USDA 

... 

D 

United States Department ofAgriculture 

Field Guide for Managing

Camelthorn in the Southwest 

Forest Southwestern 

Service Region TP-R3-16-10 Revised June 2017 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cover Photos 

Upper left: John M. Randall, The Nature Conservancy, Bugwood.org 

Right: USDA Natural Resources Conservation Service 

Bottom: John M. Randall, The Nature Conservancy,Bugwood.org 

In accordance with Federal civil rights law and U.S. Department of Agriculture (USDA) civil rights 

regulations and policies, the USDA, its Agencies, offices, and employees, and institutions participating in or 

administering USDA programs are prohibited from discriminating based on race, color, national origin, 

religion, sex, gender identity (including gender expression), sexual orientation, disability, age, marital 

status, family/parental status, income derived from a public assistance program, political beliefs, or reprisal 

or retaliation for prior civil rights activity, in any program or activity conducted or funded by USDA (not all 

bases apply to all programs). Remedies and complaint filing deadlines vary by program or incident. 

Persons with disabilities who require alternative means of communication for program information (e.g., 

Braille, large print, audiotape, American Sign Language, etc.) should contact the responsible Agency or 

USDA’s TARGET Center at (202) 720-2600 (voice and TTY) or contact USDA through the Federal Relay 

Service at (800) 877-8339. Additionally, program information may be made available in languages other 

than English. 

To file a program discrimination complaint, complete the USDA Program Discrimination Complaint Form, 

AD-3027, found online at http://www.ascr.usda.gov/complaint_filing_cust.html and at any USDA office or 

write a letter addressed to USDA and provide in the letter all of the information requested in the form. To 

request a copy of the complaint form, call (866) 632-9992. Submit your completed form or letter to USDA 

by: (1) mail: U.S. Department of Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 

Independence Avenue, SW, Washington, D.C. 20250-9410; (2) fax: (202) 690-7442; or (3) email: 

program.intake@usda.gov. 

USDA is an equal opportunity provider, employer and lender. 

Printed on recycled paper 
 

Ecology 

Impacts/Threats 

Camelthorn is a hardy shrub that can thrive on both dry 

and wet sites. It aggressively invades disturbed areas and is 

very difficult to manage once established. Roots of 

camelthorn can send shoots upward through asphalt, and 

the plant’s sharp spines can puncture vehicle tires making 

it a hazard along roadsides. The spines also cause injury or 

discomfort to livestock and humans. 

Site/Distribution 

Camelthorn can be found along roadways, agricultural 

areas, river terraces, ditch banks, saline meadows, and 

disturbed pasture and rangeland. The species prefers deep, 

loamy soils where the water table is near the surface; but it 

can grow in many soil types ranging from sand to clay. 

Camelthorn is widely scattered on dry, open rangeland 

areas across the western United States. It is not tolerant of 

flooding or cold temperatures and is usually found from 

100 to 5,000 feet in elevation. 

Spread 

Although its seedpods may be transported by wind or 

water, camelthorn spreads mostly by underground 

rhizomes and sprouting from fragmented root crowns. New 

plants may form every 3 to 5 feet along lateral roots, and 

shoots have been noted to grow up to 25 feet away from 

the parent plant. Seeds scarified in the rumen of cattle have 

been noted to germinate successfully in manure. 

Invasive Features 

Camelthorn stores great amounts of energy reserves in its 

extensive root system. This makes it resistant to many 

control methods and very difficult to eradicate. 

Management 

Camelthorn is very persistent and difficult to eradicate. 

Any effort to contain and reduce established camelthorn 

must involve planning, integrated management, and a longterm commitment. 

line 

Camelthorn is listed as a noxious weed in both Arizona 

and New Mexico. This field guide serves as the U.S. Forest 

Service’s recommendations for management of camelthorn 

in rangelands and deserts associated with its Southwestern 

Region. The Southwestern Region covers Arizona and 

New Mexico, which together have 11 national forests. The 

Region also administers 4 national grasslands located in 

northeastern New Mexico, western Oklahoma, and the 

Texas panhandle. 

Description 

Camelthorn (synonyms: camels thorn, Caspian manna, 

Persian manna) is a deep-rooted, perennial shrub that is 

native to southeast Russia and the Mediterranean region. It 

was originally introduced into California in the early 1900s 

as a contaminant in alfalfa seed. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Camelthorn (Alhagi pesudalhagi Bieb., synonym: A. maurorum Medik) 

Pea family (Fabaceae) 

Growth Characteristics 

• Perennial, long-lived shrub with rhizomatous roots that 

can reach up to 25 feet laterally. 

• Grows 1.5 to 4 feet tall with spiny, intricate branches. 

• Leaves are simple, entire, and alternately arranged on 

the branches. They are oval to wedge shaped with 

yellowish coloration above and bluish-green 

underneath. 

• Pea-like flowers bloom mostly from May to July and 

are pinkish to maroon in color. Flowers are borne on 

short, spine-tipped branches arising from the leaf axils. 

• Seedpods are jointed and reddish-brown to tan with a 

beak-like tip. 

• Seeds are kidney shaped with a hard, thick coat that 

requires scarification for germination. 

• Reproduction is primarily vegetative through rhizomes 

or re-sprouting root fragments. Seedlings are rare, and 

their growth rate is slow. 

1 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The following actions should be considered when planning 

a management approach for camelthorn: 

• Maintain healthy plant communities to prevent or limit 

camelthorn infestations. Try to minimize soil 

disturbance when controlling the shrub and/or 

promptly revegetate disturbed areas with desirable 

perennial native species, especially grasses. 

• Detect, report, and eradicate new populations of 

camelthorn as early as possible. Map known 

infestations and keep annual records of reported 

infestations. 

• Anticipate that control methods may need to be 

combined together and repeated over several years for 

increased effectiveness. 

• Implement monitoring and a follow-up treatment plan 

to control root sprouts and seedlings. 

Table 1. Management options* 

Table 1 summarizes management options for controlling 

camelthorn under various situations. Further details on 

these management options are explained below. Choice of 

individual control method(s) for camelthorn depends on 

many local factors including extent of infestation, current 

land use, and site conditions (terrain, accessibility for 

treatment, microclimate, non-target flora and fauna 

present, etc.). Other important considerations include 

treatment effectiveness, overall cost, and the number of 

years needed to achieve control. Typically, more than one 

control method may be needed for a particular site. 

Physical Control 

Physical methods for camelthorn control that do not 

completely remove the root system are not likely to be 

successful and may actually contribute to further spread 

when improperly applied. Follow-up monitoring and retreatment of root sprouts or regrowth should always be 

anticipated after using a physical control approach. 

Site Physical Control Cultural Control Biological Control Chemical Control 

Roadsides, Hand pull or dig to Work closely with road NA Use an individual plant treatment (IPT) 

fence lines, remove as much of the crews and others to help method to apply either a foliar or soil 

or non- root as possible. identify and report active herbicide on sparse populations. 

vegetated 

areas 

Anticipate regrowth. infestations. 

Establish alternative 

ground cover by 

reseeding. 

Apply herbicide using a broadcast 

method for extensive, dense 

infestations. 

Rangeland, Mechanical methods Clean vehicles or Encourage alternative Use an individual plant treatment (IPT) 

pasture, or are generally not equipment prior to ground cover through method to apply either a foliar or soil 

riparian recommended since leaving an infested area. prescribed grazing. active herbicide on sparse populations. 

corridors disturbing the extensive 

root system may lead to 

an increase in 

population density. 

Establish alternative 

ground cover by 

reseeding. 

Apply herbicide using an aerial or 

ground broadcast method for extensive, 

dense infestations. 

Wilderness, Same as above. Place caution signs near Same as above. Same as above. 

other natural trailheads; educate public 

areas, and/or to identify and report 

small infestations; coordinate 

infestations control efforts with other 

land managers. 

Establish alternative 

ground cover by 

reseeding. 

* Choice of a particular management option must be in compliance with existing regulations for the land resource. 

2 
Manual Methods 

Hand-pulling or digging – Repetitive hand-pulling or 

digging on an annual basis can control camelthorn; but this 

approach is only practical for isolated, sparse populations. 

Extract plants when the soil is moist and remove as much 

of the root as possible. For young seedlings, it may be 

feasible to dig up the entire root. 

Mechanical Methods 

Tillage – As a single approach, tilling infested areas may 

be counterproductive since a great number of root 

fragments are left behind; re-sprouting from these root 

fragments can be prolific. Persistent and repeated tilling 

over a number of years can stress the root reserves, but this 

is costly and greatly disturbs the soil. Chemical control as 

a follow-up should be anticipated if tillage is used. To 

reduce spread, clean tillage equipment onsite following 

treatment. 

Mowing or shredding – These management tools are 

usually not recommended for camelthorn as plants regrow 

rapidly after cutting. 

Prescribed Fire 

Prescribed fire is not recommended for controlling 

camelthorn. 

Flooding 

Where feasible, maintaining a water depth of 5 to 10 

inches over a camelthorn-infested site for a period of 

several weeks can contribute to successful control. 

However, theoption to use flooding to control camelthorn 

is usually limited to areas where natural basins are formed 

and an adequate water supply is available. 

Cultural Control 

Early detection and plant removal are critical for 

preventing camelthorn establishment. Land managers, the 

local public, road crews, etc., should be educated on 

identification of nonnative invasive species so they can 

help report suspected infestations. Vehicles, humans, and 

livestock should be discouraged from traveling through 

infested areas. A program to check and remove seed or 

root fragments from vehicles and equipment after going 

through infested areas should be encouraged to help stop 

dispersal. If possible, use weed screens on irrigation water 

intakes inside infested areas to prevent seed from being 

transported by water systems. 

Biological Control 

Grazing 

Despite the thorns, leaves and pods of camelthorn are 

palatable to livestock, especially after first frost. Monitor 

grazed areas to determine if seed germination of 

camelthorn is taking place. 

Classical Biological Control 

There are no classical biocontrol agents (insects, 

pathogens, etc.) approved for use on camelthorn. 

Chemical Control 

All herbicides listed in table 2 will effectively control 

camelthorn when properly applied. However, some may 

also impact non-target species or other resources such as 

groundwater when not used according to the label. Each 

herbicide product will have different requirements and 

restrictions. Thus, it is important to read the label carefully 

and follow all instructions and guidelines when mixing 

and applying chemical herbicides. 

Herbicide Application 

The key to chemical control of camelthorn is to apply the 

appropriate dosage at a time when carbohydrate reserves 

in the shrub’s extensive root system can be depleted (see 

table 2 for time of application). Herbicide products listed 

in the table include some that are foliar sprayed and others 

that are applied to the soil surface. Equipment used to 

spray herbicide should be calibrated. Precautionary 

measures should be taken if non-target plants, including 

woody species, need to be protected. 

Foliar applications - Herbicides commonly available for 

foliar application to camelthorn include picloram, 

aminocyclopyrachlor, dicamba, imazapyr, metsulfuron, 

and clopyralid. These herbicides may be used as single 

formulations or in tank mixes with 2,4-D. Active 

ingredients may also be combined as a product for foliar 

spot spraying such as Viewpoint® which combines 

aminocyclopyrachlor, imazapyr, and metsulfuron. Consult 

the label for mixing and application directions. Add a 

3 
 

 

 

 

 

 

 

 

 

 

Table 2. Herbicide recommendations 

Common 

Chemical Name 

(active ingredient) 

Product 

Example1 

Broadcast 

Treatment 

(rate per 

acre) 

Spot 

Treatment 

(spray 

solution or 

pellets)2 

Time of 

Application Remarks 

Aminocyclopyrachlor Viewpoint 13–20 ounces Consult label for Apply as high Nonselective herbicide used on non-

+ imazapyr + spot spray volume or crop sites; may cause temporary injury 

metsulfuron methyl applications. broadcast foliar 

spray on actively 

growing plants. 

to some grass species. 

Aminocyclopyrachlor Streamline 7.5–11.5 Same as above. Same as above. Selective foliar application. Use a 

+ metsulfuron methyl ounces quality adjuvant. May cause 

temporary injury to some grass 

species. 

Clopyralid Reclaim 1-1/3 pints 3 quarts per 100 

gallons water 

On regrowth, after 

full leaf when buds 

begin to form. 

Foliar application; mainly for 

individual plant treatment (IPT) and 

follow-up treatment of re-sprouts. 

Dicamba + 2,4-D3 Weedmaster 

Veteran720 

1–4 quarts 1–3% Late summer or 

fall before 

senescence but 

during active 

growth. 

Foliar application; selective for 

broadleaf species. Used for IPT or 

broadcast spraying. Follow mixing 

instructions on label. 

Metsulfuron methyl Escort XP 1–3 fluid 

ounces 

High-volume: 1– 

3 fluid ounces per 

100 gallons. 

Consult label 

directions. 

Same as above. Same as above. 

Picloram4 Tordon 22K 2 quarts 1–3% Same as above. Same as above. 

Imazapyr Arsenal 0.75–1.5 

quarts 

0.5–2% Same as above. Foliar application; nonselective; apply 

only to foliage and stems you want to 

control. Higher rate is for heavier, 

denser infestations. 

In addition to spray drift, non-target 

plants may also be killed or injured by 

imazapyr through runoff, residue 

movement in soil, or root exudates 

from treated plants. 

Tebuthiuron Spike 80 DF 1–1.25 

pounds 

Low volume: 1 

pound per gallon 

of water 

High volume: 1 

pound per 10 

gallons of water. 

Anytime; most 

effective if applied 

before rainfall 

season or in the 

fall. 

Nonselective, soil-active herbicide 

applied to the ground surface. Use as 

an IPT or broadcast treatment. Leave 

treated plants in place for 2 years 

following application. 

For Spike 80 DF, agitate continuously; 

will be slurry-like. 

Tebuthiuron Spike 20P 1⁄4 oz. pellets 

per 3-foot 

canopy height 

Hand scatter 

pellets near 

canopy drip line. 

Same as above. Nonselective, soil-active herbicide 

applied to the ground surface. Use as 

an IPT or broadcast treatment. Leave 

treated plants in place for 2 years 

following application. 

4 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 2. Herbicide recommendations (cont.) 

Common 

Chemical Name 

(active ingredient) 

Product 

Example1 

Broadcast 

Treatment 

(rate per 

acre) 

Spot 

Treatment 

(spray 

solution or 

pellets)2 

Time of 

Application Remarks 

Hexazinone Velpar L 3 ml/3 foot 

canopy height 

Velpar L can be 

mixed w/ equal 

parts water 

(50:50) and 

applied by 

backpack sprayer. 

Same as above. Hexazinone is a nonselective, soil 

active herbicide applied to the soil 

surface. Apply as an IPT. 

Hexazinone Pronone 

Power 

Pellets 

1 pellet/2 foot 

canopy height 

Hand scatter near 

canopy drip line 

Same as above. Same as above. 

Fosamine Krenite S 1.5–6 gallons Low volume: at 

least 1.5%; high 

volume: less than 

30%. 

Same as above. Same as above. 

1 Trade names for products are provided for example purposes only, and other products with the same active ingredient(s) may be available. Individual 

product labels should be examined for specific information and appropriate use with camelthorn. 

2 Spray solution is the herbicide/water ratio in a spray mix that may be used for spot treatment with backpack or hand-held sprayers. The amount of product 

applied during an annual growing season must not exceed the maximum application rate per acre as specified by the product label – refer to the product 

label for the site type and application. 

3 2,4-D is a restricted use pesticide in New Mexico only. A certified applicator’s license is required for purchase and use. 

4 Restricted use pesticide - A certified applicator’s license is required for purchase and use. 

quality nonionic surfactant (0.25 to 0.5 percent v/v) to 

the spray mixture to ensure even coverage and 

maximum leaf uptake. 

To foliar spray camelthorn properly, all green leaves and 

shoots should be uniformly wet within the shrub’s 

canopy. Camelthorn occurring in large continuous areas 

can be broadcast sprayed using a fixed-width boom or 

boom-less spray system, such as those attached to or 

towed by a truck, ATV, or tractor. Individual plant 

treatment (IPT) or spot spraying should be used 

wherever the camelthorn population is sparse or 

scattered. There are two basic techniques available for 

spraying camelthorn using the IPT method: 

• The low-volume technique may be used for areas 

with sparse to moderate camelthorn densities. The 

technique involves applying a low quantity of 

concentrated herbicide, usually with a backpack or 

hand-held sprayer. The low volume approach is very 

flexible and can target specific plants. For success, 

the operator must be able to spray the entire canopy 

in a light, uniform manner. 

• The high-volume technique may be used for areas 

with moderate to high camelthorn densities. A high 

powered pressurized sprayer is used with this 

technique to apply herbicide until the foliage is 

visibly wet. The technique delivers a greater quantity 

of a less concentrated herbicide solution under high 

pressure, thereby allowing remote foliage to be 

sprayed at a greater distance. 

Soil application - Tebuthiuron and hexazinone are the 

primary herbicides used in a soil-applied approach for 

camelthorn control. Tebuthiuron is formulated either as a 

dry pellet or as a dry flowable powder for liquid spraying. 

Either formulation can be used for IPT or broadcast 

treatment. Hexazinone is formulated as a liquid but is best 

suited only for application as an IPT. Although these soil 

active herbicides can be applied during any time of the 

year, the optimal time is just before the rainy season or 

5 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

in the fall. Both herbicides are slow acting, and it may 

take 1 or more years before root reserves are depleted 

and the shrub is completely dead. These soil-applied 

herbicides may be inappropriate for some specific sites 

such as areas where the chemical can move through the 

soil profile into a shallow water table. 

Management Strategies 

Preventing establishment is critical to managing 

camelthorn, and it is very important to eliminate new 

plants or small infestations soon after they are 

discovered. Herbicide control of camelthorn is 

effective, but follow-up treatments will probably be 

necessary for at least 3 years. Since it is ordinarily 

useless to treat an area only one time without 

retreatment, sufficient resources must be allocated for 

the area where control is attempted. After initial 

treatment, it is especially important that resources are 

also available to respray or retreat the treated area as 

necessary. Previously treated areas should be 

continuously monitored to detect seedlings or 

recovering camelthorn plants. Failure to perform 

follow-up monitoring and adapt control methods as 

needed could result in a return of the camelthorn. 

References and 

Further Information 

California Department of Food andAgriculture. 

Encycloweedia Datasheet: Camelthorn. Available 

at http://www.cdfa.ca.gov/phpps/ipc/weedinfo/ 

alhagi.htm (accessed May 2010) 

Donaldson, S. and D. Rafferty. 2003. Identification and 

Management of Camelthorn (Alhagi pseudalhagi). 

University of Nevada Cooperative Extension Fact 

Sheet 02-41. Available athttp://www.unce.unr. 

edu/publications/files/nr/2002/FS0241.pdf 

(accessed May 2010) 

Gottfried, G.J., J.D. Shaw, and P.L. Ford, compilers. 

2008. Ecology, Management, and Restoration of 

Piñon- Juniper and Ponderosa Pine Ecosystems: 

Combined Proceedings of the 2005 St. George, 

Utah, and 2006 Albuquerque, New Mexico, 

Workshops. Proceedings RMRS-P-51. Fort 

Collins, CO: USDA Forest Service, RMRS. 218 

pp. Available at http://www.fs.fed.us/rm/pubs/ 

rmrs_p051.pdf (accessed May 2010) 

Invasive Plant Atlas of the United States. Available at 

http://www.invasive.org/weedus/index.html. 

Kerr, H.D., W.C. Robocker, and T.J. Muzik.1965. 

Characteristics and Control of Camelthorn. Weeds, 

Vol. 13, No. 2 (April 1965), pp. 156–163. 

Available at http://www.jstor.org (accessed May 

2010) 

Lee, R.D. 1999. New Mexico’s Invasive Weeds. New 

Mexico State University Cooperative Extension. 

Las Cruces, NM. 

Northam, E. and W. Meyer et al. 2009. Non-Native 

Invasive Plants of Arizona. pp. 8–9. Publ. 

AZ1482. Available at http://cals.arizona.edu/pubs/ 

natresources/az1482.pdf (accessed May 2010) 

NPS: Grand Canyon National Park Information 

Booklet: Invasive Plants. pp. 2. Available at 

http://www.usbr.gov/uc/rm/amp/amwg/mtgs/ 

08may22/Attach_04c.pdf (accessed May 2010) 

O’Connell, R. and M.C. Hoshovsky. 2000. Camelthorn 

(Alhagi pseudalhagi) in C.C Bossard et al. (eds.) 

Invasive Plants of California’s Wildlands. 

University of California Press. Berkley, CA. 

Available at http://www.cal-ipc.org (accessed May 

2010) 

Parker, K.F. 1972. An Illustrated Guide to Arizona 

Weeds. University of Arizona Press. Tucson, AZ. 

Available at http://www.uapress.arizona.edu/ 

onlinebks/weeds/titlweed.htm (accessed May 

2010) 

Parsons, W.T. and E.G. Cuthbertson. 2001. Noxious 

Weeds of Australia (2nd Edition) CSIRO 

Publishing. Collingwood, Victoria. Australia. pp. 

466. Available at http://books.google.com 

(accessed May 2010) 

6 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ramsey, S.R. and W. Kaufman. 2007. Invasive Plants: A 

Guide to Identification and the Impacts and Control 

of Common North American Species (1st ed) 

Stackpole Books. pp. 131–133. Available at 

http://books.google.com (accessed May 2010) 

Rashed Mohassel, M.H., M. Nassiri, and E.Poorkazem. 

2003. Effect of Glyphosate and Herbicide 

Combinations on Pistachio Garden Weeds in Kerman 

(Iran). Available at http://ressources.ciheam.org/ 

om/pdf/c56/01600175.pdf (accessed May 2010) 

Renz, M.J., C. Deuser, B. Hamilton, C. Nelson, and M. 

Ryan. 2008. Management of Camelthorn along the 

Virgin River (Clark County, NV).Available at 

http://www.weedcenter.org/funding/docs/ 

FinalReports_8_08/2003%20Research%20Grant%20 

Reports/Renz_M_Final_Report.pdf (accessed May 

2010) 

TexasInvasives.org. 2005. Factsheet: Camelthorn. 

Available at http://www.texasinvasives.org/ 

invasives_database/detail.php?symbol=ALMA12 

(accessed May 2010) 

USDA Plants Database. Available at 

http://plants.usda.gov/index.html (accessed May 

2010) 

Washington State Noxious Weed Control Board. 2008. 

Factsheet: Camelthorn (Alhagi maurorum). Available 

at http://www.nwcb.wa.gov/weed_info/Alhagi_ 

maurorum.html (accessed May 2010) 

Suggested Web Sites 

For information about calibrating spray equipment: NMSU 

Cooperative Extension Service Guide A-613, Sprayer 

Calibration. Available at http://aces.nmsu.edu/pubs/ 

_a/A613 

Herbicide labels online: Available at http://www.cdms.net/ 

7 
 

 

 

 

 

For more information or 

other field guides, contact: 

USDA Forest Service 

Southwestern Region 

Forest Health 

333 Broadway Blvd., SE 

Albuquerque, NM 87102 

Or visit the Southwestern Region’s 

website for invasive species: 

http://www.fs.usda.gov/goto/r3/invasivespecies 

The use of trade or firm names in this publication is for reader 

information only and does not imply endorsement of any 

product or service by the U.S. Department of Agriculture. 

Recommendations made here for 

pesticide use are not obligatory, 

nor do they imply that discussed 

uses have been registered. All 

uses of pesticides must be 

registered by appropriate State 

and/or Federal agencies before 

they can be applied. 

CAUTION: Pesticides can be 

injurious to humans, domestic 

animals, desirable plants, and fish or other wildlife—if they are 

not handled or applied properly. Use all pesticides carefully 

and lawfully. Follow recommended practices for the disposal 

of surplus pesticides and pesticide containers.