weeds of national significance
Mesquite – Prosopis species
Current Potential
Mesquite (Prosopis species) The problem
Mesquite is a Weed of National Significance. It is regarded as one of the worst weeds in Australia because of its invasiveness, potential for spread, and economic and environmental impacts.
There are four species and several hybrids Mesquite of Prosopis, which are all collectively known as mesquite.
Mesquite’s economic impacts stem from its habit of forming dense, impenetrable – Prosopis thickets which, combined with its large thorns, prevent stock accessing watering holes and make mustering difficult. Mesquite also reduces the productivity of species pastoral country by taking over grasslands Mesquite can form impenetrable thickets, preventing access and reducing productivity of land. and using valuable water resources. Photo: CSIRO Other nuisances from mesquite include damage to animal hooves and vehicle branches extending outside the main tyres from thorns, and the poisoning canopy. Key points of livestock which consume excessive Mesquite leaves are fern-like. They occur • Mesquite, which includes four species and amounts of seed pods. at each point where the branch changes several hybrids, is one of four prickle bushes direction (the zig-zag) in groups of one Environmental impacts include land that have infestations scattered throughout to three pairs, often with one or two erosion resulting from the loss of semi-arid Australia. (See the back page for thorns. The greenish cream–yellow flowers grassland habitat that supports native more information.) are arranged on a cylindrical-shaped spike plants and animals; and the provision • It is a nuisance in rangelands where it forms which resembles a ‘lambs tail’, 50–80 mm dense impenetrable stands, particularly of safe refuges for feral animals such in length. The seed pod (up to 200 mm around waterways. as pigs and cats. long) is straight or slightly curved with only very slight constrictions between • Animals eat the seed pods and spread the seeds. The weed the seeds. The bark is smooth and dark • Historical control efforts by mechanical and red-green in young stems, and rough chemical means have been expensive and The various mesquite species come in a and grey in older stems. The taproot is ultimately ineffective. range of shapes and sizes. They can be large and much branched and generally • Control requires an integrated management found as multi-stemmed shrubby bushes grows to a depth of 20 m. approach, including mechanical, chemical and or single stemmed trees with a spreading Identification of mesquite is complicated biological techniques and the use of fire and canopy, growing from 3 to 15 m tall. because there is often variation in growth grazing strategies. Branches have a characteristic zig-zag form, even within the same species, structure, and the overall impression and hybrids (or crosses) between the is of a rather untidy plant, with single main species. 2
Growth Calendar Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Flowering Pod formation Seed drop Germination Dormancy
General growth pattern Growth pattern under suitable conditions
Because mesquite is found over such a large area, and consists of several species and hybrids, there is much variation in its growth calendar. Its seeds can germinate year round as long as the soil is moist. The young seedlings are generally slow growing as resources are invested into establishing the root system. This can be extensive in mature trees, in some cases exceeding a depth of 50 m. Where winters are cold, mesquite may shed its leaves in late autumn or early winter and undergo Flowers and seed pods of Prosopis pallida at Hugenden, Qld, in August. a dormant period until early spring. Photo: Colin G. Wilson Flowering in mesquite occurs mainly in spring and early summer. The seed pods take two to three months to mature and generally drop in late summer. The seeds Animals consume the nutritious seed are dormant when dropped – the hard outer casing must be damaged to allow pods and excrete viable seed in their moisture into the seed before germination can occur. Animal consumption, fire droppings, helping to spread mesquite or wet conditions are all ways of breaking the seed casing. If the seed casing is not over shorter distances. Cattle are mainly species broken, seeds lying in soil can remain viable for very long periods. responsible, although horses, pigs, goats, sheep, emus and kangaroos are also How it spreads as an ornamental, shade or fodder tree known to consume the seed pods. around stations in the Northern Territory As long as the seeds themselves are – Prosopis Mesquite mainly reproduces via seeds, and Queensland at the start of the 19th not damaged by chewing, digestion producing one main crop annually. Each century, and in Western Australia and actually helps germination, particularly seed pod generally carries between 5 New South Wales a little later. Mesquite as the expelled seeds are deposited in moist, nutrient-rich dung. Mesquite and 20 seeds, with potentially hundreds has since spread throughout mainland of thousands of seeds produced per Australia, with the worst infestations on Apart from deliberate plantings, mature plant. pastoral land in the Pilbara in Western animals – mainly cattle – are most Humans have assisted the spread of Australia, the Barkly Tablelands in the responsible for spreading mesquite mesquite throughout Australia and the Northern Territory, and in northwestern, Seed pods can also be spread by flooding. rest of the world. It was originally planted central and southwestern Queensland. Where it grows 70 mm Mesquite has been planted and has subsequently escaped in every mainland state. In general, mesquite species are well adapted to hot climates and a wide range of soil types and annual rainfall (150–1200 mm). They are often described as hardy because they can tolerate droughts and waterlogging, low nutrient soil and highly saline or alkaline soil. In northern Australia, mesquite prefers semi-arid to arid rangelands that are
Flower spike of Prosopis pallida: Charters Towers, Qld, in December. prone to flooding and soils that have Photo: Colin G. Wilson good moisture retention.
Weed Management Guide • Mesquite – Prosopis species 3
1 m
The zig-zag structure of the stem is typical of all mesquite species. Most species also have spines guarding the base of the leaf. Photo: Colin G. Wilson Mesquite
However, different species have different building timber, fuel and livestock food, Potential distribution distributions, which reflect their initial it has been introduced and naturalised The combination of a long life cycle, plantings but also variation in their around the world. Mesquite has been – Prosopis preferred climate and surroundings. For introduced to Hawaii, Jamaica, the ability to survive droughts, high seed example, P. pallida is widely distributed Middle East, throughout Asia including production and dormancy of its seeds makes mesquite an extremely resilient across the north of Australia from the the Indian subcontinent, and Africa invader which can quickly take advantage east coast of Queensland through the including Nigeria, Sudan, Senegal and species of a suitable environment and dominate Northern Territory to the west coast of southern Africa. It is also one of the entire ecosystems. All mainland states Western Australia. However, it is not most serious weeds of the southwestern and territories have climatic conditions found in any of the southern states, United States. that are suitable for mesquite, especially whereas Prosopis velutina and the hybrid areas north of 28ºS latitude. P. velutina x P. glandulosa var. torreyana can tolerate the cooler climate of southeastern Australia.
There are four naturalised species of mesquite and a range of hybrids. Collectively, they are suited to the climate of much of inland Australia
Mesquite has a long life cycle. In its native 3 m range plants live at least 30 years, but one specimen in the Brisbane Botanical Gardens is over 115 years old.
The mesquite species that are weeds in Australia are natives of Central America, northern South America and southern North America. Because mesquite has some properties that are considered An untidy shape is also typical of mesquite: multi-stemmed Prosopis pallida, Hughenden, Qld. useful to humans, including uses as Photo: Colin G. Wilson
Weed Management Guide • Mesquite – Prosopis species 4 150 mm
Mesquite seed pods have only slight constrictions In basal bark treatment herbicide is sprayed all around the circumference of the lower stem(s), between seeds, and contain up to 20 seeds per up to a height of 750 mm for mature mesquite: P. velutina. pod: P. glandulosa. species Photo: Rachele Osmond Photo: Nathan March
Chemicals offer effective control was first attempted in the 1950s. What to do about it control However, it has continued to spread in – Prosopis many places. The experience repeated The basal bark and cut-stump techniques Preventing the further around Australia is that mesquite used with an appropriate registered spread of mesquite reinfests sites if follow-up control is not herbicide are effective on mature trees.
Mesquite The strategy to prevent the further undertaken. Chemical and mechanical Basal bark treatment (spraying around spread of mesquite starts with strictly methods have traditionally been used the entire stem up to 750 mm from the enforced quarantine procedures to to control mesquite. ground) should be used during the avoid further introductions of weedy growing season (approximately October If control efforts are not followed Prosopis species which could potentially to April, depending on species and up, mesquite will reinvade from its location). The cut-stump technique, cross-breed and produce more hybrids. substantial, long-lived seedbank Other measures aim to prevent the where herbicide is immediately applied spread of mesquite seed. For example, to a stump that has been cut horizontally Integrated management of very close to the ground, is effective year stock should be quarantined before mesquite round. Seedlings can be controlled by transport into uninfested areas, and spraying foliar herbicide over the entire animals should be fenced off from Current research is investigating plant. This is particularly effective for mesquite infestations. Feral animal integration of traditional management practices (chemical and mechanical dealing with actively growing, dense numbers could be reduced as part of control) with fire, grazing management stands of mesquite up to 1.5 m tall. mesquite management. Infestations in and biological control, which are more upper catchments should be targeted time- and cost-effective mechanisms. Mechanical control is for strategic control to prevent continual An integrated management strategy for another option reinfestation of downstream sites. mesquite will vary with the infestation’s Mechanical control techniques, ranging characteristics, including its size, age, Past control attempts from blade ploughing to grubbing and density and habitat. In general, multiple- chaining, are aimed at removing as much There have been some successful efforts stemmed mesquite are harder to control of the root system as possible to prevent to eradicate mesquite infestations since than single-stemmed trees.
Weed Management Guide • Mesquite – Prosopis species 5
Weed control contacts
State / Department Phone Email Website Territory ACT Environment ACT (02) 6207 9777 [email protected] www.environment.act.gov.au NSW NSW Agriculture 1800 680 244 [email protected] www.agric.nsw.gov.au NT Dept of Infrastructure, Planning (08) 8999 5511 [email protected] www.nt.gov.au and Environment Qld Dept of Natural Resources and Mines (07) 3896 3111 [email protected] www.nrm.qld.gov.au SA Dept of Water, Land and (08) 8303 9500 [email protected] www.dwlbc.sa.gov.au Biodiversity Conservation Vic Dept of Primary Industries/Dept 136 186 [email protected] www.dpi.vic.gov.au of Sustainability and Environment www.dse.vic.gov.au WA Dept of Agriculture (08) 9368 3333 [email protected] www.agric.wa.gov.au
Australia wide Australian Pesticides and Veterinary (02) 6272 5852 [email protected] www.apvma.gov.au Medicines Authority
For up-to-date information on which herbicides are registered to control mesquite and the best application methods and dosages, contact your state or territory weed management agency or local council. This information varies from state to state and from time to time. Contact details are listed above, including contacts for the Australian Pesticides and Veterinary Medicines Authority, which hosts the PUBCRIS database. This database contains information on all herbicides that are registered for use on weeds in each Australian state and territory.
When using herbicides always read the label and follow instructions carefully. Particular care should be taken when using herbicides near waterways because rainfall running off the land into waterways can carry herbicides with it. Permits from state or territory Environment Protection Authorities may be required if herbicides are to be sprayed on riverbanks. Mesquite
autumn and winter in a normal wet season year. However, grubbing is only cost-effective for treating light infestations – Prosopis or small areas of dense infestations – costs exceeded $200 per hectare in grubbing one dense infestation of P. pallida.
Chain pulling is the cheapest but least species effective mechanical control because of low kill rates. Permits may be required to conduct mechanical control if native species will be affected. Weed control contacts (see above) will be able to provide relevant advice.
Burning
Fire can give good control of mesquite, A 4 m stick rake with cutter bar front mounted on a large bulldozer is ideal for mesquite control. particularly P. pallida. If necessary, Photo: Jodi Graham mechanical control such as chaining can be used before burning to provide the tree reshooting. Mechanical control pasture grasses, especially if the area enough fuel to generate the heat required has varying levels of effectiveness is reseeded following blade ploughing. to kill mesquite. Fire is relatively inexpensive and, even when it does not depending on the size and species of Mesquite seedling germination will also kill the entire plant, can reduce seed the plant, but will kill mesquite if the roots increase, requiring follow-up control. production by removing vegetation and can be removed to a depth of 300 mm. Ploughs can be pulled or pushed, with killing seed lying on the ground surface. maximum costs at approximately $120 Blade ploughing is considered to be the per hectare in dense infestations. most cost-effective form of mechanical Integrate chemical, mechanical and biological control, fire and grazing control and has been shown to be In southwestern Queensland P. velutina management effective on P. velutina and its hybrid, has been mechanically controlled using and on P. pallida. Mechanical control can ‘grubber’ attachments on bulldozers and However, most of the other species of assist the germination and growth of tractors, with best results gained in late mesquite are more resistant to fire, and
Weed Management Guide • Mesquite – Prosopis species Mesquite – Prosopis species management agency. local councilor state orterritoryweed required tolightfires –checkwithyour non-target effects. Permitsmaybe fuel andattentiontosafetydetails and generally require careful preparation of including hybridsinthePilbara, but fires cankillthesemore resistant species, is removed byfire. Extremely intense resprout from therootstock ifthecrown Photo: ColinG.Wilson near Hughenden,Qld,inDecember. These seedlingswere foundgrowing from dung Cattle are themaincauseofmesquitespread. Photo: ColinG.Wilson Mesquite spinescanpuncture trucktyres.
300 mm Weed Weed aaeetGuide •Mesquite– Management holding yards willrequire treatment. period isadequate. Seedlingsinthe through thegut,a7–8dayquarantine available forthepassagetime of seeds Although nodetailedinformation is transported intounaffected areas. should alsobequarantinedbefore being spread anddensityofmesquite.Stock during seeddrop willhelpreduce the Preventing stockaccesstoinfestations Grazingshouldbediscouragedafter • Grazingmayneedtobereduced • Cattleare mainlyresponsible for • mesquite control forthree reasons: part oftheintegratedapproach to Grazing managementisanimportant Grazing management and establishment. reduce mesquiteseedlinggermination growth inperennial grassesandhelp any control efforts, toencourage build-up ofsufficient fuel. inorderbefore toallowthe burning infestations. the spread ofseedsandtherefore 6 Prosopis established but not affecting mesquite. Natural Resources and Mines are widely by theQueenslandDepartment of seed-feeding beetlesthatwere released numerous introduction efforts. Two enough todamagemesquitedespite establish itselfinpopulationslarge doubtful thatthesecondspecieswill and growth ratesare reduced. Itis the Pilbararegion where seedproduction an impactonmesquite,particularlyin itself atmostrelease sitesandishaving in 1998.Thefirstspecieshasestablished flava and aleafsuckingbug( can allpotentiallyspread seed. animals (egpigs,kangaroos andemus) similarly tocattle,otherferalandnative While horsesandsheepcanbemanaged ( Entomology in1994.Aleaftyingmoth program wasinitiatedbyCSIRO been released sinceabiologicalcontrol Two insectspeciesfrom Argentinahave Biological control Evippe ) thatcausesdiebackwere released sp. #1)thatcausesdefoliation species Prosopidopsylla Mesquite – Prosopis species Management Qld DNRM and species Pilbara region. To this end, a 2 km-wide this To Pilbara region. been established containment line has a four- infestations. Also current around is investigating project year research of the best practice management best to integrate mesquite, including how with biological and mechanical fire techniques. control containment mesquite crossing stop To quarantine Station at Mardie lines, staff holding paddock stock in a mesquite-free one week until any mesquite for around the gut. All seed has passed through heavy machinery that enters the property leaving the washed before is thoroughly that station. The cleaning is so thorough a mesquite seed was once found in the air conditioning duct of a bulldozer. at the station also work with groups Staff Australia such as Conservation Volunteers to strategically spray mesquite that beyond containment to break threatens lines along the boundary of the station. The ‘Mesquite Best Practice Manual’, a and management control comprehensive guide compiled by the the National Prickle Bush launched at was recently Group Station. Mardie Prosopis ...case study ...case 7 ) was released in 1998. It in 1998. ) was released case study moth biocontrol ties leaves together, reducing growth and seed production. and seed production. growth reducing ties leaves together, moth biocontrol Evippe Evippe back. All the previous control effort did effort control previous back. All the of the spread not manage to prevent land previously any mesquite or recover lost to mesquite. (the leaf tying agent A biological control moth has significantly rapidly established and leaf cover and pod production. reduced of the defoliating the success Ironically, of the effectiveness moth may reduce is less foliar herbicides because there to absorb herbicides. However, leaf area that follows rainfall new leaf growth could be strategically targeted for herbicide application. to efforts to the previous In response Station, mesquite on Mardie control the Pilbara Mesquite Management Committee was formed in April 2000. pastoralists, mining Representing companies, government agencies and the CSIRO, it is partly funded through Natural Commonwealth Government’s Acknowledging that Heritage Trust. eradication is unachievable, its priority of mesquite of spread is the prevention and into neighbouring properties plus the development of reserves, a long-term management strategy for the The Photo: Rieks van Klinken , P. velutina P. , Management Guide • Mesquite – . The hybrids grow Weed Weed P. pallida P. and Prosopis glandulosa Battling mesquite on Mardie Station on Mardie mesquite Battling The mesquite first planted around Mardie first planted around The mesquite the 1930s was Station homestead in a thornless used as shelter and variety since that time livestock feed. However, wild thorny to the have reverted the trees hybrid So far, type and also hybridised. the from forms have been identified species P. juliflora P. Acknowledgments Shane Information and guide revision: CRC), Rieks Campbell (Qld DNRM/Weeds CRC), Nathan van Klinken (CSIRO/Weeds Carter (NSW (Qld DNRM), Richard March CRC), Jodi Dept Agriculture/Weeds Graham (Pilbara Mesquite Management Committee) and John Thorp (National Management Facilitator). Weeds Committee. Maps: Australian Weeds Legislation to control legally required Landholders are all mainland mesquite across or treat Check states and the Northern Territory. with your local council or state/territory government agency about the latest for mesquite control. requirements mostly as multi-stemmed shrubs and mostly as multi-stemmed trees. occasionally as single-stemmed Station mesquite infestation The Mardie (150,000 ha) is the largest single core infestation in Australia. Station mesquite has spread At Mardie rapidly after cyclonic rain events, with occurring along the the densest growth floodplain tributaries of the Fortescue on saline coastal mud It grows River. patches flats, heavy alluvial clay and bare little else will grow. of earth where to as a threat Mesquite was recognised the pastoral industry in the 1940s and extensive mechanical and chemical commenced in 1952. efforts control achieved Although some successes were returned of infestation were and areas to useful herbage, whenever control the mesquite came relaxed were efforts Quick reference guide
Prevention of spread over the long term. Integration involves: • biological control which can damage • chemical control which, due to mesquite, especially in the Pilbara. Preventing the spread of mesquite is the expense, is best suited for small, most cost-effective management strategy. Ongoing follow-up control is required isolated infestations Quarantining stock before movement because there will be large numbers of into uninfested areas is an important way • mechanical control which is relatively mesquite seeds remaining in the soil of preventing further spread. inexpensive but gives varying results that can survive for many years. In the with different species past, when mesquite control has not Integrated management • fire which is inexpensive and can provide been followed up, it has rapidly returned. excellent control especially if used Given the excessive costs and failures of These control efforts may be more or strategically after mechanical control past control attempts, and the limitations less effective with the four different • grazing management such as (eg costs, time, effectiveness) associated species and hybrids that are naturalised quarantine, exclusion from seed pods with individual techniques, the new in Australia. Consult your local council or destocking, to promote regrowth species approach to mesquite involves integrating or state or territory weed management of grasses for fuel and to compete all control methods together with grazing agency for the best approach for your with seedlings management systems to minimise impacts species of mesquite. – Prosopis How to identify the prickle bushes
Mesquite is one of four prickle bushes that are yellow-flowering, seed pod forming, woody weeds of northern Australia. For further information on identification, distribution, ecology, management and control of mesquite, and additional case studies, Mesquite see the ‘Mesquite Best Practice Manual’, compiled by Qld DNRM and the National Prickle Bush Management Group.
Feature Mesquite Mimosa bush *Parkinsonia *Prickly acacia Prosopis spp. Acacia farnesiana Parkinsonia aculeata Acacia nilotica Pod size Up to 200 mm, very slight Up to 60 mm, cigar shaped, Up to 100 mm, straight, long Up to 230 mm, large and shape constrictions between seeds slightly curved thin constrictions between seeds constrictions between seeds Pod colour, Straw coloured, sometimes Brown to black; no hairs Straw coloured; no hairs Grey-green; fine hairs hairiness purple; no hairs Flowers Greenish cream – yellow Golden yellow, ball shaped, Four all yellow petals and one Golden yellow, ball shaped, ‘lambs tail’ cylindrical flower 10 mm across erect petal either orange or 10 mm across spike, 50–80 mm yellow with an orange spot Leaves Fern-like, paired Fern-like, paired (2–4 pairs Narrow, flat, paired (1–3 pairs) Fern-like, paired (1–3 pairs, often with a gap with a gap between leaves) green leaf stalks with small (3–10 pairs at each point between leaves) green oblong leaflets along the stem) Bark Young: smooth dark Grey with prominent Smooth and green, straw Young: a tinge of orange red – green white spots coloured at base of older trees and/or green Mature: rough grey Mature: dark, rough Tree shape Untidy spreading tree, up to Rounded shrub to 3 m, Shrub or small tree to 8 m, Spreading tree to 10 m, and size 15 m, single or multi-stemmed usually multi-stemmed single or multi-stemmed usually single-stemmed
Table reproduced with permission of the Department of Natural Resources and Mines, Queensland. *See other guides in this series on these Weeds of National Significance. © 2003 Information which appears in this guide may be reproduced without written permission provided the source of the information is acknowledged. Printed in Australia on 100% recycled paper. ISBN 1-920932-09-7 Disclaimer While every care is taken to ensure the accuracy of the information in this publication, the CRC for Australian Weed Management, the Commonwealth Department of the Environment and Heritage and the Queensland Department of Natural Resources and Mines take no responsibility for its contents, nor for any loss, damage or consequence for any person or body relying on the information, or any error or omission in this publication.