Tasmanian blue gum wildlings on Kangaroo Island

The Kangaroo Island Landscape Board is working with Kangaroo Island Council, the Kangaroo Island Country Fire Service, Parndana Progress Association, Kangaroo Island Tourism Alliance and KI Eco-Action on a shared approach to remove self-sown Tasmanian blue gums from natural areas. We have tested control methods and are seeking funding with our partners to treat wildlings across the island.

What is a Tasmanian blue gum wildling?

Tasmanian blue gum (Eucalyptus globulus) is native to other parts of Australia but not Kangaroo Island. A wildling is a tree not planted and maintained for commercial or public amenity purposes. The current key area of concern are self-sown wildlings growing within native vegetation. Large numbers established within and outside of plantations, spreading into high value native vegetation after the 2019–20 bushfires scorched tree canopies, released seed and created conditions for germination. The current declaration applies to wildlings; it does not apply to trees planted and maintained for domestic, public amenity or commercial purposes.

Why their spread matters

Blue gums have been planted for timber on several continents. Wildlings have spread beyond plantations in countries including Portugal and Spain. Deadly fires in Portugal in 2017 burned through blue gum plantations, and dense introduced eucalypt stands have raised fire and biodiversity concerns in California. These examples show the scale of the problem when introduced trees spread; on Kangaroo Island they have already established in bushland after fire.

The Board estimates 3.68 million wildlings across 1,769 hectares along about 1,067 kilometres of plantation boundary with native vegetation, mainly in western and central Kangaroo Island. As the trees grow and spread, dense stands can:

• crowd out native plants and degrade habitat used by Kangaroo Island wildlife;
• increase fuel loads and increase fire intensity; and
• reduce surface water runoff by 85% impacting water dependent ecosystems.

Early treatment of smaller, scattered trees is generally less difficult and less costly than removing dense stands later. Sites with dense wildlings may need different methods and careful planning to protect remaining native vegetation.

What the pilot found

In 2025, the Kangaroo Island Landscape Board and the Department for Environment and Water tested six ways to remove blue gum wildlings at MacGill North, part of the Kiland estate. Local contractors and Board staff used machinery, hand control and herbicides on scattered trees and dense stands along 18.7 kilometres of plantation edge. The Native Vegetation Council approved a management plan for this specific trial, including measures to protect native vegetation.

In the dense areas surveyed, machinery reduced standing wildlings by 94 per cent. The pilot did not remove every tree. Crews will need to return to treat trees that resprout and new seedlings that appear after the initial work.

The pilot helped the Board plan the work needed across the island and estimate its cost. Landholders would clear existing blue gum plantation blocks to prevent more seed spreading. Crews would first treat scattered wildlings, then map dense areas and obtain the approvals needed to work in native vegetation. They would use machinery followed by hand control where trees are thickest, return to treat regrowth and new seedlings, and make a final search for any wildlings left behind.

The plan and the funding needed

The proposed program begins with landholders clearing existing plantation blocks. Teams would treat scattered wildlings first, map dense areas, obtain any required approvals, use appropriate machinery and hand control in dense stands, return to treated sites, then search for remaining trees. Work beside cleared or harvested plantations would be prioritised; other areas would follow as plantations are cleared. 

The Board and community partners are seeking an initial $1.69 million for priority treatment and planning. The full wildling control program is currently modelled at $10.44 million, including repeat treatment, delivery costs and contingencies. Clearing existing plantation blocks is a separate landholder responsibility. The timing and extent of work will depend on funding, access, site priorities and approvals.

What to do if you have wildlings on your property

Under the current declaration for Kangaroo Island, landowners must take reasonable steps to kill wild Tasmanian blue gums and prevent their spread. If you think you have wildlings:

Landowners on Kangaroo Island must take reasonable steps to kill plants and prevent their spread. Enforceable by the Kangaroo Island Landscape Board.

This only applies to Tasmanian blue gum growing wild in this region. It does not apply to trees that are planted and maintained for domestic, public amenity or commercial purposes.

Act early on small, accessible infestations. The right control method depends on the size of the trees, the site and nearby native vegetation.

If you are unsure of the species, contact the Board for identification advice.

The Board can advise you on identification, suitable control options and who to speak to about approvals. Contact us on 08 8553 2476 or email ki.landscapeboard@sa.gov.au. Please include photos and the property location if you can.
Learn more about treatment options available on the PIRSA weed profile of Tasmanian blue gum wildlings.