Mesquite: declared pest

Page last updated: Friday, 4 October 2019 - 5:40pm

Please note: This content may be out of date and is currently under review.

Mesquite (all Prosopis species and hybrids) are declared pests in Western Australia (WA). This article describes the nature of the plant with links to requirements land owners/occupiers must adhere to and pest control methods.

Form: tree — perennial

Status: present in WA

Mesquite is a common name for several plants in the genus Prosopis, which contains over 40 species of small leguminous trees. Native to North and South America, mesquite plants were introduced to Australia as fodder for stock, ornamentals in station homestead or town gardens, and used in mine dumps and other soil stabilisation programs. Mesquite is a Weed of National Significance.


Evergreen or deciduous shrub or low tree with one to several trunks and arched branches. It has different growth forms depending on its location and water supply.

  • Drier soils – short, many stemmed shrubs one to three metres high
  • Near permanent water – large single trunk 6-15 metres high
  • Floodplains – branching from the base, forming dense thickets five to eight metres high, particularly along the banks of intermittently flowing creeks

Reproduces by seed and suckers.

Branches: Small branches have a zigzag appearance. Plants can have an irregular outline, with some branches protruding out of the canopy. Spines are solitary or paired along the stem, and range from 4-75 millimetres in length.

Leaves: Bipinnate (like jacaranda leaves), that is, divided twice, with one to four pairs of pinnae, each with seven to 21 pairs of small opposite leaflets.

Flowers: Long finger-like spikes (5-12 centimetres long) of many small greenish, cream or yellow flowers, all densely crowded. Stamens 10 in number and protrude out of the flower.

Seed: Pods are 5-20 centimetres long, compressed, straight to curved, smooth or with slight restrictions between the seeds. Ripe pods are yellow, purple, or yellow with purple streaks and patches. The flat seeds are oval or elliptical 2.5-7 millimetres long by two to three millimetres wide, each enclosed in a flattened fibrous case, and surrounded by sweet pulp.

Agricultural and economic activity

Invades rangelands. Mesquite thickets can out-compete other vegetation, interfere with mustering and block access to watering places.

Economic modelling indicates that mesquite would cost Western Australia $12.0 million each year if it is not managed and $3.0 million if it is managed (Cook, D., 2014 Agricultural Resource Risk Management. Strategic Report. Impact Assessments for Declared Plants in Western Australia. Department of Agriculture and Food WA)

Declared pest category

The Western Australian Organism List (WAOL) contains information on the area(s) in which this pest is declared and the control and keeping categories to which it has been assigned in Western Australia (WA). Search for mesquite in the WAOL using the scientific name Prosopis.

Requirements for land owners/occupiers and other persons

Requirements for land owners/occupiers and other persons if this pest is found can be sourced through the declared plant requirements link.

Search > detect > report

MyPestGuide™ Reporter
via app or online
(Select 'Send report to MyWeedWatcher' from menu)

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080

Control method

Report the presence of this organism before undertaking a control measure. Control methods for this declared plant can be found through the mesquite control link.

Further information

Further information on mesquite can be found on the mesquite: what you should know page.

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080
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