HomeMy WebLinkAboutbocc.ord.027.2005AN ORDINANCE OF THE BOARD OF
COUNTY COMMISSIONSERS OF PITKIN COUNTY, COLORADO,
An Ordinance of the Board of County Commissioners Repealing and Re -Enacting
Section 6.32 of the Pitkin County Code Noxious Weed Management Plan.
ORDINANCE # 94 -01% -Doti
RECITALS
1. Pitkin County adopted the Pitkin Noxious Weed Management Plan in November
1999 by Ordinance # 99-48(the "Plan"), and the Plan was adopted by The Town
of Snowmass Village and The City of Aspen through the Pitkin County Noxious
Weed Management Plan Intergovernmental Agreement dated March 8s' , 2000.
The Plan has been revised by the Pitkin County Weed Advisory Board and Pitkin
County Land Management staff to incorporate The Rules Pertaining to the
Administration and Enforcement of the Colorado Noxious Weed Act. The new
rule re-classifies the Colorado Noxious Weed List into three separate management
objectives. "List A" noxious weed species are designated for eradication, "List B"
noxious weed species are designated for containment, and "List C" noxious weed
species are designated for suppression. The recent changes made to the Pitkin
County Weed Management plan will bring the Plan into compliance with the
Colorado Noxious Weed Act and make future changes to the Plan accessible
without re -writing the Plan. A complete copy of the revised plan is attached
hereto as Exhibit A.
3. The County, City of Aspen, and Town of Snowmass Village have agreed through
The Pitkin County Noxious Weed Management Plan Intergovernmental
Agreement, section 4.01, to authorize the Board of County Commissioners to
have the sole and final authority to approve, modify, or reject the Plan.
4. Copies of the Plan and Exhibit A are available for inspection at the office of
Public Works, 76 Service Center Road, Aspen, Colorado 81611, (970-920-5390)
and also at the Clerk and Recorder's Office, Jeanette Jones, at 530 East Main
Street, Aspen, Colorado 81611, during regular business hours.
NOW THEREFORE IT BE ORDAINED by the Board of County Commissioners
of Pitkin County Colorado that:
1. The revisions to the Pitkin County Weed Management Plan, as set forth in Exhibit
A, attached, be adopted.
2. Ordinance # 99-48 remains in full force and effect with respect to the Plan as
amended herein.
INTRODUCED, FIRST READ, AND SET FOR PUBLIC HEARING, BY THE
BOARD AT ITS REGULAR MEETING ON THE 8u' DAY OF June, 2005.
PUBLISHED, INCLUDING NOTICE OF PUBLIC HEARING, IN THE ASPEN
TIMES ON THEJ; DAY OF�V 2005, AND NOTICE OF PUBLIC
HEARING ONLY ON THE 12n'K DAY OF CA& & 4-_, 2005.
APPROVED AND ADOPTED UPON SECOND READING AND AFTER A
DULY -NOTICED PUBLIC HEARING BY A MAJORITY OF THE BOARD AT
ITS REGULAR MEETING ON THE gj_� DAY OF 14V A4r , 2005.
PUBLISHED, BY TITLE ONLY, AFTER ADOPTION IN THE ASPEN TIMES ON
THE 3�4 DAY OF 12005.
BOARD OF COUNTY COMMISSIONERS
OF PITKIN COUNTY, COLORADO
46a&
Patty C. Clapper (Date) 0% -41 -0J -
Chair
CONTENT:
Brian Pettet
Director of Public Works
Land Management
Ch 6y ern (-L � �-• 7
Chonnie Bliss -Jacobson, Chairperson
Pitkin County Weed Advisory Board
ATTEST:
i z
Jeannette Jones (Date)
Deputy Clerk and Recorder
APPROVIMAS TO FORM:
County Attorney
'-- MA AGER PROV
Hilary th
County Manager
t
7—
s
Pitkin County
Noxious Weed Management Plan
TABLE OF CONTENTS
Section I: The Plan
1.01
Introduction...................................................................3
Noxious Weeds Designated for Eradication .....................8
1.02
Mission Statement............................................................3
"List B"
L03
Statement of Weed Problem................................................3
3.03
1.04
Purpose of the Plan...........................................................4
16
1.05
Enactment Authority..........................................................4
Noxious Weeds Designated for Suppression .....................9
1.06
Goals of Plan..................................................................5
"List C"
Section II: Designated Noxious Weeds
2.01 "List A" Noxious Weeds......................................................6
2.02 "List B" Noxious Weeds.......................................................6
2.03 "List C" Noxious Weeds......................................................7
Section III: Pitkin County Designated Noxious Weed List
3.01
"List A"
Noxious Weeds Designated for Eradication .....................8
3.02
"List B"
Noxious Weeds Designated for Eradication ......................8
3.03
"List B"
Noxious Weeds Designated for Containment .....................8
16
3.04
"List B"
Noxious Weeds Designated for Suppression .....................9
3.05
"List C"
Noxious Weeds Designated for Eradication ......................9
19
3.06
"List C"
Noxious Weeds Designated for Containment .....................9
3.07
"List C"
Noxious Weeds Designated for Suppression .....................9
3.08
Declaration of Additional Noxious Weeds...................................9
Section IV: Description of Pitkin County's Noxious Weeds
Meadow Knapweed.....................................................................11
MyrtleSpurge............................................................................12
Orange Hawkweed.......................................................................13
Absinth Wormwood......................................................................14
BlackHenbane............................................................................15
Bounc ingbet..............................................................................
16
BullThistle................................................................................17
ChineseClematis..........................................................................18
Common Teasel.. .........................................................................
19
CutleafTeasel.............................................................................
19
Dalmatian Toadflax.......................................................................20
Dame's Rocket............................................................................21
DiffuseKnapweed........................................................................22
Plumeless Thistle...........................................................................23
Russian Knapweed.......................................................................24
Section V:
Section VI:
Salt Cedar/Tamarisk......................................................................25
Overview..........................................................................
SpottedKnapweed........................................................................26
7.02
Sulfur Cinquefoil.........................................................................27
OxeyeDaisy...............................................................................28
State Lands........................................................................52
RussianOlive...............................................................................29
7.04
ScotchThistle.............................................................................30
CanadaThistle............................................................................31
Municipalities....................................................................54
CommonTansy...........................................................................32
HoaryCress...............................................................................33
YellowToadflax..........................................................................34
Houndstongue.............................................................................35
LeafySpurge...............................................................................36
MuskThistle..............................................................................37
Perennial Pepperweed....................................................................38
Quackgrass.................................................................................39
Scentless Chamomile.....................................................................40
WildCaraway.............................................................................41
Chickory...................................................................................42
DownyBrome.............................................................................43
CommonBurdock........................................................................44
CommonMullein.........................................................................45
Field Bindweed...........................................................................46
PoisonHemlock...........................................................................47
Native Thistles in Pitkin County
American Thistle.........................................................................48
Overview..........................................................................
FrostyBall Thistle........................................................................48
7.02
Meadowor Elk Thistle....................................................................................49
Creamy or Prairie Thistle...............................................................49
State Lands........................................................................52
Parry's Thistle............................................................................49
7.04
The Threat of Escaped Ornamentals...............................................50
Section VII: Jurisdictional Overview of Areas in Pitkin County
7.01
Overview..........................................................................
51
7.02
County Land.....................................................................51
7.03
State Lands........................................................................52
7.04
Federal Lands....................................................................53
7.05
Municipalities....................................................................54
Section VIII: Enforcement
8.01 Enforcement Policy............................................................55
8.02 Purpose of Policy................................................................55
i
3
8.03
Noxious Weeds Deemed a Public Nuisance.. . ..............................
55
8.04
Authorized Agent for Eradication.............................................55
8.05
Methods of Identification and Inspection....................................56
8.06
Notice to Control Identified Noxious Weeds................................56
8.07
Right of Entry....................................................................57
8.08
Right to Assess Whole Cost of Management................................57
8.09
Failure to pay assessment......................................................57
8.10
Liability...........................................................................57
8.11
Code Authority...................................................................57
Section IX Priorities.................................................................................58
Section X Rules, Regulations and Policies......................................................58
Section XI Plan of Work
12.01 Short term Goals...............................................................60
12.02 Long Term Goals...............................................................60
Section XII Prior Acts Validated...................................................................61
Section XIII Repeal of Conflicting Provisions. .................................................... 61
Section XIV Resource Directory.....................................................................62
Section XV Definitions.................................................................................64
`-,
Acknowledgments
Pitkin County Public Works department would like to extend a special thanks to the Pitkin
County Weed Advisory Board who invested many hours of their valuable time preparing and
implementing the Pitkin County Noxious Weed Management Plan. The Pitkin County Weed
Advisory Board consists of the following: Chonnie Bliss, Tish Bartlett, Eric Petterson, Ann
Larson, Amber McKeague, Steve Child and Connie Knuth.
Pitkin County Public Works would like to recognize Renee Hassle for her tireless efforts in
seeing this project through to completion.
A special thank you is also extended to the Pitkin County Board of County Commissioners for
all of their support and for adopting the Plan.
Grateful acknowledgment also goes to the Pitkin County Attorney's Office, for all of their
knowledge and legal support.
Thanks to each of the following agencies for reviewing the Plan and providng feedback to help
us create a comprehensive Plan: Pitkin County Open Space and Trails, Bureau of Land
Management, United States Forest Service, Colorado Division of Wildlife, State of Colorado
Weed Coordinator, City of Aspen, Town of Snowmass Village, Town of Basalt, Colorado
Department of Transportation, and the counties of Eagle, Garfield and Gunnison.
The Pitkin County Noxious Weed Management Plan should be cited as follows:
"Pitkin County Noxious Weed Management Plan, prepared in 1999 revised in 2005 by Pitkin
County Staff and the Pitkin County Weed Advisory Board, and adopted by the Pitkin County
Board of Commissioners."
This document has undergone rigorous review; however, some errors may have gone
undetected. The Pitkin County Land Management office assumes responsibilityfor this Plan.
Please let us know about any necessary revisions so that we can correct future editions.
Section I
The Plan
1.01 Introduction
The health of our environment is clearly a high priority for residents of Pitkin County and the
Roaring Fork Valley. Yet, the health and productivity of our natural plant communities are
being threatened by the introduction of numerous invasive noxious weeds. Without a major
integrated weed management program, these aggressive nonnative plants will continue to infest
and degrade the lands that we value so highly. It is estimated that we lose approximately 5,000
acres of native habitat per day on Western public lands alone to noxious weeds. In an effort to
address this issue, the State Legislature passed The "Colorado Noxious Weed Act" §§35-5.5-
101-119 C.R.S. (2003) and the "Permanent Rules Pertaining to the Administration and
Enforcement of the Colorado Noxious Weed Act" 8 CCR 1203-19. These Acts both require that
the local governing authority adopt and administer a noxious weed management program to
prevent further damage by these noxious weed species.
1.02 Mission Statement
To provide education, regulatory direction, and environmental awareness to preserve and
protect our natural resources from the degrading impacts of invasive noxious vegetation in
Pitkin County and surrounding areas, quickly detect and eradicate noxious weed species with
isolated or limited populations, and improve the management of those noxious weeds that are
already well established and widespread in the County.
1.03 Statement of Weed Problem
Thousands of acres of land in Pitkin County are already infested with many of the "List B," and
"List C" noxious weed species. Experts in weed science estimate this figure increases 15
percent annually if no control measures are imposed. Such an increase in weed populations is a
serious threat to the recreational, agricultural, economic and environmental value of land in
Pitkin County. The noxious weed problem in Pitkin County is of concern not only to the
agricultural community, but to urban communities, the small landowner, recreational land users
and public land managers as well. Problem areas include: roadsides, housing subdivisions,
lands within municipalities, private property, state and federal lands.
a
1.04 Purpose of the Plan
The purpose of this Pitkin County Noxious Weed Management Plan is to provide guidelines
for effectively managing designated noxious weeds which represent a threat to the continued
economic and environmental value of lands in Pitkin County. This plan implements the
mandates of the Colorado Noxious Weed Act by detailing integrated management options for
designated noxious weeds. Such options include education, preventative measures, good
stewardship, and control techniques. It is this plan's intent to incorporate those options that
are the least environmentally damaging yet practical, timely, and economically feasible.
Furthermore, it is the responsibility of all landowners to use integrated methods to manage
noxious weeds, and the responsibility of local governing bodies to assure that these plants are
in fact managed.
1.05 Enactment Authority
The Colorado Weed Management Act (C.R.S. 35-5.5-101, et. seq.) was signed into state law
in 1990 and amended in 2003. Now known as the "Colorado Noxious Weed Act" §§35-5.5-
101-119 C.R.S. and the "Permanent Rules Pertaining To The Administration and
Enforcement of the Colorado Noxious Weed Act": 8 CCR 1203-19, it requires that the local
governing authority adopt and administer a noxious weed management program to prevent
further damage by noxious weed species.
The Act also directs that the Board of County Commissioners (BOCC) of each county in the
state shall adopt a Noxious Weed Management Plan for all unincorporated land within the
county. The Act directs the Board of County Commissioners to appoint a local Weed
Advisory Board, whose power and duties are as follows:
• To develop a noxious weed list;
• To develop a Weed Management Plan for managing designated noxious weeds;
• To recommend to the Board of County Commissioners (BOCC) that
identified landowners are required to submit an integrated weed
management plan for managing designated noxious weeds.
1.06 Goals of Plan
1.6.1 The goals of this Pitkin County Weed Management plan are to comply with
and execute the requirements of the "Colorado Noxious Weed Act" §§35-5.5-
101-119 C.R.S. and 8 CCR 1203-19 "Rules Pertaining to the Administration
and Enforcement of the Colorado Weed Management Act" as each applies to
the district.
1.6.2 Institute district -wide integrated weed management programs that address the
following fundamentals:
• Awareness, education and training
• Prevention and detection
• Inventory, survey and mapping
• Integrated control (Biological, Chemical, Cultural and Mechanical)
• Monitoring and evaluation
• Reporting
1.6.3 institute within Pitkin County government the regulations, guidelines and
policy that emphasize prevention and improve communication in regard to
noxious weeds.
1.6.4 Foster a spirit of cooperation among landowners (federal, state, county,
municipal or private) by working with these stakeholders to institute integrated
weed management.
7
/�t
Section II
Designated Noxious Weeds
The following weeds are designated as noxious weeds subject to management pursuant to
this plan and § 25-5-5-101, et seq.:
2.01 All "List A" noxious weed species classified by the Colorado Commissioner of
Agriculture.
"List A" populations have been designated by the Colorado Commissioner of
Agriculture for eradication in Colorado. This means it is a violation to allow any "list
A" species to produce seed or develop other reproductive features. It is the intent of the
State and the County to eliminate these particular species before they become too
widespread.
8 CCR 1203-19 "Rules Pertaining to the Administration and Enforcement of the
Colorado Weed Management Act" (Part 6) allows for the local governing authority to
file for a compliance waiver if it is determined that eradication is not a practical
management objective for specific populations.
2.02 All "List B" noxious weed species classified by the Colorado Commissioner of
Agriculture for eradication, containment and suppression within Pitkin County.
8 CCR 1203-19 "Permanent Rules Pertaining to the Administration and Enforcement of
the Colorado Weed Management Act" (Part 6) allows for the local governing authority
to file for a compliance waiver if it is determined that eradication is not a practical
management objective for a specific population.
The County may adopt eradication, containment or suppression standards more
stringent than those designated by the Colorado Commissioner of Agriculture.
The Pitkin County Weed Advisory Board (WAB) shall establish management
recommendations for the "List B" and "List C" noxious weed species. These
recommendations will be submitted to the BOCC for adoption.
The BOCC's adopted management objectives for "List B" and "List C" noxious weed
species will be communicated to the Colorado Commissioner of Agriculture.
2.03 All "List C" noxious weed species classified by the Colorado Commissioner of
Agriculture for eradication, containment and suppression within Pitkin County.
8 CCR 1203-19 "Permanent Rules Pertaining to the Administration and Enforcement of
the Colorado Weed Management Act "(Part 6) allows for the local governing authority
to file for a compliance waiver if it is determined that eradication is not a practical
management objective for a specific population.
The County may adopt eradication, containment or suppression standards more
stringent than those designated by the Colorado Commissioner o f Agriculture.
The Pitkin County Weed Advisory Board shall establish management recommendations
for the "List B" and "List C" noxious weed species. These recommendations will be
submitted to the BOCC for adoption.
The BOCC's adopted management objectives for "List B" and "List C" noxious weed
species will be communicated to the Colorado Commissioner of Agriculture.
Section III
Pitkin County Designated Noxious Weed List
3.01 The BOCC adopts eradication as the Pitkin County Land Management objective
for the entire "List A" noxious weed species listed in section 2.4.
Meadow knapweed (Centaurea pratensis)
Myrtle spurge (Euphorbia myrsinites)
Orange hawkweed (Hieracium aurantiacum)
3.02 The BOCC adopts eradication as the Pitkin County Land Management objective
for the "List B" noxious weed species listed in section 2.5.
Absinth wormwood (Artemisia absinthium)
Black henbane (Hyoscyamus niger)
Bouncingbet (Saponaria officinalis)
Bull thistle (Cirsium vulgare)
Chinese clematis (Clematis orientalis)
Common teasel (Dipsacus fullonum)
Cutleaf teasel (Dipsacus laciniatus)
Dalmatian toadflax, broad-leaved (Linaria dalmatica)
Dalmatian toadflax, narrow -leaved (Linaria genistifolia)
Dame's rocket (Hesperis matronalis)
Diffuse knapweed (Centaurea diffusa)
Plumeless thistle (Carduus acanthoides)
Russian knapweed (Centaurea repens)
Salt cedar (Tamarix chinensis)
Salt cedar (Tamarix, rainosissima)
Spotted knapweed (Centaurea maculosa)
Sulfur cinquefoil (Potentilla recta)
3.03 The BOCC adopts containment as the Pitkin County Land Management objective
for the "List B" noxious weed species listed in section 2.6.
Oxeye daisy (Chrysanthemum leucanthemum)
Russian olive (Elaeagnus angustifolia)
Scotch thistle (Onopordum acanthion)
Scotch thistle (Onopordum tauricum)
I�
3.04 The BOCC adopts suppression as the Pitkin County Land Management objective
for the "List B" noxious weed species listed in section 2.7.
Canada thistle (Cirsium arvense)
Common tansy (Tanacetum vulgare)
Hoary cress (Cardaria draba)
Houndstongue (Cynoglossum officinale)
Leafy spurge (Euphorbia esula)
Musk thistle (Carduus nutans)
Perennial pepperweed (Lepidium lat folium)
Quackgrass (Elytrigia repens)
Scentless chamomile (Matricariaperforata)
Wild caraway (Carom carvi)
Yellow toadflax (Linaria vulgaris)
3.05 The BOCC adopts eradication as the Pitkin County Land Management objective
for the "List C" noxious weed species listed in section 2.8.
Chicory (Cichorium intybus)
3.06 The BOCC adopts containment as the Pitkin County Land Management objective
for the "List C" noxious weed species listed in section 2.9.
Downy brome (Bromus tectorum)
3.07 The BOCC adopts suppression as the Pitkin County Land Management objective
for the "List C" noxious weed species listed in section 2.10.
Common burdock (Articum minus)
Common mullein (Verbascum thapsus 1.)
Field bindweed (Convolvulus arvensis)
Poison hemlock (Conium maculatum)
3.08 Declaration of additional noxious weeds
The BOCC may declare additional noxious weeds, within its jurisdictional boundaries,
after a public hearing with thirty days prior notice to the public. Any declaration of
additional noxious weeds pursuant to subsection (3) shall include the management
objectives for all affected landowners (per §35.5.5-108).
The integrated management of noxious weed species, as required by the "Colorado
Noxious Weed Act" §§35-5.5-101-119 C.R.S. and 8 CCR 1203-19 "Rules Pertaining to
the Administration and Enforcement of the Colorado Noxious Weed Act" and this plan,
shall be the responsibility of the landowner.
10
13
Section IV
Description of Pitkin County's Noxious Weeds
Pitkin County's "List All Noxious Weeds Designated for Eradication.
Meadow Knapweed (Centaurea pratensis)
Description:
Meadow knapweed is a member of the Sunflower family. It is a perennial that grows up to 3 '/2
feet tall with many branches. Lower leaves are entire, coarsely lobed, or toothed, while middle
and upper leaves are entire or toothed. Flowers are large pink to purplish -red heads at the end of
the branches; involucral bracts are deeply fringed, light to dark brown. This species is
considered to be a hybrid between brown knapweed and black knapweed. Meadow knapweed is
native to Europe. It infests roadsides, waste areas, fields and pastures.
Comments:
Meadow knapweed is rare in Pitkin County, but
has been identified in the Little Elk Creek
subdivision. Leaves are not finely divided like they
are with spotted and diffuse knapweed.
Biological control:
There are several approved biological control
agents for meadow knapweed. For most effective
control, use a combination of several different
kinds of insects. For more information please
contact the Colorado Department of
Agriculture/DPI Biological Pest Control Program.
Chemical control:
Contact Pitkin County Land Management or a
licensed applicator for specific recommendations.
Cultural control
Meadow knapweed tends to form monocultures by
eliminating other plants. Therefore, sowing
desirable plant species is necessary after the weed
is controlled. If a meadow knapweed stand is not
too old and grasses are still present, stimulating
grass growth by irrigation (where possible) should
increase grass competition with knapweed and
keep it under continual stress.
Mechanical control:
Plants that are periodically mowed will generally continue to flower and produce seed on
shorter plants below the mower blade. Repeated cultivation can be effective if combined with
monitoring for and controlling re -sprouts.
11
N
Pitkin County's "List A" Noxious Weeds Designated for Eradication (continued).
Myrtle Spurge (Euphorbia myrsinites)
Description:
Myrtle spurge is a highly invasive ornamental plant popular in xeriscapes and rock gardens.
This plant is rapidly expanding into sensitive ecosystems, displacing native vegetation and
reducing forage for wildlife. Myrtle spurge is a low -growing perennial with trailing stems of
fleshy blue-green alternate leaves. Flowers are inconspicuous, surrounded by yellow -green
flower-like bracts that appear from March to May. Myrtle spurge reproduces only by seed and
is capable of projecting seeds up to 15 feet. This plant exudes toxic, milky latex which can
cause severe skin irritations.
Comments:
This plant has been known to occupy ornamental gardens
on Red Mountain, the City of Aspen, and Town of
Snowmass Village. Wearing gloves, long sleeves, and
shoes is highly recommended when in contact with this
plant, as all parts are considered poisonous. Alternatives to
planting Myrtle Spurge include native plants such as
Sulphur flower (IEri€ronum urnhellatuui) or Kinnikinnick
(ArIcostaphylos uva-ursi), or a variety of other non-
invasive succulents.
Biological control:
No known biological controls at this time.
Chemical control:
Due to the waxy cuticle, an appropriate surfactant must be
used with the chosen herbicide;
Contact Pitkin County Land Management or a licensed
applicator for specific recommendations.
Cultural control:
Keeping desirable vegetation heahhy and thick will help
keep invaders out.
Don't let invasive plants go to seed.
Mechanical control:
Putting/digging small patches can be the best control method. It is important to get the root.
Make sure to wear protective clothing to protect yourself against toxins in the plant.
Prevention — Learn to identify plants; choose alternate plants for landscaping; do not
allow ornamentals to escape.
12
I
Pitkin County's "List A" Noxious Weeds Designated for Eradication (continued).
Orange Hawkweed (Hieracium aurantiacuni)
Description:
A member of the Sunflower family, orange hawkweed is a fibrous rooted perennial herb that
grows up to 12 inches tall. The leaves are basal with 1 or 2 small leaves occasionally occurring
on the bristly stem. The plant contains a milky juice. It has 5 to 35 flower heads. The strap -
shaped flowers are red -orange with notched tips. It is spread by windborne seeds, below ground
rhizomes and above ground stolons. Orange hawkweed can form near monocultures with few
other plants apparent on the dominated sites. The plant tolerates shade but thrives in open
meadows and lawns.
Comments:
One possible occurrence of this has been
documented near Norrie Colony on the Frying
Pan, but has not been confirmed. Pitkin County
land management crews have searched for it in
past years and have not seen any signs of this
aggressive species. Rosettes look similar to a
dandelion. There are many native hawkweeds,
except for white hawkweed, all natives have
yellow flowers.
Biological control:
None available, research ongoing.
Chemical control:
Contact Pitkin County Land Management or a
licensed applicator for specific recommendations.
Cultural control:
Good vegetative cover helps avoid initial
infestation, but orange hawkweed can invade healthy sites.
Mechanical control:
Orange hawkweed will not withstand regular tillage but cutting and pulling are ineffective
unless done with frequency and diligence to eliminate re -growth.
If you see this plant please call your County Land Management Department.
13
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Absinth Wormwood (Artemisa absinthium)
Description:
Absinth wormwood is a member of the Sunflower family. It is
a robust perennial that grows 16 to 48 inches tall with large
light gray leaves which are oblong in shape. Stems arise from
a taproot and branch from the base. Stems are % inch or
greater in diameter, and reddish in color. Flowering occurs in
late summer. It is frequently found near streams, lakes or
irrigation ditches.
Comments:
In Pitkin County it can be found near Hwy -133 near the
Garfield/Pitkin County line.
Biological control:
No known biological controls at this time.
Chemical control
Several herbicides are effective at label rates with an adjuvant
helping to penetrate hairs to leaf surface. Re -treatments in late
June to mid-August have given better control the following
season than spring or fall treatments.
Cultural control:
Good perennial grass resists infestation.
Mechanical control:
Summer fallow and fall tillage prevent establishment on cultivated land, but spring tillage is
less effective. Cutting or mowing reduces seed production.
Prevention — Learn to identify plants; know your property; beware of fill dirt, hay and
seed from outside your area.
14
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Black henbane (Hyoscyamus niger L.)
Description:
Black henbane, a member of the nightshade family, may
be an annual or biennial which grows from I to 3 feet
tall. The leaves are coarsely -toothed to shallowly -lobed
and pubescent. Flowers bloom along the long racemes,
are brownish -yellow with a purple center and purple
veins. The plant has a foul odor. Black henbane is a
native of Europe and has been cultivated as an
ornamental. It has spread throughout the United States
and is a common weed of pastures, fence rows,
roadsides, and waste areas.
Comments:
Black henbane contains hyoscyamine and other
alkaloids which can cause livestock poisoning. It is
considered a poisonous plant to humans. This plant is
relatively rare in Pitkin County, with most outbreaks
happening in areas where heavy earth moving has
occurred. Black henbane plants have been identified on
Brush Creek Road and near the Aspen Recreation
Center.
Biological control:
No known biological controls at this time.
Chemical control:
Several herbicides are effective at label rates. It is generally easier to control when young,
before the stalk(s) elongate.
Cultural control:
Good vegetative cover substantially reduces chance of infestation.
Mechanical control:
Cutting reduces seed production.
Prevention — Learn to identify plants; know your property; beware of fill dirt, hay and
seed from outside your area.
15
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Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Bouncingbet (Saponaria off:cinalis)
Description:
Bouncingbet is a member of the Pink family. It is a
perennial with stout, erect, smooth, branching stems,
up to 3 feet tall, with swollen nodes. Leaves have three
distinct veins from the base, are smooth, narrow and 2
to 4 inches long. Flowers are conspicuous, and
crowded at the ends of the main stem and branches,
with petals that are generally pink. Bouncingbet was
introduced from Europe as a garden plant and has now
escaped and become established as a weed. It spreads
rapidly and replaces plants of greater value.
Comments:
It is poisonous but rarely grazed. An alternative to
planting bouncingbet is garden phlox (Phlox
paniculata).
Biological control:
No known biological controls at this time.
Chemical control:
Several herbicides are effective at label rates. Contact
Pitkin County Land Management or a licensed
applicator for specific recommendations.
Cultural control:
Maintain pastures in good condition, keeping weeds
mowed. This alone will discourage most broadleaf
plants from growing, including bouncingbet. Exercise
caution when preparing hay or other feeds, so that no
seeds or other plant parts become incorporated into the
mixture.
Mechanical control:
Cutting reduces seed production.
If you see this plant please call your County Land Management Department.
16
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Bull Thistle (Cirsium vulgare)
Description:
Bull thistle is a member of the Sunflower family. This
native of Eurasia is now widely established in North
America. Bull thistle is a biennial with a short, fleshy
taproot. The stem is 2 to 5 feet tall, bearing many spreading
branches. It is green or brownish, sparsely hairy, irregularly
and spiny winged. Leaves in the first year form a rosette.
Stem leaves are pinnately-lobed, hairy and prickly on upper
side and cottony underneath. Flowers are a dark purple, 1 %z
to 2 inches wide, clustered at the end of branches.
Flowering occurs July through September.
Comments:
Bull thistle can be found in the Crystal River Valley and
Capitol Creek areas of Pitkin County.
Biological control:
One seed eater insect is widespread, for more information
please contact the Colorado Department of Agriculture/DPI
Biological Pest Control Program.
Chemical control:
Several herbicides are effective at label rates. Apply before
stem elongation, for best results. Contact Pitkin County
Land Management or a licensed applicator for specific
recommendations.
Cultural control:
Good vegetative cover helps slow establishment, but bull
thistle can invade healthy stands including healthy lawns.
Mechanical control:
Bull thistle will not withstand regular cutting or tillage. Don't let it go to seed, cut and bag if
flower heads are present.
17
)6
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
(Management plan "list B" species)
Chinese Clematis (Clematis orientalis)
Description:
Chinese clematis is a member of the Aristolochiaceae family. It is an herbaceous perennial to
woody ornamental vine. It has solitary flowers with four yellow sepals (petal -like structures),
often nodding. Each flower produces numerous feathery long-tailed seed heads which are
conspicuous all winter. Chinese clematis reproduces by seeds only.
Comments:
The only recommendation available for
preventing the spread of this species is by
eliminating seed production from
established stands, and discontinuing its
use as an ornamental. Chinese clematis
stands can be found in the Town of
Snowmass Village. There are many native
clematis species in Colorado, all having
white flowers.
Biological control:
No known biological controls at this time
Chemical control:
Contact Pitkin County Land Management
or a licensed applicator for
recommendations.
Cultural control:
Maintain health of site.
Mechanical control:
Hand pull woody vine before seed heads
mature.
Prevention — Learn to identify plants; choose alternate plants for landscaping; do not
allow ornamentals to escape.
18
L� l
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Common Teasel (Dipsacus fullonum) and
Cutleaf Teasel (Dipsacus lanciniatus
Description:
Although usually called a biennial, teasel is better described as a monocarpic perennial. A
member of the Teasel family, this plant grows as a basal rosette for a minimum of one year,
then sends up a tall flowering stalk and dies after flowering. During the rosette stage leaves
vary from somewhat ovoid in young plants to large and oblong leaves that are quite hairy in
older rosettes. During the rosette stage teasel develops a large tap root. The tap root may be
over 2 feet in length and 1 inch in diameter at the crown. Cutleaf teasel blooms from July
through September, and common teasel blooms from June through October. Flowering plants
have large, oblong, opposite, sessile leaves that form cups (the cups may hold water) and are
prickly, especially on the lower midrib. Stems are also prickly. Teasel's unique inflorescence
makes the plant readily identifiable when blooming. Flowers are small and packed into dense
oval-shaped heads. The heads (inflorescences) are subtended by up -curved bracts and are
located terminally on the flowering stems. Cutleaf teasel usually has white flowers, while
common teasel usually has purple flowers. Cutleaf teasel can also be distinguished from
common teasel by its irregularly pinnately-lobed upper stem leaves. Upper stem leaves of
common teasel have smooth margins. Flowering stems may reach 6-7 feet in height.
Comments:
If treated in the early stages of infestation it is
possible to cheaply and quickly control teasel
before it becomes too widespread. If teasel is
noticed outside, but near a natural community,
get control of the plant before it gets into the
natural community. As with all exotics, start
control before it becomes a serious problem.
Biological control:
No known biological controls at this time.
Chemical control:
The most cost effective control method for
heavily infested sites is the use of foliar
applied herbicides. Contact Pitkin County
Land Management or a licensed applicator for
recommendations.
Cultural control:
Maintain health of site.
Mechanical control_
Mechanical methods work quite well. Young rosettes can be dug up using a dandelion digger
Flowering plants can be cut before seed set.
19
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Dalmatian Toadflax (Linara genistifoli assp.)
Description:
Dalmatian toadflax is a member of the figwort family. It was introduced as an ornamental
from Europe, and is now rapidly invading dry rangeland from 5,000 to 8,000 feet. It is a
creeping perennial that closely resembles yellow toadflax. The leaves are waxy, heart -shaped,
and clasp the stem. The stems are from 2 to 4 feet tall. The flowers are snapdragon -shaped,
bright yellow, with orange centers. Dalmatian toadflax is especially well -adapted to and sites
and can spread rapidly once established. Because of its deep, extensive root system, waxy
leaves, and heavy seed production, this plant is difficult to manage.
Comments:
Dalmatian toadflax is still relatively rare in Pitkin
County but common in Glenwood Springs.
Single plants of Dalmatian toadflax have been found
along roadsides throughout the County.
Biological control:
The defoliating moth, Calophasia himtla, has been
released on Dalmation and yellow toadflax. It may
defoliate up to 20% of the leaves of the plant. Please
contact the Colorado Department of Agriculture/DPI
Biological Pest Control Program.
Chemical control:
A few herbicides are effective if proper timing to
promote translocation to the roots is combined with an
appropriate surfactant to penetrate the waxy leaf
surface.
Cultural control:
Good ground cover helps avoid initial infestation.
Dalmatian toadflax can invade healthy dry sites. Re-
seed disturbed areas adjacent to toadflax infestations
with appropriate perennial grasses.
Mechanical control:
Will not stand regular cultivation but occasional tillage or cutting and pulling are not sufficient
due to extensive root system. Repeated mowing 2-3 times per year will slow the spread and
reduce seed production.
20
93
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Dame's Rocket (Hesperis matronalis)
Description:
This escaped ornamental is a member of the
Mustard family and is also known as dame's
violet. This native of Europe may be either a
biennial or perennial which grows from 1/2 to
4 feet tall, and has flowers ranging in color
from white to pink to purple.
Comments:
This persistent plant is often sold in local
nurseries and is found in wildflower seed
mixes. As a result, it has escaped cultivation
and become a problem throughout the Roaring
Fork Valley, tending to invade riparian and
wetland habitat. The best form of control is to
not plant this species. There is little
information available on dame's rocket control.
This plant is very prolific in areas of
Snowmass Village, Red Mountain, and
Thomasville up the Frying Pan River.
Biological control:
No known biological controls at this time.
Chemical control:
Selectively applying a broadleaf herbicide like
glyphosate to seedlings according to label
recommendations is an effective means of control. To avoid damaging adjacent native
vegetation apply herbicide in late fall when the rosettes are still green.
Cultural control:
Good ground cover helps avoid initial infestation.
Mechanical control:
Cutting or pulling the flower heads after they bloom may need to be done for several years to
prevent new plants established from the seed bank. Pulling or use of a dandelion digger is most
effective when the soil is moist.
Prevention — Learn to identify plants; choose alternate plants for landscaping; do not
allow ornamentals to escape.
21
qq
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Diffuse Knapweed (Centaurea dii Lusa)
Description:
Diffuse knapweed is a member of the Aster
family. Diffuse knapweed was introduced from
Europe and is a biennial or short-lived perennial
forb, which reproduces only by seed. The plant
usually produces a single main multi -branched
stem that is 1 %: to 2 feet tall. The flower is white
or pink with bracts.
Comments:
Diffuse knapweed is increasingly common in
Pitkin County. The largest infestations are found at
the base of Smuggler Mountain Road, and in
Snowmass Village across from the Snowmass
Conoco. An early detection and early treatment
philosophy could eradicate this weed in Pitkin
County.
Biological control:
Two seed head flies, Urophora affinis and U.
quadrifasciata, are available to reduce seed
production. A root -boring moth, Agapeta �oegana,
causes considerable damage to roots. Please
contact the Colorado Department of
Agriculture/DPI Biological Pest Control Program.
Chemical control:
There are several effective herbicides at label rates.
The rosette and early bolt stages are the best time
for treatment.
Cultural control:
Competitive vegetation helps but can be displaced.
Fertilizing and irrigation generally favor grasses.
Mechanical control:
Tillage, digging, pulling and cutting will reduce or eliminate plants if repeated frequently,
thoroughly and prior to seed production.
22
Pitkin County's "List B" Noxious Weeds Designated for Eradication.
(Management plan "list B" species)
Plumeless Thistle (Carduus acanthoides)
Description:
Plumeless thistle is a member of the Aster family.
Introduced from Eurasia, it is a winter annual or
biennial. This plant can be distinguished from musk
thistle by its smaller flowers from '/z to 1 inch in
diameter. The leaves of plumeless thistle lack the
prominent white margin present on musk thistle
leaves. The plant may grow to a height of 5 feet or
more. Flowers are reddish -purple and are either
solitary or clustered. Taproots are large and fleshy.
Plumeless thistle is an extremely prolific seed
producer. It is found in pastures, river valleys, and
along roadsides.
Comments:
Plumeless thistle is primarily found in the tri -county
areas of Eagle, Garfield and Pitkin Counties. It has
been classified by the Colorado Department of
Agriculture as a "list B" eradication species.
Biological control:
The seed -head weevil, Rhinocyllus conicus, which
attacks musk thistle, also feeds on plumeless thistle
seeds. Another musk thistle weevil, Trichostrocah,
horridus, has been released on plumeless thistle in Pitkin County.
ineffective on plumeless.
For additional information please contact the Colorado Department of Agriculture/DPI
Biological Pest Control Program.
This weevil appears to be
Chemical control:
There are several herbicides effective at label rates. Apply herbicide at the vegetative stage
either in the fust or second year of the lifecycle (spring/fall).
Cultural control:
Good vegetative cover tends to inhibit establishment but plumeless thistle can invade healthy
sites. The best management is to minimize disturbance and revegetate with competitive
perennial species.
Mechanical control:
Regular cultivation, digging or cutting are effective because of seed -only spread.
23
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Russian Knapwced (Acroptilon repens)
Description:
Russian knapweed is a member of the Aster family introduced from Europe. It is a perennial
that reproduces by seed and creeping, horizontal roots. The ridged stems are stiff and I to 3
feet high, with thistle -like flowers that are lavender to white. The plant flowers in June to
August and seed is produced in later summer to early fall. Russian knapweed is a serious
noxious weed. It is very difficult to control or eradicate once it becomes established.
Comments:
This weed is beginning to show up on roads throughout Pitkin County with more frequency.
Hwy -133 has numerous small patches. Snowmass Creek Road has infestations from Windstar
up to the end of the asphalt. Other small patches on Watson Divide, Brush Creek and McLain
Flats Roads have all been eradicated over the last three years. The key to Russian knapweed
control is to stress the weed and cause it to expend nutrient stores in the root system. An
integrated management plan should be developed that places continual stress on the weed.
Currently, the best management plan includes cultural control combined with mechanical
and/or chemical control techniques. A single control strategy, such as mowing or an herbicide,
usually is not sufficient.
This plant is toxic to horses, however they must consume it over a period of time before
poisoning will occur. Once poisoning occurs horses are unable to chew and advance food
to the back of their mouths, swallowing is impaired and horses can drink only if they
immerse their head in water far enough to get water to the back of their mouths.
Poisoning is irreversible and death by starvation will
occur.
Biological control:
A gall -forming nematode established in Washington may
eventually assist control.
Please contact the Colorado Department of Agriculture/DPI
Biological Pest Control Program.
Chemical control:
Several herbicides are effective at label rates, but timing is
critical, with bud stage and after a light frost being the two
best times.
Cultural control;
Russian knapweed tends to form monocultures by
eliminating other plants. Therefore, sowing desirable plant species is necessary after the weed is
controlled. Research indicates that the native grasses stream -bank wheatgrass and thickspike wheatgrass
will establish in an area after Russian knapweed is suppressed with herbicides. If the Russian knapweed
stand is not too old and grasses are still present, stimulating grass growth by irrigation (where possible)
should increase grass competition with knapweed and keep it under continual stress.
Mechanical control:
Mowing, pulling and cultivation are ineffective controls because of root spread.
24
)fl
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Salt Cedar or Tamarisk (Tamarix ramosissima L)
Description:
Salt cedar, also called tamarisk, was
introduced from Eurasia and is now wide-
spread in the United States. Salt cedar is a
member of the Tamarisk family. It is a
deciduous or evergreen shrub or small tree
that grows from 5 to 20 feet tall. The bark
on saplings and stems is reddish brown.
Leaves are small and scale -like and flowers
are pink to white and five -petalled.
Saltcedar is also an enormous water
consumer. A single large plant can absorb
200 gallons of water a day. The stems and
leaves of mature plants secrete salt,
forming a crust above and below ground,
which inhibits native plants from
establishing.
Comments:
In Pitkin County, salt cedar/tamarisk has
been found along the Crystal River by
Penny Hot Springs, and occasionally
popping up along roadside ditches.
Presently, there are no known stands of Tamarisk in Pitkin County. This plant should be
eliminated whenever possible. Once tamarisk is established it is very difficult to control.
Biological control:
There are experimental projects being conducted which are not cleared for general release.
Please contact the Colorado Department of Agriculture/DPI Biological Pest Control Program.
Chemical control:
Several herbicides are effective at label rates but care must be used around moist areas.
Cultural control:
Competitive vegetative cover helps but cannot prevent spread in susceptible sites.
Mechanical control:
Repeated digging can be effective.
If you see this plant please call your County Land Management Department.
25
12
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Spotted Knapweed (Centaurea maculosa)
Description:
Spotted knapweed is a member of the Aster family. Native to
central Europe, it is a simple perennial that reproduces from
seed and forms a new shoot each year from a taproot. The
plant can have one or more shoots up to 4 feet tall. Flower
color is usually lavender to purple. Spotted knapweed
occupies dry meadows, pastures, stony hills, roadsides, and
the sandy or gravel flood plains of streams and rivers, where
soils are light textured, well -drained, and receive summer
precipitation. Spotted knapweed tolerates dry conditions,
similar to diffuse knapweed, but will survive in higher
moisture areas as well.
Comments:
Spotted knapweed is one of the most invasive, aggressive
weeds to plague the western United States. Very rare in Pitkin County, the largest infestation is
found at the base of Independence Pass along State Highway 82 above Tagert Lakes. This
infestation has been monitored and treated yearly. It is imperative that this infestation not be
allowed to spread into the fragile sub -alpine ecosystem.
Biological control:
The seed -head flies, Urophora affinis and Urophora quadrifasciata, have been released in
many Front Range counties. These insects cause plants to produce fewer viable seeds and
abort terminal or lateral flowers. Root feeding insects may have more of a detrimental effect
on knapweed populations than seed feeding insects. Larvae of the yellow winged knapweed
moth feed on the roots of spotted knapweed. Please contact the Pitkin county Land
Management Department or the Colorado Department of Agriculture/DPI Biological Pest
Control Program for more information.
Chemical control:
Several herbicides are effective at label rates. The rosette and early bolt stages are the most
effective time for treatment.
Cultural control:
If desirable grass competition is evident in spotted knapweed stands, judicious herbicide
application that does not injure grasses may release the grass to compete effectively with the
weeds. Irrigation may help stimulate grass competition in these cases. Seeding suitable
perennial grasses is necessary to prevent weed re -invasion.
Mechanical control:
Tillage, digging, pulling and cutting will reduce or eliminate plants if repeated frequently,
thoroughly and prior to seed production.
IR
9 1
Pitkin County's "List B" Noxious Weeds Designated for Eradication (continued).
Sulfur Cinquefoil (potentilla recta)
Description:
Sulfur cinquefoil, a member of the Rose family, is a perennial growing up to 1'/z feet tall. It has
a well developed rootstock. Leaves palmately compound and have 5 to 7 toothed leaflets on
each leaf. Leaves are sparsely hairy and appear green on the underside rather than silvery as in
many Potentilla species. Flowers are light yellow with 5 petals, each flower producing
numerous single -seeded oval achenes. Sulfur cinquefoil is often found in disturbed areas such
as roadsides and pastures. Colonies of plants can also be seen in undisturbed sites.
Comments:
Many native cinquefoils in our area are similar,
but their flowers are either white or brighter
yellow/gold. Sulfur cinquefoil is rare in Pitkin
County.
Biological control:
No known biological controls at this time.
Chemical control:
Several herbicides are effective at label rates but
may require repeated treatments because of
extensive woody root system.
Cultural control:
Competitive vegetative cover helps but does not
completely prevent infestation of sulfur
cinquefoil.
Mechanical control:
Repeated tillage or digging are both effective.
27
30
Pitkin County's "List B" Noxious Weeds Designated for Containment.
Oxeye Daisy (Chrysantheum leucanthemum)
Description:
Oxeye daisy, a member of the Sunflower family, is an erect, rhizomatous perennial plant with
white ray and yellow disk flowers which bloom from June to August. A native of Eurasia,
this aggressive plant has escaped cultivation and has become a troublesome weed in the West.
Oxeye daisy is transplanted as an ornamental despite its tendency to crowd out more desirable
vegetation.
Comments:
Originally planted intentionally in Pitkin
County in wildflower mixes, this escaped
ornamental has spread throughout Pitkin
County. Especially common in and around
the Redstone area, it's beginning to dominate
the Crystal river drainage area. Alternatives
to planting oxeye daisy include native
daisies, black-eyed susan, Shasta daisy, and
blanket flower.
Biological control:
No known biological controls at this time.
Chemical control:
Several herbicides are effective at label rates.
Commercial nitrogen alone is nearly as
effective at sufficient rates.
Cultural control:
Nitrogen fertilizer greatly enhances ability of grasses to out -compete this weed
Mechanical control:
Repeated tillage or digging will eventually eliminate rhizomes.
Education:
The key to oxeye daisy management is to create an awareness among homeowners, nurseries,
landscapers, and landscape architects that oxeye is a noxious weed and therefore should not be
specified in plantings, sold in nurseries, or planted in home gardens or large-scale landscape
projects.
Prevention — Learn to identify plants; choose alternate plants for landscaping; do not
allow ornamentals to escape.
28
3�
Pitkin County's "List B" Noxious Weeds Designated for Containment (continued).
Russian Olive (Elaeagnus angustifolia L.)
Description:
Russian olive is a member of the Oleaster family. A hardy, fast-growing tree introduced from
Europe, Russian olive has been promoted for windrow and ornamental plantings. Russian olive
can be found in dry to moist soils, but does particularly well in sandy flood plains. This tree
may reach heights from 10 to 25 feet. The trunk and branches are armed with 1 to 2 inch woody
thorns. The leaves are covered with small scales which give the foliage a distinctive silvery
appearance. The fruit is berry -like, and silvery when first formed but turns brown at maturity.
This tree is rapidly replacing native riparian species and eliminating valuable nesting sites for
birds. It should be eliminated whenever possible.
Comments:
To date Russian olive has not been a
problem in Pitkin County but has the
capability to spread if left unchecked.
This weed is starting to establish
itself along the Crystal River Valley,
and should be controlled if signs of
spreading occur.
Biological control:
No known biological controls at this
time.
Chemical control:
Several herbicides are effective at
label rates but care must be used
around moist areas. Contact Pitkin
County Land Management or a
licensed applicator for
recommendations.
Cultural control:
Plant native trees or less aggressive
introduced trees. In riparian areas establish native riparian vegetation.
Mechanical control:
Small trees may be controlled mechanically by using an appropriate tool or shovel. Seedlings
and sprouts can be hand -pulled when the soil is moist to insure removal of the root system. On
larger plants, cutting alone results in thicker, denser growth. Burning during the dormant season
also results in vigorous re -sprouting.
29
39-
Pitkin County's "List B" Noxious Weeds Designated for Containment (continued).
Scotch Thistle (Onopordum acanthium, Onopordum tauricum)
Description:
Scotch thistle is a member of the Aster family. It is a biennial that was introduced from
Europe or eastern Asia and can reach a height of 8 feet. The rosette forms the first year and
can have leaves up to 2 feet long and 1 foot wide. The second year the plant produces flowers
that are reddish -purple to violet. It is found primarily along roadsides and railroads, but can
become an impassable obstacle to livestock on rangeland and pastures.
Comments:
Scotch thistle is abundant in Garfield and
Eagle Counties to the North, but still
relatively rare in Pitkin County. Scotch
thistle has begun to appear along Hwy -82 as
far up valley as Cozy Point Ranch. A few
infestations can be found in the Town of
Snowmass Village and along Capitol Creek
Road.
Biological control:
No known biological controls at this time
Chemical control:
Several effective at label rates; best timing is
in early spring when plants are in rosette
stage and again in fall when more rosettes
germinate.
Cultural control:
Competitive vegetation helps reduce open
spaces for invasion.
Mechanical control:
Mowing can stop seed production in short term, but plants can re -grow; digging, cutting and
cultivation are effective; monitor for new growth all season long; seed bank will be present for
2-4 years.
30
33
Pitkin County's "List B" Noxious Weeds Designated for Suppression.
Canada Thistle (Cirsium arvense)
Description:
Canada thistle is a member of the Aster family. Canada thistle was introduced from Europe.
It is a perennial which reproduces by seeds and fleshy, horizontal roots. The erect stem is
hollow, smooth and slightly hairy, 1 to 5 feet tall, simple, and branched at the top. The
color is primarily lavender, pink, or purple.
Comments:
Canada thistle emerges in June in most parts of
Pitkin County. It is one of the most widespread
and economically damaging noxious weeds in
Colorado. Infestations are found in cultivated
fields, riparian areas, pastures, rangeland,
forests, lawns and gardens, roadsides, and in
waste areas. Because of its seeding habits,
vigorous growth, and extensive underground
root system, control or eradication is difficult.
Canada thistle is best managed through an
integrated management system that emphasizes
competitive, desirable plants.
Biological control:
There are currently three types of insect available:
The Thistle Stem Weevil (Ceutorhvncus litura)
is a weevil that stresses the crown of the plant.
The Thistle Defoliating Beetle (Cassida
rubiginosa) is a leaf eating beetle, which will also e.
thistles.
The Thistle Stem Gall Fly (Urophora cardui) is a fly which attacks the primary and lateral
stems of Canada thistle, reducing seed production.
Chemical control:
Some herbicides are effective at label rates if strict attention is paid to timing (usually at bud
stage and/or fall) which helps promote translocation to the extensive root system. Make sure to
use appropriate herbicide if working in or around wet areas.
Cultural control:
Maintain soil disturbances, and encourage desirable plant growth.
Mechanical control:
Canada thistle is very difficult to mechanically control because each time a root is cut, it serves
to increase the number of plants; regular cutting or tillage can wear down plant reserves and
reduce population and vigor but results are often erratic.
31
Pitkin County's "List B" Noxious Weeds Designated for Suppression (continued).
Common Tansy (Tanacetum vulgare L)
Description:
Common tansy is a member of the Aster family. Originally imported from Europe as an
ornamental, it is a perennial plant that grows from 1% to 6 feet talll with yellow button -like
flowers and fern -like leaves. Reproducing by both seed and rootstock, tansy is difficult to
control. Tansy is particularly aggressive when growing along irrigation ditches where it can
restrict water flow.
Comments:
Common tansy is found throughout the US.
Also, widespread in Pitkin County, usually
in small dense patches in sub -irrigated
areas along roads, ditches, and in waste
areas and pastures. Alternatives to planting
tansy include tall Yellow Yarrow and
Wooly Cinquefoil.
Biological control:
No known biological controls at this time.
Chemical control:
Several herbicides are effective at label
rates with best application time dependant
on the herbicide used. Contact Pitkin County
Land Management or a licensed applicator
for recommendations.
Cultural control:
Competitive vegetative cover helps but
does not completely prevent infestation of
common tansy.
Mechanical control:
Repeated mowing or cutting will inhibit
seed production. Pulling or digging is
ineffective.
Prevention — Learn to identify plants; choose alternate plants for landscaping; do not
allow ornamentals to escape.
32
i
Pitkin County's "List B" Noxious Weeds Designated for Suppression (continued).
Hoary Cress or Whitetop Cardaria draba
Description:
Hoary cress, a member of the Mustard family,
was probably introduced from Europe in
alfalfa seed. It is a perennial which reproduces
by seed and roots. The extensive root system
spreads horizontally and vertically with
frequent shoots arising from the rootstock. It
grows erect from 10 to 18 inches high and has
a gray -white color. The alternate leaves clasp
the stem and are oval or oblong with toothed
or almost smooth margins. The leaves are
often covered with very fine white hairs. Each
leaf is `h to 2 inches long with blunt ends. The
flowers are white, 1/8 inch across, and
numerous in compact flattop clusters.
Comments:
Whitetop is becoming increasingly common in
parts of Pitkin County. It is extremely prolific and moving quickly throughout the Little Elk
Creek and Old Snowmass areas towards East Sopris Creek. Hoary cress is one of the earliest
perennial weeds to emerge in the spring. Flowers are produced in late April and May.
Biological control:
No known biological controls at this time.
Chemical control:
There are several herbicides effective at label rates. Whitetop may require repeat treatments to
kill root systems. Treatment is most effective before bloom or in the fill.
Cultural control:
Mowing or cultivation effectiveness will be increased if other plants like perennial native grasses or
alfalfa are seeded in the whitetop stands as competitors. Maintain range and pasture in good
condition. Promote healthy grass growth through proper irrigation and fertilization. Do not
overgraze.
Mechanical control:
Cutting/tilling will not achieve control due to the underground root system. Removal of top
growth is somewhat effective. Repeated treatments may reduce seed production and spread.
Pitkin County's "List B" Noxious Weeds Designated for Suppression (continued).
Yellow Toadflax (Linaria vulgaris Mill)
Description:
Yellow toadflax is a member of the Figwort family and is sometimes called
common toadflax or butter and eggs. It was introduced from Europe as an
ornamental and has now become a serious problem to rangeland and
mountain meadows. It is a perennial reproducing from seed, as well as from
underground rootstalk. The flowers are bright yellow with deep orange
centers and resemble the snapdragon. Yellow toadflax does well in all types
of soils. Its displacement of desirable grasses not only reduces ecological
diversity, but also reduces rangeland value and can lead to erosion problems.
Because of its early vigorous growth, extensive underground root system,
and effective seed dispersal methods, yellow toadflax is difficult to control.
Comments:
Yellow toadflax is common from Redstone to Marble, Snowmass Village
and City of Aspen including Aspen Mountain, the Ashcroft area of Castle
Creek, and the Frying Pan drainage. Alterative plants include yellow
snapdragon.
Biological control:
There are currently three insect species:
The Toadflax Stem -Boring Weevil (Calophasia lunula) is a weevil that
severely damages the flowers and reproduction features of yellow toadflax.
The Toadflax Flower -Feeding Beetle (Brachypterolus pulicarius) is a tiny insect with a big
appetite for toadflax which focuses on destroying the floral parts that produce seed.
The Toadflax Seed Capsule Weevil (Gymnetron antirrhini) is a weevil which takes up feeding
where the Flower Beetles leave off. These weevils feed on the developing seed capsules of yellow
toadflax and further reduce the number of seeds each year.
Cultural control:
Attempt to maintain competitive communities of desirable species. Re -seed any open ground with
native, perennial grasses to prevent invasion by yellow toadflax and other weed species.
Chemical control:
Several herbicides are effective at label rates. In Colorado the best results have been shown by
applying herbicide just after a killing frost in the fail or during flowering when the plant reserves
are low. Picloram (Tordon) has been shown to provide the most effective control. The frost assists
in breaking up the cuticle of the leaves and allows greater penetration of the herbicide. Yellow
toadflax usually requires repeat treatments to kill the extensive root systems.
Mechanical control:
Usually will not stand regular cultivation, regular cutting and digging can weaken infestations but
must be repeated to be effective, Digging and pulling where feasible can provide effective control if
conducted annually for 10 to 15 years.
34
31
Pitkin County's "List B" Noxious Weeds Designated for Suppression (continued).
Houndstongue (Cynoglossum officinale L.)
Description:
Houndstongue is a member of the Borage family. It is a biennial introduced from Europe. It
reproduces by seeds and appears as a leafy rosette in its first year. The stem is erect, stout,
heavy, l'/1 to 3 feet high, usually branched above. The leaves are alternate, the basal and lower
ones are broad, and oblong to lance -shaped. The upper leaves are narrow and pointed, almost
clasping. The flowers are terminal and reddish -purple in color. The fruit consists of four nut -
lets (seeds), each about 1/3 inch long. The seeds are covered in short, barbed prickles, which
are rapidly scattered by animals. Houndstongue is toxic to horses and cattle. The weed contains
alkaloids that may cause liver cells to stop reproducing.
Comments:
Houndstongue is widespread throughout Pitkin County,
particularly in areas of past or current livestock grazing.
Houndstongue is a prolific seed producer, and the seeds arc
readily spread by their ability to stick to wildlife and domestic
animals.
Biological control:
None available to date, but a promising agent may be
available very soon...
Chemical control:
There are several effective herbicides at label rates. Using an
adjuvant is helpful due to hairy leaf structure.
Cultural control:
Re -seed disturbed sites with fast growing native grasses.
Maintain range and pasture in good condition. Promote healthy
grass growth through proper irrigation and fertilization. Do not
overgraze.
Mechanical control:
Physical removal of the plant at flowering or early seed formation, by pulling or digging, will
break the cycle of the plant. Regular cultivation, digging, pulling and cutting are effective if done
frequently; if done after flowering, plants need to be removed from site and disposed of to
prevent seed spread.
35
3g
Pitkin County's "List B" Noxious Weeds Designated for Suppression (continued).
Leafy Spurge (Euphorbia esula L)
Description:
Leafy spurge is a member of the Spurge family, introduced from Europe. It is a perennial that
reproduces by seed and extensive creeping roots. The roots can extend as deep as 30 feet on a plant that
grows I to 3 feet tall, with pale green shoots and small yellow -green flowers. The plant, including the
root, has milky latex that is damaging to eyes and sensitive skin. Leafy spurge is an extremely difficult
plant to control because of its extensive sprouting root. It has adapted to a wide variety of habitats in the
state and is very competitive with other plant species. If it becomes established in rangeland, pasture,
and riparian sites, it may exclude all other vegetation due to its competitive nature.
Comments:
Leafy spurge is widespread from Starwood to the Lower Rio Grande Trail and Jaffee Park to Pitkin Iron
Property to Hannon Creek to the Woody Creek Valley. Leafy spurge is an extremely difficult to control
perennial weed that will require re -treatments to achieve adequate control. Development of a management
plan is helpful to manage large areas of leafy spurge.
Biological control;
Sheep or goats will graze leafy spurge. If livestock graze leafy
spurge after seed formation, hold animals in a corral for at least
seven days before moving them to an uninfested area to avoid
spread.
There are several insects available:
The Black Dot Spurge Flea Beetle (Aphthona nigriscutis) is the
most successful of the biological controls because the adult beetle
feeds on the leaves and bracts, while the larvae feed internally on
the roots.
The Brown -Legged Spurge Flea Beetle (Aphthona lacertosa)
offers similar characteristics as the Aphthona nigriscutis,
mentioned above.
The Red -Headed Spurge Stem Borer (Oberea ervthrocephala)
as an adult feeds on the leaves, bracts and girdles the stems of leafy spurge.
The Spurge Shoot -Tip Gall Midge (Spurgia esulae) can effectively prevent flowering and seed
production on the stem and reduce plant carbohydrate reserves.
Chemical control:
There are a few herbicides which are effective. Apply herbicides using the correct rates, timing, mixtures,
and adjuvant. Leafy spurge generally requires a licensed operator. Treat infestations at a noted rate for 3-4
consecutive years in the spring following the appearance of true flowers or during fall re -growth, Re-
treatment will be necessary in subsequent growing seasons with reduced herbicide rates.
Cultural control:
Any activity which encourages vigorous grass growth is very important. Do not overgraze.
Mechanical control:
Persistent, almost zealous digging or cultivation is required to be at all successful. Mowing leafy spurge at
14-21 day intervals may cause higher susceptibility to fall applied herbicides.
36
3�
Pitkin County's "List B" Noxious Weeds Designated for Suppression (continued).
Musk Thistle (Carduus nutans L.)
Description:
Musk thistle is a member of the Aster family. Introduced from Eurasia, it is a winter annual or
biennial which reproduces by seed. The first year's growth is a large, compact rosette from a
large, fleshy, corky taproot. The second year stem is erect, spiny, 2 to 6 feet tall and branched
at the top. The waxy leaves are dark green with a light green midrib and mostly white margins;
flowers are purple or occasionally white. Musk thistle is also known as "nodding thistle" and is
commonly found in pastures, roadsides, and waste places. It prefers moist bottomland soil, but
also can be found on drier uplands.
Comments:
This species of thistle was once very widespread in
Pitkin County but has been drastically reduced by the
Rinocillus Conicus (weevil). The plant still occurs on
Hwy -133 and in a few areas in Old Snowmass Creek
road.
Biological control:
The musk thistle seed head weevil Rinocillus conicus is
widespread in Colorado. Larvae of this insect destroy
developing seeds but are not 100 percent effective by
themselves. The weevil normally impacts seed
production by about 50 percent. Herbicides can be
combined with weevils if the insects are allowed to
complete their life cycles. Another weevil
Trichosirocalus horridus attacks the crown area of musk
thistle rosettes and weakens the plant before it bolts.
This weevil has reduced stand density in areas where it
has become well established. A leaf -feeding beetle,
Cassidia rubiiginosa, causes considerable damage by
skeletonizing leaves. It is recommended to release more
than one type of insect on a weed since each type may
work on different parts of the plant.
Chemical control:
There are several herbicides effective at label rates. The best timing is when plants are in the
rosette stage or early bolt stage. Effective control may require applications in the spring and
again in fall to new rosettes.
Mechanical control:
Mowing, cutting, digging, pulling or cultivation are all effective if done prior to flowering and
repeated if necessary. Musk thistle seed bank will be present for 2-6 years.
37
q�
Pitkin County's "List B" Noxious Weeds Designated for Suppression (continued),
Perennial Pepperweed (Lepidium latifolium L.)
Discription:
Perennial pepperweed or tall whitetop is a member
of the Mustard family. It was introduced from
Europe or western Asia. It is a deep-rooted
perennial plant with extensive, vigorous creeping
root stalks. Perennial pepperweed is similar to
whitetop; however, it is much taller. Perennial
pepperweed stands 3 to 5 feet high with a heavy,
sometimes woody, crown. The lower leaves are
oblong with toothed margins. The upper leaves do
not clasp the stem as in whitetop. Flowers are
white. Perennial pepperweed can be found in
pastures, riparian areas, roadsides, and waste
places. It has a limited range in Colorado from
5,500 to 8,000 feet. This weed has taken over
thousands of acres in the San Luis Valley.
Comments:
This plant is known to occupy at least two areas in
Pitkin County; Phillips curves on Hwy -82 and Old
Snowmass Road. It is nearly as bad as Hoary cress
and should be watched closely,
Biological control:
No known biological controls at this time.
Chemical control:
Some broad leaf herbicides are effective at label rates, but must be used with care around moist
sites.
Cultural control:
Re -seed disturbed sites with fast growing native grasses. Maintain range and pasture in good
condition. Promote healthy grass growth through proper irrigation and fertilization.
Mechanical control:
Repeated hand pulling and digging are good for limited infestations. Clean tillage equipment to
avoid spreading roots. Do not overgraze.
38
q I
Pitkin County's "List B" Noxious Weeds Designated for Suppression (continued).
Quackgrass (Elytrigia repens)
Description:
Quackgrass is a perennial weed in Colorado, and a troublesome weed to eliminate from the home
landscape. The Latin name means a "sudden fire", and attests to its ability to take over lawns,
fields and gardens. Quackgrass is native to Europe. It has been growing in the U.S. for over 200
years in all states except Hawaii, Arizona and Florida. Quackgrass is an aggressive perennial
grass with long slender white rhizomes; which have yellowish and sharp -pointed tips. The base
of the leaf blade has claw-like appendages that clasp the stem. Spike -lets up to 6 inches long are
in 2 long rows born flat -wise to the stem easily regenerated from very small broken rhizome
fragments making mechanical control difficult.
Comments:
The auricles of this weed help to immediately distinguish it
from most other grass weeds, however tall fescue (Festuca
arundinacea), annual ryegrass (Lolium multi�lorum), and
perennial ryegrass (Lolium perenne) are similar grass weeds
that also have auricles. However, none of these grass weeds
have rhizomes like quackgrass.
Biological control:
None are available to date.
Chemical control:
Herbicides are important for quackgrass management, but use
them in combination with other control methods. Timely
glyphosate application during a fallow period in early spring or
fall can provide effective control of quackgrass.
Cultural control:
Mowing or cultivation effectiveness will be increased if other
plants like perennial native grasses or alfalfa are seeded in the
quackgrass stands as competitors. Maintain range and pasture in
good condition. Promote healthy grass growth through proper
irrigation and fertilization. Do not overgraze.
Mechanical control:
Mowing, plowing, and disking are some commonly used mechanical control methods in
agronomic crops. Vigorous tillage before or after an effective herbicide treatment provides good
control of quackgrass.
III
q
Pitkin County's "List B" Noxious Weeds Designated for Suppression (continued).
Scentless Chamomile (Matricaria perforata)
Description:
Scentless chamomile is a member of the Aster family that was imported from Europe as an
ornamental and now grows worldwide. It is an annual that grows 1/2 to 2 feet tall in a bushy
shape with showy white flowers. It is nearly identical in appearance to the strong scented
species, but can be easily distinguished by its lack of odor.
Comments:
The plant has become widely established in Pitkin
County. Scentless chamomile has no forage value and
can cause blistering of muzzles, and skin rashes. This
weed is very common along the Hwy -82 corridor and
throughout the City of Aspen and Town of Snowmass
Village.
Biological control:
No known biological controls at this time.
Chemical control:
Several herbicides are effective at label rates. The earlier
the application the more effective the control, herbicide
application is not effective when the majority of the plants
are flowering because seed production has already
occurred. Contact Pitkin County Land Management or a
licensed applicator for recommendations.
Cultural control:
Re -seed disturbed areas with fast growing native grasses.
Mechanical control:
Mowing should occur early and often with successive mowing lower than the previous. Plant
should be cut before the first flowers are fully formed. Scentless chamomile will form new
flowers below the cutting height of the swather or mower. Hand pulling is effective in preventing
the spread into new areas. This method is limited to small infestations. Once plants are pulled,
they should be placed in plastic bags and disposed of properly.
Education:
The key to scentless chamomile management and other escaped ornamentals is to create an
awareness among homeowners, nurseries, landscapers, and landscape architects that scentless
chamomile is a noxious weed and therefore should not be specified in plantings, sold in nurseries
or planted in home gardens or large-scale landscape projects.
40
�� 3
Pitkin County's "List B" Noxious Weeds Designated for Suppression (continued).
Wild caraway (Carom can,i)
Description:
Wild caraway is a member of the Parsley family. It is a
biennial plant, producing a low growing rosette of leaves in its
first year of growth, and then a flowering stalk (bolt) in the
second year. Wild caraway can even bolt and flower a third
year before dying. It develops a narrow taproot and grows in a
wide range of soil types. Bolting plants can tolerate some
spring flooding and seedlings can survive light frost. Stems are
erect, branched, and grow 11/2 to 3 feet tall. There can be
several stems per plant. The leaves are alternate and very
finely divided (carrot -like). The leaves of the first-year
rosettes can be very similar to yarrow, a native plant. The
flowers of wild caraway are white, but occasionally pinkish,
and occur in groups at the top of stems.
Comments:
Wild caraway is grown in Canada as a spice crop; however it
has escaped cultivation and has been invading pastures,
rangeland and natural areas for several years now. This plant
is prolific in Pitkin County. Small infestations have been
noticed in Maroon Bells Park.
Biological control:
No known biological controls at this time.
Chemical control:
Several herbicides are effective at label rates. The plant is easiest to control in its first year of
growth with a residual herbicide. Once bolting has started, the plant becomes much more difficult
to control.
Cultural control:
Competitive vegetation helps reduce disturbed spaces for invasion.
Mechanical control:
Hand -pulling of bolting stalks is effective at preventing seed production, but at maturity the seed
heads are extremely fragile and shatter easily. At this stage a plastic bag can be carefully placed
over the mature plant, and closed tightly around the stem while hand -pulling. Carefully done, this
method can remove seed without accidentally spreading it, Collected seed should be disposed of
in landfill -bound garbage or thoroughly burned. Mowing is not effective because the plants will
stay short and bloom.
41
Pitkin County's "List C" Noxious Weeds Designated for Eradication.
Chicory (Cichorium intubus L.)
Description:
Chicory is a member of the Sunflower family. It is a native
of the Mediterranean region, but now it is broad-based in the
northern hemisphere. Chicory is a tap -rooted perennial with
milky juice growing to 1 to 6 feet tall; low growing rosette
leaves resemble dandelion but are hairy; blue flowers
(occasionally pink or white) usually close by midday, leaves
are used as a salad and roots when dried are used as a coffee
substitute.
Comments:
Chicory has been identified in the Crystal River Valley of
Pitkin County as well as roadside of Capitol Creek and
Sopris Creek roads.
Biological control:
None known at present time.
Chemical control:
There are several effective herbicides at label rates; best timing is when plants are actively
growing. To provide more complete control, add an agriculture surfactant and/or a drift control
additive for improved deposition.
Cultural control:
Prevent the establishment of new infestations by minimizing disturbances and seed dispersal,
eliminating seed production and maintaining healthy native communities.
Mechanical control:
Chicory may be controlled by mowing, cutting, or pulling plants before seed production. This
process may have to be repeated annually to exhaust nutrient reserves in the roots of the plants as
well as to control seeding plants that emerge from soil seed bank.
Education:
This perennial weed is difficult to eliminate. Because it prefers disturbed areas, the maintenance
of healthy plant communities and revegetation of disturbed areas can help prevent the spread of
chicory. Combine preventive measures with mechanical and chemical control.
42
Pitkin County's "List C" Noxious Weeds Designated for Containment.
Downy Brome (Bromus tectorum)
Description:
Downy brome or cheatgrass is an annual or winter annual introduced from Eurasia that
reproduces by seed. The plants are 4 to 30 inches tall and are covered with soft hairs at all
stages of growth. Mature cheatgrass seedheads, 2 to 6 inches long, contain seed, 318 to 3/4 inch
long. The awns are usually purplish at maturity. Cheatgrass competes with more desirable
perennial grasses for moisture because of its winter and early spring growth habit. After
maturity it becomes a nuisance and fire hazard.
Comments:
Under field conditions, downy brome seeds
germinate in fall, winter and spring. Most seeds
germinate within one year of maturation.
Constant late summer or late fall rains will cause
rapid germination and abundant fall growth.
However, if adequate fall moisture is not
available, downy brome can act like a spring
annual.
Biological control:
Scientists are working on specific bacteria for
biological control, but this is still at the testing
stage.
Chemical control:
Several herbicides are effective at label rates. The
most important factor to consider when initiating
a control program is timing. This weed must be controlled early in the season, prior to seed set,
or late fall.
Cultural control:
Mowing or cultivation effectiveness will be increased if other plants like perennial native grasses
or alfalfa are seeded in the downy brome stands as competitors. Maintain range and pasture in
good condition. Promote healthy grass growth through proper irrigation and fertilization. Do not
overgraze.
Mechanical control:
Neither mowing nor burning are effective controls to prevent seed set. Seed will continue to
mature on cut-off plants. One option is mowing and removing plants from the field. Burning is
not effective, as many of the seeds drop to the ground before the heat can kill them. Early spring
tillage of fallow ground, tillage prior to planting spring -season crops, and tillage operations that
bury downy brome seeds (mold -board plowing) are effective mechanical methods.
43
1-/C�
Pitkin County's "List C" Noxious Weeds Designated for Containment (continued).
Common Burdock (Arctium minus)
Description:
Common burdock is a member of the Aster
family. It is an introduced biennial which
reproduces by seeds. In the first year of growth
the plant forms a rosette; the second year the
plant grows erect. Burdock grows to 6 feet tall,
has enormous leaves and prickly burs. The
flowers are purple and white in numerous
heads. Burdock grows along roadsides, ditch
banks, and in neglected areas.
Comments:
This plant is a very serious threat to sheep as
the burs can significantly damage the quality of
their wool. Common burdock is found
throughout Pitkin County.
Biological control:
None known at present time.
Chemical control:
Several herbicides are effective at label rates.
Adjuvants increase up -take and effectiveness.
Cultural control:
Prevent the establishment of new infestations by minimizing disturbances and seed dispersal,
eliminating seed production and maintaining healthy native communities.
Mechanical control:
Burdock will not stand repeated cultivation, cutting, digging or pulling. Mechanical control is
difficult but effective; properly bag and dispose of mature burs.
Prevention — Learn to identify plants; know your property; beware of fill dirt, hay and seed
from outside your area.
44
Pitkin County's "List C" Noxious Weeds Designated for Containment (continued).
Common Mullein (Verbascum thapsus L)
Description:
Common mullein is a member of the Figwort
family. It was introduced from Europe, but is a
native of Asia. Common mullein is a deep tap -
rooted biennial growing up to 7 feet tall with
large, soft, very hairy leaves; yellow flowers
are borne in large terminal spikes; produces a
large rosette up to 2 feet in diameter the first
year. Dipped in tallow, mature stalks made
good torches in ancient times; called "witch's -
stick".
Comments:
It can be found throughout Pitkin County
along dried-up river bottoms, pastures,
meadows, fencerows and disturbed areas. It is
especially prevalent on gravelly soils.
Biological control:
None present and no current research.
Chemical control:
A few are effective but only if combined with
a surfactant to aid in penetration past the hairs.
Cultural control:
Good vegetative cover and management are the best means to avoid proliferation of mullein.
Mechanical:
It will not stand tillage. Pulling or cutting below root crown when the soil is damp is effective if
done prior to seed production.
45
y
Pitkin County's "List C" Noxious Weeds Designated for Containment (continued).
Field Bindweed (Convolvulus arvensis L.)
Description:
Field bindweed is a member of the Morning-glory family. This creeping perennial was
introduced from Europe. It reproduces by seed and horizontal roots. The stems are smooth,
slender, slightly angled, I to 4 feet long, and spread thickly over the ground or wind around
erect plants or other objects. The leaves are alternate, 1 to 2 inches long with great variation in
shape. They are somewhat arrow shaped with spreading, pointed, or blunt lobes at the base.
The flowers are white or pink bell shaped about 1/4 to I inch broad. Field bindweed is one of the
most competitive perennial weeds in Colorado. A two or three year food supply is stored in the
root system, making this plant very difficult to kill, Seeds can stay viable in the soil for up to
40 years. This plant is also poisonous to horses.
Comments:
Control by means other than herbicides is
difficult. It is best to eliminate young
bindweed plants before they have a chance to
develop their extensive root system. The
biggest threat posed by field bindweed in
Pitkin County is to hay producers who are
trying to have their hay certified as weed free.
Biological control:
No known biological control.
Chemical control:
Several effective at label rates but usually
requires repeat treatment to kill extensive root
systems.
Cultural control:
Good vegetative cover helps but does not
prevent establishment or spread of field
bindweed.
Mechanical control:
Cultivation will chop up the root system and spread it more rapidly.
46
Pitkin County's "List C" Noxious Weeds Designated for Containment (continued).
Poison Hemlock (Conium maculatum)
Description:
Poison hemlock is a member of the Parsnip family, It
is a biennial introduced from Europe that may grow up
to 9 feet tall. This plant, with a fleshy stout taproot,
forms a rosette of fern like, pinnately divided leaves
during the first year of growth. Stems of poison
hemlock have purple spots at all growth stages. The
white flowers are borne in umbrella shaped clusters,
each supported by a stalk. All plant parts are
extremely poisonous to humans and most domestic
livestock. Children have been poisoned by using the
hollow stem as a whistle. Adults have been poisoned
by mistaking this plant as parsley.
Comments:
One of the most widespread weeds in Pitkin County. Common in East and West Sopris Creek,
Prince Creek, Watson Divide, Woody Creek, and Lenado. The entire plant is toxic to humans and
animals. The plants contain the intensely poisonous alkaloid coniine and other related alkaloids.
Most poisonings occur because the leaves are mistaken for parsley, the roots for parsnips, or the
seeds for anise. The plant has such an unpleasant taste and odor that toxic quantities are seldom
consumed. If not lethal, recovery occurs within a few days. Symptoms of poisoning are a burning
sensation in the mouth and throat, nervousness, trembling, un -coordination of the body
movements, dilation of pupils, muscular weakness, coldness of extremities, weakened and
slowed heartbeat, convulsions, and coma. Death occurs through respiratory paralysis. There was
a case of hemlock ingestion by local school children a few years ago. One of their teachers told
the children that the plant was a wild carrot and that they could blow on it like a whistle. They
did and subsequently took ill. The local hospital called our staff to verify that the plant was
hemlock (it was). The hospital prescribed an antidote and the children recovered.
Biological control:
The poison hemlock moth has been a very effective defoliator of Poison hemlock plants where
introduced on large infestations.
Chemical control;
Several herbicides are effective at label rates, but care must be given near water.
Cultural control:
Good vegetative cover lessens likelihood of initial infestations of poison hemlock.
Mechanical control:
Tillage, digging and pulling are all effective controls but care must be used in handling.
47 _ „
Section V
Native thistles in Pitkin County
You've learned about how bad some thistles can be for our environment. You're primed and
ready to pull or spray. Good for you! But before you target all thistles, remember that there are
20 native thistle species in Colorado, and these play an important role for wildlife. Native
thistles should not be killed, because they are not noxious weeds.
How do you tell a native thistle from a noxious thistle?
Generally, if the stand of thistles is very dense or very tall (6'), it is usually noxious.
If you are above timberline and see a thistle, it's probably native.
Native thistles tend to be shorter, and are often found as individual plants or in very small groups
of 2-4 plants.
A thistle with a white or yellow flower (the FLOWER, not the fluffy dandelion -like seeds), is
probably native.
Pictures of native thistles in Pitkin County
American Thistle Cirsium centaurae - native
American thistle is a perennial, growing to 3 feet tall, in
colonies, with erect, reddish, cobwebby stems. Flowering time is
June to August. Flower heads are 1 '/2 inches high, without ray
flowers. Disk flowers are white to tannish, with purple stripes;
bracts are spine -tipped, with lattice-like hairs. Leaves are deeply
incised, whitish and hairy beneath, and spiny.
Note reddish stem and whitish brown flowers for distinctions
from noxious thistles.
American thistle are commonly found in ravines and forest
openings, and on rocky slopes and banks.
Frosty Ball Thistle Cirsium scoPularum — native
Perennial growing to 2 feet tall. The flowers are hermaphrodite
(have both male and female organs) and are pollinated by bees,
flies, Lepidoptera (Moths & Butterflies) and beetles. The plant is
self -fertile. The plant prefers light (sandy), medium (loamy) and
heavy (clay) soils. The plant prefers acid, neutral and basic
(alkaline) soils. It cannot grow in the shade. It requires moist
soil.
Look for Frosty Ball in sunny areas in meadows, slopes, and
along roadways or trails.
IF
Meadow Thistle or Elk Thistle Cirsium scariousum - native
This thistle can either be stemless, or have a short stem.
Characteristics: A fairly easy thistle to identify in that it is
frequently without stems. Stems are generally very short and
thick, with the flower heads sessile. Flowers are white to a pale
pink -purple. The leaves are spiny, but entire to somewhat
scalloped. Elk thistle flowers from June into August.
Habitat: Meadows and other moist places from the foothills to
10,500 feet.
Creamy Thistle or Prairie Thistle Cirsium canescens -
native
Creamy thistle is a perennial growing to 3 feet tall, with a
stout, branched, cobwebby stem. Creamy thistle flowers
from July to September. Flower heads are 1 '/4 inch high,
with creamy white disk flowers and no ray flowers. Leaves
are up to 8 inches long, bright green on top and whitish
beneath, extending down the stem, with spines of varying
lengths on the margins. This thistle is a much lighter pink (or
even white), so it is easy to distinguish from musk thistle.
Parry's Thistle Cirsium parryi - native
Parry's thistle grows from the foothills to 10,500 feet tall.
Habitat for parry's thistle is moist meadows and stream
sides. Flowers bloom from mid July to August. Flowers are
greenish -yellow to yellow. Outer leaves are straight with
terminal spines and spiny margins. Involucres with long
hairs, appearing cob -webby.
Ez
Section VI
The threat of Escaped Ornamentals
Most plants used for landscaping purposes lack the ability to proliferate outside of the
cultivated environment of the home garden. Yet certain exotic plants and seeds were imported
to the United States for their aggressive growth habits, xeriscape potential, or re -seeding
capabilities. Such plants are known as escaped ornamentals or invasive ornamentals, and
include dame's rocket, common tansy, Mediterranean sage, oxeye daisy, purple loosestrife,
scentless chamomile and toadflax. The very traits which make these plants desirable for a
garden or landscape may also enable them to thrive outside cultivated areas and become fierce
competitors with our native vegetation. Because they exist here without the presence of any
natural predators, these plants have the ability to spread extensively and pose a severe threat to
the delicate balance of our native ecosystems.
Since various invasive ornamental plants are attractive and establish themselves quickly, they
are popular with landscapers and gardeners and may be purchased through certain nurseries in
the Roaring Fork Valley. It is imperative that we educate landscape architects, gardeners, and
nursery growers about the need to eliminate such plants from their landscape plans. Otherwise
these plants will inevitably escape from the cultivated garden and jeopardize the natural
wildflower and plant communities that we cherish. Native wildflowers such as Colorado Blue
Columbine, our state flower, cannot compete with invasive ornamental plants for nutrients,
sunlight, and water. As a result, our biologically diverse mountain meadows, grasslands, and
wetlands are in danger of being overrun by non-native invasive ornamental plants.
Native stand of wildflowers with a small
population of oxeye daisy.
Same site two years later
50
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Section VII
Jurisdictional overview of areas in Pitkin County
7.01 Overview
This section will provide the casual observer with a thumbnail sketch of the current status of
noxious weed infestations in Pitkin County. This section, in general terms, will discuss county
lands, state and federal lands, municipalities, and private lands.
The County has adopted an "early detection, early treatment" philosophy. Early detection is
identifying and documenting newly introduced weed species into an area. Early treatment is the
follow-up that could possibly eradicate new infestations.
This section will serve as a reference point for "early detection, early treatment" and will
emphasize areas that have new emerging infestations of weed species.
7.02 County Land
County property is categorized by: Roads, Airport, Solid Waste Center, Open Space and Trails
and County grounds.
Roads:
Pitkin County has about 300 miles of county roads. It has been the County's philosophy to
minimize the use of herbicides, and thus the impacts on desirable vegetation, by selectively
spot treating noxious weeds with a handgun from a truck -mounted spray unit. There will be no
general herbicide applications to non -listed weeds unless specifically requested by the Road
and Bridge Supervisor, or the Board of County Commissioners, to treat a roadside for safety
and sight reasons. Roadside weed treatment starts every year on the roads located in the
northwestern portion of the county where the elevations are lower and the growing season
starts earlier. Generally treatment in these areas is in late April or early May. Each county
maintained roadside will be treated at least once. Heavily infested roadsides or roadsides that
require unique control measures will be treated a second or third time.
Airport:
The airport consists of about 250 acres of treatable land, which has undergone extensive
expansion since 2002. Because of the disturbances to the soil, widespread weed control is
required. The primary weeds at the airport are plumeless and Canada thistle, houndstongue, and
oxeye daisy. There have been two outbreaks of leafy spurge, one on the northeast side next to
the ARF building and the other on the southwest side next to the access gate. Russian
knapweed has also been treated along the lower portion of Radar Road.
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Solid Waste Center:
The Solid Waste Center consists of about 45 acres of property, with about 20 acres of treatable
land. Weed populations at the Solid Waste Center have been significantly reduced in the last
ten years; however this area continues to be a priority for weed treatment as it is a center of
activity. The primary weeds at the landfill are scentless chamomile, plumeless and Canada
thistle, and common burdock. Leafy spurge also continues to be a problem in parts of the Solid
Waste Center.
Open Space and trails:
The Open Space and Trails program consists of over 2000 acres of property. For the purposes
of the Weed Management Plan, we will not make distinctions between lands managed by Pitkin
County and those managed by Pitkin County Open Space & Trails. For specific management
objectives of Open Space and Trails properties, please contact the Open Space and Trails
Department at 920-5232.
7.03 State Lands
Colorado Department of Transportation:
Since 1991, Pitkin County has had an Intergovernmental Agreement with CDOT to treat
noxious weeds on State Highways 133 and 82. This has been approximately $7,500 per year.
This agreement is on an annual basis and is for the treatment of designated noxious weeds.
State Land Board:
The Colorado State Land Board owns approximately 475 acres of land which comprise most of
Williams Hill between Watson Divide and Old Snowmass.
SH -82:
There are 55 miles of State Highway 82 in Pitkin County, which are estimated to be 10%
infested. This is a reduction from the estimates in the 1987 Pitkin County Weed Control
Manual, which put the infested percentage at 50%. The major weeds on Hwy 82 are as follows:
Plumeless thistle, Canada thistle, common mullein, field bindweed, downy brome, common
burdock, scentless chamomile, houndstongue, common tansy, and oxeye daisy. Russian
knapweed has also been treated up Independence Pass.
SH -133:
The 20 miles of State Highway 133 in Pitkin County are estimated to be 15% infested. Musk
thistle is the dominant weed along Hwy 133. Plumeless and Canada thistle are beginning to
infest areas of SH -133. In any given year there are six to ten patches of Russian knapweed
found along Hwy 133. These knapweed patches should be continually monitored and treated on
an as -needed basis. Oxeye daisy, yellow toadflax, and common tansy are becoming a problem
along Hwy 133 from Redstone to the Marble road.
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7.04 Federal Lands
White River National Forest:
The US Forest Service has extensively mapped and inventoried its land in Pitkin County. That
information is available through the White River National Forest or the Pitkin County Land
Manager's office.
Bureau of Land Management:
The Bureau of Land Management has been mapping infestations of Canada thistle, plumeless
thistle and houndstongue in the Prince Creek drainage and the Crown area. Insects were
released as many as 10 years ago on Canada thistle in the Prince Creek enclosure. The release
had little noticeable result, mainly due to low survival success of the biological agents. The
weed infestation in the area is moderate and management efforts should continue. The BLM
has had more funding for its weed management program in past years and expects it to
continue at the higher level into the near future.
Bureau of Reclamation:
Official surveys have not been done at this time, however reports indicate that over 60 acres of
USFS(Bureau of Reclamation land are infested with plumeless thistle.
7.05 Municipalities
City Of Aspen:
County Land Management staff mapped and inventoried city trails in 1998. This information is
recorded in the County Assessor's Global Information System (GIS). Responsibility for
noxious weed management within the city of Aspen falls under the jurisdiction of the Aspen
Parks Department. The Parks Department has had a treatment program in place for the past ten
years on its parks and Open Space and Trails lands. The Department has managed to
significantly reduce thistle populations on its property in the last five years. The escaped
ornamentals (common tansy, chamomile, yellow toadflax, myrtle spurge and oxeye daisy) are
rapidly becoming a problem on city -owned property.
Town of Snowmass Village Public Works:
The Town coordinates noxious weed programs within the town limits. They have been fairly
aggressive in treating plumeless thistle on major thoroughfares within the town in the past five
years. Poison hemlock remains a problem around the perimeter of the golf course and along
upper Brush Creek. Several new noxious weed species have been found in Snowmass Village
in the past few years, which include yellow toadflax, hoary cress, Russian knapweed, myrtle
spurge and chicory. These infestations should be treated and closely monitored before they
become too large to control.
The new golf course, base village, and any new construction areas should also be closely
monitored for the introduction of noxious weeds. Weed enforcement on private lands within
town limits should also be a priority.
53
Town of Basalt:
Basalt is located in both Pitkin and Eagle counties. It is recommended that Basalt adopt both
counties' noxious weed lists. Most noxious weed issues are addressed by the Town's Public
Works Department. The most common weeds in Basalt are plumeless thistle, common tansy
and oxeye daisy. Musk and plumeless thistle are both prevalent along the Frying Pan. Other
weeds to watch for in the Basalt include both myrtle and leafy spurge. Both of which are highly
invasive and controlled immediately.
Intentional planting of invasive ornamentals and weed enforcement on private lands within
town limits are should be a priority.
PITKIN COUNTY, ASPEN, SNOWMASS VILLAGE, AND BASALT NEED TO HAVE
DESIGNATED DEPARTMENTS WITHIN THEIR JURISDICTIONS TO DEAL WITH THE
WEED ENFORCEMENT ISSUE
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Section VIII
Enforcement
8.01 Noxious Weed Management Enforcement Policy
The policy shall be known as and referred to as the "Pitkin County Noxious Weed Management
Enforcement Policy" and shall be effective throughout unincorporated areas of Pitkin County.
8.02 Purpose of Policy
The Colorado Noxious Weed Act, §§35-5.5-101, et seq., C.R.S., (hereinafter "the Act") states
that certain noxious weeds pose a threat to the continued economic and environmental value of
the land in Colorado; and that they must be managed by all landowners in the State. The Act
states that local governments are directed to take the necessary steps to manage the noxious
weeds in their respective jurisdictions. As a result, Pitkin County established a Noxious Weed
Advisory Board and a Weed Management Enforcement Policy.
8.03 Noxious Weeds deemed a public nuisance
Pursuant to § 35-5.5-113, C.R.S., the noxious weeds listed in section 11 of this plan, at any and all
stages are declared to be public nuisances and, in addition to the remedies contained in the Pitkin
County Weed Management Plan, are subject to all of the laws and remedies relating to the
prevention and abatement of nuisances, including, but not limited to, those set forth in Section
35-5.5-113, C.R.S.
8.04 Authorized agent for enforcement
Pursuant to Section 35-5.5-105(2), C.R.S., The Public Works Land Manager and his or her
employees and agents, are hereby designated "authorized agents" to enforce the Noxious Weed
Management Enforcement Policy in unincorporated areas of the County, by utilizing those
procedures set forth in Section 35-5.5-108,-108.5,-109, and -110, C.R.S., and any other
applicable state and federal statutes, rules, regulations and ordinances, including the remaining
provisions of this chapter.
55
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8.05 Methods of identification and inspection
A. In all actions taken to administer and enforce this plan, an authorized agent shall adhere to
the procedures set forth in 35-5.5-108, -108.54, -109, and -110, C.R.S. The following are
intended to assist in complying with the statutory procedures.
B. If permission to enter is granted by the affected landowner, an may upon any premises,
lands, or places, whether public or private, during reasonable business hours, for the
purpose of inspecting for the existence of noxious weed infestations when at least one of
the following events has occurred:
1. The landowner or occupant has requested an inspection;
2. A neighboring landowner or occupant has reported a suspected noxious weed
infestation and requested an inspection; or
3. The authorized agent has made a visual inspection from the public right-of-
way or
other area and has reason to believe that a noxious weed infestation exists
8.06 Notice to control identified noxious weeds
The authorized agent has the authority to notify a landowner or occupant of such lands of the
presence of noxious weeds ("Notice to Control Identified Noxious Weeds'). Such notice shall be
by certified mail, and shall include the following:
1. The name(s) and address(es) of the landowner or occupant;
2. The property's Assessors Office Parcel # and legal description:
3. The noxious weeds to be managed;
4. Advisement to the landowner or occupant to manage the noxious weeds within
ten (10) days of mailing the notice;
5. The best available control methods of integrated management;
6. The options of notice compliance;
7. The consequences for non-compliance; and
8. A statement that the authorized agent will seek a warrant from a court of
competent jurisdiction to enter the property and manage identified noxious
weeds unless the landowner/occupant complies with the notice, or submits a
written weed management plan with an acceptable completion date, or
requests an arbitration panel develop a weed management plan pursuant to
Section 35-5.5-109 (4) (a) (111) and (4) (b).
brx
8.07 Right of entry
Prior to entering private lands for the purpose of enforcing the notice, the authorized agent shall
first obtain a warrant from a court of competent jurisdiction, no less than ten (10) days after a
Notice to Control Identified Noxious Weed has been sent to the landowner or occupant of the
private lands and said owner or occupant has failed to comply with said notice.
8.08 Right to assess whole cost of management
The authorized agent shall assess the whole cost of such enforcement, including up to twenty
percent (20%) for inspection and other incidental costs in connection therewith, upon the tract of
land where the noxious weeds are located. Notice of such assessment shall be mailed to the
landowner or occupant by certified mail. Failure to receive notice of assessment shall not act as a
defense to such assessment.
8.09 Failure to pay assessment
Any assessment which is not paid within thirty-three (33) days after the date of mailing by
certified mail to the landowner or occupant of private lands upon which the authorized agent has
performed enforcement work, shall constitute a lien against each lot or tract of land until paid and
may be certified by resolution of the Board of County Commissioners to the County Treasurer to
be collected in the same manner as provided for collection of taxes upon private lands in
accordance with Section 35-5.5-109 (5) (a), C.R.S.
8.10 Liability
This Chapter shall not be intended to create a civil cause of action against the Board of County
Commissioners of Pitkin County, or any other person that administer this chapter in any manner.
8.11 Code Authority
Private Lands: Per §35-5.5-108.5 and 109 C.R.S. and 8 CCR 1203-19
Public lands: Per §35-5,5-110 C.R.S.
Public Rights-of-way: Per §35-5.5-112 C.R.S.
57
Section IX
Priorities
Awareness, Education and Training: Education is pivotal to the sustained success of this weed
management plan. Most weed species, if detected early, can be managed. Groups targeted for
noxious weed education include those with agricultural interests, homeowners associations, the
green industry, developers, recreational groups, environmental and open space land management
non-profit organizations, youth groups and schools. This instruction will be coordinated by the
authorized agent.
Integrated Control: Carry out weed control practices on Pitkin County owned lands and rights-of-
way.
Surveying and Mapping: In a continuing effort to manage noxious weeds with sound strategy,
existing noxious weed inventories will be compared to new mapping data. These data will
encompass County, State and Federal properties, as well as major rights-of-way that are not
county maintained and private lands.
Private lands will be included after permission has been granted by the owner or occupant.
Intergovernmental Agreements: Formal cooperative agreements will he sought between Pitkin
County, federal and state landowners, and local governments to facilitate a coordinated regional
effort in managing the noxious weeds listed in this document.
Partner with environmental non-profit organizations and private landowners.
Prevention and Early Detection: Prevent establishment of new noxious weeds and manage
existing noxious weed populations to prevent spread to previously un -infested areas.
Section X
Rules, Regulations and Policies
All land use request files shall include mitigation measures consistent with the requirements of
this plan; these measures are to be included within the Land Management plan section, when
noxious weed species are inventoried.
Mitigation measures should be prepared by an expert in the discipline of integrated Land
Management. Recommendations for chemical control should meet the requirements of the
"Pesticide Applicators' Act" §§35 -1Q-101 et seq. C.R.S. and the "Rules and Regulations
Pertaining to the Administration and Enforcement of the Pesticide Applicators' Act. "
The district's authorized agent shall review land use request files with noxious weed mitigation
measures.
58 (^
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District issued building permits that regulate the removal and subsequent revegetation of the
surface vegetation community that cover areas larger than .75 Acres (32,670 square feet) shall
require the permit applicant to implement noxious weed mitigation measures consistent with the
district's weed management plan.
In all instances the local governing authority shall be solely responsible for its permitting process
and oversight.
In instances it has been determined that Pitkin County issued building permit holders are not
performing noxious weed mitigation measures consistent with state law or the district's weed
management plan this non-compliance shall be communicated to the district's authorized agent.
Lands destined for Pitkin County Open Space and Trails fund expenditures shall be inventoried
for noxious weeds. This inventory shall be provided to and reviewed by the district's authorized
agent.
Lands with noxious weed populations can be considered for funding, provided the landowner
develops and implements an approved weed management plan.
The weed management plan shall be reviewed by the authorized agent and the Pitkin County
Weed Advisory Board.
The landowner shall provide the authorized agent reasonable access to open space funded
property(s) and upon receipt of open space funding, grants permission to the authorized agent to
collect and display noxious weed inventory data.
59
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Section XI
Plan of Work
12.01 Short Term Goals
• Increase public awareness of the "Colorado Noxious Weed Act" §§ 35-5.5-10 t -I 19
C.R.S.(2004).
• Coordinate the formation of the Pitkin County Cooperative Weed Management Area;
• Enter into intergovernmental agreements with federal agencies, state agencies and
local governing bodies to maximize weed management efforts.
• Enter into cooperative agreements or contracts with non-governmental organizations
interested in environmental protection in regard to noxious weed management.
• Encourage the implementation of noxious weed control activities on all
infested
acreage within the district.
• Educate district residents by coordinating workshops, scheduling landowner
consultations, maintaining an internet web -page, writing press releases for local media
and providing other miscellaneous noxious weed educational materials. Areas of
educational emphasis include but are not limited to:
• Update the existing Noxious Weeds GIS layer and distribute population information
through the Pitkin County website.
• Develop a cooperative spirit within the County's departments which encourages
prevention of noxious weeds through pro -active planning efforts.
12.02 Long Term Goals
• Manage existing infested acreage aggressively to prevent spread and reduce
population
density.
• Develop and implement revegetation guidelines in cooperation with other district
entities.
• Implement control activities for noxious weed species that are new to the district
through education and quick response.
• Survey the district for noxious weed species and expand the Noxious Weeds GIS
layer
60
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to encompass federal, state, county, municipal and private land holdings.
• Conduct biological control releases, when appropriate, throughout the district.
• Work with municipal authorities to put into practice a comprehensive weed
management program for all lands within the boundaries of the district.
• Coordinate the formation of the Pitkin County Cooperative Weed Management Area;
• Enter into intergovernmental agreements with federal agencies, state agencies and
local governing bodies to maximize weed management efforts.
• Enter into cooperative agreements or contracts with non-governmental organizations
interested in environmental protection in regards to noxious weed management.
• Meet the State mandate for plumeless thistle eradication zone.
Section XII
Prior Acts Validated
All prior actions of the BOCC, the Pitkin County Weed Advisory Board, and the
authorized agent in accordance and consistent with this plan are declared to be valid and
ratified.
Section XIII
Repeal of Conflicting Provisions
All former County ordinances, resolutions, rules or regulations or parts thereof, in
conflict with this plan are hereby repealed.
61 G CI
Section XIV
Resource Directory
(Government Agencies)
Bureau of Land Management
Glennwood Springs Resource Area
PO Box 1009
Glenwood Springs, CO 81602
(970) 947-2800
City of Aspen Parks Department
130 S. Galena
Aspen, CO 81611
(970) 920-5120
Colorado Department of Agriculture
Eric Lane, State Weed Coordinator
700 Kipling St., Suite 4000
Lakewood, CO 80215-5894
(303)239-4182
E -Mail: Eric.Laneta�as.state co.us
Colorado Department of Transportation
Region 3 Maintenance Section No. 2
222S.6 1h St., Room 317
Grand Junction, CO 81501
(970) 248-7361
Colorado State University
Department of Weed Science and Pest Mgmt.
(970) 491-7568
Colorado Weed Management Assoc.
PO Box 1910
Granby, CO 80446-1910
(970) 887-1228
E -Mail: cwma 7rkymtnhi.com
Department of Agriculture Insectary
Service
PO Box 400
Palisade, CO 81526
(970) 464-7916
Eagle County Weed Department
PO Box 239
Eagle, County CO 81631
(970)328-3544
Garfield County Land Management
PO Box 1112
Rifle, CO 81650
(970) 625-8601
Pitkin County Land Management
76 Service Center Road
Aspen, CO 81611
(970) 920-5214
E -Mail: iiml@co.pitkin.co.us
Town of Basalt Public Works
101 Midland Ave.
Basalt, CO 81621
(970) 927-4723
Town of Snowmass Village
PO Box 5050
Snowmass Village, CO 81615
(970) 923-5524
White River National Forest
PO Box 309
Carbondale, CO 81623
(970)963-2266
Natural Resource Conservation
Glenwood Springs, CO 81602
(970) 945-5494
62 (_
Resource Directory
(Help from the Web)
Colorado Weed Management Assoc.
http://www.cwma.ore
National Wildlife Federation
http://www.nwf.org
National Pesticide Telecommunications
http://Nvww.nntnkace. orst. edu
North American Weed Management Association
httO://www.n4w111a org
USDA APHIS Noxious Weed Home Page
http://Www.ai3his.usda.pov/r)i)ci/weeds/weedhome.html
NPS Alien Plant Invaders of Natural Areas
http://www.nDs.Qov/Diants/alien/moreinfo.htm]
Bureau of Land Management
httn://www.bim.gov.Jeducation.html
National Invasive Species Council
http://www.invasivesl2ecies.gov
EPA Pesticide Safety Programs
http://www.gpa.cov/pesticides/safetv/
Western Society of Weed Science
http://www.wsweedscience.org
Pitkin County Land Management
http://www.aspenpitkin.com/dents/65/veg_mgmtWgez to com
63
Section XV
Definitions
1. Act -The Colorado Noxious Weed Act, Title 35 C.R.S., Article 5.5 as amended
2. Adjacent -Having a common boundary that meets or touches at some point.
3. Aggressive -Fast growing, tending to spread quickly.
4. Agriculture -Uses involving the cultivation of land, production of crops, and/or the
keeping of livestock and the preparation of these products for man's use and disposal.
5. Alien Plant -A plant species that is not indigenous to the State of Colorado.
6. Annual -A plant which lasts one growing season, completing it's life cycle from seed
to seed in one year.
Biennial -A plant which lives in two calendar years. The first year is usually a
vegetative form, such as a rosette of leaves. The second year the plant grows a
flowering shoot, sets seeds and dies.
8. Biological Management -The use of organisms to disrupt the growth of noxious
weeds.
4. Bolt -To flower or produce seeds prematurely or develop a flowering stem from a
rosette.
10. BOCC- Board of County Commissioners.
11. Bract -A reduced or modified leaf often surrounding the base of a flower.
12. Browse -Tender shoots, twigs, and leaves of trees and shrubs fit for food for
wildlife.
13. Chemical Management -The use of agents or plant growth regulators to disrupt or
inhibit the growth of noxious weeds.
14. Commissioners -Refers to the Pitkin County Board of Commissioners.
64
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15. Containment- The creation and enforcement of appropriate containment perimeters
via:
1. Eradication of plants on the exterior of the infestation's designated
perimeter; and
2. Eradication of plants within the boundaries of the perimeter along
vector corridors (e.g., roads, streams, trails) that may facilitate
spread of the infestation beyond the perimeter.
16. County -The unincorporated areas of Pitkin County.
17. Cultural Management -Methods or management practices which favor the growth of
desirable plants over noxious weeds, including maintaining optimum fertility and
plant moisture status in an area, planting at optimum density and spatial arrangement
in an area, and planting species most suited to a particular area.
18. Designated Noxious Weed -A non-native, invasive plant or plant parts that is identified
as a threat to native plant communities and included on the Pitkin County Noxious
Weed list.
19. Desirable Plants -Plants considered to be advantageous and beneficial to the
environmental viability of the county.
20. Eradication- The implementation of a short-term but intensive control effort (often 3-
10 years depending upon seed longevity and recruitment of the target species) to
eliminate a targeted infestation permanently from a given area.
21. Escaped Ornamental -A plant originally intended for horticultural or landscape
situations that has escaped its intended boundaries.
22. Exotic Plant -A plant that is not a regular member of the native or natural community
in which it is found.
23. Forb-A broad -leafed, non -woody plant other than grass that dies back to the ground
after each growing season.
24. Fora e -Food for animals, especially when taken by browsing or grazing.
25. Glyphosate- Active ingredient of herbicides such as ROUND -UP
26. Herbaceous - Applies to plants of soft texture whose stems die back to the ground
after each growing season; Green and leaf like, not woody.
27. Infestation -To have overrun or inhabit so as to be harmful or bothersome.
• Heavy Infestation -Dense, 25-100 percent canopy cover.
• Moderate Infestation -Widely scattered plants, 5-25 percent canopy cover.
• Light Infestation -Occasional plant per acre, less than 5 percent canopy cover.
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28. Integrated Management -The planning and implementation of a coordinated program
utilizing a variety of methods for managing noxious weeds, the purpose of which is to
achieve desirable plant communities. Such methods may include but are not limited to
education, preventive measures, good stewardship and biological, cultural, herbicide
and mechanical management.
29. Invasive -An aggressive plant capable of invading a plant community and creating a
monoculture.
30. Invasive Ornamental -A plant originally intended for horticultural or landscape
situations that has escaped its intended boundaries and is capable of invading a plant
community and creating a monoculture.
31. Involucre bracts- A circle or cluster of bracts at the base of the flower -cluster.
32. Landowner -Any owner of record of state, municipal or private property including an
owner of any easement, right-of-way, or estate within the county.
33. "ListB" management plan saecies- A "list B" species designated by the State for
eradication.
34. Lobe -A division or segment of a leaf or other plant part, especially a rounded one.
35. Local Noxious Weed -Any plant of local importance which has been declared an
invasive or undesirable plant by the Pitkin County Weed Advisory Board.
36. Management -Any activity that prevents a plant from establishing, reproducing, or
dispersing itself.
37. Management Plan- A plan developed by the local Weed Advisory Board and
implemented by the Board of County Commissioners in order to, control the spread of
noxious weeds.
38. Mechanical Management -Methods or management practices that physically disrupt
plant growth including tilling, mowing, burning, flooding, mulching, hand -pulling,
shoveling, hoeing and chopping.
39. Monocarpicperennial- A perennial plant which flowers and bears fruit only once.
40. Monoculture -A single homogeneous crop without diversity or dissension.
41. Native Plant -A plant species that is indigenous to a particular locale.
42. Nei hg boring -Any property located within a one-half mile radius of the boundary of a
subject property.
66 I C
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43. Noxious Weed -An alien plant or parts of an alien plant that has been designated as
being invasive and undesirable and has been declared a noxious weed by the County
Weed Advisory Board and meets one or more of the following criteria:
a) aggressively invades or is physically destructive to economic crops or native
plant communities;
b) is detrimental directly or indirectly to the environmentally sound management of
natural or agricultural ecosystems;
c) is poisonous to livestock;
d) is a carrier of detrimental insects, diseases or parasites.
44. Noxious Weed Management-The_planning and implementation of an
integratedprogram to manage undesirable or problematic plant species.
45. Ornamental -A decorative, aggressive, non-native plant often sold through nurseries or
spread through seed collection; a threat to native plant species because it has no natural
predators and thus competes against the plants of the natural ecosystem.
46. Perennial -A plant that grows for three years or more. Usually flowering and producing
fruit each year. The above ground part of the plant may die, but new growth comes from
the roots or the crown each spring.
47. Petiole -A slender stem that supports the blade of a foliage leaf.
48. Pinnately lobed- Having veins, lobes, or divisions in the form of feather.
49. Pitkin County Weed Advisory Board - A group of individuals appointed by the Board
of County Commissioners of Pitkin County to advise on matters of management of
noxious weeds.
50. Rhizome -An elongated subterranean plant stem that produces shoots above and roots
below, and is distinguished from a true root in possessing buds, nodes and scale -like
leaves.
51. Rosette -A cluster of closely crowded leaves in a compact circle, usually at ground
level.
52. Sessile- Lacking a stalk.
53. State Noxious Weed -Any weed identified by the commissioner of the State of
Colorado Department of Agriculture after surveying the Local Weed Advisory
boards and prioritizing the top ten problematic plants. Said survey is to be conducted
every three years.
54. State Weed Commission- Commissioner of noxious/invasive weeds at the State level.
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55. Subject Lands -All public and private lands within unincorporated Pitkin County with
the exception of:
a) any municipal property owned or leased to an incorporated
municipality;
b) any land managed or administered by a federal agency.
56. Suppression- The use of a wide variety of weed management techniques that reduce
the density and severity of infestations within the boundaries of containment
perimeters in order to mitigate the harm to agriculture, the environment and other
values caused by widespread and well-established populations of noxious weeds.
57. Surfactant -A compound that improves the emulsifying, dispersing, spreading, wetting,
or other surface modifying properties of liquids.
58. WAB- Weed Advisory Board.
59. Weed Inspector-The_agent or employee appointed to conduct the duties and functions
as defined under this plan.
60. Weed Office -The office of the Weed Inspector out of which all noxious weed
administration and enforcement activities are conducted.
61. Wildflower -The flower of a wild or uncultivated plant or the plant bearing it.
M
Notes
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