Secrecy, lax rules bug canopy fight (8 Mar 2025)
The secrecy that shrouds the handling of the exotic pest wreaking havoc on Perth’s tree canopy could be making the situation worse, says Curtin MP Kate Chaney.
The polyphagous shot-hole borer was first detected at East Fremantle in 2021 and since then 4249 trees across the metro area have been chopped down to stop it spreading, especially to regional fruit crops.
The state government is adamant that the only solution is eradication by mulching infested trees.
But Ms Chaney said government reluctance to share information about this program was worrying industry experts.
“People in Curtin are really at the epicentre of this national issue and have borne the brunt of it,” she said.
“I’ve spoken to a range of stakeholders, and there are some pretty serious concerns that I’m raising with the state minister.
“There are industries such as fruit growers that are likely to be affected once this gets out of the metro area that are not being engaged with.”
In response to Ms Chaney’s comments, a state department spokesman said they were open to new solutions and continued to engage with local scientists to explore research opportunities in WA.
Concerns were raised with Ms Chaney about the current practice of chopping down trees. There have been many examples in the western suburbs of months of inactivity between an infestation being detected and the trees being pruned or removed.
Piles of mulch are often left for weeks or months to be blown about in the wind.
The POST has heard from several residents about happening to trees on their verges.
In Claremont, giant figs at Lake Claremont Nature Playground at the end of Stirling Road were found to be heavily infested with the borer last April.
They were not chopped down until November and this week Ms Chaney inspected big piles of woodchips that still had ot been removed.
Woodchips must be double mulched and solarised over three months to kill the pest.
This is supposed to happen at a site in Jandakot where Ms Chaney said 150 cubic metres of contaminated mulch is taken every day.
“Any truck that has had contaminated mulch in it is meant to be cleaned and the mulch removed, but there’s no clarity about what that actually means, and no enforcement of whether it’s happening,” Ms Chaney said industry experts had told her.
“Mulch gets very sticky, and so it’s pretty hard to get it out of the truck.
“Stakeholders have told me there’s nowhere on site to appropriately clean the trucks on the way out.
“There are real concerns about whether that actually could be contributing to the spread.
“There are also reports of wood chips being transported with just a tarp over them over long distances.
“The site itself at Jandakot appears to not have the capacity to actually hold that (amount of contaminated mulch) for the 12 weeks that’s required.”
A Department of Primary Industries and Regional Development spokesperson said all borer-infested tree material is removed by qualified arborists and disposed of in line with strict biosecurity requirements.
“PSHB cannot survive in mulch so PSHB infested wood is chipped to less than 2.5cm diameter – providing a greater than 99.9 per cent kill rate,” the spokesperson said.
“DPIRD’s biosecurity inspectors ensure all known infested material is chipped to the correct size at the time of tree removal.
“Chipped material is also being processed efficiently by a commercial hot composting facility in the Perth metropolitan area.
“The PSHB response plan is reviewed regularly by the national consultative committee on emergency plant pests.”
Ms Chaney said other concerns raised with her centred on information sharing by the government.
“Non-disclosure agreements have been signed with the local governments to protect privacy of individuals, so that means stakeholders are not able to plan in areas that are likely to be next to be infested.
“They’re also not able to learn quickly from the areas previously affected and act accordingly.
“There are various industries, such as fruit growers, that are likely to be affected once this gets out of the metro area that are not being engaged with.
“There’s very little information being shared with the public or broader stakeholders about the treatment process.
“We need the public to be aware and proactive and have faith in the process.
“And there hasn’t been a national-level cost-benefit analysis on eradication. If that was undertaken and shared, it would build a case for a much more comprehensive, effective and widely supported response.”
DPIRD said the PSHB response plan is reviewed regularly by the national consultative committee on emergency plant pests.
DPIRD said they were open to new solutions and continued to engage with local scientists to explore research opportunities in WA.
