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Sicklebush (Dichrostachys cinerea)

Dichrostachys cinerea is a fast-growing tree that can form dense, impenetrable thickets, particularly in areas affected by overgrazing. It can persist after disturbance because it regrows from root fragments and suckers, and its seeds can remain in soil for long periods.

Key facts

Type: Weed, tree.

Native to: Described as exotic and also as native to parts of Australia.

Established in: QLD, NT.

Other names: Aroma, Marabou-thorn, Cailliea cinerea, Desmanthus cinereus.

Identification

  • It is a thorny tree with strong alternate thorns reported to reach 8 cm long.
  • Its bipinnately compound leaves are reported to reach 15 cm long.
  • The rough, yellow to grey-brown bark is frequently fissured.
  • Fragrant, hanging flower spikes have a lilac or purple upper part and a yellow lower part.
  • Its mustard-brown pods are twisted or spiralled and reported to reach 100 mm by 15 mm.

Where it grows

It grows in thickets, grassland, woodland, dry deciduous forest, brushwood, hedges and teak forest.

Why it matters

  • Dense, impenetrable thickets can make areas difficult to access and manage.
  • Root fragments and root suckers can drive regrowth and reinfestation.
  • Long-lived seeds in the soil can allow infestations to persist and re-establish after disturbance.

How it spreads

  • It can regenerate from small root fragments and produce root suckers.
  • Seeds can persist for long periods in soil.
  • Soil and plant material carried on machinery or vehicles can spread seeds and root fragments between properties or paddocks.

Control options

  • Where feasible, mechanically remove plants while targeting the root system to limit regrowth and root suckering.
  • Use a cut-stump approach on freshly cut woody stems to reduce reshooting from the base and roots.
  • Revisit treated areas and manage regrowth, as root fragments and suckers can produce new growth.
  • Check current requirements with the state biosecurity authority, as local declaration status may vary.

Hygiene and washdown

  • Clean down machinery and vehicles and remove soil and plant material before moving between properties or paddocks.
  • Pay particular attention to material that could carry seeds or root fragments.
  • 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: Restricted matter, category 3. Do not give it away, sell or release it into the environment. 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: Not listed. Not found in the Western Australian Organism List. Check with DPIRD before moving or keeping it.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Check NT list. There is no NT weed profile for it. Check the NT declared weeds list for its current status.
  • Australian Capital Territory: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

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)
  • Northern Territory: Territory Parks and Wildlife Conservation Act 1976 (NT), administered by NT Department of Lands, Planning and Environment

Sources