Camel thorn (Alhagi maurorum)

Camel thorn is an erect perennial shrub found mostly in pastures and neglected areas.

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How does this weed affect you?

Camel thorn is a hardy, fast growing shrub that:

• outcompetes pastures, though it is sometimes eaten by cattle, horses and sheep
• invades crops
• injures stock, wildlife and people with its sharp spines
• damages roads as the roots can grow and sprout through bitumen. 

What does it look like?

Camel thorn is a perennial shrub that grows up to 1.5 m tall. It has stiff, branching stems that are covered in sharp spines. The plants shoot from the roots in spring, grow throughout summer and die off in autumn.

Leaves are:

• yellow-green on top, blue-green and hairy underneath
• 5-30 mm long and 2-14 mm wide
• oval often with a notch in the tip
• fleshy 
• usually located at the base of spines
• alternate along the stem
• sparse in dry conditions.

Flowers are:

• pea-like
• 7-12 mm long
• pinkish purple to red and yellow
• in clusters of 1- 8 flowers
• present in summer.

Fruit are:

• smooth pods, constricted between each seed and usually with a small beak at the end
• 8-30 mm long and 3 mm wide
• red-brown.

Seeds are:

• yellow to reddish brown or greyish-brown
• 2-3 mm long
• kidney shaped
• smooth with a hard coat.

Stems:

• are woody at the base
• are stiff with many branches
• are greenish
• have yellow-tipped spines that are 1-4 cm long.

Roots:

• are up to 2 m deep
• include rhizomes (underground stems that grow horizontally) that grow up to 8 m from the main stem
• sucker readily.

Where is it found?

In NSW camel thorn has been found in the North West, Riverina, Murray and Western region. Camel thorn also grows in Victoria and South Australia.

Camel thorn is native to Europe and Asia. It is also a weed in the United States of America and South Africa.

What type of environment does it grow in?

Camel thorn grows in temperate and subtropical regions that have arid to semi-arid conditions. It grows best in alkaline soils and is tolerant of salty soils. In moist subsoils or irrigated sites it produces more leaves and less thorns and it can tolerate some waterlogging. The leaves are damaged by frosts as the plant is intolerant of cold weather. 

It grows in pastures, along river banks, drainage lines, irrigated areas and disturbed areas

Maps and records

• Recorded presence of Camel thorn during property inspections (Map: Biosecurity Information System - Weeds, 2017-2024)
  These records are made by authorised officers during property inspections under the Biosecurity Act 2015. Officers record the presence of priority weeds in their council area and provide this to the NSW Department of Primary Industries. Records reflect the presence of the weed on the date of inspection.
  
  

How does it spread?

By seeds

Plants usually start setting seed when they are one year old. Pods and seeds are spread by wind, water, and through livestock eating the pods and spreading the seeds in their manure. Seeds sprout in spring and have a low survival rate. However, they grow well when deposited in animal manure and germination is more likely if the seed has passed through the gut of livestock. Seeds can remain viable in the soil for at least 3 years.

By plant parts

New plants can develop from rhizomes up to 8 m from the main stem. Plants can also sprout from broken root fragments. Roots fragments can spread by:

• livestock
• contaminated fodder
• machinery, especially cultivation machinery.

References

Parsons, W.T., & Cuthbertson, E. G. (2001). Noxious weeds of Australia. CSIRO publishing.

Pirasteh-Anosheh, H. (2020). Breaking Seed Dormancy of Camelthorn (Alhagi maurorum) Using Different Treatments and Salinity Tolerance Threshold Level Evaluation at Germination Stage. Iranian Journal of Seed Research, 7(1), 181-192.

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved:16 November 2022 from https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Alhagi~maurorum

Richardson, F.J., Richardson, R.G. and Shepherd, R.C.H. (2016) Weeds of the south-east: an identification guide for Australia (3rd Ed). R.G. and F.J. Richardson, Meredith, Australia.

VicFlora (2022). Flora of Victoria, Royal Botanic Garden. Retrieved 16 November 2022 from: https://vicflora.rbg.vic.gov.au/flora/taxon/92372e60-1b7f-41c5-ab6f-e0c0ccc583af

More information

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Control

Camel thorn can be difficult to control because of its large root system. Plants often re-sprout or sucker from root fragments.

A combination of control methods will give the best results. It is important to consider the plant’s life cycle and repeat treatments are needed in spring and early summer when the plants are actively growing. Control efforts should also be repeated over several years to exhaust the plant’s root systems.

Plants often grow back quickly after cutting. Disturbing roots and the surrounding soil can also encourage plants to sucker and grow. The following methods are not recommended:

• slashing
• mowing
• mulching
• cultivation, including tillage.

Prevention

Avoid moving soil, vehicles and machinery contaminated with camel thorn roots or seeds. Healthy pasture plants may be able to outcompete camel thorn and prevent invasion.

If possible, prevent livestock from eating the pods and spreading the seeds to new paddocks.

Early detection

Camel thorn is easier to control and eradicate when infestations are detected early. Learn to identify camel thorn and remove plants as soon as possible to reduce the chance of spread.

Monitor paddocks for new plants if livestock have been grazing on camel thorn.

Physical removal

Seedlings can be hand-pulled or dug out. Remove as much of the root as possible. This method is only practical for small, isolated plants or infestations and works best when soils are moist. Check for regrowth.

Disposal

Contact your local council for information about disposal.

Chemical control

Spot spray

Spray actively growing plants with leaves present. Cover all of the foliage with the herbicide mix.

Cut stump

Cut the stump close to the ground and apply herbicide to the stump within 15 seconds. If there are pods present dispose of them carefully. 

Herbicide options

See Using herbicides for more information.

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Glyphosate 360 g/L (Various products)
Rate: 10 mL per 1 L water
Comments: Spot spray (smaller plants)
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

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Picloram 44.7 g/L + Aminopyralid 4.47 g/L (Vigilant II ®)
Rate: Undiluted
Comments: Cut stump application: Apply a 3–5 mm layer of gel for stems less than 20 mm. Apply 5 mm layer on stems above 20 mm. Stem inject application for trees: Make a series of cuts 15-20 mm deep around the trunk using an axe or saw. Space cuts evenly with no more than a 20-40 mm gap between them. Apply a 5 mm layer of gel over the lower surface of the cut.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area	Duty
All of NSW	General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.
North West	Regional Recommended Measure* (for Regional Priority - Prevention) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here

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Reviewed 2023