Joondalup Halts Marri Tree Planting Amid Invasive Beetle Threat
The City of Joondalup has suspended the planting of native marri trees in parks and street verges indefinitely, as officials work to curb the spread of the destructive polyphagous shot-hole borer across Perth's northern suburbs. This decision comes in response to a growing number of confirmed cases, with twenty-nine trees now removed from six locations within the city, a significant increase from just three cases reported on council-managed land in June 2025.
Beetle Infestation and Tree Removal
Confirmed infestations on city-managed land have been identified in Duncraig and Kingsley, with an additional case on private property in Sorrento. The polyphagous shot-hole borer, a sesame seed-sized beetle, poses a severe threat to trees by boring into them and introducing a fungus that can block water and nutrient flow, ultimately leading to tree death. Since its first detection in Western Australia in 2021, thousands of trees across Perth have been lost to this invasive pest.
Rejection of Marri Tree Planting Request
The suspension of marri tree planting was revealed following an elector's motion that requested the city plant 100 marri trees across Gascoyne, Chichester, and Timberlane parks to support endangered Carnaby's and red-tailed black cockatoos. While the council supported the motion, a report did not recommend planting marri trees, as this species is a known reproductive host for the borer. Instead, the city will assess opportunities to plant alternative tree species at these parks to provide food sources for the black cockatoos.
"The marri is currently listed as a preferred tree species within the city's street verge guideline, but this species has now been identified as a reproductive host for the highly invasive and damaging polyphagous shot-hole borer," city staff stated in the report. "In its efforts to combat the spread of this borer, the city has suspended the planting of tree species that have been identified as a reproductive host."
Mayor's Statement and Future Plans
Joondalup Mayor Daniel Kingston emphasized that the decision is a temporary precaution based on advice from the Department of Primary Industries and Regional Development (DPIRD). "This is a temporary precaution to help protect our urban forest, and we'll review regularly in line with updated advice from DPIRD and as part of the city's ongoing management strategy," Mr. Kingston said. The city has secured grant funding to replace canopy cover lost to the borer, equating to approximately three new trees for every tree removed.
As part of the city's winter tree planting program, 61 trees are planned for Duncraig, in addition to 22 previously planted. This year, nearly 1,000 trees are scheduled to be planted across Beldon and Heathridge. The request for suitable species to support cockatoos at Gascoyne, Chichester, and Timberlane parks will be included in the 2027 winter tree-planting program, ensuring continued efforts to maintain biodiversity while addressing the beetle threat.
