City of Joondalup denies request to plant 100 marri trees as invasive beetle threat grows
Native marri trees are not being planted in parks and street corners in the City of Joondalup for the foreseeable future as authorities try to limit the spread of the polyphagous ball-hole borer in Perth’s northern suburbs.
Twenty-nine trees have been removed at six locations in the city due to positive cases of the probe since three cases were reported on municipally managed land in June 2025.
The confirmed cases on city-managed land were in Duncraig and Kingsley, and one was on private property in Sorrento.
The decision not to plant marri trees was announced after a voter motion asked the city to plant 100 marri trees in Gascoyne, Chichester and Timberlane parks to support endangered Carnaby’s and red-tailed black cockatoos in the area.
A report on the motion supported by the council did not recommend planting marri trees because the species is a known breeding host for the polyphagous shooting hole wolf, but said the city would consider opportunities to plant alternative species in parks to support black cockatoos.
“Marri is currently listed as a preferred tree species in the city’s street boundary guide, but this species has now been identified as the breeding host of the highly invasive and damaging polyphagous shot hole borer,” city staff said in the report.
“As part of efforts to combat the spread of this weevil, the city has suspended planting of tree species identified as breeding hosts.”
Marri trees, formally known as corymbia calophylla, are endemic to south-west WA.
Joondalup mayor Daniel Kingston said the decision was based on recommendations from the Ministry of Primary Industries and Regional Development.
“This is an interim measure to help protect our urban forest and we will review it regularly in line with updated advice from DPIRD and as part of the city’s ongoing management strategy,” Mr Kingston said.
“The city received grant funding to offset loss of canopy cover due to the impact of the polyphagous shothole borer; the funding will equal approximately three new trees for every tree removed.”
As part of the city’s winter tree planting program, 61 trees are planned to be planted in Duncraig, in addition to the 22 trees previously planted.
Approximately 1,000 trees are planned to be planted by the city this year along Beldon and Heathridge.
The request to plant suitable species to provide a food source for cockatoos in Gascoyne, Chichester and Timberlane parks is planned to be included in the 2027 winter tree planting programme.
Thousands of trees across Perth have been lost to the polyphagous shot hole borer since the pest was first detected in WA in 2021.
The sesame seed-sized insect is deadly to trees because it carries a fungus that can burrow into trees and kill them by restricting or blocking the movement of water and nutrients.
