Mesquite, Algaroba, Quilpie Mesquite

Mesquite, Algaroba, Quilpie Mesquite - Prosopis spp.
Family: MIMOSACEAE
The Problem
Mesquite is a Weed of National Significance and a Class 2 declared
plant in Queensland. There are at least three species and one hybrid
present in Queensland, collectively referred to as Mesquite.
It is highly invasive with potential to spread across most of
Queensland, causing serious economic and environmental impacts.
Mesquite forms dense thickets which impede stock movement and
access to water and make mustering difficult.
The large thorns of mesquite cause injury to stock and humans,
damaging animal hooves and vehicle tyres.
Mesquite takes over pastures, reducing grass loads by up to 80%.
The structure of native grasslands, woodlands and wetlands is
significantly altered as a result of mesquite invasion, lowering their
value for conservation and for tourism.
The aggressive root system of mesquite results in the loss of soil
moisture and groundcover species, and an increase in soil erosion.
Thickets formed by mesquite harbour pest animal species such as
pigs.
Controlling Mesquite is a Priority.
Mesquite has the potential to infest large areas of south west
Queensland. Once established it is difficult and expensive to control.
South West NRM Ltd has identified mesquite as a priority weed
species for control and is working with landholders, local and state
governments to control current infestations and prevent further
spread.
Weed of
National
Significance
Main Photo: R Cobon, QDPI
Main Photo: Quilpie Mesquite, Prosopis velutina
Above Left: Characteristic zig-zag stems and thorns of mesquite. Right: Flower (P. pallida)
Description
Mesquite varies from 3—5 m high multi- stemmed trees (Quilpie
Mesquite, Prosopis velutina), to 15m high trees with a spreading
canopy (P.pallida). Can be confused with other ‘prickle bushes’.
All mesquites have a characteristic zig zag stem.
Mesquite is capable of growing on a wide variety of soil types.
Infestations usually begin along, but are not restricted to,
watercourses and spread out to higher ground.
Flowers are greenish yellow in colour, occurring predominantly in
early spring and summer.
Leaves are bi-pinnate, bright green to bluish green leaves, giving
an overall fern like appearance.
Fruit is a pod between 12 and 20cm in
length and 1 cm wide. Each pod contains
between 5- 20 hard seeds that remain viable
for a long of time.
Dispersal is primarily via domestic and wild
animals that consume the nutritious seed
pods and excrete viable seeds.
Above: Infestation of Quilpie Mesquite near Quilpie.
Community Information Sheet No 17
Author: Nathan Kirby, Geodorum Consulting
Flood waters also assist in dispersal.
Produced by South West NRM Ltd
Updated: April 2007
Control Methods
In order to be successful, most mesquite control programs will need
to adopt an integrated approach, using several control methods on
an ongoing basis over several years.
Different mesquite species respond differently to individual control
techniques. Methods will vary depending upon location, accessibility
and density of infestations.
Traditional control methods include mechanical and chemical
treatments. Fire, grazing management and biological control
methods can also be utilised.
Mechanical control aims to remove as much of the root material as
possible. Grubbing attachments on dozers and tractors, dozer
pushing, chain pulling and blade ploughing can be used to achieve
this.
Chemical control using cut stump and basal bark application of
registered herbicides is effective on mature trees. Foliar spraying is
most effective on seedlings up to 1.5m in height.
Fire is most effective on P. pallida, particularly if there is sufficient
fuel load to sustain a high intensity fire and if used in conjunction
with other methods, such as following mechanical control . Other
species have the ability to regrow from rootstock following fire. For
these species fire can be a useful tool to remove dead material that
has resulted from previous chemical or mechanical treatments.
Grazing management is an important part of any mesquite
management program. It is important to restrict cattle from
infestations during seed drop in order to prevent further dispersal.
Stock exclusion prior to planned burns can help build up fuel loads.
Exclusion following treatment will assist the establishment of
desirable species which will help reduce reinfestation of mesquite.
Biological control agents such as the leaf-tying moth, Evippe spp.
assist in reducing the vigour and seed set of mesquite, and may
make them more susceptible to other control methods. Research
into further biological control agents is currently being undertaken.
As with any weed, prevention of spread and early detection and
eradication of new and isolated infestations is the most cost effective
method of control.
This can be achieved by the quarantining stock prior to movement
from areas known to have mesquite present, controlling feral
herbivores that disperse seed and by adopting the control of
mesquite seedlings as a routine land management duty.
Bulloo River Infestation
A major infestation of Quilpie mesquite is present on the Bulloo River at
Quilpie.
This infestation originated from a couple of seedlings planted around a
homestead in the 1930’s. The core, dense infestation is now 4000ha with
a further 300,000 ha infested with scattered mesquite.
The Ellrot Blade plough, pictured above, has been successfully used as part
of this control effort with control rates of up to 95% being reported.
Significant progress has been made in the control of this infestation.
Mesquite (Prosopis spp.) Distribution, 2006.
Map based on 2006 Annual Pest Distribution Survey Data supplied by Department of Natural Resources and
Water. Compiled on approx 17 * 17km grid squares. For further details visit http://www.dpi.qld.gov.au
References and further reading.
Department of Natural Resources and Water, Land Protection, 2001, Pest Fact Mesquite - Prosopis spp. PP37.
Department of Natural Resources and Water, 2003, Best Practice Manual - Mesquite. Control and management options for mesquite
(Prosopis spp.) in Australia.
South West NRM Ltd, 2006, Community Information Sheet 4: Ellrot Blade Plough.
CRC for Australian Weed Management, 2003, Weed Management Guide - Mesquite -
Prosopis species.