot-hole borer will likely be left in state hands.
And at that point, the spread across the Nullarbor will happen, invasive species expert Bruce Webber predicts.
Authorities are devising a plan to manage the pest in WA.(ABC News: Nicholas Martyr)
The damage to Hyde Park seen from the air. (ABC News: Nicholas Martyr)
Efforts are underway to rehabilitate Hyde Park.(ABC News: Nicholas Martyr)
Shot-hole borer has more than 500 plant species on its hit list.(ABC News: Nicolas Perpitch)
“We simply don’t have the resources to manage shot-hole borer along with all of the other invasive pests that we’re already managing,” he said.
Bruce Webber says state authorities don’t have the resources to manage shot-hole borer.(ABC News: Grace Burmas)
“That’s when we start to see greater impacts, greater risk of spread and damage to other ecosystems and industries.”
So what’s most at risk?
The borer attacks the branches of pear trees.(ABC News: Kate Forrester)
Mandarins and other citrus are at risk from shot-hole borer.(ABC News: Bridget McArthur)
There are concerns shot-hole borer could devastate local avocado businesses.(ABC News: Meg Bolton)
The shot-hole borer has more than 500 plant species on its hit list.
Avocados, citrus, mangoes and pears trees are all susceptible and the borer could devastate local business and entire industries.
The shot-hole borer seems to attack tree branches more than the trunks.(ABC News: Anthony Pancia)
Many native trees also fall into the high risk category, including the marri and red flowering gum.
“We have a very small proportion of native trees found in the Perth urban environment so we simply don’t know what those impacts are going to be on our native forests here in Western Australia, but also native forests elsewhere in Australia,” Mr Webber said.
Marri and red flowering gum trees have been infected by the borer.(ABC News: Anthony Pancia)
In other capital cities, the threat is dire.
Melbourne is dominated by London plane trees. Sydney has a large population of native fig trees. Brisbane is abundantly covered in poincianas. Adelaide proudly hosts Moreton Bay fig trees.
All of which are highly vulnerable to the shot-hole borer.
What’s being done?
For the past three years, the task was simple but not easy – kill the beetle by cutting down infested trees.
Research is underway to test the use of chemical and biological controls against the borer.(ABC News: Rhiannon Shine)
That strategy spurred a contentious debate between industry, researchers, and the government — but there was no money on the table for research into alternative methods like chemical treatments.
Now eradication of the pest is no longer deemed feasible, the WA government has allocated more than $2 million for university research to provide a framework for dealing with the beetle.
The Department of Primary Industries and Regional Development has taken charge of borer managerment efforts.(ABC News: Rhiannon Shine)
There has been limited funding for research into borer treatment options.(ABC News: Rhiannon Shine)
In the meantime, quarantine zones controlling the transport of wood are in place around the Perth metro area.
Going rogue
Neighbours Cim and Jen opted into a citizen science trial to save a tree from polyphagous shot-hole borer.(ABC News: Grace Burmas)
With no government solution in sight, local councils and residents began taking matters into their own hands, turning to independent, privately funded research instead.
Neighbours Cim and Jen banded together to save a poinciana that separates their homes in Perth’s affluent suburb of Mosman Park.
Cim and Jen didn’t know the tree was infected until authorities told them it had to be removed.(ABC News: Grace Burmas)
“We didn’t notice that anything was wrong with the tree until the authorities told us that they were going to chop it down,” Cim said.
The families tried to stop government officials entering their properties but were told they didn’t have a choice.
John Szymanski is trialling a new treatment against shot-hole borer.(ABC News: Grace Burmas)
That’s when John Szymanski from BioHerbicides Australia got involved.
He’s trialling a treatment that injects a capsule filled with pesticides and fungicides into the trunk of an infested tree.
“Everyone was enlivened and excited by the fact that this could actually work, so that was the start,” Mr Szymanski said.
It’s shown great success so far.
Mr Szymanski said the treatment was showing promising signs of success.(ABC News: Grace Burmas)
The treatment involves injecting a capsule of pesticides and fungicides into the tree trunk.(ABC News: Grace Burmas)
Mr Szymanski said his team would conduct annual health checks on the treated trees.(ABC News: Grace Burmas)
Mr Szymanski said the response to the trials has been positive. (ABC News: Grace Burmas)
“We then made the offer; we’ll treat their [council] trees if they get some data for us,” Mr Szymanski said.
His treatment includes regular tree health check-ups to monitor progress.
The trials have since spread across Perth and Mr Szymanski said a group of 10 arborists could easily treat a few thousand trees a day if the government wanted that to happen.
Mr Szymanski’s treatment meant Cim and Jen could keep their poinciana and when he went back to check its progress, he found dead beetles borers and dead fungus.
While it may be missing some limbs, the tree is now one of hundreds across Perth considered “vaccinated” against the pest.
Future uncertain
The rise in global trade, coupled with Australia’s isolation, makes it more susceptible to invasive species.
The government is managing about 3,000 different pests and it’s not cheap.
Professor Ben Phillips says the number of invasive pests affecting Australia continues to grow.(ABC News: Grace Burmas)
“They cost the Australian economy around about $40 billion a year,” Curtin University professor of population biology Ben Phillips said.
“That’s a really big number and the scary thing about that number is that it’s doubling every six years.
“We have this great biosecurity system but it’s stretched really thin.
“The threats are increasing faster than the system is able to cope with it.”
Invasive pest management costs Australia about $40 billion a year.(ABC News: Pia Scanlon , DPIRD)
The only way to ensure the country’s precious horticultural industries are protected is to strengthen the government’s response tactics.
Professor Phillips said WA failed to eradicate shot-hole borer because it was difficult for the state government to share data and fund external research.
“You need to be able to lubricate the flow of data in between organisations,” Professor Phillips said.
“We need to be able to spin up research and development projects really quickly.To do that we’re going to need really robust partnerships between government, industry and universities.
“There’s quite a lot of work to be done.”
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The good news for the rest of Australia is it has the gift of warning.
Professor Phillips said WA started on the back foot with shot-hole borer and had few examples to model its response on, so it failed.
The government-funded research and independent trials will give other state governments a guide to better their chances at winning the battle with the beetle and any other pest that may follow it.
“Polyphagous shot-hole borer is just one of many invasive species that are out there and will turn up in Australia at some point and many of those species are going to be more damaging,” Professor Phillips said.
“This is really urgent.”
Loading…CreditsWords: Grace BurmasProduction: ABC News Perth digital teamLoading