United States Department ofAgriculture

Field Guide for Managing

Sweet Resinbush

in the Southwest

Forest 

Service

Southwestern

Region TP-R3-16-30 Revised June 2017
Cover Photos

Top left: Patti Fenner, USDA Forest Service, Tonto National Forest

Top right: Bob Celaya, Arizona State Forestry

Bottom left: Bob Celaya, Arizona State Forestry

Bottom right: Steve Hurst, USDA NRCS PLANTSDatabase

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1 

Sweet Resinbush (Euryops multifidus, synonym: E. subcarnosus ssp. vulgaris) 

Sunflower family (Asteraceae), Senecioneae tribe

Sweet resinbush is currently listed as a noxious weed in 

Arizona. This field guide serves as the U.S.Forest 

Service’s recommendations for management of sweet

resinbush in forests, woodlands, and rangelands associated

with its Southwestern Region. The SouthwesternRegion

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

Sweet resinbush (synonym: hawk’s eye) is a low-growing 

shrub with whitish stems and linear leaves divided into 3 to 

6 lobes at the tip. This invasive weed is very drought 

tolerant and was introduced into southern Arizona from 

South Africa in the 1930s as a potential forage plant and

for erosion control. 

As its name implies, a sweet, yet slightly foul-smelling 

resin exudes from the woody stems. Leaves feel sticky and

have tufts of hair in the leaf axils. Prolific flowers also 

smell sweet but are disagreeable. Animals typicallyavoid

eating resinbush, likely because of its foul smell and taste. 

Growth Characteristics

• Perennial shrub/subshrub with whitish-colored

stems; typically grows to 3 feet tall although some 

may grow over 5 feet.

• Bright green linear leaves are divided into 3 to 6 

lobes at the tip; turkey foot-like; 1-inch long. Leaf 

axils have tufts of whitish hairs; may drop leaves

during particularly dry seasons.

• Numerous yellow daisy-like flowers are borne singly 

on 1 to 1.5-inch long, thread-like peduncles along the 

stem and are interspersed among the green leaves. 

Both disk and ray flowers are yellow with partially 

fused phyllaries at the base. Flowers bloom in late 

winter or early spring; may bloom and produce seed 

twice in 1 year if adequate soil moisture is available.

• Reproduces mainly by seed. Fruit is achene-like with 

a pappus of soft, white-barbed bristles; the fine hairs 

readily attach to fleece, fur, and clothing. Fruit occurs 

in star-shaped clusters of 10.

Ecology

Impacts/Threats

Sweet resinbush has a tendency to form monocultures over

time. The species has the ability to invade both intact and 

disturbed natural areas; it can out-compete desirable 

rangeland grasses and forbs for soil moisture, sunlight, and 

nutrients. Despite being planted originally as potential 

forage, sweet resinbush may possibly be toxic to wildlife 

and livestock. Neither does the species serve well for

erosion control due to its ability to form monocultural 

stands interspersed with extensive patches of bare ground.

Site/Distribution

Sweet resinbush thrives in granitic soils and commonly 

grows in sandy loam to clay loamsites. Elevation 

preference is from 2,300 to 4,900 feet. 

Currently, sweet resinbush is known to be present only in

Arizona. Ten separate populations have been identified 

south of the Mogollon Rim. Most populations are

reportedly found nearby (within 6 to 7 miles) where they 

were intentionally planted in the 1930s. 

Spread

Reproduces from seed that is covered with fine, barbed 

hairs; the hairs exude a resinous substance to aid 

attachment. New plants mostly establish below or near the 

parent plants; however, seed is readily carried by fleece, 

fur, clothing (especially socks), and vehicles. Seed is also 

easily transported overland by water, and new populations

often establish in washes and rills. Specific seed longevity

is unknown, although they probably remain viable in the

seed bank for at least 3 years.
2 

Invasive Features

Sweet resinbush is extremely efficient at obtaining soil 

moisture, thereby making it very drought tolerant. 

Sweet resinbush has moist, sticky seed hairs, which may

allow germination to occur at lower levels of soil 

moisture than those necessary for native plants. When 

the plant is cut or burned, it re-sprouts from axillary 

buds above the crown; its fragments can also produce a 

new plant. The species appears to inhibit establishment 

of native plants, although allelopathic effects have not 

yet been confirmed or refuted.

Management

Sweet resinbush can penetrate healthy rangeland plant 

communities, and encroaching infestations will 

eventually establish a monoculture if overlooked. 

However, the species is often inconspicuous within the 

shrub and pinyon-juniper communities it occupies, 

especially when not in bloom. Physical control methods 

(including fire) can be limited because of the unsuitable 

terrain where it is often found. Grazing is not an option 

for control since sweet resinbush foliage is not highly

palatable or preferred. There are no classical biological

controls at this time. Herbicide control is the main

option for sweet resinbush control, but care is needed 

not to impact desirable plants.

The following actions should be considered to contain

and reduce sweet resinbush populations:

• Educate and involve the public in active control 

efforts to stretch available resources and aid in

eradication of sweet resinbush.

• Detect and eradicate new plants as early as possible, 

especially along roadways, vehicle turnout areas,

waterways, and ditches.

• Hand removal by pulling, digging, or hoeing is 

difficult but can be an effective means of

eliminating isolated populations.

• Use foliar active or soil active herbicides at 

recommended rates for effective control of 

widespread populations of sweet resinbush. Since 

many of the herbicides available for use on sweet

resinbush are nonselective, consider using an

individual plant treatment (IPT) application method

to limit exposure to non-target species.

Table 1 summarizes some management options for

common situations involving sweet resinbush. Further 

details on these management options are explained 

below. Choice of control method(s) for sweet resinbush

depends on the land use and current site conditions

(accessibility, terrain, soil and air temperature, weather, 

density and extent of infestation, other flora and fauna 

present, etc.). Other considerations include treatment 

effectiveness, cost, and the time needed to achieve 

control. Combining control methods and using more

than one control method for each site may increase

effectiveness.

Physical Control

Because of rough terrain, sweet resinbush is generally

difficult to control by solely using mechanical 

techniques. It is more practical and economical to use 

physical methods in combination with chemical

treatments to obtain effective long-term control. 

Manual Methods

Hand Removal – Grub, pull, dig, or hoe plants. Hand

removal treatments need to ensure that plants are cut

below the crown; otherwise, remove both the root and

aboveground portions of the plant when possible. 

Monitor for seedlings and continue hand removal of 

seedlings and young plants year after year until seed is 

depleted from the soil. Involving the public to help with 

control can make this method more feasible.

Mechanical Methods

Mowing – Cutting or regular mowing will suppresstop

growth but may stimulate regrowth and increase crown 

density if not done continuously. If using machinery to 

manage sweet resinbush, the equipment should be 

cleaned after use to prevent movement of seed into uninfested areas.

Prescribed Fire

Using a broad-scale burn in areas occupied by sweet

resinbush is usually impractical because fine fuels
3 

Table 1. Management options*

Site Physical Control Cultural Control Biological Control Chemical Control

Roadsides Hand extraction, digging, or 

hoeing can be used to target

individual plants.

For plants in large patches, 

combine suppression

methods (e.g., mowing) with

a chemical treatment.

Limit disturbances along

roadsides near resinbush 

infestations. 

Implement requirements for 

vehicle operations and for 

reporting of infestations along

roads.

None known at this

time.

Use truck or tractor spraying 

equipment. Wash

underneath to prevent

spread.

Ditches and

waterways

Hand extraction, digging, or 

hoeing can be used to target

individual plants.

Limit disturbances along

waterways and ditches near 

resinbush infestations. 

Increase public awareness and 

reporting of plant presence

along ditches and roadways.

Same as above. Use herbicide with approved 

aquatic labeling for use near

or in water.

Rangeland Hand extraction, digging, or 

hoeing can be used for 

smaller infestations and to

targetseedlings.

Inspect animals, clothing, and 

vehicles after moving livestock

or vehicles through infested

areas. Remove any seeds

(including any seed-bearing

mud) before entering uninfested areas.

Same as above. When plants are widely 

scattered in rough terrain,

consider individual plant

treatment with a backpack

sprayer.

Wilderness or 

other natural

areas

Hand extraction, digging, or 

hoeing with follow-up

monitoring to detect

seedlings.

Post signs warning visitorsto

remove seeds.

Same as above. Same as above.

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

needed to sustain a fire are often limited. Sweet resinbush 

will quickly regrow when fire temperatures are not hot

enough to completely damage growing buds. In some 

situations, a planned fire might be considered when there 

is an abundance of dried fine fuels such as those produced 

when annualsthrive during a wet spring.

Cultural Control

Early detection and plant removal, especially seedlings

and young plants, are critical for preventing sweet

resinbush establishment and spread. Land managers, road 

crews, and the local public should be educated on 

identification so they can report suspected populations. 

Vehicles, humans, and livestock should be discouraged 

from traveling through infested areas. Hay, straw mulch, 

planting seeds, and other related products should be 

certified to be weed free before use in areas undergoing

treatment.

Biological Control

Grazing

Grazing with livestock as a means to control sweet resinbush 

is impractical. Sweet resinbush produces chemicals to

defend itself from being grazed; therefore, cattle, sheep, and

goats typically avoid eating the shrub. In addition to its foul 

smell, some of the chemical defense compounds may be 

toxic to livestock and wildlife.

Classical Biological Control

There are no biocontrol agents (insects, pathogens, etc.) 

known for sweet resinbush at this time.

Chemical Control

Field trials conducted jointly by the USDA Natural 

Resources Conservation Service (NRCS), DuPont 

Agricultural Chemical Co., and the Univ.of Arizona Coop. 

Extension Service have shown that metsulfuron-methyl 
4

can be used as a selective, systemic herbicide option for

sweet resinbush that provides effective long-term control. 

Tebuthiuron and hexazinone are other reliable herbicides

for control; however, they are nonselective and may 

cause injury to nearby desirable species.

Herbicides listed in table 2 have specific requirements 

and restrictions. Therefore, it is important to read the

label carefully and follow all instructions when mixing

and spraying.

Herbicide Application

General considerations for applying herbicide to sweet 

resinbush include:

• Plant condition and growth stage at the time of 

herbicide application is critical for control success.

When using a foliar spray, treating sweet resinbush 

that is healthy and robust in pre-bloom to bloom 

stage (early to mid-February) is optimal.

Treatments made in the post-bloom stage in the fall 

have also been effective. Metsulfuron-methyl 

activity is poor when applied to plants stressed by 

drought, disease, insects, or other causes that have 

resulted in die-back, yellowing, or other evidence 

of plant damage. 

• Weather conditions at the time of herbicide

application are very important. Foliar-applied 

herbicide coverage is best with low wind speeds (3 

to 8 m.p.h.). Do not spray if a rainstorm is expected 

within 6 hours of application. While metsulfuronmethyl is selective, it may cause temporary damage

or discoloration to grasses if it is applied after 

prolonged cold temperatures, when there are

extreme temperature variations between night and 

day or following very heavy rainfall. 

• Soil type and pH should be determined before

applying any herbicide. Metsulfuron-methyl is less 

effective in soils with pH greater than 7.9. 

Tebuthiuron performs best in sandy-loamy soils and

is not effective in tight clays or soils high in organic

matter. Hexazinone is best applied in loam to

sandy-loam soils and should not be applied if soil

texture exceeds 85 percent sand.

• Plant communities involved with a sweet resinbush 

population should be closely evaluated before and 

after treating an area. Anticipate that nonselective 

herbicides may damage nearby vegetation.

• Time required to gain initial control may be slow,

especially when soil active herbicides are applied.

Follow-up monitoring and spot treating seedlings are 

important for long-term sweet resinbush control.

A foliar-applied herbicide like metsulfuron-methyl may be 

applied by backpack or handheld-sprayers or by ATVor 

UTV sprayers. Any equipment used to spray herbicide 

should be calibrated. The herbicide is absorbed through the 

leafsurface. Solid-type herbicides such as granules or 

pellets may be hand cast or broadcast onto the soil surface 

using a powered applicator. The granules or pelletsremain

intact until dissolved by rainfall, and the chemical is then

moved from the surface into the root zone. To mitigate 

impacts from these nonselective herbicides, an individual 

plant treatment (IPT) method may be used to target isolated 

sweet resinbush plants.

Management Strategies

The most crucial element for sweet resinbush control is to 

eradicate whenever possible or least attempt containment. 

Early detection and control of new sweet resinbush 

populations, especially those that are escaping near

waterways and ditches, are important in slowing the spread

of this noxious weed. Based on research and practical

experience, hand removal or treating plants with a foliar or 

soil-applied herbicide are the quickest and easiest waysto

stop sweet resinbush.

Consider using a combination of control practices that meet

the needs of each situation. For example, application of 

hexazinone on Frye Mesa in Arizona was initially successful 

in greatly reducing sweet resinbush. Annual applications of 

tebuthiuron combined with hand grubbing were then made

on surviving resinbush plants. Controlled burning was also 

used to remove plants on the mesa. Infested areas have been 

monitored, and grass growth has been encouraged to

minimize the return of sweet resinbush. Ongoing control

measures are outlined in the site plan for Frye Mesa 

(McReynolds 2003-04, 2005, 2006, 2008, 2010).
5 

Table 2. Herbicide recommendations

Common

Chemical

Name (active 

ingredient)

Product

Example1

Broadcast 

Treatment 

(rate per 

acre)

Spot Treatment

(spray solution, 

granules, or 

pellets)2

Time of

Application Remarks

MetsulfuronmethylEscort XP 1.66 ounces 

per acre + 

0.25–0.5 

percent v/v 

non-ionic 

surfactant 

(NIS) 

1 ounce in 100 

gallons

Late summer Selective; foliar applied. Effectively controls 

sweet resinbush as long as not applied to soils

with pH greater than 7.9.

No grazing or haying restrictions. Grasses 

may be damaged temporarily or discolored if

applied after or immediately before very

heavy rainfall, prolonged cold weather, or

when day/night temperatures vary widely. 

Add 2,4-D or MCPA when treating sweet 

resinbush located in wheel tracks and dry, 

dusty conditions exist. 

Tebuthiuron Spike 20P 10 pounds of 

pellets

See label August, ideally

just before a

rain event.

Nonselective; will likely damage associated

vegetation. Apply only on sandy or coarse

soils.

Consider applying following use of a physical 

method since best results are obtained when 

woody plants are less than 18 inches in height 

or diameter.

Hexazinone Pronone 10G, 

Pronone 

Power Pellets

25 pounds per 

acre for

granular 

formulations; 

up to 600 

pellets per acre 

per season for 

pelleted 

formulations

See label August, ideally

just before a

rain event.

Nonselective; requires adequate rain to

activate and carry it into root zone. In soils 

with 85 percent sand or more, hexazinone 

may pass through the root zone too rapidly to 

be effective. 

In densely infested areas where sweet 

resinbush is in a monoculture, consider 

broadcast application. Grazing is restricted 

for 30 days following application.

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 mixing information and appropriate use with sweet resinbush.

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.

Always perform follow-up control for at least 2 years after

initial treatment and continue monitoring for at least 10 

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.

References and Further

Information

Clark, L.J. and R. Walser. 2000. Sweet Resinbush

Herbicide Study at Marijilda and Frye Mesa Sites 

1998-1999. In: Univ. of Arizona College of 

Agriculture and Life Sciences Report October 

2000. Available athttp://ag.arizona.edu/pubs/crops/ 

az1185/ (accessed Dec. 2012)
6

DiTomaso, J.M. and E.A. Healy. 2007. Weeds of

California and Other Western States Vol. 1; p. 390.

University of California Agriculture and Natural

Resources.

Duncan, K., K. McDaniel, and M. Renz. 2005. Chemical

Weed and Brush Control for New Mexico 

Rangelands. Las Cruces: New Mexico State Univ.

College of Agriculture and Home Economics and 

Cooperative Extension Service. Pp. 2

DuPont, E.I. de Nemours and Company. 2008. Escort XP 

Supplemental Labeling for Pasture and Rangeland.

Available athttp://www.cdms.net/LDat/ld5QT021. 

pdf (accessed Dec. 2012)

DuPont and CPS. 2009. Arizona Invasive Species Tour

Powerpoint. May 12-14, 2009.

Howery, L.D., B.D. Munda, D.G. Robinett, and H.H.

Buck. 2003. Sweet resinbush on the Santa Rita

Experimental Range: An eradication effort. In

M.P. McClaran et al. (tech. coords.) Santa Rita 

Experimental Range: 100 years (1903 to 2003) of 

accomplishments and contributions; conf.

proceedings. 2003 Oct. 30–Nov. 1; Tucson, AZ. 

Proc. RMRS-P-30. Ogden, UT: US Forest Service, 

Rocky Mountain Research Station. pp. 169-174.

La Plata County Weed Office, 2500 Main Avenue,

Durango, CO. Available at http://www.treesearch. 

fs.fed.us/pubs/36021 (accessed November 2012)

Littlefield, J. 2002. Invasive Weeds on Rangelands: 

Controlling Sweet Resinbush and YellowStarthistle. In Arizona Agricultural Experiment Station

Research Report. The Univ. of Arizona College of 

Agriculture and Life Sciences. Available at 

http://cals.arizona.edu/pubs/general/resrpt2001/

12.Html.

McReynolds, K. (2003-04, 2005, 2006, 2008 and 2010).

Frye Mesa Sweet Resinbush Control Monitoring 

Report. The University of Arizona Graham County 

Cooperative Extension.

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

Invasive Plants of Arizona. Produced by

Conservation Districts and RC&D Areas of Arizona

and the University of Arizona Cooperative 

Extension. Peer reviewed publication AZ1482. Pages

60-61. Available at http://cals.arizona.edu/pubs/

natresources/az1482.pdf (accessed November 2012).

Pacheco, J. 2009. Sweet Resinbush Control - a new

selective herbicide tool determined. Email 

communication from JeffPacheco to May 12-14 tour 

participants dated Friday,June 5, 2009.

Personal email communication from Connie Forsyth 

(cforsyth@ag.arizona.edu). May 23, 2012. Frye 

Mesa Sweet Resinbush Control Monitoring Reports 

for 2003-04, 2005, 2006, 2008 and 2010. NRCS and 

Graham County Cooperative Extension.

Pierson, E.A. and J.R. McAuliffe. 1995. Characteristics and 

Consequences of Invasion by Sweet Resinbush into 

Arid Southwestern United States. Pp. 219–230. In 

L.F. DeBano et al. (coords.), Biodiversity and 

Management of the Madrean Archipelago: The Sky 

Islands of Southwestern United States and 

Northwestern Mexico. Sept. 19-23, 1994, Tucson, 

AZ. Gen. Tech. Rep.RM-GTR-264. US Forest 

Service. Available athttp://www.fs.fed.us/rm/pubs 

_rm/rm_ gtr264/rm_gtr264_219_230.pdf

Schalau, J. 2001. Backyard Gardener: Sweet Resinbush 

Invading Cottonwood. Arizona Cooperative 

Extension, Yavapai County. Available at 

https://ag.arizona.edu/yavapai/anr/hort/byg/archive/s

weetresinbush.html

USDA Natural Resources Conservation Service. 2010. 

National Plant Database. Baton Rouge, LA. 

Available at http://plants.usda.gov/java/ 

reference?symbol=EUMU.

Suggested Web Sites

For information on invasive species:

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

For information about calibrating spray equipment: NMSU 

Cooperative Extension Service Guide A-613,

Sprayer Calibration. Available at 

http://aces.nmsu.edu/pubs/_a/A-613.pdf
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.