Pest Control

Since arriving in Fremantle from SE Asia in 2021, the polyphagous shot-hole borer beetle (PSHB) has been infesting many of our favourite trees (natives and exotic) in the streets and gardens of Perth.

 

Already, some of Perth’s most iconic large trees, Moreton Bay Figs, have had to be felled because of this pest.

 

The beetles reproduce quickly and an infested tree can be so weakened by bore holes and the fungus the beetles carry that its limbs or the whole tree can fall down. Local councils are alarmed at the risks to passers by of collapsing street trees and they are working with 100s of staff at the Department of Agriculture to identify infestations and to destroy them.

 

There is an extensive description of the problem at Polyphagous shot-hole borer | Agriculture and Food and at Biosecurity Alert: Polyphagous Shot-Hole Borer - City of Cockburn

 

In 3 years, the beetles have spread east to Kalamunda and Gosnells. They have been reported in Beeliar but not yet in the rural areas of Banjup, Jandakot, and Treeby. We need to keep it that way.

 

Many properties in our area have trees that the borer particularly likes, including:

 

Paperbark

Coral / Flame tree

Fig

Mulberry

Golden wattle

Avocado

Mango

Sheoak

Acer

Poinciana

Red flowering gum

Flooded gum

Marri

Oak

Frangipani

Wedding bush

Lilly Pilly

Wisteria

 

The full list of over 100 is at PSHB-WA-Host-List_2.pdf

 

Detection of beetles is difficult because they are very small – about the size of a sesame seed. Their bore holes are a millimetre or so in diameter – see photos below.

 

However, there are several symptoms that indicate a tree may be infested: 

 

• Beetle entry/exit holes roughly the size of a ballpoint pen tip (see photos below)

• When pruning branches or inspecting fallen branches, check for evidence of galleries caused by tunnelling beetles  

• Discoloration/staining on bark

• Thick resin or sap exuding from bore holes

• Frass or “noodles” caused by tunnelling may be seen on the tree exterior, indicating a high level of infestation  

• Sugar volcanoes – crystalline foam exuded from entry/exit holes, are a common sign of infestation on Avocado trees  

• Dieback and tree death.   

 

If you notice any of these symptoms or anything unusual on a tree in your property, take a photo and report it to the Ag Dept urgently – see  Report PSBH   If you can, take the photo with a tip of a ball point pen in the frame; this will provide a scale by which the holes can be assessed.

  

There is no treatment for a shot-borer infestation. Limbs or whole trees have to be cut down, removed, and destroyed by the Ag Dept. There is no cost to the property owner.

 

Do not cut and burn trees you suspect to be infested. Get expert advice from the Ag Dept. Burning infested wood prompts the beetles to fly away and infest another tree.