More pine trees will be removed from two Adelaide reserves after fresh detections of a destructive pest capable of eventually killing infected trees.
A small number of non-native pine trees infected with Giant Pine Scale have been found in the eastern section of Hope Valley Reservoir Reserve and western section of Highbury Aqueduct Reserve during spring surveillance.
The new detections are close to areas where previous infestations have been identified and removed in recent years.
Giant Pine Scale, or GPS, is a sap-feeding insect that attacks susceptible trees including pines, firs and spruces. Once a tree is infected, it cannot recover, with infestations causing branch dieback and ultimately tree death.
Work is now underway to remove the newly infected trees along with nearby at-risk pines in an effort to stop the pest spreading further.
Removing infected and surrounding susceptible trees is currently considered the most effective method of eradication in South Australia. At Highbury, authorities generally remove susceptible pine trees within at least a 50-metre buffer because GPS can be difficult to spot in the early stages.
The latest discoveries come after considerable tree removal and revegetation work around Hope Valley and Highbury since Giant Pine Scale was first detected in the area in 2023.
More than 4,500 native trees, shrubs and grasses had already been planted across previously affected areas by February this year as part of the Giant Pine Scale Revegetation Program.
Further native revegetation is planned for areas affected by the latest removals.
The pest poses a risk not only to Adelaide’s established pine trees but also South Australia’s plantation forestry industry.
Previous outbreaks have remained concentrated around Adelaide’s north-eastern suburbs, with detections recorded at sites including Hope Valley Reservoir, Highbury Aqueduct Reserve, Elliston Reserve, Silverlake Reserve and Holden Hill.
Primary Industries and Regional Development Minister Clare Scriven said, “Through comprehensive surveillance activities undertaken in partnership with South Australia’s forestry sector, we are detecting this pest as early as possible.
“By picking up Giant Pine Scale infestations early, we’re minimising their impacts and protecting other trees in our beloved green spaces.”
Surveillance is being carried out by the Department of Primary Industries and Regions alongside ForestrySA, the Australian Forest Products Association, the Department for Environment and Water and SA Water.
Monitoring of at-risk parks, reserves and plantations will continue through spring and into 2027.
People can also help spot the pest. One of its most recognisable signs is a white, cotton-like waxy secretion on the trunk or branches of an affected pine tree.
Anyone who suspects they have found Giant Pine Scale should avoid moving affected plant material and report the sighting to the Exotic Plant Pest Hotline on 1800 084 881.
