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Honey locust (Gleditsia triacanthos)

Honey locust is an invasive tree that can out-compete and replace native vegetation and destroy pasture. Dense thickets, particularly along waterways, can block stock access to water, while the tree’s thorns can injure people and livestock and shelter feral animals.

Key facts

Type: Weed, tree.

Native to: Eastern and central North America.

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

Other names: McConnel's Curse, Bean Tree, Sweet Locust, Three-thorned Acacia.

Identification

  • It is a deciduous, leguminous tree that can grow to 25 metres tall.
  • From spring to autumn it bears prolific green leaves, up to 20 centimetres long, with about twelve pairs of opposite leaflets.
  • The trunk and limbs of wild trees usually have large, branched spines that can grow more than 10 centimetres long.
  • In October and November it bears hanging clusters of creamy-yellow flowers, up to 10 centimetres long.
  • The flowers develop into brown, slightly sickle-shaped pods, 20 to 30 centimetres long, with sweet pulp around the seeds.
  • Look-alike: It is unlikely to be confused with another plant because its prominent, branched thorns are highly distinctive.

Where it grows

In Australia it is recorded in New South Wales, Queensland and Victoria, especially along waterways and on alluvial soils, and is also present but not reported as naturalised in South Australia and Western Australia.

Why it matters

  • If uncontrolled, it can smother desirable pasture grasses and form dense thickets that prevent stock access to water.
  • It can out-compete native vegetation, create dense monocultures with restricted habitat for native fauna, and injure wildlife with its sharp barbs.
  • Its thickets can provide a haven for introduced foxes, cats and rabbits.
  • Its strong spines can seriously injure people and livestock, cause infections, and damage vehicle tyres; dead plants can still have injurious spines.

How it spreads

  • It spreads by seed and suckering.
  • Seeds are spread in animal dung, and pods can float and be carried by water.
  • People can spread it by planting it as an ornamental or fodder tree.

Control options

  • A combination of control methods is likely to be most efficient; follow physical control with other approved methods, such as cultivation or registered herbicides.
  • Continual grazing can suppress seedlings, but may also spread seeds; it can be used after herbicide treatment to control seedlings and regrowth if plants are not bearing seed pods.
  • Bulldozing can break plants at or above ground level, but they regrow vigorously from broken bases and roots; on arable land, dozing followed by deep ploughing requires regular cropping or spot spraying of regrowth.

Hygiene and washdown

  • It notes that seeds spread in animal dung and that pods can float and be carried by water.
  • 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: Regional priority in 6 of 11 regions. Regional priority weed in Central Tablelands, Central West, Hunter, North Coast, North West, 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: 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: 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