Polyphagous shot-hole borer

Page last updated: Friday, 22 October 2021 - 12:41pm

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 the fungus Fusarium euwallaceae, cultivating 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 industry (particularly avocado, citrus and stone fruit).

Current Situation

The Department of Primary Industries and Regional Development is responding to the confirmed detection of an exotic beetle Polyphagous Shot-Hole Borer (PSHB) in a backyard maple tree in East Fremantle. 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

 

To stop the spread, a Quarantine Area Notice is now in place for parts of the suburbs of Fremantle, East Fremantle, North Fremantle, Palmyra and Bicton for an initial period of six months.

Quarantine Area Requirements

Residents, as well as gardening contractors located within the Quarantine Area must not move any PSHB host wood or green waste material outside the Quarantine Area without prior approval.

This includes prunings, wood products, bark, potted plants, firewood, green waste, logs, plant cuttings, mulch, timber, wood or wood chips.

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

Any gardening machinery or equipment used for tree lopping, gardening, mulching, wood chipping or handling green waste must not be moved outside of the Quarantine Area unless it has been cleaned of all green waste material and decontaminated.

Council FOGO and green waste verge collections

DPIRD has established a procedure with local councils to ensure FOGO bin collection and green waste verge collections continue as normal. Waste from these collections will be treated and disposed of in a process that ensures PSHB can not spread.

Fremantle Recycling Centre is currently not accepting any green waste from residents located within the Quarantine Area.

Applying for a permit

Quantities of PSHB host material that cannot be disposed of through the approved council green waste collection (see above), will require assessment for a permit before host plant material is moved outside of the Quarantine Area.

PSHB host material includes all hosts listed in the Quarantine Area Notice.

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.

Residents are also asked to inspect green waste for borer damage, and if they see any of the symptoms, to keep the material on their property and make a report to the department via the MyPestGuide® Reporter app.

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 up to 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 is irresistible to PSHB beetles.

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

Polyphagous shot-hole borer trap

What plants are affected?

The beetles attack a wide range of plants, a PSHB host list is included in the Quarantine Area Notice.

Reproductive hosts are susceptible trees in which both the beetle and the fungus establish galleries and reproduce. The 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)
  • Castorbean (Ricinus)

Non-reproductive hosts are attacked by the beetle, but PSHB are not 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, stonefruit, fig, grapes and jacaranda.

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.

Beetle entry hole Photo: Pia Scanlon - DPIRD

Beetle entry hole

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

Discolouration/Staining of wood, Photo: FABI, University of Pretoria

Discolouration or staining of wood

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

gumming, Photo: FABI, University of Pretoria

Gumming

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

Sugar volcano on Avocado tree, Photo: FABI, University of Pretoria

"Sugar Volcanoes"

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

Frass / "noodles", Photo: University of California

Frass

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

Dieback, Photo: University of California

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

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

DPIRD Pest and Disease Information Service

MyPestGuideTM

 

Contact information

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