Mesquite (Prosopis species)

Also known as: algaroba, honey mesquite, black mesquite, velvet mesquite

Mesquite is a woody weed that invades open grasslands, rangelands and the banks of watercourses by forming impenetrable, thorny thickets.

Profile

How does this weed affect you?

Mesquite is a woody weed that invades open grasslands, rangelands and the banks of watercourses, forming thick, impenetrable, thorny thickets. There are four known species of mesquite in Australia and several hybrids. 

Mesquite has a long lifecycle, very high seed production, the ability to survive droughts and long seed dormancy. These features make it an exceptionally resilient plant that can quickly take advantage of suitable environments and dominate entire ecosystems. Its deep taproot and extensive root system allow it to thrive in hot and dry conditions.

Where is it found?

Mesquite is native to the America’s from southern USA through to northern South America. In its native range its timber is used for fence posts, woodworking and fuel. It has become an invasive weed in many parts of the world including South Africa, Hawaii, West Indies, Iraq, India, Pakistan, Sri Lanka and parts of Africa. It has also become invasive in areas of its native range, particularly southern USA.

Originally planted as a fodder, shade and ornamental tree in northern Australia, mesquite was also planted around mining sites for soil stabilisation and dust reduction. It has now spread throughout mainland Australia, with the worst infestations occurring in the Pilbara region of Western Australia, the Barkly Tablelands of the Northern Territory and western Queensland.

In New South Wales (NSW), infestations of mesquite have mostly occurred throughout the Broken Hill and Milparinka areas in the Western Region. Isolated plants are in the south-western Riverina district and in the north-western areas of Gilgandra, Coonamble and Bourke. Mesquite has the potential to invade all areas of western NSW.

Maps and records

• Recorded presence of Mesquite during property inspections (Map: Biosecurity Information System - Weeds, 2017-2024)
  These records are made by authorised officers during property inspections under the Biosecurity Act 2015. Officers record the presence of priority weeds in their council area and provide this to the NSW Department of Primary Industries. Records reflect the presence of the weed on the date of inspection.
  
  

How does it spread?

Mesquite reproduces by seed which is dispersed when livestock feed on seed pods (seeds pass through the digestive tract and remain viable), and when pods and seeds move in flood waters. Native and feral animals also assist in spreading mesquite by eating the sugar- and protein-rich seed pods.

Each plant is capable of producing thousands of seeds per year that can remain dormant in the soil for very long periods. Seeds will only germinate once the hard outer casing has been damaged allowing moisture into the seed. Animal consumption, fire and wet conditions can effectively damage the seed casing and trigger germination.

To reduce the risk of spread it is recommended that during summer months livestock be removed from paddocks where mature seed pods are available; and be quarantined from mesquite areas for at least one week before being transported.

What does it look like?

Mesquite can be either a single-stemmed tree (up to 15 m in height) or a multi-stemmed shrub with drooping branches (3–5 m high). The whole plant has an untidy appearance with single branches extending outside of the main canopy.

Key identification features

• Branches have a characteristic zig-zag shape. Bark is smooth and dark red-green in young stems, and rough and grey in older stems.
• Fern-like leaves occur at each point where the branch changes direction and contain 1–4 pairs of leaf branches.
• A pair of spines, 4–75 mm long, normally arise above each leaf stalk or along the main stem.
• Flowers are a greenish cream-yellow, 5–8 cm long and cylindrical in shape, resembling a ‘lamb’s tail’. Flowers appear in spring and early summer.
• The seed pod is smooth, up to 20 cm long with slight constrictions between each seed. Each pod contains 5–20 seeds and varies in colour from green when young to either straw-coloured or purplish when mature.

Acknowledgements

Adapted from CRC Weed Management Guide (2003) Mesquite; Reviewed by: Peter Gray; Edited by: Elissa van Oosterhout.

References

Hosking JR, Sainty GR, Jacobs SWL & Dellow LL (in prep) The Australian WeedBOOK

More information

back to top

Control

Mesquite can be managed by a variety of control methods. The control program for mesquite will depend on the size of the infestation and the species present.

Identification of mesquite can be difficult due to the variations in growth from. If you suspect you have found mesquite contact your local council weeds officer who will assist with identification, removal and eradication.

Biological control

Two biological control agents have been released in NSW for mesquite control a leaf tier (Evippe sp.) and a psyllid (Prosopidopsylla flava). 

Herbicide options

See Using herbicides for more information.

---

Picloram 100 g/L + Triclopyr 300 g/L + Aminopyralid 8 g/L (Grazon Extra®)
Rate: 350 mL in 100 L of water
Comments: Controls seedlings, plants in full leaf and flowering before podding. Thoroughly wet all foliage, stems and soil around the base of the plants. Add a wetting agent at the rate of 100 mL per 100 L of water (Uptake® Spraying Oil, BS1000 Biodegradable Surfactant, Chemwet 1000, Spreadwet 1000 Wetting Agent, or Pulse Penetrant) for best results. Do not spray plants bearing pods.
Withholding period: Where product is used to control woody weeds in pastures there is a restriction of 12 weeks for use of treated pastures for making hay and silage; using hay or other plant material for compost, mulch or mushroom substrate; or using animal waste from animals grazing on treated pastures for compost, mulching, or spreading on pasture/crops.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

---

Picloram 44.7 g/L + Aminopyralid 4.47 g/L (Vigilant II ®)
Rate: Undiluted
Comments: Cut stump application: Apply a 3–5 mm layer of gel for stems less than 20 mm. Apply 5 mm layer on stems above 20 mm. Stem inject application for trees: Make a series of cuts 15-20 mm deep around the trunk using an axe or saw. Space cuts evenly with no more than a 20-40 mm gap between them. Apply a 5 mm layer of gel over the lower surface of the cut.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

---

Triclopyr 240 g/L + Picloram 120 g/L (Access™ )
Rate: 1.0 L in 60 L of diesel (or biodiesel such as Biosafe).
Comments: Basal bark application for plants with stems less than 5 cm diameter at the base. Liberally spray the bark around the stem from ground level to 30 cm high, wetting thoroughly to the point of runoff. Cut stump application for plants with stems up to and over 5 cm in diameter. See label for information about using biodiesel.
Withholding period: Nil
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

---

Triclopyr 300 g/L + Picloram 100 g/L (Various products)
Rate: 350 mL in 100 L of water
Comments: Controls seedlings, plants in full leaf and flowering before podding. Thoroughly wet all foliage, stems and soil around the base of the plants. Add a wetting agent to increase efficacy. Do not spray plants bearing pods.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

---

back to top

Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area	Duty
All of NSW	General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.
All of NSW	Prohibition on certain dealings Must not be imported into the state, sold, bartered, exchanged or offered for sale. All species in the genus Prosopis have this requirement
Central West	Regional Recommended Measure* (for Regional Priority - Eradication) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
North West	Regional Recommended Measure* (for Regional Priority - Eradication) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
Riverina	Regional Recommended Measure* (for Regional Priority - Eradication) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. Your local biosecurity weeds officer can help to identify, advise on control, and how to remove this weed.
Western An exclusion zone is established for all lands in the Western Local Land Services region, except the core infestation area, which comprises all lands within the counties of Evelyn, Yantara, Mootwingee, Yancowinna, Menindee, Tandora, Livingstone and Windeyer.	Regional Recommended Measure* (for Regional Priority - Containment) Whole of region: Land managers mitigate the risk of new weeds being introduced to their land. Within exclusion zone: Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. Within core infestation: Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value.
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here

back to top

Reviewed 2023