The Department of Primary Industries and Regional Development (DPIRD) is currently working with the goal of eliminating the pest, which at present means removal of some infected trees, or the removal of infected limbs.
First detected in Western Australia in 2021, it has been confirmed at 428 sites across Perth ranging from backyards and street verges to public open spaces, parks and reserves. PSHB has been found in trees in the Town of Vic Park.
Why is PSHB such a problem?
A recently introduced pest, PSHB carries and farms a fungus in infested trees. The spread of the fungus within the tree disrupts the flow of water and food causing dieback, which over time causes the tree to decline and, in some cases, die.
The environmental impact of PSHB in Australia cannot be fully predicted, however, experiences of the pest in other countries (inc South Africa, Israel, and the USA) have shown it has the potential for significant environmental damage.
PSHB is considered both an agricultural and environmental pest, with more than 400 host species including ornamental, fruit, nut, native and amenity trees. Mated female PSHBs can fly, spreading the infestation. People can also inadvertently help spread the infestation by moving infected wood and plants, carrying the PSHB to new areas.
What plants are affected?
PSHB causes serious damage to many types of trees and plants. However, it is particularly drawn to Box Elder Maples (Acer negundo). DPIRD is asking people who have a box elder maple on their property or who identify one on the street or any public areas, to report the location of these trees. This is crucial so we can inspect the trees determine if they are infested with PSHB or have a high probability of becoming infested.
Reproductive hosts are susceptible trees in which both the beetle and the fungus successfully establish and reproduce. The global host list is extensive, with over 100 reproductive hosts. The top hosts are:
Maple (Acer)
Black locust (Robinia)
Coral tree (Erythrina)
Plane tree (Platanus)
Fig (Ficus)
Poinciana (Delonix)
Mirror bush (Coprosma)
Castor oil (Ricinus)
Non-reproductive hosts are plants that can be attacked by the beetle however, PSHB is not reported to be able to successfully establish galleries and complete their lifecycle in these species.
While the fungus may be present in these hosts the disease does not establish and these hosts are not expected to die. Pruning of these hosts of the affected areas are possible, to be able to save the plant. Non-reproductive hosts include citrus (Citrus) and grapes (Vitis).
For a full list of affected trees, visit: www.agric.wa.gov.au/borer
You can help by checking your yard and keeping an eye out when visiting the Town's green spaces!