Biosecurity Spotters logo

Mesquite (Neltuma spp. (syn. Prosopis spp.))

Thorny shrubs and trees that form dense thickets in arid and semi-arid rangelands, taking over pasture, waterholes and stock routes.

Key facts

Type: Weed, tree.

Native to: The Americas.

Established in: QLD, NSW, SA, WA, NT.

Identification

  • Shrub or tree to 15 m with paired thorns at the nodes.
  • Fern-like leaves divided into many small leaflets.
  • Cream to yellow flowers in finger-like spikes, followed by straw-coloured pods.
  • Look-alike: Prickly acacia has yellow ball flowers and grey constricted pods.

Where it grows

Floodplains, drainage lines, bore drains and stock watering points in arid and semi-arid regions.

Why it matters

  • Forms impenetrable thickets.
  • Reduces pasture and access to water.
  • Harbours feral animals.

How it spreads

  • Livestock and feral animals eat pods and spread seed in dung.
  • Floodwater.

Control options

  • Basal bark, cut stump or soil-applied registered herbicides.
  • Mechanical removal followed by regrowth control.
  • Biological control agents are established in some areas.

Hygiene and washdown

  • Hold stock that have been eating pods in a clean yard before moving them to clean country.
  • 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): Weed of National Significance. One of 32 nationally agreed priority weeds, managed through national strategies with all states and territories.
  • Queensland: Restricted matter, category 3 (other species prohibited). The established mesquites are category 3 restricted matter: do not give them away, sell or release them. Other mesquite species are prohibited matter. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Sale prohibited; Regional priority in 4 of 11 regions. It must not be imported into NSW or sold anywhere in the state. Regional priority weed in Central West, North West, Riverina, Western. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: State prohibited weed. State prohibited weeds are the highest priority: the Victorian Government is responsible for eradicating them, so report any sighting to Agriculture Victoria.
  • South Australia: Declared plant. Depending on the declaration, it can be an offence to move it on public roads or sell it, and landowners may be required to control it on their land.
  • Western Australia: Declared pest (C1), some species prohibited. C1 Exclusion: to be kept out of WA, or out of the parts of WA where it is not established. Report any sighting to DPIRD. Some species must not be brought into WA (prohibited organism).
  • Tasmania: Declared weed. Property managers are required by law to control declared weeds, and their import and sale are prohibited.
  • Northern Territory: Declared weed, Class A. Class A: to be eradicated. All declared weeds are also Class C, so they must not be brought into the NT.
  • 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
  • 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
  • Northern Territory: Territory Parks and Wildlife Conservation Act 1976 (NT), administered by NT Department of Lands, Planning and Environment

Sources