Acacia dealbata

Silver Wattle

Acacia dealbata

Quick facts

Origin
south eastern Australia
Growth form
Small tree
Life cycle
Perennial
Weed Status
Permitted s11
Seedbank
5 years
Flower
Yellow
Dispersal
Wind

Form and function

Silver wattle is native to eastern Australia, introduced as a garden plant and escaped cultivation to be become a weed in southern Western Australia. A prolific seeder, it invades native bushland by spreading in water, through birds ingesting seed, seed transported by ants, propagules attaching to animals fur or feathers, soil movement and garden refuse. It also reproduces readily from root suckers.

Trunk

Habitat requirements

Silver wattle is most common in the south-west of Western Australia, prefers annual rainfall >1000mm/year. Preferred landscape position is on a high plateau or in a valley with a damp southern aspect in a tall open forest or woodland. Preferred soil type is a deep clay loam. Species has low tolerance to poor drainage, dryness and a very high frost tolerance. Silver wattle can form dense stands, has a long-lived seed bank that is stimulated by fire. The species can also resprout after disturbance, making it difficult to control. As a result, it can outcompete native vegetation and reduce biodiversity

Leaves

The leaves are compound and alternately arranged, giving the plant a distinctive bluish-grey to silvery appearance, although they may sometimes appear green. They are typically 5–12 cm long and consist of numerous pairs of pinnae, each bearing many very small, narrow leaflets. The leaflets are slightly hairy, particularly along their margins and undersides, while the central leaf stalk is also hairy and features a small gland near its base.

Leaves

Flowers and seeds

The flowers occur in small, yellow, globular heads measuring about 4–7.5 mm in diameter. Each flower head contains numerous tiny flowers and is arranged in larger, many-flowered clusters. Flowering mainly occurs from winter through to spring.  Seeds are formed in pods up about 11.5 cm long.

Seed

Impact

Reduces and outcompetes native grassland species, especially grasses and wildflowers, has less effect on native trees and shrubs. It changes soil properties, including increasing water repellency and reducing water infiltration (Patuma and Sheunesu, 2025)

How to control

Arum Lily

Physical / Mechanical

Arum Lily

Chemical

Arum Lily

Cultural / Managerial

Physical / Mechanical

For smaller, light infestations of seedlings hand weeding is suitable. Small shrubs/trees can be hand pulled, ensuring removal of the taproot.

For older plants, ringbarking can be done by stripping away at least 10cm all the way around the trunk, ensuring that the strip is deep enough.

For larger saplings and mature trees, removal by felling followed by chemical treatment.

Following the removal of large trees by felling and/or chemical treatment, should be followed by hand pulling the flush of seedlings that are likely to appear.

Chemical

For mature trees, apply a mix of 30g of picloram (120g/L) and 60g of tricloclopyr (240g/L) with 15L of diesel to the basal 50cm of the trunk using a sprayer.

For mature trees, stem injection by using a drill and fill method which involves drilling holes at intervals around the circumference of the tree into which a strong (50%) glyphosate (540g/L) is injected into the tree.

Foliar herbicide application is not recommended due to the thick waxy leaf cuticles.

Cultural / Managerial

In large dense stands a hot fire may be used to kill old trees and encourage seed to germinate so they may be controlled by herbicides or manually.  However, avoid further burning once this has been done or denuding the area as this will encourage seedling establishment.  Monitor the site through regular visits for newly emerging seedlings from the seedbank, recording their occurrence and assessing density and growth stages.

Further
reading

Minor use permit
external link Permit PER96642 for picloram and tricloclopyr
external link Permit PER96570 for glyphosate

Weed Distribution Map

LSID number: [51286863] | full LSID: [https://id.biodiversity.org.au/taxon/apni/51286863] | field_lsid: [] | taxon: [Acacia dealbata]

ALA Reference

References

  • Agriculture Victoria (2019) Silver wattle.
  • Brown, K., & Brooks, K. J. (2003). Bushland weeds: a practical guide to their management With case studies from the Swan Coastal Plain and beyond. Environmental Weeds Action Network.
  • Kodela, P. G. (n.d.). Factsheet - Acacia dealbata subsp. dealbata. Lucidcentral.
  • Moore, J & Wheeler, J (2020) Southern Weeds and their Control. DPIRD Western Australia
  • Patuma, B., & Sheunesu, R. (2025). Effects of Acacia dealbata Invasion and Removal on Soil and Vegetation in Communal Grasslands in Eastern Cape, South Africa. African Journal of Ecology.
  • PlantNET - FloraOnline (n.d.) Acacia dealbata.
  • Western Australian Herbarium (1998–) Florabase—the Western Australian flora. Department of Biodiversity, Conservation and Attractions. (Accessed 9 June 2026).
  • Kodela P.G. & Tindale M.D. Acacia dealbata, in P.G. Kodela (ed.), Flora of Australia. Australian Biological Resources Study, Department of Climate Change, Energy, the Environment and Water: Canberra. [Date Accessed: 10 July 2026]

Weed lifecycle calendar

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Notes
Germination
Flowering
Lorem ipsum dolor sit amet consectetur adipisicing elit.
Fruiting
Regularly or most commonly
Occasionally, given suitable conditions
Last updated: October 2026