Perth Voice Interactive

ONE in five trees in Hyde Park may have to be removed because of a polyphagous shot-hole borer infestation, with the oldest and grandest ornamental trees most likely to be among the casualties.

Agriculture minister Jackie Jarvis visited the park this week and announced: “Unfortunately the only way to deal with this invasive pest is to remove the infected trees.

“Hyde Park is highly susceptible, we know this borer targets European tree species. 

“We’ve already had to remove a number of trees in King’s Park and Perth Zoo, and unfortunately now in Hyde Park we’re going to have to remove some trees to deal with this pest.”

Hyde Park has already had a few trees removed and several other limb loppings to try to halt the bug’s spread. But this latest cull is the most drastic yet.

“There are about 900 trees in Hyde Park,” Ms Jarvis said. 

“We’re estimating about 20 per cent of those trees may have to go.”

Dead trees can become launch pads for the insects to rapidly spread. 

“This borer infects the tree with a fungus that then causes dieback,” Ms Jarvis said. 

“If we don’t treat these trees, they will die anyway… It is absolutely devastating but we are doing all we can to stop the spread of this invasive species.”

South Africa has been struggling against the borer since 2012, and research there has shown that once borers infest London Plane trees, about 50 per cent of them die. There’s a near-100 per cent fatality rate for box elder maples, English oaks, and other maples in the South African studies, and all those species are commonly planted in Perth’s parks and streets too. 

A trial of a directly-injected chemical treatment is underway in Perth after showing some success in California, but there’s a lot of unknowns about how effectively the substance works on different tree species. South Africa has tried many interventions, from chemical cocktails to a predatory fungus strain that targets borers, but none have worked very well and their only effective measure that remains is just removing dying trees. 

The borer originates in South East Asia, and Ms Jarvis said: “This is a really timely reminder for the people of Perth not to bring in untreated wood products… I’m also asking Perth residents to check their trees, so any trees you have in your garden, I’m asking you to look for borer holes. They are tiny holes in the trees, you might see traces of sawdust. You probably won’t see the borer, it’s incredibly small, but I’m asking people to look for any signs of disease.”

Reports can be made via mypestguide.agric.wa.gov.au or the MyPestGuide Reporter phone app.

Perth MP John Carey and Mt Lawley MP Simon Millman are holding a community forum about the problem.

“We want to arrange a briefing from the experts so people can directly ask any questions and test any ideas,” Mr Carey told us. 

He said the idea of cutting down trees has been hard for many to accept. “I understand people saying ‘let the tree be’, but then the tree will spread it to the rest of the park.

Devastated

“I love Hyde Park, I use this park every morning or night, and I know that so many people love using Hyde Park. I think a lot of people are going to be devastated.”

Around 20 trees are being removed from the Mounts Bay Garden patch of Kings Park, mostly Moreton Bay figs, Port Jackson figs and coral trees (“Tree killer,” Voice, January 20, 2024). 

The Botanic Gardens and Parks Authority is planning to replace them with native trees, in recognition of the area’s significance to Noongar history and because native species are less susceptible to the borer.

Mr Carey says there’s not yet been talk on what species might replace the trees that have to be felled at Hyde Park.

The forum is on at Perth Soccer Club on February 19 at 6pm, RSVP for numbers via www.johncareymla.com.au/events/

by DAVID BELL