Polyphagous Shot-Hole Borer

The City of Fremantle is working with the Department of Primary Industries and Regional Development’s (DPIRD) to help stop the spread of the invasive pest Polyphagous shot-hole borer (PSHB).

What is PSHB?

Polyphagous shot-hole borer or PSHB (Euwallacea fornicatus) is a beetle native to Southeast Asia. About the size of a sesame seed, PSHB excavates tunnels in trees where they cultivate fungus as a food source.

This fungus spreads in the tunnels of trees disrupting the flow of water and nutrients.

Trees damaged by PSHB can become a perpetual reservoir of beetles, capable of dispersing and affecting neighbouring trees.

The environmental impact of this species is likely to be high. Establishment of the pest in WA may result in significant impacts to the urban tree canopy.

How to spot infected trees?

Detection of PSHB is difficult as they are very small – about the size of a sesame seed. However, there are a number of symptoms that indicate a tree may be infested.

The top hosts of PSHB include Maple (Acer), Plane (Platanus), Robinia (Robinia), Poplars (Populus), Oak (Quercus), Avocado (Persea), Fig (Ficus) and Coral Tree (Erythrina).

Symptoms of infestation vary from species to species. The main things to look for include:

• Beetle entry/exit holes – approximately the size of a ballpoint pen tip.
• Galleries – when pruning branches or inspecting fallen branches, check for evidence of galleries caused by the tunnelling action of PSHB beetles.
• Discoloration/staining – this is caused by the Fusarium fungus.
• Gumming – thick resin or sap.
• Frass – produced by the beetles tunnelling, frass or ‘noodles’ may be seen on the tree exterior. This can indicate a high level of infestation.
• Sugar volcanoes – a common sign of infestation on Avocado trees, crystalline foam is exuded from entry/exit holes.
• Dieback and tree death – the fungus disrupts the tree vascular symptom causing dieback and death.

Quarantine Area

The City of Fremantle is included in DPIRD’s Quarantine Area.

PSHB has been confirmed in more than 80 suburbs across the metropolitan area in backyards, street verges, public open spaces, parks and reserves. A Quarantine Area is in place for most of the Perth metropolitan area. If you think you have this destructive little beetle, please report it via the DPIRD Pest and Disease Information Service on +61 (0)8 9368 3080 or padis@dpird.wa.gov.au.

To find out more about the Polyphagous shot-hole borer, the quarantine area and related restrictions visit the DPIRD website below.