Mesquite

Native to North and South America, mesquite is a shrub or tree that can form dense, impenetrable thickets. Three mesquite species and a mesquite hybrid have been recorded in Queensland. Once used for soil stabilisation and as a shade tree around homesteads, mesquite has spread significantly in Queensland.

Biosecurity Queensland encourages people to report this pest plant and take actions to help stop the establishment, prevent the spread, and to control this pest.

Scientific name

Prosopis glandulosa, P. pallida, P. velutina, P. spp. hybrid

Other names

Algaroba, Quilpie algaroba

Description

  • Multi-stemmed shrub up to 5m or tree up to 15m tall.
  • Branches are small, zigzag-shaped, with smooth, dark red or green bark.
  • Leaves are fern-like, with 1-4 pairs of leaf branches, 6-18 pairs of individual leaflets.
  • Foliage is usually dark green but can vary to bluish-green.
  • Paired thorns occur just above each leaf axil.
  • Seed pods are 10-20cm long, straight to slightly curved, smooth, with slight constrictions between seeds.

Habitat

  • Found along waterways, floodplains, roadsides and in horse paddocks near homesteads.

Distribution in Queensland

  • Infestations are small scale but common across most of western Queensland with isolated occurrences in north, central and southern Queensland.

Life cycle

  • Extended flowering may occur August-December, with pod formation October-March.
  • Long-lived.

Impacts

Environmental

  • Forms dense, impenetrable thickets.
  • Out-competes other vegetation.
  • Quickly invades upland country.

Economic

  • Sharp thorns can puncture vehicle tyres.

Social

  • Sharp thorns can injure animals and humans.

How it is spread

  • Seeds spread by stock faeces, some pest animals and native animals.

Control

Mechanical control

Stick raking
  • Effective on medium to high-density infestations of Prosopis pallida, particularly if a cutter bar is attached to bottom of stickrake. Best results are achieved when soil moisture is sufficient to allow machinery to work with minimum strain, but soil is dry enough so root system desiccates (late autumn/winter for normal wet season).
Pushing
  • Dozer pushing of singled-stemmed Prosopis pallida has been effective around Cloncurry and Hughenden. Little suckering results, although some seedling emergence will be promoted. Not so effective on multi-stemmed species, which often break off at ground level and reshoot vigorously.
Chain-pulling
  • Chain-pulling using dozers may kill high proportion of trees in a Prosopis pallida infestation. However, effectiveness of control may be reduced when either very dense infestations or high proportion of young trees and seedlings is present.
  • Fire is often necessary as follow-up measure to pulling, and paddocks may need to be rested from grazing to allow a build-up of grass. It is better if burning can be delayed until seedlings have germinated, as they will then be destroyed in fire. Chain-pulling is best undertaken July-October.
  • Chain-pulling on its own is not effective on Prosopis velutina or other multi-stemmed species (including hybrids) due to their growth structure and potential for regrowth at root system.
Blade-ploughing
  • Either front-mounted or rear-mounted blade plough can be used on all mesquite species.
  • Front-mounted Ellrott blade ploughs have proven effective in controlling hybrid mesquite at McKinlay and Prosopis velutina at Quilpie.
  • Trial work using 4.2m Homan rear-mounted blade plough on Prosopis velutina has proven effective, giving very high kill rates on treated area.
Fire
  • Effective against Prosopis pallida in Cloncurry and Hughenden areas. Burnt Prosopis pallida have died quickly, with bark splitting away from trunk a few weeks after fire. Both mature trees and seedlings are susceptible.
  • However, it is often not possible to kill a complete infestation because rarely is there an even distribution of fuel across a whole site.
  • Multi-stemmed species appear to be more tolerant of fire and reshoot from the base afterwards.

Herbicide control

Foliar spray
  • Effective method for the control of seedlings up to 1.5m tall.
  • Spray leaf and stems to the point of run-off. A wetting agent must be used.
Basal bark
  • Spray around base of plant to about 30cm above ground level.
  • Thoroughly spray all crevices and each stem of multi-stemmed trees. Larger trees may be controlled by spraying to a greater height, up to 100cm above ground level. The best time to spray is during autumn when plants are actively growing and soil moisture is good.
Cut stump
  • Cut stems off horizontally as close to ground as possible and immediately (within 15 seconds) swab cut surface with herbicide mixture. This treatment can be used at any time of year.

See the Mesquite fact sheet (PDF, 1.8MB) for herbicide control and application rates.

Biological control

  • Four species of insects have been introduced as biological control agents against mesquite:
    • The larvae of the seed beetles Algarobius bottimeri and Algarobius prosopis destroy mesquite seeds in mature pods both in trees and on the ground. Only A. prosopis has been found in more recent surveys and this beetle is unlikely to be having much effect.
    • Prosopidopsylla flava is a sap-sucking psyllid that causes dieback. It appears to prefer cooler climates and may be present in small populations in south-western Queensland.
    • The leaf-tying moth Evippe spp. has established at all release sites, but is most abundant in northern Queensland where it is causing moderate defoliation.

Legal requirements

All Prosopis spp. and hybrids not yet found in Queensland are prohibited invasive plants except. Prosopis glandulosa, P. pallida and P. veluntina that are restricted invasive plants under the Biosecurity Act 2014.

Prohibited

  • This is a prohibited invasive plant under the Biosecurity Act 2014.
  • The Act requires that all sightings tobe reported to Biosecurity Queensland within 24 hours.
  • By law, everyone has a general biosecurity obligation (GBO) to take all reasonable and practical steps to minimise the risk of it spreading until they receive advice from an authorised officer.

Restricted

  • This is a restricted invasive plant under the Biosecurity Act 2014.
  • It must not be given away, sold, or released into the environment without a permit.
  • The Act requires everyone to take all reasonable and practical steps to minimise the risks associated with invasive plants and animals under their control. This is called a general biosecurity obligation (GBO).
  • At a local level, each local government must have a biosecurity plan that covers invasive plants and animals in its area. This plan may include actions to be taken on certain species. Some of these actions may be required under local laws. Contact your local government for more information.

More information