Fact Sheet FS-01-55
mite and a midge, are approved for the control of rush
skeletonweed (Cullen 1974). The rust, Puccinia
chondrillina, infects form A, and has shown positive results in limiting the flowering capability and seed production.
Rust strains for forms B and C of rush skeletonweed have
not been successful in field experiments (Sheley and Petroff
1999). The gall mite, Aceria chondrillae, is the most destructive of all the bioagents. The gall mite causes stunting
of the plant and greatly reduces seed production (Cullen
1974). The gall only infects form A of rush skeletonweed,
therefore limiting its success at controlling all infestations.
The only bioagent that infects all three forms of rush
skeletonweed is the gall midge, Cystiphora schmidti (Groves
and Cullen 1981). The gall midge’s impact on the weed is
less than that of the rust or the mite, which could be explained by it’s sensitivity to climactic conditions. The midge
may not be able to overwinter in areas of extreme cold.
Keep in mind that no control method is flawless, and
long-term success is only reached through years of consistent effort. Land managers should be aware of all invasive
weeds and take the necessary steps to protect their land from
infestations. Remember, the least expensive and most effective invasive weed to control is the first one! If you have any
questions regarding procedures and warnings, contact Dr.
Wayne S Johnson at (775) 784-1931, or your local extension
office.
Internet Invasive Weed Resources
University of Montana http://invader.dbs.umt.edu/
Western Society of Weed Science www.wsweedscience.org/
California Weed Science Society www.cwss.org/
Colorado State University www.arapcsuext.org/agri/noxious2.htm
Bureau of Land Management site http://www.blm.gov/weeds/
University of Nevada Cooperative Extension Offices
Battle Mountain
Logandale
815 N Second St., 89820-2334
(775) 635-5565
1897 Moapa Valley Blvd.
P.O. Box 126, 89021-0126
(702) 397-2604
Caliente
Lovelock
360 Lincoln St.
P.O. Box 728, 89008-0728
(775) 726-3109
810 6th St.
P.O. Box 239, 89419-0239
(775) 273-2932
Carson City
Minden/Gardnerville
2621 Northgate Ln., Suite 15
89706-1651
(775) 887-2252
1329 Waterloo Ln., Gardnerville
P.O. Box 338, Minden 89423-0338
(775) 782-9960
Elko
Pahrump
1500 College Pkwy., 89801-3347
(775) 738-7291
1651 E. Calvada Blvd.
89048-1090
(775) 727-5532
Ely
Reno
995 Campton St., 89301-0210
(775) 289-4459
5305 Mill St.
P.O. Box 11130, 89520-0027
(775) 784-4848
Eureka
Tonopah
701 S. Main St.
P.O. Box 613, 89316-0613
(775) 237-5326
#1 Frankee St.
P.O. Box 231, 89049-0231
(775) 482-6794
Fallon
Winnemucca
111 Sheckler Rd., 89406-8951
(775) 423-5121
1085 Fairgrounds Rd.
89445-2927
(775) 623-6304
Incline Village
Yerington
865 Tahoe Blvd., Ste. 110
P.O. Box 8208, 89452-8208
(775) 832-4150
504 S. Main St.
P.O. Box 811, 89447-0811
(775) 463-6541
Literature Cited
Bringing the University to You
Rush Skeletonweed: Prevention and Control in Nevada
John R. Zimmerman, Graduate Student, University of Nevada, Reno
Wayne S Johnson, Associate Professor, Applied Economics and Statistics, Nevada Agricutural Experiment Station,
State IPM Specialist, University of Nevada Cooperative Extension.
In Idaho, Rush Skeletonweed
increased from a few plants in
1954 to 4 million acres in 2001.
Las Vegas
2345 Red Rock St., Ste. 100
89146-3160
(702) 222-3130
I nformation herein is offered with no discrimination. Listing a product does not imply endorsement by the authors, Nevada Cooperative Extension or its personnel. Likewise, criticism of products or equipment not listed is neither implied nor intended. University of Nevada Cooperative
Extension and its authorized agents do not assume liability for suggested use(s) of chemicals or
other pest control measures suggested herein. Pesticides must be applied according to the label
directions on the pesticide container to be lawfully and effectively applied.
COOPERATIVE EXTENSION
Nevada Department of Agriculture Cooperating
Dawn Rafferty, Invasive Weed Specialist
350 Capitol Hill Ave., Reno, NV, 89502-2923
(775) 688-1182, ext. 269
Asher, J. 1998. Wildland Weeds: Scope, Impacts, Strategies. Bureau of Land Management.
Cheney, T.M., W.S. Belles, and G.A. Lee. 1980. Herbicidal control of rush skeletonweed (Chondrilla juncea L.) Proc. Weed Sci. Soc. Am. 33:52-6.
Cullen, J.M. 1974. Seasonal and regional variation in the success of organisms imported to combat skeleton weed (Chondrilla juncea L.) in
Australia. Miscellaneous Publication, Commonwealth Biology Control No. 8, 111-17.
Groves, R.H., and J.M. Cullen. 1981. Chondrilla juncea: the ecological control of a weed. The Ecology of Pests. R.L. Kitchig and R.E. Jones
(eds.), Commonwealth Scientific and Industrial Research Organization, Melbourne, Australia, 7-17.
Heap, J.W. 1993. Control of rush skeletonweed (Chondrilla juncea) with herbicides. Weed Technology. 7:954-59.
Lee, G.A. 1986. Integrated Control of Rush Skeletonweed (Chondrilla juncea) in the Western U.S. Weed Science. 34:2-6.
Liao, J.D., S.B. Monsen., V.J. Anderson and N.L. Shaw. 2000. Seed biology of rush skeletonweed in sagebrush steppe. Journal of Range
Management. 53:544-49.
Schirman, R. and W.C. Robocker. 1967. Rush skeletonweed-threat to dryland agriculture. Weeds 15:310-12
Sheley, R.L., J.M. Hudak, and R.T. Grubb. 1999. Rush Skeletonweed. In Biology of Management of Noxious Rangeland Weeds. Sheley, R.L. and
J.K. Petroff. Oregon State University Press. Corvallis, OR.
Zimbdahl, R.L. 1980. Weed crop competition Int. Plant Protection Center, Corvallis, OR.
Cover photograph credits, clockwise from top left: rush skeletonweed infested hillside, Jerry Asher; rush skeletonweed mature plant, University of
Idaho; rush skeletonweed infested rangeland, Washington State University.
Editing: Christie South and Sue Strom
The University of Nevada, Reno is an Equal Opportunity/Affirmative Action employer and does not discriminate on the basis of race, color,
religion, sex, age, creed, national origin, veteran status, physical or mental disability, sexual orientation, in any program or activity it
operates. The University of Nevada employs only United States Citizens and aliens lawfully authorized to work in the United States.
The value of a weed infested
ranch in North Dakota recently
was reduced by 60 percent.
A 1,300 acre ranch near Klamath Falls, Oregon was recently
abandoned due to weed infestations and was later sold at auction for a tenth of the value of
surrounding property.
ush skeletonweed (Chondrilla juncea) is a taprooted perennial. This noxious weed is native to
Asia Minor and the Mediterranean and has invaded Australia, Argentina, Italy, Lebanon, New Zealand, Portugal,
Spain, and the former Yugoslavia. It was first reported in
the United States near Spokane, WA in 1938 (Parsons and
Cuthbertson 1992). Since then, rush skeletonweed has invaded productive range and pasture lands, creating dense
monocultures and displacing native plants. It currently infests more than 6.2 million acres of rangeland in the Pacific Northwest and California. In Nevada, only Elko county
has reported the presence of skeletonweed. Rush
skeletonweed quickly invades disturbed or open sites and
can infest undisturbed rangelands and croplands. In the
Pacific Northwest alone, its annual rate of spread is approximately 98,000 acres. Although, it is primarily spreading on rangelands, rush skeletonweed is a serious threat to
agricultural crops because it competes aggressively for light,
water, and soil nutrients (Schirman and Robucker 1967,
Zimdahl 1980).
Monitoring weed invasions is time consuming and expensive because of the vast expanses of wilderness that
must be explored. Many counties simply do not have the
ability to effectively monitor invasive weeds. Consequently,
rush skeletonweed has more than likely infested a larger
number of acres in Nevada than are reported. Regardless
of the total amount of infested acres, only judicious monitoring, prevention, eradication and habitat restoration will
keep rush skeletonweed from spreading across Nevada.
This fact sheet is intended to provide relevant information
on why and how to prevent weed invasions and to supply
land managers with the necessary knowledge needed to
control and eradicate rush skeletonweed.
There is still time to defend Nevada against an invasion of rush skeletonweed. Many control measures have
proven effective in suppressing and eradicating the weed
in areas where it has become established. With all control
measures, use caution, seek professioal advice where
needed and most importantly, do not ignore invasive weeds.
They will continue to spread without abatement and they
are costing western states hundreds of millions of dollars
annually.
daptive ability: Rush skeletonweed thrives in
many diverse ecosystems with fairly different climactic and geographic features including: annual precipitation between 9 and 60 inches, elevations between 700
and 6,000 feet, and many soil types. In Montana, big sagebrush/bitterbrush habitat types are highly susceptible to invasions of rush skeletonweed. Comparitively, Nevada will
provide rush skeletonweed with optimal growing conditions.
Land managers, federal/state agencies, and the general public must be aware of prevention guidelines and work to-
A
gether to keep this weed out of Nevada.
iology: In the U.S., three forms of rush
skeletonweed have been identified. They are designated A, B, and C. They have narrow, intermediate, and
broad rosette leaves, respectively (Sheley and Petroff 1999).
Understanding the unique differences among these three
forms may lead to better management of rush skeletonweed.
Characteristics of seed production/germination, root growth/
regeneration, weed growth rate, and adaptive environmental preference must also be known to prevent rush
skeletonweed from gaining a foothold in Nevada.
Seed germination of rush skeletonweed begins in the
fall. Plants overwinter as rosettes until longer spring days
allow the plant to produce flower stalks and then seed. A
mature rush skeletonweed plant can produce 15,000 to
20,000 seeds, although, most young plants produce between
250 to 350 seeds. Each seed can remain viable in the soil
for up to 18 months (Lee 1986). Consequently, any control program requires vigilance for several years after the
last weed is destroyed.
B
Rush skeletonweed’s tap-root and rosette stage just
beginning stem growth in spring.
Courtesy MSU Extension Service
R
During the rosette stage (pictured above) in the first
year, rush skeletonweed grows a deep tap root. Over time
the roots can reach depths of eight feet, and if severed by
digging, cultivating, etc., they produce shoots that can reach
the surface from depths of up to four feet. Root fragments
as small as one inch in length have been known to produce
new plants under optimal soil and moisture conditions. In
late spring, the stem emerges from the center of the rosette
and can grow from one to four feet tall. The stem is green
and is responsible for the plant’s photosynthesis. Herbicides are not usually effective on this weed because its stems
are leafless and do not readily absorb the chemical.
As a perennial, rush skeletonweed flowers and produces
seeds throughout the summer and into the fall until low
temperatures kill the above ground portion of the plant.
Rush skeletonweed has the adaptability to flower and produce seeds in many areas of the Western U.S., and is ca-
pable of establishing, reproducing and dispersing seeds in
many areas where environmental factors limit native plant
growth and development (Liao et al., 2000).
enables them to create better management programs. The
next step is to determine treatment objectives, control measures, schedule of treatment, post-control monitoring procedures and create a budget.
Management Options:
Rush skeletonweed produces nearly one dozen tiny
yellow flowers per bud.
P
revention: The best recommendation when prescribing a weed prevention program is to turn an
unhealthy plant community into an ecologically sound unit
and avoid disturbing and damaging healthy functioning systems. To control any invasive weed, seed production and
dispersal must be stopped. Seeds are dispersed mainly by
wind, water, animals, and vehicles. Sometimes, natural
forces and events that distribute seeds cannot be controlled.
As a land manager however, there are several important
guidelines that can help to slow the dispersal of weed seeds.
First, avoid driving vehicles in infested areas during the
seeding period, and always wash the undercarriage of vehicles before leaving an infested area. Livestock grazed in
an infestation should be moved to a holding area for 10 to
14 days before they are moved to land absent of weeds
(Sheley and Petroff 1999). Grazing should also be properly utilized in areas free from weeds. This means using a
rotational grazing schedule and allowing native plants time
to recover. Placing stress on a native plant community by
overgrazing or disturbing the soil creates an invasive weed
pathway.
anagement begins by simply evaluating and
monitoring the landscape for the presence of
rush skeletonweed. Consider the following questions:
Where is the infestation? What is the infestation size?
What is the weed density? What type of land does it occupy? What is the soil type? From where is the infestation
coming? What is the annual precipitation? Are there grazing or recreational uses on the land? Those important questions allow land managers to understand the problem and
M
è Mechanical control through hand pulling when the
plant is young, preferably in the first spring, is most effective. Do not mow or cultivate rush skeletonweed infestations. Those are very unsuccessful methods and usually
lead to a drastic increase in the infestation. Hand pulling
provides effective control of rush skeletonweed, however,
it requires removal of plants and new growth two or three
times per year for 6 to 10 years because new plants will
grow from the severed roots. Hand pulling can be made
easier if you wet the soil first. Thoroughly burn the plant
after it is pulled and make sure the fire is very hot to ensure
complete plant destruction (Sheley and Petroff 1999).
è Cultural control with grazing and competitive legume planting is effective in controlling rush skeletonweed.
Grazing with sheep has shown some success in decreasing
rush skeletonweed infestations, and is most effective when
it is used in a continuous grazing schedule. As mentioned
previously, do not overgraze, and use rotational grazing with
all other ruminants. Competitive planting is a compliment
to grazing that also decreases weed infestations effectively.
In crop pasture rotations, it reduced the infestation of rush
skeletonweed and increased soil fertility (Wells 1969).
è Chemical control is generally more expensive and
less effective in controlling rush skeletonweed. The following provides current information collected on chemical
herbicides that are used on rush skeletonweed with application rates and trade names. Picloram (Pathway®) can be
used at 2 lb/acre, although, picloram at 1 lb/acre plus 2,4D at 1 lb/acre (Tordon 101®) is known to give better control (Cheney et al., 1980). Single applications of clopyralid
(Stinger®) at 0.2 lb/acre reduced rush skeletonweed shoots
by 60% three years after treatment (Heap 1993). A mixture of clopyralid at 0.2 lb/acre, and dicamba (Banvel
DMA ®) at 1 lb/acre was most successful for long-term control, reducing the weed infestation by 75% after three years
and by 95% with yearly application (Sheley and Petroff
1999). All herbicides are most effective when applied to
weeds infested with biological control agents. Nitrogen fertilizer alone and in combination with some herbicides has
decreased the density of some infestations, apparently by
increasing plant competition.
è Biological control of invasive weeds provides effective long-term reductions in plants with less need for
expensive labor and equipment. Unfortunately, not all
biocontrol agents adapt, survive and reproduce at every site
where they are released. Rush skeletonweed has three biological enemies that affect the weed’s expansion. A rust, a