Just four months into a new chemical trial, the City of Canning believes it has found a way to combat the polyphagous shot-hole borer.
In the trial, 131 infested trees were injected with a small vitamin-like capsule containing insecticide and fungicide, and are now showing no signs of live beetles or larvae.
The tiny invasive tree-killing pest was detected in 2021 and has since led to the destruction of more than 4,000 trees in the Perth metropolitan area as the state government follows an elimination strategy.
It has devastated some of Perth’s iconic green spaces, including Hyde Park and Kings Park.
Despite its small size, the shot-hole borer beetle can quickly destroy trees. (ABC News)
City of Canning Mayor Patrick Hall hoped the trial could be replicated across Australia and the world.
“It’s an extraordinary outcome from a trial that all of us hoped would work. We’re overcome and heartened by the results,”
he said.
He said the method did not pose a risk to wildlife, as the trees absorbed the capsule.
“The insecticide is a very small dose, injected deep into the tree, and then we put a plug behind it to make sure it can’t leach out. And that traps the insecticide inside the tree — that then goes up the vascular system.”
Matthew Clark, urban forest supervisor at the City of Canning, examines a branch for the shot-hole borer. (Supplied: City of Canning)
Councils collaborate
Mr Hall said councils across Perth had been collaborating and discussing the trial.
“They are all standing ready to act; they just need the green light to do so,” he said.
“They need the support of government and funding for them to pull the levers necessary to arrest the spread of this cursed beetle.”
There are several different trials taking place around Perth, as scientists and local governments look for answers beyond chopping the trees down.
Multiple organisations are involved in the City of Canning trial, including BioHerbicides Australia, ArbWest, and the University of Queensland.
The trial has shown promising early results against the shot-hole borer with systemic chemicals. (Supplied: City of Canning)
John Szymanski from BioHerbicides Australia described the treatment as simple.
“I heard the minister of agriculture say there were no known treatments in the world,” Mr Szymanski said.
“I thought that can’t be right. I did a five minute google search and found them.”
Mr Szymanski said that once out of the trial stage, the estimated cost of treating the 131 trees would be around $2,000.
John Szymanski demonstrates how to use a tool that inserts the capsule. (ABC Radio Perth: Kate Leaver)
“At this stage, we need more trials to learn how long the tree is protected for. It’s very likely in three or four years we need to reinject,” he said.
“I’ve been involved in BioHerbicides Australia for 15 years, and I’ve helped with trials in other places using the same application technique but with different goals.
“It was a very simple step to go from: ‘This is a beetle, this is a fungus, why don’t we put an insecticide and a fungicide into a capsule and see if that works?’ It’s not a surprise that it did.”
ArbWest, the City of Canning, and BioHerbicides Australia worked collaboratively during the trial. (Supplied: City of Canning)
Trials welcomed by DPIRD
In a statement, a state government spokesperson said the government was committed to working with scientists to support further research.
“This includes collaborations with the City of Perth and the City of Vincent and more than $2 million through the WA Agricultural Research Collaboration for local PSHB research initiatives,” the statement said.
“The state government, through the Department of Primary Industries and Regional Development (DPIRD), has provided technical support to the City of Canning’s trials and welcomes the opportunity to view more detailed, peer-reviewed trial results from the City of Canning as they progress their research.”
