Weed Alert: Mesquite
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- Declared in NSW under the Noxious Weeds Act 1993 (Current Status)
- Weed of National Significance (definition)
Contacts and Further InformationIf you find this weed please help to prevent its further spread by contacting your local Council Weeds Officer or the nearest NSW Department of Primary Industries office immediately for positive identification and further assistance.
Alternatively call the NSW Weeds Hotline on
1800 680 244 or send an email to firstname.lastname@example.org
Mesquite (Prosopis species)
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.
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, with isolated plants found 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.
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.
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.
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.
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.
Mesquite is a Class 2 Regionally Prohibited Weed in parts of NSW under the Noxious Weeds Act 1993. It must be eradicated and land must be kept free of the plant. As a notifiable weed, all outbreaks must be reported to the local council within 24 hours, and the plant is prohibited from sale in NSW.
Adapted from CRC Weed Management Guide (2003) Mesquite; Reviewed by: Peter Gray; Edited by: Elissa van Oosterhout
Hosking JR, Sainty GR, Jacobs SWL & Dellow LL (in prep) The Australian WeedBOOK