Polyphagous shot-hole borer

Page last updated: Wednesday, 21 December 2022 - 10:41am

Please note: This content may be out of date and is currently under review.

Polyphagous shot-hole borer (PSHB) Euwallacea fornicatus is a beetle native to Southeast Asia. The beetle attacks a wide range of plants by tunnelling into trunks, stems and branches.

PSHB has a symbiotic relationship with a Fusarium fungus, farming it inside the tree as a food source for the beetle and its larvae. In susceptible trees, the fungus kills vascular tissue causing Fusarium dieback and tree death.

Establishment of this pest in WA would have significant impact on amenity trees, native vegetation, and the fruit and nut tree industries.

Current Situation

The Department of Primary Industries and Regional Development is responding to the confirmed detections of an exotic beetle Polyphagous Shot-Hole Borer (PSHB) in the Perth metropolitan area. Response activities include:

  • Conducting surveillance to determine the distribution of PSHB
  • Containing the pest to prevent further spread to non-infested regions within Western Australia
  • Providing advice and information to residents, industry and other stakeholders
  • Ensuring that all response activities are conducted safely, consistently and efficiently

Quarantine Area (QA)

 

To stop the spread, a Quarantine Area Notice (QAN) is in place to support the Department of Primary Industries and Regional Development’s ongoing surveillance program to determine the spread of the pest.

The Quarantine Area covers 21 local government areas. The new areas added to the expanded QAN are the City of Bayswater, City of Belmont, Town of Bassendean and three localities in the City of Swan – South Guildford, Guildford and Caversham.

The QAN continues to apply to the local government areas of Cambridge, Canning, Claremont, Cockburn, Cottesloe, East Fremantle, Fremantle, Melville, Mosman Park, Nedlands, Peppermint Grove, Perth, South Perth, Stirling, Subiaco, Victoria Park and Vincent.

Quarantine Area Requirements

It is important that people living or working within the QA are aware of the restrictions on the movement of wood and plant material from their properties as they could act as hosts and potentially spread the borer.

  • Movement of wood and plant material within the QA is permitted
  • Wood must be chipped to pieces that are less than 2.5cm in diameter before leaving the QA.
  • Living plants with woody stems greater than 2cm in diameter must not leave the QA.
  • Machinery used to handle green waste must be cleaned of wood material prior to leaving the QA.
  • A permit is required if these conditions are unable to be met.

Wood means wood that is not treated. Treated or seasoned (> 6 months) timber or wood products that are in use for construction, fencing, furniture or packaging and pallets are not considered to be wood and are therefore not considered to be PSHB risk material.

The borer does not affect grass so lawn clippings can be disposed of as normal.

Living plants means any PSHB host plant, organ or plant part (including plant cutting) with woody stems that are greater than 2 cm in diameter. 

Wood machinery means any vehicle, equipment or other mechanical apparatus of any kind that has been used in relation to arboriculture, wood mulching, wood chipping or handling of any other wood.

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Applying for a permit

An inspection and permit is required if the conditions of the Quarantine Area Notice can not be met.

For example, you purchase a mature tree (woody stems greater than 2cm) from a nursery within the QA and wish to move the tree to your property outside the QA. A permit is required before you move the tree outside the QA.

To apply for a permit or to arrange an inspection please email PSHB@dpird.wa.gov.au. or call the Pest and Disease Information Service on 9368 3080.

Trapping

DPIRD is conducting trapping and surveillance to determine the spread of the pest.

Traps are being distributed through the Quarantine Area and across the metro area, these will remain in place for at least six months.

Traps contain a yellow sticky trap in a cage (to prevent trapping birds, micro bats, rodents etc) with a lure. The lures contain Querciverol, an aggregation pheromone that attracts PSHB beetles.

If you see a trap, don't touch them! They have a very important job to do. 

Polyphagous shot-hole borer (PSHB) trap

What plants are affected?

PSHB causes serious damage to many types of trees, but it particularly loves to hide in the box elder maple (Acer negundo). We are asking people who have a box elder maple on their property or street to report the location of these trees, so we can check if they are infested with PSHB.

Reproductive hosts are susceptible trees in which both the beetle and the fungus establish galleries and reproduce. The global host list is extensive with over 100 reproductive hosts, this includes:

  • Maple (Acer)
  • Oak (Quercus)
  • Plane (Platanus)
  • Coral tree (Erythrina)
  • Avocado (Persea)
  • Willows (Salix)
  • Acacia (Acacia)
  • Castor oil (Ricinus)

Non-reproductive hosts are attacked by the beetle, but PSHB are not reported as able to establish galleries and complete their lifecycle on these species. While the fungus may be present in these hosts the disease does not establish and these hosts are not expected to die. Non-reproductive hosts include citrus (Citrus), grapes (Vitis) and Eucalypts (Eucalyptus).

View WA host list.

Management of infested trees

PSHB can severely damage host trees, with some species dying within two years of infestation.

Trees damaged by PSHB can quickly become safety hazards and a constant source of beetles that can disperse to neighbouring trees.

Early detection and the prompt removal or pruning of infested trees is key to containing PSHB spread and minimising further impact on neighbouring trees.

DPIRD is working with local councils, other government agencies and local residents to keep beetle populations down while this incursion is fully considered as part of the nationally co-ordinated response.

Contact DPIRD for advice regarding treatments or tree removal – incorrect treatments can cause further damage to the tree.

A direction to remove an infested tree will only come via DPIRD following the issue of a Pest Control Notice (PCN).

What do I look for?

Female PSHB are approximately 2mm in length and range from brown to black in colour. Only females have the ability to fly and disperse to other trees. Males are smaller at approximately 1.6mm in length and have no wings.

Mature larvae are approximately 3.5mm long and 1.1mm wide. They are white, ‘C’ shaped and legless with a reddish head.

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.

PSHB Beetle entry hole

Beetle entry hole

The entrance holes of PSHB are approximately the size of a ballpoint pen tip.

Staining due to PSHB infestation

Discolouration or staining of wood

The Fusarium fungus cultivated by the beetle can cause dark discolouration.

PSHB Gumming symptoms

Gumming

Thick resin or sap sometimes pushes the beetle out of the gallery.

PSHB sugar volcano on Avocado

"Sugar Volcanoes"

Crystalline foam may be exuded from entry/exit holes. This is a common sign of infestation on avocado trees

Frass / Noodles due to PSHB infestation

Frass

Produced by the beetle's tunnelling, frass or "noodles" may be present extruding from trees. This can indicate the infestation level is high.

PSHB Dieback symptoms

Dieback

In susceptible trees the Fusarium fungus kills tree vascular tissue causing branch dieback and tree death.

How does the pest and its symbiotic fungus survive and spread?

Native to Southeast Asia, PSHB has spread to Israel, California and South Africa.

It is possible PSHB hitchhiked to Australia on untreated wooden articles and packaging materials. Subsequent spread can be aided by the movement of infested wood (eg pruned trees, firewood) or wooden products such as furniture.

Only female PSHB beetles have the ability to fly and disperse to other trees. 

Actions to minimise spread

Firewood - buy it where you burn it

PSHB does not move far on its own but can travel long distances when people move firewood.

You can help protect our natural resources, urban trees and truffle, fruit and nut tree industries by doing the following:

  • Don't move firewood long distances including when you go camping - buy it where you burn it.
  • Don't burn wood from host trees, especially if it looks like it has borer damage. PSHB beetles disperse when infested wood is burnt.
  • Encourage family and friends not to move firewood.
  • Report suspect borer damage.

Early detection

  • Monitor susceptible species including street trees for signs of PSHB damage and report suspect infestation to DPIRD.
  • Speak to your friends and neighbours to create awareness.

Keep your trees healthy

  • Use grass clippings or compost as mulch in your garden as wood chips can spread PSHB
  • Provide additional water during summer as PSHB targets stressed trees
  • Disinfect pruning tools. Any tools (including chainsaws and woodchippers) that come into contact with infected wood should be sanitised before using on uninfected trees
  • Avoid moving prunings or wood products from a known PSHB infestation area

Report suspect PSHB infestation

Please include a ballpoint pen or ruler in photos of bore holes. This assists us in assessing the size of the bore holes.

DPIRD Pest and Disease Information Service

MyPestGuideTM

 

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080