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Cootamundra wattle (Acacia baileyana)

Cootamundra wattle is an Australian native that has become an environmental weed well beyond its restricted natural range. It competes with native plants, can hybridise with other wattles, and has a long-lived soil seedbank that makes control a sustained effort.

Key facts

Type: Weed, shrub.

Native to: The Cootamundra, Stockinbingal and Temora district in the Western Slopes of New South Wales..

Established in: QLD, NSW, ACT, VIC, TAS, SA, WA.

Other names: Golden Mimosa.

Best time to act: Treat plants before they fruit; flowering generally occurs from June to September and pods mature from October to January.

Identification

  • It is a shrub or tree growing up to 10 m high, with a spreading crown and smooth grey or brown bark.
  • Its finely divided, bipinnate leaves are silvery grey-green or blue-green and have a whitish bloom.
  • Golden yellow, ball-shaped flower heads are arranged in elongated clusters, generally flowering from late winter to spring.
  • The flattened seed pods are 3–10 cm long, bluish-green when young and purplish-brown or reddish-brown when mature.
  • Mature pods split open to release dark brown to black, hard-coated seeds.
  • Look-alike: Silver wattle (Acacia dealbata) has similar-coloured foliage, but generally has longer leaves with up to 20 or more pairs of leaflets; Cootamundra wattle usually has shorter leaves with 2–4 pairs, sometimes up to 6.
  • Look-alike: Cootamundra wattle can hybridise with other bipinnate wattles, including silver wattle, and the intermediate appearance can make identification more difficult.

Where it grows

In Australia it grows in open woodland and mallee in its native range, and beyond that range invades woodlands and forests in drier areas with annual rainfall above 400 mm; it is naturalised in parts of Queensland, Western Australia, South Australia, the ACT, Victoria and New South Wales.

Why it matters

  • Beyond its native range, it competes with native shrubs, small trees and ground flora and impedes their regeneration.
  • It threatens heathland and heathy woodland, lowland grassland and grassy woodland, dry sclerophyll forest and woodland, and riparian vegetation.
  • It is reported to hybridise with at least six other Australian wattles, threatening the genetic integrity of native wattle populations.

How it spreads

  • Hard, long-lived seeds are spread by birds and ants.
  • Seeds can also be spread on machinery and in garden waste.
  • The species has been extensively planted in gardens and shelter-belts and remains available in nurseries, garden centres, fetes and markets.

Control options

  • Hand-pull seedlings and dig out small plants; mature plants do not usually reshoot and can be ring-barked or cut down without herbicide.
  • Use registered herbicides where suitable, including cut-stem painting for younger plants, drill-fill treatment, or spraying seedlings and smaller plants.
  • Fire destroys plants and stimulates seed germination, allowing resulting seedlings to be removed manually or sprayed.
  • Treat plants before they fruit, remove and bag pods, and follow up for several years to exhaust the soil-stored seedbank.

Hygiene and washdown

  • Clean machinery after working around infestations, as seeds can be spread on machinery.
  • Do not move garden waste or pods from infested areas, as seeds can spread in garden waste.
  • Inspect and clean vehicles, plant and footwear before leaving an infested area, paying attention to tyres, radiators, belly plates, tracks and floor mats.
  • Wash down at a designated bay where runoff is contained and can be monitored for seedlings.
  • Record each washdown so the client has evidence of clean entry and exit.

Classification by state

  • Australia (national): No national listing. Managed under state and territory law.
  • Queensland: Prohibited matter. Report it to Biosecurity Queensland on 13 25 23 within 24 hours and do not move or deal with it. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Not a priority weed. Not a state or regional priority weed in NSW. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Not declared. Not on the NT A to Z weed list, and Weeds Australia does not list it as declared in the NT. Check the NT declared weeds list before moving or planting it.
  • Australian Capital Territory: Declared pest, prohibited. It is a declared pest throughout the ACT. Dealing with it, such as selling, moving or keeping it, is prohibited.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • Queensland: Biosecurity Act 2014 (Qld), administered by Biosecurity Queensland (13 25 23)
  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Australian Capital Territory: Biosecurity Act 2023 (ACT), administered by ACT Biosecurity
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources