WA Government launches major tree replanting program in wake of destructive borer infestation

The WA Government has announced a $7.2 million funding package into a new tree planting program following the destruction of more than 3000 trees due to the invasive polyphagous shot-hole borer. The announcement on Saturday comes amid mounting concerns by councils, experts and residents about the impact of the borer on the environment and the slow pace of tree removals across Perth aimed at controlling the pest’s spread. Almost 200 trees in Hyde Park were earmarked removal earlier this year due to the infestation. The cutting program has been delayed due to lengthy departmental approval procedures. While the Department of Primary Industries and Regional Development has now sought those approvals, it and the City of Vincent are now reviewing plans after a recent audit found infestation was lower than first estimated. Already five trees, including a Port Jackson Fig near William Street, has been removed from the park. All the trees on the two lake islands at Hyde Park have been identified for removal. Most are a native Melaleuca, despite the borer mostly targeting imported species. The global host tree list has grown to more than 500 species, of which 130 are in WA. The box elder maple, Moreton Bay fig, and Port Jackson fig have been found to be the susceptible to the borer. The borer’s devastation has resulted thousands of mature heritage trees being removed from suburbs, streetscapes, and parks across the state — prompting alarm among local councils. Concerns over the State Government’s response to the outbreak were raised during a recent State Council meeting of the Western Australian Local Government Association (WALGA), with mayors expressing increasing anxiety over the slowed tree removal efforts. WALGA President Karen Chappel in May wrote to Premier Roger Cook, emphasizing the seriousness of the situation and calling for a comprehensive recovery plan. The peak local government body later launched a campaign in July calling for a “fighting fund” to help councils pay for the removal and replacement of infected trees. More than 60 volunteers from ArbWest, local councils, and DPIRD recently assessed several trees and collected prevalence data, with more assessments taking place on Saturday. City of Vincent Mayor Alison Xamon stated that the council is revising its tree management plan after a early results from the audit revealed that the infestation levels in some trees were lower than initially thought. This pest, first detected in California in 2003 and subsequently in other parts of the world, tunnels into trees and farms a fungus to host its young, which blocks the tree’s water and nutrient flow, ultimately leading to the tree’s death. There is currently no known cure for the infestation making tree removal and pruning the only viable methods to reduce its spread. “Sadly, no treatment options have proven effective worldwide, and tree pruning and removal are the only ways to stop the spread of the shot-hole borer,” WA Agriculture Minister Jackie Jarvis said. “Early intervention is key in reducing the spread and will help protect WA’s trees and our important horticulture sector.” Shadow environment minister Neil Thomson labelled the funding as “the latest belated response from the State Labor Government” — only prompted after grass roots pressure and community concern. “While any additional focus is welcome, the promise to plant more trees will do little to allay the concerns of the community noting recent revelations of the pests spread,” the upper house Liberal said. “The coming months are a critical time as temperatures favour the spread of the pest and reports are still being made of delays on infected tree removal, which is unacceptable.” “Local authorities and land owners need to be confident they will be supported where an infestation is identified and that infestations are dealt with promptly, and that confidence is not being projected by either Minister Whitby or Jarvis.” Trees have been cut, mulched, and treated at a commercial facility in Jandakot by a private contractor. However, DPIRD recently disclosed that the borer has been found outside the designated quarantine areas, including regions such as Gosnells, Armadale, Kalamunda, and Ellenbrook. Arborists warn that with warmer weather on the horizon, the beetle will become more active, increasing the urgency to contain its spread. Research from California has shown that extreme temperatures below 15°C and above 30°C can slow the beetle’s reproductive rate, suggesting that spring and autumn are its preferred seasons for spreading. Environment Minister Reece Whitby said: “Planting trees is one of the simplest things Western Australians can do to help fight climate change. It’s important we replace trees lost to PSHB infestation.” WALGA has advocated for a diverse mix of borer and climate-resistant tree species to replace those lost and has called for investment in alternative treatment methods to combat the pest effectively. Under a national cost sharing agreement, $44 million has been allocated nationally to fund the emergency biosecurity response. A 163-strong team, established in the Department, has been scrambling to contain the destructive borer since it was first detected in 2021 near Fremantle. Report borer damage through the MyPestGuide Reporter app, phone the Exotic Plant Pest Hotline on 1800 084 881, or visit the department’s website.