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Legislative Council - Fifty-Fifth Parliament, First Session (55-1)
2025-08-21 Daily Xml
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Giant Pine Scale

The Hon. J.M.A. LENSINK (14:46): I seek leave to make a brief explanation before addressing some questions to the Minister for Primary Industries regarding the giant pine scale outbreak.

Leave granted.

The Hon. J.M.A. LENSINK: In May this year, I asked the minister about giant pine scale and in her response the minister advised that the government has committed $1 million to revegetation works at the Hope Valley Reservoir. She also stated and I quote:

…we are aiming to eliminate all known detections of the pest…

Further that:

The priority of the response program is really twofold: it's to protect amenity tree plantings through the urgent removal of infested trees, as well as to protect, to the extent possible, our forest industries.

My questions to the minister are:

1. Can the minister confirm whether there are giant pine scale-infested trees within the Hope Valley Reservoir that have not yet been removed?

2. If so, when was the infection first detected and how many trees are affected?

3. Is the government proceeding with revegetation or other works, such as footpath installation, at the Hope Valley Reservoir and when are these works anticipated to begin?

4. Have there been any additional detections outside of the currently identified sites of the Highbury Aqueduct, Silverlake Reserve, Elliston Reserve, Hope Valley Reservoir and the Supashock site and, if so, where, when and are those trees still in place?

5. Has the government undertaken, or does it intend to undertake, any communication with the local community about giant pine scale to increase the likelihood of detection in a similar way to fruit fly?

The Hon. C.M. SCRIVEN (Minister for Primary Industries and Regional Development, Minister for Forest Industries) (14:48): I thank the honourable member for her question. Giant pine scale is native to the eastern Mediterranean region and causes a number of different impacts: branch dieback, gradual desiccation and eventually tree death. It feeds exclusively on plants from the pine family, such as pines, firs, and spruces.

As I think I have mentioned in this place before, giant pine scale is a threat to both the softwood forestry industry and wood processing industries in South Australia, as well as to the trees that are pines and similar in our urban landscape. Giant pine scale in Australia is now considered to be endemic, so no longer an exotic pest, and as such management of the pest rests with land managers, landowners and industry. In South Australia, people are obliged to report infestations to PIRSA as doing so allows potentially affected stakeholders to assess new detections and to decide on actions.

Giant pine scale has been detected in metropolitan Adelaide on three recent occasions. The 2023 detections at Hope Valley Reservoir and Elliston and Highbury Aqueduct reserves resulted in the removal of 913 trees. It is important to note that the majority of those trees were not infested themselves, but they were removed to create a buffer to prevent the spread of giant pine scale.

A comprehensive surveillance program supported by our forest industries recently surveyed thousands of trees across North Adelaide, Adelaide, Hope Valley, Highbury and the suburbs in between. As part of this surveillance, giant pine scale was detected in 2024 on trees at the Highbury Aqueduct Reserve and Hope Valley Reservoir Reserve as well as nearby Silverlake Reserve and on private land at Holden Hill. Trees at Highbury Aqueduct Reserve, Silverlake Reserve and Holden Hill were removed in April of this year, with tree removal at Hope Valley Reservoir pending.

A total of about 500 trees are anticipated to be removed at Hope Valley soon. The majority of these are not infested but, again, are removed to create a buffer. It is important to note that a buffer is the only known way to effectively prevent the spread. The timing of removal operations takes into account the life cycle stages of the pest to ensure a new generation does not hatch and spread to adjacent sites or trees.

Giant pine scale has only been found in areas adjacent to the 2023 control areas, so that suggests the pest is not becoming more widespread and that it can be eradicated here in South Australia. That is certainly a very positive aspect that I am able to report. Once the operations are complete, if no further giant pine scale is detected in Adelaide for two years, it can then be considered locally eradicated.

The removal of the affected trees remains the best known option for eliminating giant pine scale and is regarded as the quickest and most effective eradication method against the pest. Best practice control involves creating a 50-metre buffer around infested trees, which means that susceptible nearby trees are also removed. This prevents undetected scale from remaining as they can crawl up to 50 metres to find another host. It is probably worth pointing out that when we talk about removal in that 50-metre buffer zone, that is only of pine trees or the same type of trees. As I mentioned, they are the pine family: pines, firs and spruces.

I think it is fair to say that when people see reasonably widespread felling of trees it can be quite distressing. Certainly, communication is an important aspect of that. Communications have been continuing, and indeed I was part of a community get-together probably 2½ months ago. They are talking about the revegetation of one of the areas. We will continue to work with industry and with local landowners and land managers to attempt to eradicate giant pine scale from Adelaide and therefore South Australia.

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