Polyphagous Shot-Hole Borer: A Growing Threat to Perth's Trees
The polyphagous shot-hole borer (PSHB) poses a significant threat to Perth's urban forest and beyond. This tiny beetle, first detected in 2021, has spread to over 80 suburbs, destroying thousands of trees. PSHB attacks various tree species, introducing a lethal fungus. A $41.29 million response plan aims to contain and eradicate the pest. Residents can help by monitoring trees, following quarantine guidelines, and reporting suspicious activity promptly.
Perth's urban forest is under siege from a tiny but formidable enemy: the polyphagous shot-hole borer (PSHB). This invasive beetle, no larger than a sesame seed, has been wreaking havoc on trees across the city since its detection in 2021. As the infestation spreads, it threatens not only our beloved street trees but also our native forests and horticultural industries. This article delves into the PSHB crisis, exploring its impact, the efforts to control it, and how Perth residents can join the fight to protect our green spaces.
What is the Polyphagous Shot-Hole Borer?
The polyphagous shot-hole borer (PSHB) is a minuscule beetle, measuring just 2mm in length. Originally native to Southeast Asia, this pest has found its way to Perth's shores, bringing with it a destructive potential that belies its small size. What makes the PSHB particularly dangerous is its symbiotic relationship with a Fusarium fungus. As the beetle burrows into trees, it introduces this fungus, which can be lethal to susceptible species.
The PSHB is not a picky eater. It has been known to attack over 400 different tree species, including:
Amenity trees that line our streets and fill our parks
Native species crucial to our local ecosystems
Horticultural trees vital to Western Australia's agricultural industry
This wide-ranging appetite makes the PSHB a significant threat to urban, natural, and agricultural landscapes alike.
Polyphagous Shot-Hole Borer (PSHB)
The Spread in Perth
The first alarm bells rang in August 2021 when the PSHB was detected in East Fremantle. Since then, the spread has been alarmingly swift. As of the latest reports:
The beetle has been found in over 80 suburbs
25 local government areas have confirmed infestations
There are 15 confirmed infested premises and 4 suspect detections
This rapid expansion highlights the urgency of the situation and the need for a coordinated response to contain the pest.
Impact and Potential Threats
The damage inflicted by the PSHB is already substantial:
Over 3,000 trees within the quarantine zone have been destroyed
The environmental impact includes loss of habitat for native wildlife and reduced urban cooling
Economic costs are mounting, both in terms of tree removal and potential losses to the horticultural industry
If left unchecked, the PSHB could devastate Perth's urban tree canopy, altering the character of our leafy suburbs. The potential spread to native forests could have far-reaching ecological consequences, while the threat to crops poses a significant risk to Western Australia's agricultural sector.
Response and Management Efforts
Recognising the severity of the threat, authorities have launched a comprehensive response:
A $41.29 million Response Plan has been approved, aimed at eradicating the PSHB
A Quarantine Area (QA) has been established, encompassing 30 local government areas around Perth
Strict regulations are in place to restrict the movement of wood and plant material, helping to contain the spread
Currently, the primary management strategy involves the removal and destruction of infested trees. While drastic, this approach aims to eliminate breeding grounds for the beetle and slow its advance.
Challenges in Pest Control
Despite these efforts, controlling the PSHB presents significant challenges:
There are concerns that the pest could enter an "explosive phase" as warmer weather approaches, accelerating its spread
Experts are calling for increased research into alternative management options, including potential chemical treatments
Debate continues about whether complete eradication is still feasible, given the extent of the infestation
These challenges underscore the need for ongoing research and adaptive management strategies as the situation evolves.
How to Identify PSHB Infestation
Perth residents play a crucial role in early detection. Here are the key signs to watch for:
Multiple small entry holes on tree trunks or branches, about the size of a ballpoint pen tip
Sawdust-like material (frass) around entry holes or on the ground beneath trees
Gumming or sap oozing from entry holes
Crystalline foam (sugar volcanoes) exuding from entry holes
Bark discolouration around entry holes
Tree wilting or dieback of branches
Some tree species are particularly susceptible, including box elder maple, coral trees, Moreton Bay and Port Jackson figs, and London plane trees. Extra vigilance is required for these species.
What Residents Can Do
Community action is vital in the fight against PSHB. Here's how you can help:
Monitor your trees regularly, especially susceptible species
Do not move firewood outside the Quarantine Area, particularly when going camping
If you must move wood, chip it into pieces smaller than 2.5cm in diameter
Avoid moving living plants with woody stems greater than 2cm in diameter out of the Quarantine Area
Clean any machinery used to handle green waste or wood material before leaving the Quarantine Area
It's worth noting that Lumberjacks WA is committed to following these guidelines meticulously. The company ensures strict adherence to protocols when handling green waste, chipping wood, and cleaning machinery. This commitment helps prevent the spread of PSHB and sets an example for best practices in the industry.
Reporting Suspected Infestations
If you suspect PSHB activity:
Take clear photos of the symptoms
Report your findings to the Department of Primary Industries and Regional Development (DPIRD) via:
Swift reporting can make a significant difference in containing new outbreaks.
Conclusion
The polyphagous shot-hole borer presents a serious threat to Perth's urban forest, native ecosystems, and horticultural industries. While the challenge is significant, a coordinated effort between authorities and the community can help manage this invasive pest. By staying informed, vigilant, and proactive, Perth residents can play a crucial role in protecting our valuable tree resources for future generations.
Additional Resources
For more information on the PSHB and current management efforts, visit:
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