Polyphagous Shot Hole Borer

Polyphagous shot-hole borer (PSHB), a wood-boring exotic beetle which has been gradually spreading across the Perth metropolitan area since August 2021, was first detected in a street tree in the Town of Cambridge in February 2023.

Trees in Floreat, West Leederville, Wembley, Lake Monger and Wembley Golf Course have since been detected to have PSHB.

The Town anticipates a general increase to PSHB spread rate, and an increase in secondary infections in line with global trends, as pest numbers increase and tree health declines due to persistent pest pressure.

The Town is working closely with the Department of Primary Industries and Regional Development (DPIRD) to monitor and respond to the situation. Where trees are infected, DPIRD will be implementing prescribed treatments, which can include pruning of the tree or its full removal.

In the event that a tree has to be removed, the Town will endeavour to replace it with an alternative tree species as soon as reasonably practicable.

Mayor Gary Mack said: “The Town has a dedicated team who manage our Urban Forest, and we are actively managing the spread of PSHB across our suburbs through early intervention. We cannot accurately predict how many more trees will be infected, but the range of highly vulnerable species is limited. For now, we’d encourage our residents to help monitor for PSHB, as early detection is key to minimising further impact on neighbouring trees.”

There are a number of symptoms that indicate a tree may be infested, including:

• Beetle entry holes (approximately the size of a ballpoint pen tip or sesame seed);
• Discolouration or staining of wood;
• ‘Gumming’; the appearance of thick resin or sap;
• ‘Galleries’; intricate tunnels or galleries where PSHB farm fungus;
• Frass; or sawdust that can be present extruding from trees, produced by the beetle’s tunnelling; and
• Dieback.

Reproductive hosts and important trees to check are Maple, Plane, Coral tree, Robinia, Poinciana, Fig, Mulberry, Willow and Avocado.

Residents who suspect they have borer damage to trees should call the DPIRD’s Pest and Disease Information Service on (08)9368 3080, reported via the MyPestGuide® Reporter app, or email padis@dpird.wa.gov.au.

Further information on the beetle can be found at www.agric.wa.gov.au/borer.