Giant pine scale
Giant pine scale (Marchalina hellenica) is an insect that lives by sucking the sap of pine trees. It was reported for the first time in Australia in late 2014 when it was found in pine trees in suburbs east of Melbourne and in Adelaide.
In late 2016, the Department of Primary Industries and Regions, South Australia, successfully eradicated giant pine scale in South Australia. 91 infested trees were removed and the sites decontaminated.
In Victoria, it has not been possible to destroy the pest. There are more than 4 300 infested trees in the south east suburbs of Melbourne. In September 2018, the National Management Group (NMG) agreed that the transition to management phase had been successfully completed, bringing the response to an end.
Infested trees in Victoria were treated with the insecticide imidacloprid but the chemical injection treatments did not work as effectively as expected and live scale insects remain present on treated trees.
The Consultative Committee on Emergency Plant Pests (CCEPP) considered alternative eradication options in Victoria but concluded that giant pine scale cannot be eradicated. This is because:
- chemical controls have shown to be ineffective
- the only other control option was to remove all infested trees, which would not have been publicly acceptable
- there is low confidence that the pest is detectable at very low densities
- costs would be considerably high to achieve full eradication of the pest.
The CCEPP’s recommendations were supported by NMG in October 2016.
Giant pine scale has not been found in other parts of Australia, nor has it been detected in any pine plantations. However, as a sap sucking insect, it poses a threat to Australia’s softwood plantation industry.
Containment and management activities
While it has been agreed that the pest cannot be eradicated from Victoria, attention to limiting the spread and managing the impact of giant pine scale in Victoria will now be the focus.
Agriculture Victoria will continue to work with the softwood industry, arborists, local government and the community to manage the pest.
The softwood plantation industry is working with private landowners, councils and government to assist in the control or removal of isolated outbreaks. This is strategically important to limiting the spread of giant pine scale and reducing the risk of introduction to commercial pine plantations.
The following websites have more information:
What you need to do
You should continue to be on the lookout for signs of giant pine scale infestation in all jurisdictions.
Do not touch, move or collect samples should you see any white and waxy secretions on pine, fir or spruce trees.
Report any findings to the Exotic Plant Pest Hotline, 1800 084 881. This will put you in contact with your state or territory department of agriculture or primary industries.
Alternatively, if you are in Victoria you can email photos of the suspected pest to Plant Protection. In the email, please also provide your contact phone number and location of the suspected tree(s).
About giant pine scale
Giant pine scale is an insect that lives by sucking the sap of pine trees and some other trees. The insect produces white, waxy, cotton-like secretions that are visible on infected trees.
This insect prefers the lower part of the pine tree and mainly infests the main trunk but infestations may be observed on branches and sometimes exposed roots.
Large populations of the insect can cause gradual dehydration, causing the dieback of branches that eventually kills the tree.
There are no records of previous detections of this insect in Australia. It is known to occur on species of the Pinaceae family (pines, firs and spruces) in Armenia, Crete, Georgia, Italy, Russia and Turkey.
It is not known how it got into Australia, or how long it’s been here.
Photo courtesy of the Victorian Department of Economic Development, Jobs, Transport and Resources.