Mesquite

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Scientific name

Neltuma glandulosa, syn. Prosopis glandulosa
N. pallida, syn. P. pallida
N. velutina, syn. P. velutina
N.  spp. and hybrids

Other names

• Honey mesquite
• Algarroba
• Quilpie algarroba
• Quilpie mesquite

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

• Infestations are small-scale but common across most of western Queensland with isolated occurrences in northern, 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.
• Outcompetes 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.

Prevention

• Find out how farmers can prevent weed spread.
• Find out how gardeners and outdoor enthusiasts can prevent weed spread.

Control

Mechanical control

Stick-raking

• Effective on medium- to high-density infestations of Neltuma 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 for root system to desiccate (late autumn/winter for normal wet season).

Pushing

• Dozer pushing of singled-stemmed Neltuma 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 Neltuma 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 Neltuma 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 Neltuma velutina at Quilpie.
• Trial work using 4.2m Homan rear-mounted blade plough on Neltuma velutina has proven effective, giving very high kill rates on treated area.

Fire

• Effective against Neltuma pallida in Cloncurry and Hughenden areas. Burnt Neltuma 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.

Read the mesquite fact sheet 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

Some mesquite species are prohibited invasive plants and others are restricted invasive plants.

Prohibited

• All Neltuma spp. and hybrids except N. glandulosa, N. pallida and N. veluntina are prohibited invasive plants under the Biosecurity Act 2014. You must not:
  • keep them
  • move them
  • give them away
  • sell them
  • release them into the environment.

  If you do any of these, penalties may apply.

• You must not take any action that is reasonably likely to exacerbate the biosecurity threat posed by Neltuma spp.
• You must take any action that is reasonably likely to minimise the biosecurity threat posed by Neltuma spp.
• You must report any sightings immediately using 1 of these methods:
  • Report online.
  • Phone Biosecurity Queensland on 13 25 23.
  • Phone the Exotic Plant Pest Hotline on 1800 084 881.

Restricted

• N. glandulosa, N. pallida and N. veluntina are category 3 restricted invasive plants under the Biosecurity Act 2014. You must not:
  • give them away
  • sell them
  • release them into the environment.

  If you do any of these, penalties may apply.

• You must take all reasonable and practical measures that are under your control to minimise the biosecurity risks associated with dealing with N. glandulosa, N. pallida and N. veluntina. This is part of your general biosecurity obligation.
• Each local government must have a biosecurity plan that covers invasive plants in its area. This plan may include actions to be taken for N. glandulosa, N. pallida and N. veluntina. Some of these actions may be required under local laws. Contact your local government for more information.

Further information

• Contact us online, by phone or in person.
• Read the mesquite fact sheet.
• Find out more from the identification of prickle bushes fact sheet.
• Read Weeds Australia's profile of mesquite.