❓ A WA parliamentary question addresses the Polyphagous Shot-Hole Borer outbreak, covering detection, management transition, funding, research, and community engagement. The Minister provides detailed responses, outlining actions taken and future plans.
AnsweredQoN 765Legislative Assembly
QuestionView source ↗
I refer to the Polyphagous Shot-Hole Borer (PSHB) outbreak response, and I ask: (a) can the Minister confirm the exact date and location of the initial detection of the PSHB in Western Australia; (b) as of today, how many suburbs or local government areas within WA have confirmed detections of PSHB; (c) has PSHB been detected outside of the Perth metropolitan area: (i) if so, where and when; (d) what is the current extent of the quarantine zones declared under biosecurity regulations and how many premises are currently under active movement restrictions; (e) when did the Department of Primary Industries and Regional Development (DPIRD) formally transition from an eradication approach to a containment and management strategy for PSHB; (f) what was the scientific or technical advice received that underpinned the decision to abandon eradication; (g) has the Minister reviewed the effectiveness of the early response to the outbreak: (i) if so, what were the findings; (h) how much funding has been allocated by the State Government specifically to the PSHB response efforts since its detection in 2021; (i) of the total funding, how much has been directed to: (i) tree removal and disposal; (ii) community engagement and public education; (iii) research and treatment trials; and (iv) surveillance and diagnostic activities; (j) has the State Government sought co-investment from the Federal Government or other jurisdictions for the management of PSHB; (k) what coordination has taken place between the State and local governments to manage infected trees on public land, such as in Kings Park and Hyde Park; (l) can the Minister confirm how many mature trees have been removed in response to PSHB infection: (i) of those, how many were heritage or iconic specimens; (m) what species of native trees have been confirmed as PSHB hosts in WA; (n) has any risk modelling or climatic suitability mapping been conducted by DPIRD to assess the likelihood of PSHB spread into regional areas or forested zones in the South West; (o) are there active surveillance programs in place in regional or peri-urban areas outside the current quarantine zones; (p) what treatments or chemical injections are currently being trialled as alternatives to the “cut-and-chip” method, and who is conducting these trials ; (q) has the State Government considered trialling or approving biological control agents such as nematodes, as used in other jurisdictions; (r) what steps are being taken to inform and educate the public, landowners, and businesses about the signs of PSHB infestation and reporting procedures; (s) has the Minister reviewed concerns raised by arborists and local councils regarding non-disclosure agreements and the inability to publicly share the location of infected trees; (t) how many staff are currently employed by DPIRD to work specifically on PSHB surveillance, enforcement, and community engagement; (u) what compliance activity has taken place in relation to breaches of quarantine controls, such as the movement of mulch, firewood or infested green waste; (v) what is the projected cost of rehabilitating green spaces where significant canopy loss has occurred due to PSHB removals; (w) what replanting strategies or commitments has the State Government made for areas such as Hyde Park and Kings Park following widespread tree removal; (x) is the State Government providing any direct financial or technical assistance to local governments managing the impacts of PSHB; (y) has the Minister commissioned or received any independent reviews of WA’s PSHB management response to date; and (z) what criteria or thresholds will trigger a review of the State’s current containment approach, and is eradication still considered feasible if new tools become available?
AnswerView source ↗
Answered
14 October 2025
Responded by
Minister representing the Minister for Agriculture and Food
Response time
4 days
(a) PSHB was first detected in August 2021 in East Fremantle.
(b) 196 suburbs.
(c) There has been no detections to date of PSHB infestations outside the Perth metropolitan area.
(d) Details of the gazetted Quarantine Area are available on Department of Primary Industries and Regional Development (DPIRD) website. Two premises are currently under active movement restrictions.
(e) 1 July 2025.
(f) The Consultative Committee on Emergency Plant Pests and the National Management Group considered a range of detailed scientific and technical advice in determining whether PSHB remained technically feasible to eradicate including improved understanding of the biology of the pest and life cycle, particularly under local conditions, and the extent of infestation and host species in WA.
The need to find and destroy every single female borer across a large, open environment and available detection and eradication tools has let to it being determined it is not possible to eradicate the pest.
(g) Yes.
(i) DPIRD responded immediately to the public report of borer symptoms and rapidly undertook inspection, sampling and diagnostics to confirm the presence of the exotic pest. Following the detection DPIRD responded rapidly and appropriately.
(h) $20.07 million.
(i) The response has been funded by the Australian, state and territory governments. The details of expenditure are subject to contractual confidentiality requirements.
(j) Yes. Cost-sharing arrangements are in place with the Commonwealth, state and territory governments.
(k) DPIRD works closely with all landholders to manage infested trees. This includes relevant local government authorities, Botanic Gardens and Parks Authority, and Department of Biodiversity, Conservation and Attractions.
(l) 5,027 trees have been removed.
(i) As the shot-hole borer response plan does not define heritage or iconic trees, data according to these categories cannot be provided.
(m) The WA shot-hole borer host list, which includes all host species identified to date, is publicly available and can be found on DPIRD’s website.
(n) A number of studies have been completed independently, including climate suitability modelling by Warnakula & Parsons (2024), Li X (2023) and Coates & Phillips (2025). I am advised further work on impact modelling will be undertaken as part of the transition to management.
(o) Yes.
(p) Several small-scale trials and ad hoc tests have been undertaken to test chemical controls for shot-hole borer including:
(i) trunk injection of fungicide and insecticide as a prophylactic and curative treatment
(ii) wound protectants to prevent re-infestation of trees post-pruning
(iii) intensive topical insecticidal treatment as a curative treatment under specific conditions.
I am also aware that some local governments and private organisations are undertaking their own small-scale trials.
Further research is being delivered by the University of Western Australia, Murdoch University and Curtin University, in partnership with DPIRD and funded by the WA Government through the WA Agricultural Research Collaboration.
(q) Trials on the efficacy of certain entomopathogenic nematodes for the control of shot-hole borer have commenced as part of the research funded through the WA Agricultural Research Collaboration.
(r) The State Government has undertaken an extensive public education campaign, including television, radio and print advertising, social media, roadside signage, signage in key locations and public transport hubs, and in-person presentations and events.
(s) Yes, DPIRD ensures data sharing meets legislative requirements and balances the need to provide access to relevant data with privacy requirements.
(t) 88 FTE.
(u) Authorised inspectors issue notices under the Biosecurity and Agriculture Management Act 2007 to require relocation of risk materials found to be in breach of the Quarantine Area Notice requirements to an authorised green waste processing site.
(v) – (w) Given the range of land-managers involved, the overall cost of rehabilitation is not known. Through the 2025-26 State Budget, the WA Government is providing $16.9 million for urban tree canopy and Treebates programs to support rehabilitation efforts.
(x) Yes. The government is providing both technical and financial assistance to local governments impacted by PSHB.
(y) Standard post-incident review processes will be undertaken through DPIRD and Plant Health Australia.
(z) The progress of the national Transition to Management Response Plan is monitored against identified milestones and trigger points. A national review of the plan and strategy will occur if milestones are not met or if trigger points are reached. The Government will consider the opportunity provided by any scientifically validated tools as they become available.
(b) 196 suburbs.
(c) There has been no detections to date of PSHB infestations outside the Perth metropolitan area.
(d) Details of the gazetted Quarantine Area are available on Department of Primary Industries and Regional Development (DPIRD) website. Two premises are currently under active movement restrictions.
(e) 1 July 2025.
(f) The Consultative Committee on Emergency Plant Pests and the National Management Group considered a range of detailed scientific and technical advice in determining whether PSHB remained technically feasible to eradicate including improved understanding of the biology of the pest and life cycle, particularly under local conditions, and the extent of infestation and host species in WA.
The need to find and destroy every single female borer across a large, open environment and available detection and eradication tools has let to it being determined it is not possible to eradicate the pest.
(g) Yes.
(i) DPIRD responded immediately to the public report of borer symptoms and rapidly undertook inspection, sampling and diagnostics to confirm the presence of the exotic pest. Following the detection DPIRD responded rapidly and appropriately.
(h) $20.07 million.
(i) The response has been funded by the Australian, state and territory governments. The details of expenditure are subject to contractual confidentiality requirements.
(j) Yes. Cost-sharing arrangements are in place with the Commonwealth, state and territory governments.
(k) DPIRD works closely with all landholders to manage infested trees. This includes relevant local government authorities, Botanic Gardens and Parks Authority, and Department of Biodiversity, Conservation and Attractions.
(l) 5,027 trees have been removed.
(i) As the shot-hole borer response plan does not define heritage or iconic trees, data according to these categories cannot be provided.
(m) The WA shot-hole borer host list, which includes all host species identified to date, is publicly available and can be found on DPIRD’s website.
(n) A number of studies have been completed independently, including climate suitability modelling by Warnakula & Parsons (2024), Li X (2023) and Coates & Phillips (2025). I am advised further work on impact modelling will be undertaken as part of the transition to management.
(o) Yes.
(p) Several small-scale trials and ad hoc tests have been undertaken to test chemical controls for shot-hole borer including:
(i) trunk injection of fungicide and insecticide as a prophylactic and curative treatment
(ii) wound protectants to prevent re-infestation of trees post-pruning
(iii) intensive topical insecticidal treatment as a curative treatment under specific conditions.
I am also aware that some local governments and private organisations are undertaking their own small-scale trials.
Further research is being delivered by the University of Western Australia, Murdoch University and Curtin University, in partnership with DPIRD and funded by the WA Government through the WA Agricultural Research Collaboration.
(q) Trials on the efficacy of certain entomopathogenic nematodes for the control of shot-hole borer have commenced as part of the research funded through the WA Agricultural Research Collaboration.
(r) The State Government has undertaken an extensive public education campaign, including television, radio and print advertising, social media, roadside signage, signage in key locations and public transport hubs, and in-person presentations and events.
(s) Yes, DPIRD ensures data sharing meets legislative requirements and balances the need to provide access to relevant data with privacy requirements.
(t) 88 FTE.
(u) Authorised inspectors issue notices under the Biosecurity and Agriculture Management Act 2007 to require relocation of risk materials found to be in breach of the Quarantine Area Notice requirements to an authorised green waste processing site.
(v) – (w) Given the range of land-managers involved, the overall cost of rehabilitation is not known. Through the 2025-26 State Budget, the WA Government is providing $16.9 million for urban tree canopy and Treebates programs to support rehabilitation efforts.
(x) Yes. The government is providing both technical and financial assistance to local governments impacted by PSHB.
(y) Standard post-incident review processes will be undertaken through DPIRD and Plant Health Australia.
(z) The progress of the national Transition to Management Response Plan is monitored against identified milestones and trigger points. A national review of the plan and strategy will occur if milestones are not met or if trigger points are reached. The Government will consider the opportunity provided by any scientifically validated tools as they become available.
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