Casuarina glauca

Casuarina

Also known as:

Grey she-oak, swamp oak

Family: Casuarinaceae

Origin: Australia

Close up of casuarina seeds.
The greyish brown bark has scales and small fissures
Photo credit: Jackie Miles and Max Campbell

Regional Pest Management Plan (RPMP) status

  • Not a legally declared pest

View more about the RPMP statuses

General description

Tree < 20 m tall. Bark is grey-brown, fissured and scaly. Branches are slender and often weeping. Leaves are minute, scale-like and borne on branchlets. Flowers are brown or red and borne in August – September. Seed pods are cone-like and contain winged seeds.

What you need to know

Although casuarina is not a legally declared pest plant, it may still be invasive in some situations. Consider lower-risk alternatives for your garden, such as native plants.

Habitats

Coastal areas, wetlands, riparian margins.

Dispersal

Seeds dispersed by wind. Vegetative spread from suckering.

Impact on environment

Can form dense stands, displacing native plants and altering water flow in wetlands. Actinorhizal nitrogen fixer.

Control

Site Management

Follow up treated areas 3 times per year. Encourage natural regeneration of native plants or replant treated areas where possible after 2-3 treatments to establish dense ground cover and minimise reinvasion.

Recommended approaches

Physical control

Method: Dig out.

Plant parts requiring disposal: All parts.

Disposal options: Remove to greenwaste or landfill if practical.

Biocontrol

Biocontrol is currently not available for this species.

Community agrichemical control recommendations

No qualifications: Cut stump and paste freshly cut base of stems with metsulfuron gel.

Basic Growsafe certified: Cut stump and spray freshly cut base with 5g metsulfuron-methyl per 1 L of water.

Certified Handler/Experienced agrichemical user: Drill and inject trees with 10g metsulfuron-methyl per 1L of water if safe to do so. Drill 18mm holes (tangentially angled downwards) in a spiral up the trunk.

For 50mm stems drill one hole. For 100mm stems drill two holes. For larger stems drill holes 150mm apart. Foliar spray seedlings with 5g metsulfuron-methyl per 10L of water and 20ml penetrant.

Safety notes

Large trees must not be drilled that are closer than 1.5 times the height of the tree from paths, walkways and property.

Trees over 4 metres in height should be removed by a qualified arborist.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Close up of casuarina branch with leaves, seeds and flowers.
Casuarina flowers are brown or red and borne in August – September.
Photo credit: Jonathan Boow
Branch of casuarina.
Casuarina can form dense stands of trees.
Photo credit: Jonathan Boow
Close up of small red flowers of casuarina.
Casuarina trees can grow up to 20 m tall.
Photo credit: Jackie Miles and Max Campbell
Casuarina cones on a branch.
The branches have numerous drooping branchlets.