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Osage orange (Maclura pomifera)

Osage orange is an introduced, spiny tree or shrub that can form dense thickets, particularly along waterways and in inland NSW. It outcompetes native plants, restricts movement and has sap that can irritate skin and eyes.

Key facts

Type: Weed, tree.

Native to: Central United States.

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

Other names: bois d’arc, bow wood, hedge apple, horse apple.

Best time to act: Treat actively growing plants with full leaf growth in spring and summer, ideally before they begin producing fruit.

Identification

  • A deciduous shrub or tree that can grow up to 21 m tall, it has a short trunk and arching branches forming a rounded crown when not crowded.
  • Its branches have sharp spines 1–5 cm long, and its leaves are oval with pointed tips, dark green and waxy above and paler below.
  • The leaves turn yellow and translucent in autumn before falling.
  • Female trees produce round, bumpy fruit 10–15 cm across, usually yellowish green when ripe and containing sticky milky latex.
  • Cut fruit and sometimes leaves or stems exude milky sap; older trunks have deeply furrowed, dark orange-brown bark.

Where it grows

In NSW, Osage orange is recorded in the Central West, Greater Sydney, Northern Tablelands, South East and Riverina, often along waterways and on disturbed sites such as degraded paddocks.

Why it matters

  • It outcompetes native plants, especially along riparian areas in inland NSW.
  • Dense, thorny thickets limit the movement of people and animals.
  • Milky sap can irritate skin and eyes, while the spines can cause injuries.
  • Its roots can reach up to 8 m deep and spread laterally, especially in shallow soil.

How it spreads

  • Trees usually begin producing fruit at about 10 years old; fruit may be seedless if no male tree is nearby.
  • Water can spread seeds, and two days in water overcomes seed dormancy; livestock and birds, including cockatoos, spread seeds after eating fruit and passing them in droppings.
  • The plant can also grow from cuttings or grafts, a method used to establish hedges in parts of NSW.

Control options

  • Treat plants before they produce fruit where possible, and wear protective clothing against thorns and milky sap.
  • Small individual plants can be dug out; larger trees can be cut down and roots removed, but minimise soil disturbance and erosion, particularly in riparian areas.
  • For chemical control, use a herbicide registered for the situation and follow its label; foliar spraying, basal barking and cut-and-paint methods are described for this weed.
  • Check with the local council weeds officer for advice; in the Northern Tablelands exclusion zone, the stated regional measure is to notify the local control authority if the plant is found.

Hygiene and washdown

  • Clean soil and plant material, including fruit and seeds, from vehicles, machinery, boots and tools before leaving an infested site, and avoid moving contaminated soil.
  • Keep livestock and fodder from carrying fruit or seeds to clean areas, and avoid transporting fruit or seed-bearing material along waterways.
  • 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: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Regional priority in 1 of 11 regions. Regional priority weed in Northern Tablelands. 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: 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)
  • 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
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board

Sources