Mount Eliza Escarpment Project
Mount Eliza Escarpment is in the process of transformation.
Updated February 2025.
Over the last year, the BGPA project team has been working hard, in partnership with the Department of Primary Industries and Regional Development (DPIRD), to control exotic plant pest polyphagous shot hole borer (PSHB) infestation on the Mt Eliza escarpment.
Polyphagous shot hole borer is an invasive pest that is deadly to many of Perth’s tree species and is quick to multiply and spread. Ongoing surveillance detected PSHB in trees on the escarpment, requiring swift removal action to continue to protect the 40,000 trees in the Kings Park Bushland, parklands and the Western Australian Botanic Garden, trees in surrounding Perth landscapes and properties and motorists on Mounts Bay Road.
The devastating but necessary tree removals have seen the scarp’s landscape impacted by these emergency biosecurity works. 
What is PSHB?
2021 saw the arrival of the declared pest Polyphagous shot-hole borer (PSHB) to the Perth region. PSHB is a beetle native to Southeast Asia. The beetle attacks a wide range of trees by tunnelling into trunks, stems and branches.
About the size of a sesame seed, PSHB excavates tunnels in trees where they cultivate a Fusarium fungus as a food source. This fungus spreads in the tunnels blocking the flow of water and nutrients in the tree. This blockage causes trees to become unsafe, and eventually die. If not removed, trees infested by PSHB can become a constant source of beetles that disperse and impact neighbouring trees.
There are no effective chemical treatment options available.
What is the risk to Kings Park and our flora?
The risk to our Western Australian Botanic Garden, natural landscape features across Kings Park and to the safety of visitors is real if we don't take action.
The Mount Eliza escarpment location of the trees identified with PSHB is in close proximity to Kings Park Bushland and the Western Australian Botanic Garden, including the many rare and endangered flora protected in its collection.
Unless decisive action was taken, these infested trees would continue to spread the beetles beyond the escarpment boundary, putting at risk the vital Perth asset of Kings Park and also the urban canopy of the surrounding suburbs.
The progression of the infestation also posed a future risk to visitors from dead and dying branches if the infested trees were not removed promptly.
PSHB explained by our arborist
Pre-removals - January 2024
Where to from here?
Mount Eliza escarpment is a special place in the hearts of Kings Park visitors and locals. The area is recognised for its significance to Whadjuk Noongar Traditional Owners as well as its post-colonial landscape features.
We have been greatly saddened at Kings Park to have to take this action to remove the trees, but we are already working on transforming the scarp back into a natural attraction for locals and visitors.
Appreciating and understanding the risks of the tree removals to the scarp slope, expert geotechnical advice is informing next steps to manage and restore the escarpment. Over the coming months works to secure slope stability will include slope reshaping to reduce slope angle, installation of erosion control matting and logs, and restoration planting. These works will be undertaken in the Mount Bay Road area towards the base of the Mt Eliza escarpment, in the immediate vicinity of the recent Stage 2B tree removal works.
Planting for the future
A key part of this restoration will be replanting of the scarp with approximately 80,000 native plant species. In 2024, nearly 18,000 plants were grown and planted at Mounts Bay Gardens (Goonininup), including 500 trees, from 16 different species native to the scarp. This winter will see further plantings of a further 20,000 grown in our nursery.
Species range in size from large eucalypts like Tuarts (E. gomphocephala) and Flooded Gum (E. rudis) to small ground cover species such as Running Postman (Kennedia prostrata) and Wattle (Acacia lasiocarpa). All the seed for these plants have been collected from the Mt Eliza escarpment.
Biosecurity and climate change are becoming greater challenges every day. Evidence shows that restoring ecological systems greatly improves resilience to these threats. Local flora species are much more resilient to threats as well as vital habitat and food for our native animals.
The PSHB fight continues
The program of tree removal and pruning is showing evidence of success.
Recent DPIRD surveillance in Kings Park recorded a significant drop in PSHB presence in traps following the tree removals on Mt Eliza escarpment in March 2024.
Surveillance is ongoing at Kings Park and any additional infested trees will continue to be managed as appropriate, including removal if required.
BGPA and DPIRD are continuing a chemical treatment and tree limb removal programme in sites of low infestation.
Putting the focus on culture
BGPA and the Department of Primary Industries and Regional Development (DPIRD) recognise the significance of the area to Traditional Owners. All efforts have been made before, during and after the project to consult Whadjuk Noongar Traditional Owners and protect cultural heritage.
The next step seeks to create an environment that reflects the cultural sensitivity and environmental stewardship of Whadjuk Noongar culture, history, and values and reestablishes Mount Eliza escarpment as a meaningful connection between Kings Park and the Swan River.
Frequently Asked Questions
What Traditional Owner engagement has been undertaken?
BGPA and DPIRD recognise the significance of Mount Eliza Escarpment to the Whadjuk Noongar people and all efforts will be made to preserve the traditional heritage of the site.
- Goonininup – The freshwater spring is of significant spiritual heritage as it is associated with the home of the Rainbow Serpent, the Waugal. Its waters are considered sacred.
- Mount Eliza – The area was used as a gathering place for water, food, ceremony, communication, and trade.
BGPA engaged with the Whadjuk Aboriginal Corporation (WAC) to provide advice on the project operations. Through WAC, representatives from the Whadjuk Noongar community were, and continue to be, consulted by BGPA and DPIRD on the project.
BGPA will continue to engage with Traditional Owners as we look to the future of Mount Eliza and Mounts Bay Gardens (Goonininup) and protecting and celebrating its cultural heritage.
Is PSHB local to Kings Park?
DPIRD is responding to the confirmed detections in the Perth metropolitan area. BGPA is coordinating an internal response to limit spread of PSHB in Kings Park and into Bold Park. This involves a response by BGPA staff and volunteers, and working closely with our colleagues at DPIRD, DBCA and other key stakeholders.
The removal of infested trees is key to containing PSHB spread and minimising further impact on neighbouring trees.
We encourage everyone to be on the lookout for PSHB damage in their communities and to report observations of suspect borer activity.
What closures are in place?
Mounts Bay Gardens (Goonininup) is closed to pedestrian and vehicle access.
For visitor safety and to allow for essential restoration works to be undertaken, BGPA has permanently closed Lovers Walk. We understand that this will be disappointing to many park users and ask for understanding during this unprecedented emergency response to PSHB. Visitors will still be able to access Kokoda Steps from the top of the escarpment within Kings Park, but there will be no access from the base of the scarp.
A gate has been installed at the bottom of the Kokoda Track Memorial Walk to manage access.
Access to the park from the escarpment base will be via Jacob’s Ladder or Spring Street.
These closures will be in place for visitor safety and we thank you for your patience and understanding.
Will this affect the slope stability?
Recent assessments of the escarpment have indicated that the slopes have undergone relatively minor erosion and deterioration. BGPA is managing the increased instability risk presented by tree removals through ongoing consultation with GHD (geotechnical engineers), regular assessments, as well as erosion control works and revegetation. Public safety measures will be in place for the duration of the project, including exclusion zones and rock catch fences. An exclusion zone will remain in place at Mounts Bay Gardens (Goonininup) and further along the escarpment in the vicinity of Lovers Walk for the duration of restoration works to manage public safety.
What is being done to combat PSHB?
The Department of Primary Industries and Regional Development is managing the response to confirmed detections of PSHB.
Visit the DPIRD website for information on the beetle and biosecurity response.
How do I report PSHB?
Suspected PSHB sightings can be reported:
DPIRD Pest and Disease Information Service
MyPestGuideTM