New Perth quarantine zones quietly adopted as shot-hole borer march advances into hills

A new polyphagous shot-hole borer quarantine zone reveals the proliferation of the destructive beetle in Perth’s hills as the state abandons its hopes of eradication in favour of a “management approach”.

The government has binned its old A and B quarantine zones, in place for the past two years, which had suggested the beetle could be contained to the Perth metro area.

A “management zone” is now in place covering a region including horticultural areas of the Perth Hills.

Meanwhile, a “containment zone” has similar boundaries to the old B zone, which spans north to Two Rocks, to Mandurah in the south, and out to Mundaring in the east.

The new zones were uploaded to the Department of Primary Industries and Regional Development with little fanfare on Thursday.

The National Management Group, which includes members from the state and Commonwealth governments, agreed to the new zones this week, and they came into effect on Friday.

Under the eradication response, which was abandoned earlier this year, more than 4000 trees were destroyed as a result of borer infection.

Now, landholders in the management zone are no longer required to remove trees or even prune affected branches, and the Department of Primary Industries and Regional Development will no longer offer that service.

“It will be their responsibility to manage their own trees and decide on management options – as with other existing plant pests or diseases – supported by DPIRD’s advice and training program,” the department said.

The department will still identify and prioritise the pruning and removal of infested trees in the containment zone.

The new zones came as the department established a team to help landholders, industry and local governments deal with the borer in the long term.

Movement restrictions on firewood, green waste and untreated plant material still apply – these controls are fundamental to helping protect WA’s horticultural and regional areas.

Opposition agriculture and food spokesman Lachlan Hunter said the expansion of the quarantine zone was yet another admission that Labor had lost control of the pest.

“Every time the map grows, it confirms their response was too slow, too quiet and too weak – and now Western Australians are paying for it,” he said.

“This is a government that has failed biosecurity, failed to protect our trees, and failed to front up to the public about the real risks to our horticulture and agricultural industries.”

Agriculture Minister Jackie Jarvis was approached for comment.

DPIRD deputy director general biosecurity and emergency management Mia Carbon said the team would deliver a pest management program, along with training, technical workshops and community education to help prepare for long-term management.

“The team will also work with arborists, nurseries and the horticulture industry to ensure they have the latest tools and knowledge to manage the borer,” she said.

“Early detection and management of high-risk infestations, particularly in the containment zone, remain critical to managing the spread and impact of shot-hole borer.”

The borer, a sesame seed-sized beetle that rapidly multiplies and kills trees through the fungus it harvests and feeds on, was first detected in Fremantle four years ago.

Despite a mammoth effort – which included the removal of dozens of old trees, including large figs along the Mount Eliza escarpment in Kings Park and in Hyde Park in Mount Lawley – Premier Roger Cook in January conceded eradication was a “tough battle”.

Start the day with a summary of the day’s most important and interesting stories, analysis and insights. Sign up for our Morning Edition newsletter.