HomeMy WebLinkAbout960412 ORDINANCE NO. 169-A
IN THE MATTER OF REPEALING AND REENACTING ORDINANCE NO. 169, THE UNDESIRABLE
PLANT MANAGEMENT PLAN FOR THE COUNTY OF WELD, STATE OF COLORADO
BE IT ORDAINED BY THE BOARD OF COUNTY COMMISSIONERS OF THE COUNTY OF WELD,
STATE OF COLORADO:
WHEREAS, the Board of County Commissioners of the County of Weld, State of Colorado,
pursuant to Colorado statute and the Weld County Home Rule Charter, is vested with the authority
of administering the affairs of the County of Weld, State of Colorado, and
WHEREAS, on May 4, 1992, the Board of County Commissioners adopted Weld County
Ordinance 169, which became effective May 12, 1992, and which provides for the adoption and
enforcement of an undesirable plant management plan in Weld County, and
WHEREAS, said Ordinance 169 designates five (5) weed species as undesirable and
mandated for management in Weld County, those being: Leafy Spurge (Euphorbia esula), Russian
Knapweed (Acroptilon repens), Diffuse Knapweed (Centaurea diffuse), Spotted Knapweed
(Centaurea maculosa), Canada Thistle (Cirsium arvense), and Musk Thistle (Carduus nutans), and
WHEREAS, upon the recommendation of the Weld County Undesirable Plant Management
Advisory Board, the Board of County Commissioners hereby finds and determines that there is a
need to add two weed species to the list of those currently designated as undesirable and mandated
for management in Weld County, the two additions being: Field Bindweed (Convolvulus arvensis)
and Scotch Thistle (Onopordum acanthium), thereby requiring, at a minimum, an amendment to said
Ordinance 169, and
WHEREAS, upon further recommendation of the Weld County Undesirable Plant
Management Advisory Board, the Board of County Commissioners hereby finds and determines that
there is a need to make other revisions to the Weld County Undesirable Plant Management Plan,
thereby requiring the repeal and reenactment of said Ordinance 169.
NOW, THEREFORE, BE IT ORDAINED, by the Board of County Commissioners of the
County of Weld, State of Colorado, that Weld County Ordinance Number 169, adopted May 4, 1992,
be, and hereby is, repealed and, by and through this Ordinance 169-A, be, and hereby is, reenacted,
as follows:
ARTICLE 1 —WELD COUNTY
UNDESIRABLE PLANT MANAGEMENT PLAN
I. INTRODUCTION
A. DESCRIPTION OF THE COLORADO UNDESIRABLE PLANT MANAGEMENT ACT
The Colorado Undesirable Plant Management Act, CRS §35-5.5-101, et. seq.,
(hereinafter "the Act") states that certain undesirable plants pose a threat to the
continued economic and environmental value of the land in Colorado and that they
)) ri must be managed by all landowners in the state. The undesirable plants designated
for mandatory management statewide are: Leafy Spurge (Euphorbia esula), Russian
Knapweed (Acroptilon repens), Diffuse Knapweed (Centaurea diffusa) and Spotted
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Knapweed (Centaurea maculosa). Additional weed species may be added to the
state list by each local jurisdiction. The Act states such that local governments (cities
and counties) are directed to take the necessary steps to manage the undesirable
plants in their respective jurisdictions. They are further directed to appoint an
advisory commission whose responsibilities are threefold:
1. Develop recommended management criteria and integrated weed
management plans for managing the designated undesirable plants;
2. Recommend the addition, if necessary, of undesirable plants that shall be
subject to integrated management;
3. Recommend to the county commissioners the names of those landowners
who shall be required to submit integrated weed management plans for
managing the undesirable plants on their property.
The Act further states that by January 1, 1992, each local governing body is to have
developed and adopted an Undesirable Plant Management Plan for all lands within
its jurisdictional boundaries.
II. DESCRIPTION OF THE COUNTY OF WELD WEED PROBLEM
A. WEED SPECIES IN WELD COUNTY TO BE CONTROLLED, PURSUANT TO WEED CONTROL
LAWS
The Pest Control Districts Law (CRS 35-5-104) enabled landowners in each county
the ability, through a lengthy petitioning and balloting process, to establish weed
control districts. Within each weed district, designated species are mandated to be
controlled. In Weld County, nine such weed districts exist. The districts occur in the
lower two-thirds of the County, and the weed species designated for control range
from three to seven species, depending upon the weed district. The weed species
that are currently being managed in at least a part of Weld County are as follows:
Leafy Spurge (Euphorbia esula),
Canada Thistle (Cirsium arvense),
Musk Thistle (Carduus nutans),
Field Bindweed (Convolvolus arvensis),
Whitetop (Cardaria draba),
Russian Knapweed (Acroptilon repens)
Wild Proso Millet (Panicum miliaceum)
Under the Act (CRS§35-5.5-101, et seq.), there are four weed species which are mandated
for county-wide management. They are Leafy Spurge, and Russian, Diffuse and Spotted
Knapweed. Canada Thistle, Musk Thistle, Scotch Thistle and Field Bindweed are added to
the county-wide undesirable plant list by this Ordinance 169-A, in accordance with
CRS §35-5.5-108(3).
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Of the weed species listed previously, Canada Thistle, Field Bindweed, Leafy Spurge, Musk
Thistle, Russian Knapweed, Whitetop and Wild Proso Millet cover the most acreage in Weld
' County and pose the greatest economic and environmental threat to the county. Diffuse
Knapweed is currently localized to a few drainages and rights-of-way in the southwest part
of the County, and there is one known Spotted Knapweed infestation in the County.
III. OBJECTIVES AND GOALS
A. STATEMENT OF OBJECTIVES
The objectives of the Weld County Public Works Department with respect to weed
management in Weld County are fourfold:
1. Develop and carry out a comprehensive noxious weed control program on all
county rights-of-way and other county property, such as in sand and gravel
mining operations, grader shed lots and open space areas.
2. Establish an educational program, by using mailings and holding educational
and calibration seminars, that will effectively communicate weed
management information to the landowners in the County.
3. Identify non-informed or negligent landowners who are not carrying out weed
management programs on their property and provide technical support for
establishing weed management plans or enforce on properties, if necessary.
4. Work with all state and federal agencies, through intergovernmental
agreements, if necessary, towards establishing effective weed management
programs on their property.
B. SHORT TERM GOALS— (January 1995 to December 1998)
1. Map all the County roads for noxious weed infestations.
2. Map on a computer program at least half of the landowners that have Leafy
Spurge, Canada Thistle and Russian Knapweed infestations.
3. Continue to establish contact with landowners on the South Platte and
Poudre Rivers who have noxious weed infestations.
4. Establish educational/calibration seminars (annually) that work directly with
150-200 landowners each year.
5. Have established contact with the Colorado Department of Highways,
Department of Parks and Recreation, Colorado Land Board, Division of
Wildlife and U.S. Forest Service. Help them develop Weed Management
Plans and where appropriate enter into cooperative intergovernmental
agreements.
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6. Have established six to eight biological control release sites throughout the
county in cooperation with the Colorado Department of Agriculture and
private landowners.
7. By 1995, have reduced the noxious weed acreage sprayed on county
rights-of-way by 15-20%.
C. LONG TERM GOALS—(January 1999 to December 2002)
1. Have mapped on the computer program most noxious weed infestations
county-wide, including private, state and federal lands.
2. Have reduced the noxious weed acreage sprayed on county rights-of-way by
40-50%.
3. Have contacted and worked with most landowners county-wide who have a
noxious weed infestation.
4. Have established 30-50 biological control release sites in the county.
IV. PLAN OF WORK - IMPLEMENTATION
A. DESCRIPTION OF INTEGRATED WEED MANAGEMENT TECHNIQUES
The weed species designated as undesirable and mandated for management are
Leafy Spurge (Euphorbia esula), Russian Knapweed ( Acroptilon repens), Diffuse
Knapweed (Centaurea diffuse), Spotted Knapweed (Centaurea maculosa), Canada
Thistle (Cesium arvense) Musk Thistle (Carduus nutans), Scotch Thistle (Onopordum
acanthium) and Field Bindweed (Convolvulus arvensis). Integrated weed
management methods are to be used in managing these weed species
(CRS §35-5.5-107). Integrated management techniques include education;
preventive measures; and control measures including cultural, mechanical, biological
and chemical control. For the purposes of this plan the following definitions for the
control measures will be used.
1. Cultural Control means those methodologies or management practices
conducted to favor the growth of desirable plants over undesirable plants,
including, but not limited to, maintaining an 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 an area.
2. Mechanical Control means those methodologies or management practices
that physically disrupt plant growth, including, but not limited to, tilling,
mowing, burning, flooding, mulching, hand-pulling and hoeing.
3. Biological Control means the use of organisms such as sheep, goats, cattle,
insects and plant diseases to disrupt the growth of undesirable plants.
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4. Chemical Control means the use of herbicides or plant growth regulators to
disrupt the growth of undesirable plants.
Management of the various undesirable plants will vary depending upon the site
where the plant is located. Management options for each weed species will be
developed for each site. The integrated management options listed below are meant
to provide various management techniques for controlling the noxious weeds in the
various environmental sites they are found. By no means are all the management
options mentioned. Additional combinations of management techniques are possible
which may be submitted by private landowners. The integrated weed management
plans submitted by individual landowners will be evaluated by the Weld County
Vegetation Management Specialist and the Integrated Weed Management Advisory
Commission on a case by case basis.
B. INTEGRATED WEED MANAGEMENT OPTIONS FOR EACH WEED SPECIES
LEAFY SPURGE: Leafy Spurge is a deep rooted perennial plant that spreads by seeds
and creeping roots. It has a vast underground root system which makes it difficult
to control with any one control technique. Leafy Spurge is found primarily in riparian
sites (along waterways such as the Poudre and South Platte Rivers) in Weld County
and also along irrigation ditches, range and pastures, roadsides and other
non-cropland sites.
1. Control Measures
a. Cultural Control: Seeding perennial grasses and forbs can be an
effective management tool. Early emerging plant species that utilize
early season moisture such as Smooth Brome (Bromus inermis) or
Crested Wheatgrass (Agropyron cristatum) have reduced Leafy
Spurge density and limited the spread and establishment of new
infestation. Sequential glyphosate applications followed by a seeding
of Luna Pubescent Wheatgrass, Ephraim Crested Wheatgrass,
Intermediate Wheatgrass, Sherman Big Bluegrass or Bozoisky
Russian Wild Rye has shown to be very effective in reducing an
existing stand of Leafy Spurge.
b. Mechanical Control: Mechanical control of Leafy Spurge is difficult
at best; however, repeated mowing every 14-21 days throughout the
summer, starting before flowering stage, will at least keep the plants
from going to seed and may reduce the underground root reserve.
Research results are not available to indicate whether stand reduction
or eradication could be achieved through use of this technique.
c. Biological Control: Grazing with sheep and goats throughout the
spring, summer, and fall will keep Leafy Spurge from going to seed
and may reduce the underground root reserve. This practice may
also weaken the plants to make them more susceptible to chemical
control.
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Several insect species that have been released by the USDA in the
United States are showing some control of Leafy Spurge. Two
species of flea beetles, Apthona flava and Apthona nigriscutis feed
on Leafy Spurge. Adults feed on the foliage during the summer and
the larvae burrow through the soil and mine the roots and fine root
hairs. These insects used alone may not control Leafy Spurge.
When used along with other insects such as Spurgia Esula, a gall
midge which feeds on the flowers preventing seed production, they
will weaken the plant and make it more susceptible to other control
methods, particularly chemical control.
d. Chemical Control: There are a number of herbicides labeled for use
on Leafy Spurge. Those that can be used independently or in
combination with each other are: picloram (Tordon®); dicamba
(Banvel®); 2,4-D (many different formulations); glyphosate
(Roundup® and Rodeo®); fosamine (Krenite®) and any EPA
approved chemicals labeled for use on Leafy Spurge.
2. Integrated Management Options by Site
a. Range, Pasture and Riparian Sites
Option#1 Biological and Chemical Control: Grazing with sheep or
goats from early April through late August or early September,
followed by a herbicide treatment in late September or early October.
Option#2 Biological and Chemical Control: The release of insects
such as Apthona nigriscutis, Apthona flava, Spurgia Esula, and other
species conducive to the area can be made. A herbicide treatment
can then be made during the true flower stage (where insects were
not released) and in the fall where insects were released. Herbicide
applications should only be carried out in the fall where insects are
used. Use of herbicides at different times if the growing season can
be instituted as additional IPM research is conducted and
recommendations are developed.
Option #3 Mechanical and Chemical Control: Mowing can be
carried out throughout the season with the first mowing cycle at the
bud stage. Mowing should stop during late August followed by a
herbicide treatment during late September or early October (before
a hard freeze).
Option #4 Biological or Mechanical Control Only: The use of
sheep or goats or mowing should be used all season to keep Leafy
Spurge from going to seed. Whether this method will keep the
existing infestation from spreading by underground root growth is
uncertain.
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Option#5 Chemical Control Only: Herbicides should be used in the
spring, early summer during the true flower stage and in the fall just
before a hard freeze. Only the herbicides labeled for the site intended
will be used.
b. Along Irrigation Ditches
Option#1 Biological and Chemical Control: The release of insects
such as Apthona nigriscutis, Apthona (lava, Spurgia Esula and other
species conducive to the area could be made. An herbicide
treatment should be carried out at the true flower stage (if the Spurgia
Esula has not kept the plants from going to seed) and/or in the fall
just before a hard freeze.
Option #2 Chemical Control Only: Herbicides can be used in the
spring or early summer during the true flower stage and in the fall just
before a hard freeze. Only the herbicides labeled for the site intended
will be used.
c. Road Rights-of-Way and Other Non-Crop Areas
Option #1 Mechanical and Chemical Control: One mowing cycle
can be carried out at the bud to early flower stage. A herbicide
application should be made at the true flower stage.
Option #2 Chemical Control Only: Herbicides can be used in the
spring or early summer during the true flower stage and in the fall just
before a hard freeze. Only the herbicides labeled for use on
roadsides and other non-cropland areas would be used.
RUSSIAN KNAPWEED: Russian Knapweed is a non-native perennial plant that spreads
by seeds and creeping roots. It has the ability to release chemicals into the
environment as foliage decays which inhibit the growth of surrounding vegetation
(allelopathic properties). Thus, once established, Russian Knapweed can colonize
an area rapidly. Russian Knapweed is found primarily in range and pastures,
roadsides and other non-cropland sites in Weld County.
1. Control Measures
a. Cultural Control: Seeding perennial grasses such as Smooth Brome
(Bromus inermis) will help to compete with Russian Knapweed and
slow its spread. In addition, stimulating grass growth by fertilizing
and/or irrigation should increase grass competition. Due to the
allelopathic properties of Russian Knapweed, other control
techniques such as judicious chemical control would have to be
implemented in order to give grasses a chance to compete.
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b. Mechanical Control: Mechanical control of Russian Knapweed could
be carried out throughout the summer with repeated mowing every
14-21 days. This would at least keep Russian Knapweed from going
to seed. Whether this control technique will reduce the root mass
and subsequently reduce an existing stand is not known.
c. Biological Control: There are currently no biological control agents
available for Russian Knapweed.
d. Chemical Control: There are a number of herbicides labeled for use
on Russian Knapweed. Those that can be used independently or in
combination with each other are: chlorsulfuron (Telar®); picloram
(Tordon®); 2,4-D (many different formulations); glyphosate
(Roundup® and Rodeo®) and any EPA approved chemical labeled
for use on Russian Knapweed.
2. Integrated Management Options by Site
a. Range and Pastures
Option #1 Mechanical and Chemical: Mowing can be carried out
throughout the season with the first and successive mowing cycles
carried out at the bud stage. A herbicide treatment can then be made
in the fall before a hard freeze.
Option #2 Cultural and Chemical: An herbicide application, using
short residual herbicides such as glyphosate and/or 2,4-D can be
made followed up by reseeding with a competitive grass such as
smooth brome or other sod forming species. In addition, fertilization
or irrigation could be instituted to stimulate increased grass growth.
Option #3 Chemical Control Only: Herbicide applications can be
made to Russian Knapweed during the bud stage, bloom to
post-bloom and/or in the fall, depending upon herbicide used.
b. Road Rights-of-Way and other Non-Crop Areas
Option #1 Mechanical and Chemical: One mowing cycle can be
carried out at the bud to early flower stage. An herbicide application
can be made during the bud stage, bloom to post-bloom and/or in the
fall, depending upon the herbicide used.
Option #2 Cultural and Chemical Control: Use of short residual
herbicides such as glyphosate and/or 2,4-D can be used in the early
summer during the bud stage. Seeding with perennial grasses such
as Smooth Brome, Luna Pubescent Wheatgrass, Ephraim Crested
Wheatgrass, Intermediate Wheatgrass, Sherman Big Bluegrass or
Bozoisky Russian Wild Rye can than be carried out later in the
summer, at the appropriate time.
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Option #3 Chemical Only: Herbicide applications can be made
during the bud stage, bloom to post bloom and/or in the fall,
depending upon the herbicide used.
DIFFUSE KNAPWEED: Diffuse Knapweed is a non-native, biennial to short-lived
perennial forb that reproduces by seed. It spreads rapidly by the mature plant
breaking off at ground level and being blown with the wind, dispersing seed. It is a
pioneer species that will quickly invade disturbed, dry sites. Diffuse Knapweed is
found in the southwest part of Weld County along rights-of-way, dry pasture sites and
in gravelly riparian sites, such as along Boulder Creek and the St. Vrain and South
Platte Rivers.
1. Control Measures
a. Cultural Control: Cultural Control of Diffuse Knapweed is similar to
Russian Knapweed in that seeding with perennial grasses such as
smooth brome and crested wheatgrass will help to compete with
Diffuse Knapweed and slow its spread. Seeding alone in infested
sites will not, however, control the existing stand.
b. Mechanical Control: Mowing Diffuse Knapweed when it is in the bud
stage and again when it is flowering can significantly reduce seed
production. Keeping Diffuse Knapweed from going to seed over a
number of years can eventually eliminate an infestation, once the
seed source in the soil is depleted.
c. Biological Control: Two species of picture-winged flies, Urophora
affinis and U. quadrifasciata have demonstrated the ability to reduce
the seed production of diffuse and Spotted Knapweed. The flies lay
eggs on the developing seed heads. As a result of the larvae feeding
on the flowering heads, the plants produce galls which reduces seed
production. The Colorado insectory is currently rearing these two flies
and has made releases in the state the last three years.
d. Chemical Control: There are a few herbicides labeled for use on
Diffuse Knapweed. Those that can be used independently or in
combination with each other are: picloram (Tordon®); dicamba
(Banvel®); glyphosate (Roundup®); 2,4-D (many different
formulations) and any EPA approved chemical labeled for use on
Diffuse Knapweed.
2. Integrated Management Options by Site
a. Pasture and Riparian Areas
Option #1 Cultural and Chemical Control: A herbicide application
can be made in early summer when Diffuse Knapweed is in the
rosette through bolting stage. Reseeding with competitive perennial
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grasses such as smooth brome and crested wheatgrass can be
followed later in the summer depending upon the herbicide used and
rate of application.
Option#2 Biological and Chemical Control: The release of insects
such as Urophora affinis and U. quadrifasciata can be made. A
herbicide treatment can then be made from the rosette through
bolting stage (where insects were not released) and in the fall where
insects were released. Herbicide applications should only be carved
out in the fall, where insects are used. The use of herbicides at
different times of the growing season can be instituted as additional
IPM research is conducted and recommendations are developed.
Option #3 Mechanical and Chemical Control: Mowing can be
carried out when Diffuse Knapweed is in the bud stage and again at
flowering. A herbicide application can then be made to any plants
that have re-bolted, if necessary.
Option #4 Mechanical Control Only: Mowing can be carried out
throughout the season which will reduce seed set.
Option #5 Chemical Control Only: Herbicide application can be
made during the rosette stage, spring or fall, and while bolting.
b. Rights-of-Way and Other Non-Crop Areas
Option#1 Cultural and Chemical Control: Same as for Option #1
in pasture and riparian areas.
Option #2 Mechanical and Chemical Control: One mowing
operation can be carried out when Diffuse Knapweed is in the bud
stage. If necessary, a herbicide application can be made to plants
that have re-bolted.
Option #3 Mechanical Control Only: Same as for Option #4 in
pasture and riparian areas.
Option #4 Chemical Control Only: Same as for Option #5 in
pasture and riparian areas.
SPOTTED KNAPWEED: Spotted Knapweed is a non-native, perennial forb that
reproduces by seed. It is a highly competitive plant in rangeland sites that will
exclude most grasses and forbs with time. There is limited Spotted Knapweed
infestations currently along the South Platte River drainage in Weld County.
1. Control Measures
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a. Cultural Control: Cultural control of Spotted Knapweed is similar to
such control of Russian and Diffuse Knapweed in that seeding with
perennial grasses such as Smooth Brome and crested wheatgrass
will help to compete with Spotted Knapweed and slow its spread.
Seeding infested sites will not, however, control the existing stand.
In range and pasture conditions, good grazing management practices
will help to reduce the spread of the knapweeds in general.
b. Mechanical Control: Mechanical control of Spotted Knapweed could
be carried out throughout the summer with repeated mowing every
14-21 days. This would at least keep Spotted Knapweed from going
to seed. Whether this control technique will reduce the root mass
and subsequently reduce an existing stand is not known.
c. Biological Control: The same as what was developed under
biological control for Diffuse Knapweed.
d. Chemical Control: There are a few herbicides labeled for use on
Spotted Knapweed. Those that can be used independently or in
combination with each other are: picloram (Tordon®), dicamba
(Banvel®), 2,4-D (many different formulations and clopyrald and 2,4-D
(Curtail®).
CANADA THISTLE: Canada Thistle is an aggressive, creeping perennial that
reproduces by seed and vegetative buds in the root system. It is a difficult plant to
control because of its extensive root system. Vertical roots may grow 6-15 foot deep
and horizontal roots may extend 15 feet or more. Canada Thistle is the most
widespread noxious weed in Weld County. It can be found in most habitat types,
including: pastures, riparian sites (along waterways such as the Poudre, South
Platte, St. Vrain and Big Thompson Rivers), irrigation ditches, along roadside rights-
of-way and in the various crop and non-cropland sites.
1. Control Measures
a. Cultural Control: Plant competition from various grasses and from
alfalfa can be an effective management tool. Early emerging grass
species such as Smooth Brome and Crested Wheatgrass can be
used to compete with Canada Thistle and slow the spread and
establishment of new infestations. Competition alone, however, is
seldom effective on Canada Thistle.
b. Mechanical Control: Mechanical Control of Canada Thistle could be
carried out throughout the summer with repeated mowing every 14
days. Such method keeps Canada Thistle from going to seed;
however, mowing has shown to stimulate new shoot growth from
roots. Consequently, mowing alone may increase shoot density in an
established stand. Whether consistent mowing for consecutive years
(two to three years) will reduce the root mass and subsequently
reduce an existing stand is unknown.
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c. Biological Control: There is one insect species, a weevil, called
Ceutorynchus litura, that is currently being used as a biological
control agent on Canada Thistle in Colorado. The female lays eggs
on the underside of the leaves in early spring and then the larvae
bore into the main leaf vein and migrate down to the crown of the
plant. The holes created by the larvae open up Canada Thistle to
secondary infection. Where high numbers of the larvae occur death
of Canada Thistle can occur.
d. Chemical Control: There are a number of herbicides labeled for use
on Canada Thistle, depending upon where the thistle is found. The
herbicides that can be used independently or in combination with
other compounds are: picloram (Tordon®); dicamba (Banvel®);
2,4-D(many different formulations); chlorsulfuron (Telar®); clopyralid
(Curtail®, Stinger®, Transline®); glyphosate (Roundup®, Rodeo®)
and any EPA approved chemicals labeled for use on Canada Thistle.
2. Integrated Management Options by Site
a. Range, Pasture and Riparian Sites
Option #1 Biological and Chemical: Release of the insect
Ceutorynchus litura can be made during the early summer. A
herbicide application can then be made at the bud stage (where
insects were not released) and in the fall where insects were
released. Herbicide applications should only be carried out in the fall,
where insects were directly released. Use of herbicides at different
times of the growing season can be instituted as additional IPM
research is coordinated and recommendations are developed.
Option #2 Mechanical and Chemical: Mowing can be carried out
throughout the season with the first mowing cycle at the bud stage.
Mowing should stop during late August followed by a herbicide
treatment during late September through October, before a hard
freeze.
Option#3 Cultural and Chemical Control: A herbicide application,
using short residual herbicides such as glyphosate and/or 2,4-D can
be made followed up by reseeding with a competitive grass such as
smooth brome or other sod forming species. In addition, fertilization
or irrigation could be instituted to stimulate increase grass growth.
Option #4 Chemical Control Only: Herbicide applications can be
made to Canada Thistle from rosette to the bud stage, and/or in the
fall, depending upon the herbicide used.
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•
b. Road Rights-of-Way and Other Non-Crop Areas
Option #1 Mechanical and Chemical: One mowing cycle can be
carried out at the bud to early flower stage. A herbicide application
can be made from rosette to bud stage and/or in the fall, depending
upon the herbicide used.
Option #2 Cultural and Chemical Control: A herbicide application
can be made in early summer when Canada Thistle is in the rosette
through bud stage. Reseeding with competitive perennial grasses
such as smooth brome and crested wheatgrass can be followed later
in the summer depending upon the herbicide used and rate of
application.
Option #3 Chemical Control Only: Herbicide applications can be
made from rosette to bud stage, and/or in the fall, depending upon
the herbicide used.
c. Cropland Sites
Canada Thistle is found in almost every crop grown in Weld County.
Prescription weed management measures developed by Colorado
State University weed scientists and the Weld County Extension
Agronomist will be used.
MUSK THISTLE: Musk Thistle is a biennial plant that reproduces only by seed.
Rosettes (Gump of leaves on the ground) are formed during the first year of growth
and the plant bolts and sets seed the second year. It is a prolific seed producer with
a single plant producing up to 20,000 seeds. Musk Thistle is found primarily in
pastures and riparian sites (along waterways such as the South Platte, St. Vrain, Big
Thompson, and Little Thompson drainages and Boulder Creek) and along irrigation
ditches, roadside rights-of-way and other non crop areas.
1. Control Measures
a. Cultural Control: Maintaining pastures and riparian sites in good
condition is the primary method of culturally managing Musk Thistle.
Promoting good grass growth by proper grazing management and
fertilizing according to soil testing recommendations will prevent
establishment of Musk Thistle.
b. Mechanical Control: Musk Thistle can be effectively controlled
mechanically. Severing the roots below ground with a shovel or hoe
or mowing Musk Thistle every time it reaches early flower stage will
reduce, if not eliminate seed production. If mowing occurs mid to late
flower stage, the thistle should be gathered and bumed to destroy any
seed that has developed.
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c. Biological Control: Two species of weevils, Rhinocyllus conicus
(seed head weevil) and Tiichosirocalus horridus, attack two different
sites of Musk Thistle. The seed head weevil, as its name implies,
attacks the seeds of Musk Thistle. Eggs are laid by the female on the
back of developing flowers and then the larvae bore into the flower,
destroying the developing seed. The seed head weevil can reduce
seed production by as much as 50%. Use of this weevil as the sole
means of controlling Musk Thistle is not very effective.
Trichosirocalus horridus attacks the crown area of Musk Thistle
rosettes, killing or weakening the plant before it bolts. Use of both
weevil species together may prove to be an effective biological
control program.
d. Chemical Control: There are a number of herbicides labeled for use
on Musk Thistle, depending upon where the thistle is found. The
herbicides that can be used independently or in combination with
other compounds are: picloram (Tordon®); dicamba (Banvel®);
2,4-D(many different formulations); chlorsulfuron (Telar®); clopyralid
(Curtail®, Stinger®, Transline®); glyphosate (Roundup®, Rodeo®)
and any EPA approved chemical labeled for use on Musk Thistle.
2. Integrated Management Options by Site
a. Pasture and Riparian Sites
Option #1 Biological and Chemical: Release of Trichosirocalus
borridus can be made at the appropriate time of the summer.
Rhinocyllus conicus is well established in Weld County and should
already be infesting the stand. A herbicide application can then be
made to Musk Thistle at the flower stage. Telar or Escort should be
used when treating Musk Thistle in the flower stage. Herbicide
applications should only be carried out in the flower stage in order to
allow the seed head weevil to complete its life cycle. Use of
herbicides to rosettes in the spring or fall should not be carried out
where Trichosirocalus horridus was released. Use of herbicides at
different times of the growing season can be instituted as additional
IPM research is conducted and recommendations are developed.
Option #2 Mechanical and Chemical Control: Mowing can be
carried out throughout the summer when Musk Thistle is in the bud
to early flower stage. A herbicide application can than be made in
October to the fall rosettes and any bolted plants.
Option#3 Mechanical Control Only: Multiple mowings (two to four)
can be carried out throughout the summer when Musk Thistle is in
the bud stage, keeping it from producing seed. If mowing occurs mid
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PAGE 15
to late flower stage, the thistle should be gathered and burned to
destroy any seed that has developed.
Option #4 Chemical Control Only: Herbicides can be used in the
spring and fall when the plant is in the rosette stage. Only the
herbicides labeled for the site intended will be used.
b. Road Rights-of-Way and other Non Crop Areas
Option#1 Biological and Chemical Control: Same as for Option #1
in pasture and riparian sites.
Option #2 Mechanical and Chemical Control: One mowing pass
can be made when Musk Thistle is in the bud stage. A herbicide
application can be made in the fall to the rosettes and re-bolted
plants.
Option #3 Chemical Control Only: Herbicides can be used in the
spring and the fall when the plant is in the rosette stage. Only the
herbicides labeled for the site intended will be used.
SCOTCH THISTLE: Scotch Thistle is a biennial plant that reproduces only by seed.
Rosettes are formed during the first year of growth and the plants bolt and set seeds
the second year. The leaves are densely covered with hair, giving the plant a
grayish-green color. Scotch Thistle is primarily found in pastures and riparian sites
(South Platte River Drainage) and along roadside rights-of-way and other non-crop
areas in southern Weld County.
1. Control Measures
a. Cultural Control: Maintaining pastures and riparian sites in good
condition is the primary method of culturally managing Scotch Thistle.
Promoting good grass growth by proper grazing management and
fertilizing according to soil testing recommendations will help prevent
establishment of Scotch Thistle.
b. Mechanical Control: Scotch Thistle can be efficiently controlled
mechanically. Severing the roots below ground with a shovel or hoe
or mowing Scotch Thistle every time it reaches bud to early flower
stage will reduce, if not eliminate seed production. If mowing occurs
mid to late flower stage, the thistle should be gathered and burned to
destroy any seed that has developed.
c. Biological Control: No biological control agents are available for
Scotch Thistle. One weevil species, Rhinocyllus conicus, will move
from Musk Thistle to Scotch Thistle; however, effective control of
Scotch Thistle has not been demonstrated.
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d. Chemical Control: There are a number of herbicides labeled for use
on Scotch Thistle, depending upon where the thistle is found. The
herbicides that can be used independently or in combination with
other compounds are: picoram (Tordon®); dicamba (Banvel®); 2,4-D
(many different formulations); chlorsulfuron (Telar®); metsulfuron
(Escort®); clopyralid (Curtail®); Stinger®; Transline®and glyphosate
(Roundup®, Rodeo®)and any other EPA approved chemical labeled
for use on Scotch Thistle.
2. Integrated Management Options By Site
a. Pastures and Riparian Sites
Option #1 Mechanical and Chemical Control: Multiple mowings
(two to four) can be carried out throughout the summer when Scotch
Thistle is in the bud stage, keeping it from producing seed. A
herbicide application can than be made in October to the fall rosettes
and any bolted plants.
Option#2 Mechanical Control Only: Multiple mowings (two to four)
can be carried out throughout the summer when Scotch Thistle is in
the bud stage, keeping it from producing seed. If mowing occurs mid
to late flower stage, the thistle should be gathered and burned to
destroy any seed that has developed.
Option #3 Chemical Control Only: Herbicides can be used in the
spring and fall when the plant is in the rosette stage. Only the
herbicides labeled for the site intended will be used.
b. Road Rights-of-Way and Other Non Crop Areas
Option#1 Mechanical and Chemical Control: One mowing pass can
be made when Scotch Thistle is in the bud stage. A herbicide
application can be made to rebolted plants in the bud stage and/or to
fall regrowth.
Option #2 Chemical Control: Herbicides can be used in the spring
and the fall when the plant is in the rosette stage. Only the herbicides
labeled for the site intended will be used.
FIELD BINDWEED: Field Bindweed is a deep rooted creeping perennial plant that
reproduces by seed and horizontal roots. Bindweed seed can survive in soil up to
40 years; therefore, it is important that bindweed be kept from going to seed. Field
Bindweed is found throughout Weld County in most habitat types including:
rangeland, pastures, along roadside rights-of-way and in various crop and
non-cropland sites.
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1. Control Measures
a. Cultural Control: Seeding perennial grasses can be an effective
management tool in providing plant competition against bindweed.
Selecting the proper native grass and/or improved cultivar grass seed
mix for a site specific location is important. For site specific
reseeding recommendations the Natural Resource Conservation
Service and the CSU Extension Office can be contacted.
b. Mechanical Control: Mechanical control of Field Bindweed can only
realistically be carried out in cultivated cropland by discing and
cultivating every 3 weeks. This would keep Field Bindweed from
producing seed and would start to reduce root reserves. Mowing is
not effective due to the creeping nature of bindweed. Discing in
range, pasture or roadside is not environmentally sound.
c. Biological Control: There are currently no biological control agents
on Field Bindweed that are cleared for release in the United States;
however, research is in process. Grazing with livestock (cattle or
sheep), with proper stocking rates, can be an effective means of
keeping bindweed from going to seed in range and pasture sites.
d. Chemical Control: There are a number of herbicides labeled for use
on Field Bindweed, depending upon where the bindweed is found.
The herbicides that can be used independently or in combination with
other compounds are: picloram (Tordon®); dicamba (Banvel 0);
2,4-D(many different formulations); glyphosate (Roundup®, Rodeo®)
and any other EPA approved chemicals labeled for use on Field
Bindweed.
2. Integrated Management Options by Site
a. Range and Pasture land
Option #1 Cultural and Chemical Control: A herbicide application
using short residual herbicides such as glyphosate and/or 2,4-D, can
be made, followed by reseeding in fall with a competitive sod forming
grass mix. In addition, fertilization according to soil tests or irrigation
could be instituted to stimulate increased grass growth.
Option #2 Biological Control: Grazing with cattle and sheep
throughout the summer and fall will keep Field Bindweed from going
to seed and may reduce the underground root reserve.
Option#3 Biological and Chemical Control: Grazing with cattle or
sheep from May through early September followed by a herbicide
treatment in late September or early October.
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Option #4 Chemical Control Only: Herbicides can be used during
the flower stage typically in June and July, and in the fall prior to a
hard freeze. Only the herbicides labeled for the site intended will be
used.
b. Road Rights-of-Way and Other Non Crop Areas
Option #1 Cultural and Chemical Control: A herbicide application
using short residual herbicides, such asglyphosate and/or 2,4-D, can
be made followed by reseeding in the fall with a competitive sod
forming grass mix.
Option #2 Chemical Control Only: Herbicide can be used during
the flower stage, typically in June and July, and in the fall just before
a hard freeze. Only the herbicides labeled for roadsides and other
non cropland areas will be used.
c. Cropland Sites: Field Bindweed is found in almost every crop grown
in Weld County. Prescription weed management measures
developed by Colorado State University weed scientists and the Weld
County Extension Agronomist can be used.
C. PREVENTION MEASURES
Preventive control means using measures which will stop or forestall weeds from
contaminating an area. Establishing preventive measures are often the most
practical and cost effective means of weed control.
The preventive measures which seem most practical for Weld County are as follows:
1. establishing weed free seed and mulch requirements for reclamation
of disturbed sites,
2. promoting the Colorado Weed Free Hay and Forage program,
3. prioritizing weed management areas along routes of dispersal, and
4. identifying noxious weed species in counties bordering Weld County.
1. Weed Free Seed and Mulch Standards
Where the ground is disturbed by activities, such as road preparation for road
resurfacing, sand and gravel lot operations and oil and gas well operations,
weeds will be the first plants to colonize or re-vegetate the site. It is important
that these sites be reclaimed so that noxious weeds do not become
established.
Weld County plans to establish standards within two to four years for using
weed free seed and mulch on all county operations concerned with the
reclamation of disturbed sites, such as on roadside resurfacing projects and
sand and gravel lot operations. Additional regulations may be considered for
similar operations being carried out on private land.
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PAGE 19
2. Weed Free Hay and Forage Program
Standards have been developed that enable growers the ability to have their
hay and forage certified as noxious weed free. These standards will
encourage growers to produce noxious weed free hay and forage so that it
can be shipped and used anywhere in the U.S. (particularly where noxious
weed free standards currently exist).
The Weld County Vegetation Management Specialist will promote the
Colorado Weed Free Forage Standards through the use of seminars, radio
spots and newspaper articles.
3. Prioritizing Weed Management Areas Along Routes of Dispersal
Weeds are spread rapidly through the dispersal of weed seeds in air and
water. Consequently, high weed seed dispersal areas are associated with
rights-of-way, such as along all roads and railroads and along waterways,
i.e., along the Poudre, South Platte, St. Vrain and Little Thompson Rivers and
irrigation canals.
The County Public Works Department will carry out a noxious weed control
program on all county roads from May through September. The noxious
weeds targeted for control include: Canada, Musk, Scotch and Bull Thistle;
Leafy Spurge; Russian, Diffuse and Spotted Knapweed; Field Bindweed;
whitetop; and wild proso millet. In addition, contact will continue to be made
with the Department of Transportation, all irrigation and ditch companies in
the county, the Union Pacific, Burlington Northern and Great Western
Railroad companies, and the oil and gas companies operating within the
county. Information regarding the Weld County Undesirable Plant
Management Act will be distributed and their cooperation will be encouraged.
Assistance in helping them develop their integrated weed management
programs will be offered. In working with landowners on private property, all
lands bordering the rivers in the county will be considered high priority areas.
Landowner compliance with the Undesirable Plant Management Act will be
encouraged.
4. Identifying Noxious Weeds in Bordering Counties That Do Not Occur in
Weld County
Contact will continue to be made with the weed control departments in the
bordering counties to identify the noxious weed species which occur in each
county that would threaten Weld County. Plans have been developed to
monitor the borders of Weld County, as necessary.
•
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PAGE 20
D. EDUCATIONAL PROGRAMS
Education of the public is one of the most important components of a Weed
Management program. Emphasis will be placed on continuing a multifaceted
educational program. The following programs have been instituted in the past and
will continue to be conducted every year.
1. Timely newspaper articles concemed with weed identification and
management.
2. Timely radio broadcasts following the information in the newspaper articles.
3. Conducting landowner weed management seminars and calibration
workshops.
4. Having an educational booth at the Colorado Farm Show.
5. Utilizing brochures and CSU Service in Action brochures to hand out to
individual landowners.
E. MAPPING
Establishing an accurate baseline map of the existing noxious weed infestations in
the county is extremely important for the ongoing evaluation of the effectiveness of
the county weed management program. Therefore, a computerized mapping
program will be established that will map the noxious weeds established in Weld
County.
County roadsides will be mapped using a computer and printer/datalogger on the
spray equipment. Private and state land will be mapped by Public Works Department
personnel taking aerial maps from the county assessor's office into the field and
mapping on site. Through the use of the Auto CADD computer mapping program,
the noxious weed infestations will be mapped. All mapping information will be stored
in the county IBM computer systems and can be retrieved for future evaluation.
F. ESTABLISHING COOPERATIVE INTERGOVERNMENTAL AGREEMENTS
Contact will be made with the following agencies concerning compliance with the
Colorado Undesirable Plant Management Act:
1. Colorado Department of Transportation
2. Colorado State Department of Parks and Recreation
3. Colorado Division of Wildlife
4. Colorado State Land Board
5. U.S. Forest Service
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Assistance will be offered in helping each agency develop integrated weed
management plans for their lands. Actual assistance in carrying out the weed control
programs on their properties will also be offered. Cooperative intergovernmental
agreements can be established if Weld County is asked to assist in implementing the
weed control measures.
G. ADOPT A ROADSIDE PROGRAM
An "Adopt a Roadside" program will be established which will give landowners the
ability to take the responsibility to manage the noxious weeds on the county
rights-of-way that borders their property.
Landowners who are chemically sensitive or for some reason do not want chemicals
sprayed or mowing activities carried out along their property, may take the
responsibility for managing the noxious weeds on the roadside rights-of-way.
Landowner agreements with specific requirements for compliance will be established.
H. ENFORCEMENT ON PRIVATE AND PUBLIC PROPERTY
Cooperation from all landowners (private and state) will be encouraged through
positive communication by mail and through personal contact. When weed control
measures are not carried out by a landowner, enforcement measures may have to
be instituted. All procedures as established by the Undesirable Plant Management
Law, CRS§35-5.5-109, the Pest Control Districts Law, CRS §35-5-108, Weld County
Ordinance 169-A, and any and all federal, state, and local regulations will be
followed, prior to any enforcement activities being carried out on private or public
property. Integrated weed management plans will be requested from certain
landowners, as determined by the Weld County Vegetation Management Specialist
and the Undesirable Plant Management Advisory Board.
Work priorities must be established due to the size of the county and the number of
landowners with existing noxious weed problems. The following list prioritizes where
enforcement activities will be carried out in ranking order of importance:
1. Lands bordering all waterways (rivers and irrigation ditches).
2. Complaint properties.
3. Landowners identified as negligent in the past.
4. Landowners with twenty percent (20%) or more of their property infested with
noxious weeds.
V. EVALUATION OF PROGRAM
The goals and the plan of work established in Sections III. and IV. of this Ordinance 169-A
will be reviewed and evaluated at the end of every year. A written evaluation will be
prepared establishing additions or changes in the plan of work for the following year. Any
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PAGE 22
•
additions or changes must be recommended by the Undesirable Plant Management Advisory
Board and approved by the Board of County Commissioners.
The Weld County Undesirable Plant Management Plan shall be reviewed and amended, as
needed, at least every three years (CRS §35-5.5-107(4)(a)).
•
•
ARTICLE 2 — ENFORCEMENT OF
UNDESIRABLE PLANT MANAGEMENT PLAN
AUTHORIZED AGENT FOR ENFORCEMENT
Pursuant to CRS §35-5.5-105(2), the Weld County Vegetation Management Specialist, his
employees and agents, are hereby authorized to enforce the above-stated Undesirable Plant
Management Plan in the unincorporated areas of County of Weld, State of Colorado, by
utilizing those procedures set forth in CRS §§35-5-108, 35-5-109, and 35-5.5-108, and any
other applicable State and Federal Statutes, rules, regulations, and ordinances, including the
remaining provisions of this Ordinance No. 169-A.
II. RIGHT OF ENTRY
Prior to entering private lands for the purpose of enforcing the Weld County Undesirable
Plant Management Plan as set forth herein, the Weld County Vegetation Management
Specialist shall first obtain a "right of entry'from the Board of County Commissioners, no less
than ten days after a Notice to Control Identified Undesirable Plants has been sent to the
owner or occupant of the private lands and said owner or occupant has failed to comply with
said notice.
III. MAILING OF ASSESSMENTS
All assessments for the whole cost of any enforcement work performed by the Weld County
Vegetation Management Specialist or his designee(s) upon private lands, including up to
15%for inspection and other incidental costs in connection therewith, shall be mailed to the
landowner or occupant by certified mail. Failure to receive said assessment shall not act as
a defense to said assessment.
IV. 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 Weld County
Vegetation Management Specialist or his designee(s) have 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 Weld County Treasurer's Office to
be collected in the same manner as provided for collection of taxes upon the private lands
in accordance with CRS §§35-5-108 and 35-5.5-109(5)(a).
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PAGE 23
ARTICLE 3 — SEVERABILITY
If any section, subsection, paragraph, sentence, clause or phrase of this Ordinance No. 169-A is.
for any reason, held or decided to be invalid or unconstitutional, such decision shall not affect the
validity of the remaining portions. The Board of County Commissioners, Weld County, Colorado,
hereby declares that it would have passed this Ordinance No. 169-A, and in each and every section,
subsection, paragraph, sentence, clause and phrase thereof irrespective of the fact that any one or
more sections, subsections, paragraphs, sentences, clauses, or phrases might be declared to be
unconstitutional or invalid.
ARTICLE 4 — LIABILITY
This Ordinance No. 169-A shall not be intended to create a civil cause of action against the Board
of County Commissioners, Weld County, Colorado, or any other person that may administer this
Ordinance No. 169-A in any manner.
ARTICLE 5 — EFFECTIVE DATE
This Ordinance No. 169-A shall become effective five (5) days after its final public notice. in
accordance with Section 3-14(2) of the Weld County Home Rule Charter.
ARTICLE 6 —COMPLIANCE WITH NOTICE REQUIREMENTS
The Board of County Commissioners hereby states and affirms that by following the reading and
publication schedule set forth below, it has and hereby does comply with the notice requirements
of CRS §35-5.5-108.
ARTICLE 7 — NO WAIVER OF IMMUNITIES/NO CREATION OF DUTIES. STANDARD OF
CARE. OR RIGHTS FOR THIRD PARTIES
No portion of this Ordinance 169-A shall be deemed to constitute a waiver of any immunities which
Weld County, Colorado, by and through the Board of County Commissioners of Weld County, or any
pest control districts and/or their Boards, or the Weld County Undesirable Plant Management
Advisory Board or their officers or employees may possess, nor shall any provision of this Ordinance
169-A be construed to create any duty, standard of care or rights in favor of any third parties with
the respect to any obligation created by this Ordinance 169-A.
BE IT FURTHER ORDAINED by the Board, if any section, subsection, paragraph, sentence,
clause, or phrase of this Ordinance is for any reason held or decided to be unconstitutional, such
decision shall not affect the validity of the remaining portions hereof. The Board of County
Commissioners hereby declares that it would have enacted this Ordinance in each and every
section, subsection, paragraph, sentence, clause, and phrase thereof irrespective of the fact that
any one or more sections, subsections, paragraphs, sentences, clauses, or phrases might be
declared to be unconstitutional or invalid.
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PAGE 24
The above and foregoing Ordinance Number 169-A was, on motion duly made and
seconded, adopted by the following vote on the day of , A.D., 1996.
BOARD OF COUNTY COMMISSIONERS
WELD COUNTY, COLORADO
ATTEST:
Barbara J. Kirkmeyer, Chair
Weld County Clerk to the Board
George E. Baxter, Pro-Tem
BY:
Deputy Clerk to the Board
Dale K. Hall
APPROVED AS TO FORM:
Constance L. Harbert
County Attorney
W. H. Webster
Initial Publication: February 1, 1996, in the North Weld Herald
First Reading: March 4, 1996
Publication: March 7, 1996, in the North Weld Herald
Second Reading: March 18, 1996
Publication: March 21, 1996, in the North Weld Herald
Final Reading: April 1, 1996
Publication: April 4, 1996, in the North Weld Herald
Effective Date: April 9, 1996
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ARTICLE 1 --WELD COUNTY
UNDESIRABLE PLANT MANAGEMENT PLAN
I. INTRODUCTION
A. DESCRIPTION OF HB 90-1175,UNDESIRABLE PLANT MANAGEMENT ACT
The Undesirable Plant Management Act which was signed into law on May 7, 1991
(CRS 35-5.5-101, et. seq.) states that certain undesirable plants 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 undesirable plants designated
for mandatory management statewide are: Leafy Spurge (Euphorbia esula), Russian
Knapweed (Ceatu&ea Acroptilon repens), Diffuse Knapweed (Acroptilon diffusa)
and Spotted Knapweed (Centaurea maculosa). Additional weed species may be
added to the state list by each local jurisdiction. The law states such that local
governments (cities and counties) are directed to take the necessary steps to manage
the undesirable plants in their respective jurisdictions. They are further directed to
appoint an advisory commission whose responsibilities are threefold:
1. Develop recommended management criteria and integrated weed
management plans for managing the designated undesirable
plants;
2. Recommend addition of undesirable plants that shall be subject
to integrated management;
3. Recommend to the county commissioners,those landowners who
shall be required to submit integrated weed management plans
for managing the undesirable plants on their property.
The law further states that by January 1, 1992, each local governing body is to have
developed and adopted an Undesirable Plant Management Plan for all lands within
its jurisdictional boundaries.
Undesireable Plant Management Plan
Page 2
IL DESCRIPTION OF THE COUNTY WEED PROBLEM
A. WEED SPECIES IN WELD COUNTY TO BE CONTROLLED PURSUANT TO WEED
CONTROL LAWS
The Pest Control Districts Law(CRS 35-5-104)enabled landowners in each County
the ability, through a lengthy petitioning and balloting process, to establish weed
control districts. Within each weed district, designated species are mandated to be
controlled. In Weld County,nine such weed districts exist. The districts occur in the
lower two-thirds of the county, and the weed species designated for control range
from three to seven species,depending upon the weed district. The weed species that
are currently being managed in at least a part of Weld County are as follows:
Leafy Spurge (Euphorbia esula),
Canada Thistle (Cirsium arvense),
Musk Thistle (Carduusnutans),
Field Bindweed (Convolvolus arvensis),
Whitetop (Cardaria draba),
Russian Knapweed (Centatt,,,aAcropt lon repens)
Wild Proso Millet (Panicum miliaceum)
Under the Undesirable Plant Management Act(CRS 35-5.5-101, et seq.) there are four weed
species which are mandated for county-wide management. They are Leafy Spurge, and
Russian,Diffuse and Spotted Knapweed. Canada Thistle,-and Musk Thistle, Scotch Thistle
and Field Bindweed have been added to the county-wide undesirable plant list by the Weld
County Commissioners, in accordance with CRS 35-5.5-108(3).
Of the weed species listed previously, Canada Thistle, Field Bindweed, Leafy Spurge, Musk
Thistle,Russian Knapweed,Whitetop and Wild Proso Millet cover the most acreage in Weld
County and pose the greatest economic and environmental threat to the county. Diffuse
Knapweed is currently localized to a few drainages and rights-of-way in the southwest part
of the County, and there are no known Spotted Knapweed infestations in the county.
Undesireable Plant Management Plan
Page 3
III. OBJECTIVES AND GOALS
A. STATEMENT OF OBJECTIVES
The objectives of the Weld County Public Works Department are
fourfold:
1. Develop and carry out a comprehensive noxious weed control
program on all county right-of-way and other county property,
such as in sand and gravel mining operations, grader shed lots
and open space areas.
2. Establish an educational program,by using mailings and holding
educational and calibration seminars, that will effectively
communicate weed management information to the landowners
in the county.
3. Identify non-informed or negligent landowners who are not
carrying out weed management programs on their property and
provide technical support for establishing weed management
plans or enforce on properties, if necessary.
4. Work with all state and federal agencies, through
intergovernmental agreements,if necessary,towards establishing
effective weed management programs on their property.
B. SHORT TERM GOALS—(1-3-it,as s)January 1995 to December 1998
1. Map all the County roads for noxious weed infestations.
2. Map on a computer program (Design-CARD) at least half of the
landowners that have Leafy Spurge, Canada Thistle and Russian
Knapweed infestations.
3. Continue to Establish contact with every landowners on the South
Platte and Poudre Rivers that have Leafy Spurge noxious weed
infestations.
4. Establish 3.5 educational/calibration seminars (annually) that work
directly with 150-200 landowners each year.
Revised 1995
Undesireable Plant Management Plan
Page 4
5. Have established contact with the Colorado Department of Highways,
Department of Parks and Recreation, Colorado Land Board, Division
of Wildlife and U.S. Forest Service. Help them develop Weed
Management Plans and where appropriate enter into cooperative
intergovernmental agreements.
6. Have established six to eight biological control release sites
throughout the county in cooperation with the Colorado Department
of Agriculture and private landowners:
7. By the fourth ycar 1995 have reduced the noxious weed acreage
sprayed on county right-of-way by 15-20%.
C. LONG TERM GOALS—(4-8-j..aia) January 1999 to December:2002
1. Have mapped on the computer program all the most noxious weed
infestations county-wide, including private, state and federal lands.
2. Have reduced the noxious weed acreage sprayed on county right-of-
way by 40-50%.
3. Have contacted and worked with cvcry most landowners county-wide
who has have a noxious weed infestation.
4. Have established 30-50 biological control release sites in the county.
Revised 1995
Undesireable Plant Management Plan
Page 5
IV. PLAN OF WORK- IMPLEMENTATION
A. DESCRIPTION OF INTEGRATED WEED MANAGEMENT TECHNIQUES
The weed species designated as undesirable and mandated for management are Leafy
Spurge (Euphorbia esula), Russian Knapweed (Centuao,u Acroptlon repens),
Diffuse Knapweed (Centaurea diffusa), Spotted Knapweed (Centaurea maculosa),
Canada Thistle (Cirsium arvense) and Musk Thistle (Carduus nutans),_Scotch
Thistle'(Onopordwn acanthium) and Field Bindweed (Convolvulus arvensis).
Integrated weed management methods are to be used in managing these weed species
(CRS 35-5.5-107). Integrated management techniques include education;preventive
measures; and control measures including cultural, mechanical, biological and
chemical control. For the purposes of this plan the following definitions for the
control measures will be used.
1. Cultural Control means those methodologies or management
practices conducted to favor the growth of desirable plants over
undesirable plants, including but not limited to maintaining an
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 an area.
2. Mechanical Control means those methodologies or management
practices that physically disrupt plant growth, including but not
limited to tilling,mowing,burning, flooding, mulching,hand-pulling
and hoeing.
3. Biological Control means the use of organisms such as sheep, goats,
cattle, insects and plant diseases to disrupt the growth of undesirable
plants.
4. Chemical Control means the use of herbicides or plant growth
regulators to disrupt the growth of undesirable plants.
Management of the various undesirable plants will vary depending upon the site the
plant is located in. Management options for each weed species will be developed for
each site where the plant is found in Weld County.
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The integrated management options listed below are meant to provide various
management techniques for controlling the noxious weeds in the various
environmental sites they are found. By no means are all the management options
developed. Additional combinations of management techniques are possible which
may be submitted by private landowners. The integrated weed management plans
submitted by individual landowners will be evaluated by the Weld County
Vegetation Management Specialist and the Integrated Weed Management Advisory
Commission on a case by case basis.
B. INTEGRATED WEED MANAGEMENT OPTIONS FOR EACH WEED SPECIES
LEAFY SPURGE: Leafy Spurge is a deep rooted perennial plant that spreads by seeds
and creeping roots. It has a vast underground root system which makes it difficult
to control with any one control technique. Leafy Spurge is found primarily in
riparian sites (along waterways such as the Poudre and South Platte Rivers) in Weld
County and also along irrigation ditches, range and pastures,roadsides and other non
cropland sites.
1. Control Measures
a. Cultural Control: Seeding perennial grasses and forbs can be an
effective management tool. Early emerging plant species that utilize
early season moisture such as Smooth Brome (Bromus inermis) or
Crested Wheatgrass (Agropyron cristatum) have reduced Leafy
Spurge density and limited the spread and establishment of new
infestation. Sequential glyphosate applications followed by a seeding
of Luna Pubescent Wheatgrass, Ephraim Crested Wheatgrass,
Intermediate Wheatgrass, Sherman Big Bluegrass or Bozoisky
Russian Wild Rye has shown to be very effective in reducing an
existing stand of Leafy Spurge.
b. Mechanical Control: Mechanical control of Leafy Spurge is
difficult at best, however, repeated mowing every 14-21 days
throughout the summer, starting before flowering stage, will at least
keep the plants from going to seed and may reduce the underground
root reserve. Research results are not available to indicate whether
stand reduction or eradication could be achieved through use of this
technique.
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c. Biological Control: Grazing with sheep and goats throughout the
spring, summer, and fall will keep Leafy Spurge from going to seed
and may reduce the underground root reserve. This practice may also
weaken the plants to make them more susceptible to chemical control.
Several insect species that have been released by the USDA in the
United States are showing some control of Leafy Spurge. Two
species of flea beetles,Apthona flava and Apthona nigriscutis feed on
Leafy Spurge. Adults feed on the foliage during the summer and the
larvae burrow through the soil and mine the roots and fine root hairs.
These insects used alone may not control Leafy Spurge. When used
along with other insects such as Spurgia esula, a gall midge which
feeds on the flowers preventing seed production,they will weaken the
plant and make it more susceptible to other control methods,
particularly chemical control.
d. Chemical Control: There are a number of herbicides labeled for use
on Leafy Spurge. Those that can be used independently or in
combination with each other are: picloram (Tordon®), dicamba
(Banvel®), 2,4-D (many different formulations), glyphosate
(Roundup® and Rodeo®) and fosamine (Krenite®) and any EPA
approved chemicals labeled for use on Leafy Spurge.
2. Integrated Management Options by Site:
a. Range, Pasture and Riparian Sites
Option#1 Biological and Chemical Control: Grazing with sheep
or goats from early April through late August, early September
followed by a herbicide treatment in late September, early October.
Option#2 Biological and Chemical Control: The release of insects
such as Apthona nigriscutis,Apthonaflava,andfer Spurgia esula,and
other species conducive to the area can be made. A herbicide
treatment can then be made during the true flower stage (where
insects were not released) and in the fall where insects were released.
Herbicide applications should only be carried out in the fall where
insects are used. Use of herbicides at different times if the growing
season can be instituted as additional IPM research is conducted and
recommendations are developed.
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Option #3 Mechanical and Chemical Control: Mowing can be
carried out throughout the season with the first mowing cycle at the
bud stage. Mowing should stop during late August followed by a
herbicide treatment during late September-early October, before a
hard freeze.
Option #4 Biological or Mechanical Control Only: The use of
sheep or goats or mowing should be used all season to keep Leafy
Spurge from going to seed. Whether this method will keep the
existing infestation from spreading by underground root growth is
uncertain.
Option #5 Chemical Control Only: Herbicides should be used in
the spring, early summer during the true flower stage and in the fall
just before a hard freeze. Only the herbicides labeled for the site
intended will be used.
b. Along Irrigation Ditches
Option#1 Biological and Chemical Control: The release of insects
such as Apthona nigriscutis, Apthona flava,arte/or Spurgia esula and
other species conducive to the area could be made. A herbicide
treatment should be carried out at the true flower stage(if the Spurgia
esula has not kept the plants from going to seed)and/or in the fall just
before a hard freeze.
Option#2 Chemical Control Only: Herbicides can be used in the
spring-early summer during the true flower stage and in the fall just
before a hard freeze. Only the herbicides labeled for the site intended
will be used.
c. Road Right-of-Ways and Other Non-Crop Areas
Option#1 Mechanical and Chemical Control: One mowing cycle
can be carried out at the bud to early flower stage. A herbicide
application should be made at the true flower stage.
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Option #2 Chemical Control Only: Herbicides can be used in the
spring-early summer during the true flower stage and in the fall just
before a hard freeze. Only the herbicides labeled for use on roadsides
and other non-cropland areas would be used.
RUSSIAN KNAPWEED: Russian Knapweed is a non-native perennial plant that
spreads by seeds and creeping roots. It has the ability to release chemicals into the
environment as foliage decays which inhibit the growth of surrounding vegetation
(allelopathic properties). Thus, once established Russian Knapweed can colonize an
area rapidly. Russian Knapweed is found primarily in range and pastures, roadsides
and other non-cropland sites in Weld County.
1. Control Measures
a. Cultural Control: Seeding perennial grasses such as Smooth Brome
(Bromus inermis) will help to compete with Russian Knapweed and
slow its spread. In addition, stimulating grass growth by fertilizing
and/or irrigation should increase grass competition. Due to the
allelopathic properties of Russian Knapweed, other control
techniques such as judicious chemical control would have to be
implemented in order to give grasses a chance to compete.
b. Mechanical Control: Mechanical control of Russian Knapweed
could be carried out throughout the summer with repeated mowing
every 14-21 days. This would at least keep Russian Knapweed from
going to seed. Whether this control technique will reduce the root
mass and subsequently reduce an existing stand is not known.
c. Biological Control: There are currently no biological control agents
available for Russian Knapweed.
d. Chemical Control: There are a number of herbicides labeled for use
on Russian Knapweed. Those that can be used independently or in
combination with each other are: chlorsulfuron (Telar®), picloram
(Tordon®), 2,4-D (many different formulations), glyphosate
(Roundup® and Rodeo®) and any EPA approved chemical labeled
for use on Russian Knapweed:
2. INTEGRATED MANAGEMENT OPTIONS BY SITE
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a. Range and Pastures:
Option#1 Mechanical and Chemical: Mowing can be carried out
throughout the season with the first and successive mowing cycles
carried out at the bud stage. A herbicide treatment can then be made
in the fall before a hard freeze.
Option#2 Cultural and Chemical: A herbicide application, using
short residual herbicides such as glyphosate and/or 2,4-D, can be
made followed up by reseeding with a competitive grass such as
smooth brome or other sod forming species. In addition, fertilization
or irrigation could be instituted to stimulate increase grass growth.
Option#3 Chemical Control Only: Herbicide applications can be
made to Russian Knapweed during the bud stage, bloom to post-
bloom and/or in the fall, depending upon herbicide used.
b. Road Right-of-Way and other Non-Crop Areas.
Option #1 Mechanical and Chemical: One mowing cycle can be
carried out at the bud to early flower stage. A herbicide application
can be made during the bud stage, bloom to post-bloom and/or in the
fall, depending upon the herbicide used.
Option #2 Cultural and Chemical Control: Use of short residual
herbicides such as glyphosate and/or 2,4-D can be used in the early
summer during the bud stage. Seeding with perennial grasses such
as Smooth Brome, Luna Pubescent Wheatgrass, Ephraim Crested
Wheatgrass, Intermediate Wheatgrass, Sherman Big Bluegrass or
Bozoisky Russian Wild Rye can than be carried out later in the
summer, at the appropriate time.
Option #3 Chemical Only: Herbicide applications can be made
during the bud stage, bloom to post bloom and/or in the fall,
depending upon the herbicide used.
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DIFFUSE KNAPWEED: Diffuse Knapweed is a non-native, biennial to short lived
perennial forb that reproduces by seed. It spreads rapidly by the mature plant
breaking off at ground level and being blown with the wind, dispersing seed. It is a
pioneer species that will quickly invade disturbed, dry sites. Diffuse Knapweed is
found in the southwest part of Weld County along rights of way, dry pasture sites and
in gravelly riparian sites, such as along Boulder Creek and the St. Vrain and South
Platte Rivers.
1. Control Measures
a. Cultural Control: Cultural Control of Diffuse Knapweed is similar
to Russian Knapweed in that seeding with perennial grasses such as
smooth brome and crested wheatgrass will help to compete with
Diffuse Knapweed and slow its spread. Seeding alone in infested
sites will not, however, control the existing stand.
b. Mechanical Control: Mowing Diffuse Knapweed when it is in the
bud stage and again when it is flowering can significantly reduce seed
production. Keeping Diffuse Knapweed from going to seed over a
number of years can eventually eliminate an infestation,once the seed
source in the soil is depleted.
c. Biological Control: Two species of picture-winged flies, Urophora
ainis and U quadrifasciata have demonstrated the ability to reduce
the seed production of diffuse and Spotted Knapweed. The flies lay
eggs on the developing seed heads. As a result of the larvae feeding
on the flowering heads, the plants produce galls which reduces seed
production. The Colorado insectory is currently rearing these two
flies and has made releases in the state the last three years.
d. Chemical Control: There are a few herbicides labeled for use on
Diffuse Knapweed. Those that can be used independently or in
combination with each other are: picloram (Tordon®), dicamba
(Banvel®), glyphosate (Roundup®), 2,4-D (many different
formulations), and any EPA approved chemical labeled for use on
Diffuse Knapweed.
2. Integrated Management Options by Site
a. Pasture and Riparian Areas
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Option #1 Cultural and Chemical Control: A herbicide
application can be made in early summer when Diffuse Knapweed is
in the rosette through bolting stage. Reseeding with competitive
perennial grasses such as smooth brome and crested wheatgrass can
be followed later in the summer depending upon the herbicide used
and rate of application.
Option#2 Biological and Chemical Control: The release of insects
such as Urophora affinis and U quadrifasciata can be made. A
herbicide treatment can than be made from the rosette through
bolting stage (where insects were not released) and in the fall where
insects were released. Herbicide applications should only be carried
out in the fall, where insects are used. Use of herbicides at different
times of the growing season can be instituted as additional IPM
research is conducted and recommendations are developed.
Option #3 Mechanical and Chemical Control: Mowing can be
carried out when Diffuse Knapweed is in the bud stage and again at
flowering. A herbicide application can then be made to any plants
that have re-bolted, if necessary.
Option #4 Mechanical Control Only: Mowing can be carried out
throughout the season, reducing seed set.
Option #5 Chemical Control Only: Herbicide application can be
made during the rosette stage, spring or fall, and while bolting.
b. Right-of-Ways and Other Non-Crop Areas
Option#1 Cultural and Chemical Control: Same as for Option#1
in Pasture and Riparian Areas.
Option #2 Mechanical and Chemical Control: One mowing
operation can be carried out when Diffuse Knapweed is in the bud
stage. If necessary, a herbicide application can be made to plants
that have re-bolted.
Option #3 Mechanical Control Only: Same as for Option #4 in
Pasture and Riparian Areas
Option #4 Chemical Control Only: Same as for Option #5 in
Pasture and Riparian Areas.
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SPOTTED KNAPWEED: Spotted Knapweed is a non-native, perennial forb that
reproduces by seed. It is a highly competitive plant in rangeland sites that will
exclude most grasses and forbs with time. There ate is hued
Spotted Knapweed infestations currently along the South Platte River drainage in
Weld County.
1. Control Measures
a. Cultural Control: Cultural Control of Spotted Knapweed is similar
to Russian and Diffuse Knapweed in that seeding with perennial
grasses such as Smooth Brome and crested wheatgrass will help to
compete with Spotted Knapweed and slow its spread. Seeding
infested sites will not, however, control the existing stand. In range
and pasture conditions, good grazing management practices will help
to reduce the spread of the knapweeds in general.
b. Mechanical Control: Mechanical control of Spotted Knapweed
could be carried out throughout the summer with repeated mowing
every 14-21 days. This would at least keep Spotted Knapweed from
going to seed. Whether this control technique will reduce the root
mass and subsequently reduce an existing stand is not known.
c. Biological Control: The same as what was developed under
biological control for Diffuse Knapweed.
d. Chemical Control: There are a few herbicides labeled for use on
Spotted Knapweed. Those that can be used independently or in
combination with each other are: picloram (Tordon®), dicamba
(Bane®1), 2,4-D (many different formulations and clopyrald and
2,4-D (Curtail®).
CANADA THISTLE: Canada Thistle is an aggressive, creeping perennial that
reproduces by seed and vegetative buds in the root system. It is a difficult plant to
control because of its extensive root system. Vertical roots may grow 6-15 foot deep
and horizontal roots may extend 15 feet or more. Canada Thistle is the most
widespread noxious weed in Weld County. It can be found in most habitat types
including; pastures,riparian sites (along waterways such as the Poudre, South Platte,
St. Vrain and Big Thompson Rivers), irrigation ditches, along roadside rights-of-
way and in the various crop and non-cropland sites.
1. Control Measures
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a. Cultural Control: Plant competition from various grasses and from
alfalfa can be an effective management tool. Early emerging grass
species such as Smooth Brome and Crested Wheatgrass can be used
to compete with Canada Thistle and slow the spread and
establishment of new infestations. Competition alone, however, is
seldom effective on Canada Thistle.
b. Mechanical Control: Mechanical Control of Canada Thistle could
be carried out throughout the summer with repeated mowing every 14
days. This would keep Canada Thistle from going to seed, however,
mowing has shown to stimulate new shoot growth from roots.
Consequently, mowing alone may increase shoot density in an
established stand. Whether consistent mowing for consecutive years
(two to three years) will reduce the root mass and subsequently
reduce an existing stand is unknown.
c. Biological Control: There is one insect species, a weevil, called
Ceutorynchus litura, that is currently being used as a biological
control agent on Canada Thistle in Colorado. The female lays eggs
on the underside of the leaves in early spring and then the larvae bore
into the main leaf vein and migrate down to the crown of the plant.
The holes created by the larvae open up Canada Thistle to secondary
infection. Where high numbers of the larvae occur death of Canada
Thistle can occur.
d. Chemical Control: There are a number of herbicides labeled for use
on Canada Thistle, depending upon where the thistle is found. The
herbicides that can be used independently or in combination with
other compounds are: picloram(Tordon®), dicamba(Banvel®), 2,4-
D (many different formulations), chlorsulfuron(Telar®), clopyralid
(Curtail®, Stinger®, Transline®), glyphosate (Roundup®, Rodeo®)
and any EPA approved chemicals labeled for use on Canada Thistle
2. Integrated Management Options by Site
a. Range, Pasture and Riparian Sites
Option #1 Biological and Chemical: Release of the insect
Ceutorynchus litura can be made during the early summer. A
herbicide application can then be made at the bud stage (where
insects were not released) and in the fall where insects were released.
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Herbicide applications should only be carried out in the fall, where
insects were directly released. Use of herbicides at different times of
the growing season can be instituted as additional IPM research is
coordinated and recommendations are developed.
Option#2 Mechanical and Chemical: Mowing can be carried out
throughout the season with the first mowing cycle at the bud stage.
Mowing should stop during late August followed by a herbicide
treatment during late September through October, before a hard
freeze.
Option #3 Cultural and Chemical Control: A herbicide
application, using short residual herbicides such as glyphosate and/or
2,4-D, can be made followed up by reseeding with a competitive
grass such as smooth brome or other sod forming species. In
addition, fertilization or irrigation could be instituted to stimulate
increase grass growth.
Option#4 Chemical Control Only: Herbicide applications can be
made to Canada Thistle from rosette to the bud stage, and/or in the
fall, depending upon the herbicide used.
b. Road Right-of-Ways and Other Non-Crop Areas
Option #1 Mechanical and Chemical: One mowing cycle can be
carried out at the bud to early flower stage. A herbicide application
can be made from rosette to bud stage and/or in the fall, depending
upon the herbicide used.
Option #2 Cultural and Chemical Control: A herbicide
application can be made in early summer when Canada Thistle is in
the rosette through bud stage. Reseeding with competitive perennial
grasses such as smooth brome and crested wheatgrass can be
followed later in the summer depending upon the herbicide used and
rate of application.
Option#3 Chemical Control Only: Herbicide applications can be
made from rosette to bud stage, and/or in the fall, depending upon the
herbicide used.
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c. Cropland Sites
Canada Thistle is found in almost every crop grown in Weld County.
Prescription weed management measures developed by Colorado
State University weed scientists and the Weld County Extension
Agronomist will be used.
MUSK THISTLE: Musk Thistle is a biennial plant that reproduces only by seed.
Rosettes (clump of leaves on the ground) are formed during the first year of growth
and the plant bolts and sets seed the second year. It is a prolific seed producer with
a single plant producing up to 20,000 seeds. Musk Thistle is found primarily in
pastures and riparian sites (along waterways such as the South Platte, St. Vrain, Big
Thompson, and Little Thompson drainages and Boulder Creek) and along irrigation
ditches, roadside rights-of-way and other non crop areas.
1. Control Measures
a. Cultural Control: Maintaining pastures and riparian sites in good
condition is the primary method of culturally managing Musk Thistle.
Promoting good grass growth by proper grazing management and
fertilizing according to soil testing recommendations will prevent
establishment of Musk Thistle.
b. Mechanical Control: Musk Thistle can be effectively controlled
mechanically. Severing the roots below ground with a shovel or hoe
or mowing Musk Thistle every time it reaches early flower stage will
reduce, if not eliminate seed production. If mowing occurs mid to
late flower stage,the thistle should be gathered and burned to destroy
any seed that has developed.
c. Biological Control: Two species of weevils, Rhinocyllus conicus
(seed head weevil) and Trichosirocalus horridus, attack two different
sites of Musk Thistle. The seed head weevil, as its name implies,
attacks the seeds of Musk Thistle. Eggs are laid by the female on the
back of developing flowers and then the larvae bore into the flower,
destroying the developing seed. The seed head weevil can reduce
seed production by as much as 50%. Use of this weevil as the sole
means of controlling Musk Thistle is not very effective.
Trichosirocalus horridus attacks the crown area of Musk Thistle
rosettes, killing or weakening the plant before it bolts. Use of both
weevil species together may prove to be an effective biological
control program.
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d. Chemical Control: There are a number of herbicides labeled for use
on Musk Thistle, depending upon where the thistle is found. The
herbicides that can be used independently or in combination with
other compounds are: picloram(Tordon®), dicamba(Banvel®), 2,4-
D (many different formulations), chlorsulfuron(Telar®), clopyralid
(Curtail®, Stinger®, Transline®), glyphosate (Roundup®, Rodeo®)
and any EPA approved chemical labeled for use on Musk Thistle
2. Integrated Management Options by Site
a. Pasture and Riparian Sites
Option #1 Biological and Chemical: Release of Trichosirocalus
borridus can be made at the appropriate time of the summer.
Rhinocyllus conicus is well established in Weld County and should
already be infesting the stand. A herbicide application can then be
made to Musk Thistle at the flower stage. Telar or Escort should be
used when treating Musk Thistle in the flower stage. Herbicide
applications should only be carried out in the flower stage in order to
allow the seed head weevil to complete its life cycle. Use of
herbicides to rosettes in the spring or fall should not be carried out
where Trichosirocalus horridus was released. Use of herbicides at
different times of the growing season can be instituted as additional
IPM research is conducted and recommendations are developed.
Option #2 Mechanical and Chemical Control: Mowing can be
carried out throughout the summer when Musk Thistle is in the bud
to early flower stage. A herbicide application can than be made in
October to the fall rosettes and any bolted plants.
Option #3 Mechanical Control Only: Multiple,Mrnowings (two
to four)can be carried out throughout the summer when Musk Thistle
is in the bud to early flowcr stage, keeping it from producing seed.
If mowing occurs mid to late flower stage, the thistle should be
gathered and burned to destroy any seed that has developed.
Option#4 Chemical Control Only: Herbicides can be used in the
spring and fall when the plant is in the rosette stage. Only the
herbicides labeled for the site intended will be used.
b. Road Right-of-Ways and other Non Crop Areas
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Option#1 Biological and Chemical Control: Same as for Option
#1 in Pasture and Riparian sites.
Option#2 Mechanical and Chemical Control: One mowing pass
can be made when Musk Thistle is in the bud to curly flower stage.
A herbicide application can be made in the fall to the rosettes and re-
bolted plants.
Option#3 Chemical Control Only: Herbicides can be used in the
spring and the fall when the plant is in the rosette stage. Only the
herbicides labeled for the site intended will be used.
SCOTCH THISTLE: Scotch Thistle is a biennial plant that reproduces only by seed.
Rosettes are formed during the first year of growth and the plants bolt and set seeds
the second year. The leaves are densely covered with hair,giving the plant a.grayish-
green color. Scotch Thistle is primarily found in pastures and riparian sites(South
Platte River Drainage)and along roadside rights of way and other non crop areas in
southern Weld County
1 Control Measures
a. Cultural Control: Maintaining pastures and riparian sites in good
condition is the primary method of culturally managing Scotch
Thistle.Promoting good grass growth by proper grazing
management and fertilizing according to soil testing
recommendations will help prevent establishment of Scotch Thistle;
b. Mechanical Control:,Scotch Thistle can be efficiently controlled
mechanically. Severing the roots below ground with a shovel or
hoe or mowing Scotch Thistle every time it reaches bud to early
flower stage will reduce,if not eliminate seed production; If Mowing
occurs mid to late flower stage,the thistle should be gathered and
burned to destroy any seed that has developed.
c. Biological Control:No biological control agents axe available for
Scotch Thistle. One weevil species,Rhinocyllus comets,will
move from Musk Thistle to Scotch Thistle;however,effective control
of Scotch Thistle has not been demonstrated.
d. Chemical Control: There are a number of herbicides labeled for
use on Scotch Thistle,depending upon where the thistle is found.
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The herbicides that can be used independently or in combination
with other compounds are:picloram(Tordonci),dicamba
(Banvel®),2,4-D (many different formulations),chlorsulfuron
(Tel"),metsulfuron(Escort®), clopyralid(Curtail®), Stinger®,
Transline®)°and glyphosate(RounduP1 ) Rodeo.®)and any other
EPA approved chemical labeled for use on Scotch Thistle.
2. Integrated Management Options By'Site
a. Pastures and Riparian Sites
Option #1 Mechanical and Chemical Control: Multiple nowings
(two to four) can be earned out thoughtout the summer when Scotch
Thistle is in the bud stage,keeping if from producing seed.A herbicide
application can than be made in October to the fall rosettes and any
bolted plants.
Option #2 r-Mechanical Control Only: Multiple_mowings (two to
four)can be carried out throughout the summer when Scotch Thistle is
in the bud stage, keeping it from producing seed. =If mowing occurs
mid to late flower stage, the thistle should be gathered and burned to
destroy any seed that has developed.
Option #3 Chemical Control Only; Herbicides can be used in the
spring and fall when the plant is in the rosette stage, Only the
herbicides labeled for the site intended will be used,
b. Road Rights of Way and Other Non Crop Areas
Option#1 Mechanical and Chemical Control: One mowing pass can
be made when Scotch Thistle is in the bud stage. A herbicide
application can be made to rebelled plants in the bud stage and/or to
fall regrowth.
Option #2.Chemical Control: Herbicides can be used in the spring
and the fall when the plant is in the rosette stage. Only the herbicides
labeled for the site intended will be used.
FIELD BINDWEED: Field Bindweed is a deep rooted creeping perennial plant that
reproduces by seed and horizontal roots. Bindweed seed can survive in soil up to 40
years; therefore, it is important that bindweed be kept from going to seed. Field
Bindweed is found throughout Weld County in most habitat types including:
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rangeland,pastures,along roadside rights of way and in various crop and,non-cropland
sites.
1: Control Measures
a. Cultural Control: Seeding perennial grasses can be an effective
management tool in providing plant competition against bindweed
Selecting.the proper native grass and/or improved cultivar grass seed
mix for a site specific location is important. .For site specific reseeding
recommendations the Natural Resource Conservation Service and the
CSU Extension Office can be contacted.
b. Mechanical Control: Mechanical control of Field Bindweed can only
realistically be carried out in cultivated cropland by discing and
cultivating every 3 weeks. This would keep Field Bindweed from
producing seed and would start to reduce root-reserves. Mowing is not
effective due to the creeping,nature of bindweed, Discing in'range
pasture or roadside is not environmentally sound.
c. Biological Control: There are currently no biological control agents
on Field Bindweed that are cleared for release in the United:States;
however, research is in process. Grazing .with livestock (cattle or
sheep),with proper stocking rates can be an effective means of keeping
bindweed from going to seed in range and pasture sites.
d. Chemical Control: There are a number of herbicides.labeled for vse
on Field Bindweed;depending upon where the bindweed is found. The
herbicides that,can be used independently or in combination with.other
compounds are: picloram=(Tordon®), dicamba (Banvel e) 2. 4 D
(many different formulations),glyphosate(Roundup®,.Rodeonland
any other EPA approved chemicals labeled for use on Field Bindweed.
2. Integrated Management Options by-Site
a. Range and Pasture land
Option#1 Cultural and Chemical Control: A herbicide application
using short residual herbicides such as glyphosate and/or 244-D,can be
made, followed by reseeding in fall with a competitive sod forming
grass mix. In addition,fertilization according to soil tests or irrigation
could be.instituted to stimulate increased grass growth.
Revised 1995
Undesireable Plant Management Plan
Page 21
Option #2 Biological Control: Grazing with cattle and sheep
throughout the summer and fall will keep Field Bindweed from going
to seed and may reduce the underground root reserve.
Option#3 Biological and Chemical Control: Grazing with cattle or
sheep from May through early September followed by a herbicide
treatment in late September,early October Wilt give.effective control..
Option#4 Chemical Control Only: Herbicides can be used during the
flower stage,typically in June and July,and in the fall prior to a hard
freeze. Only the herbicides labeled for the site intended will'be used.
b. Road Rights of Way and Other Non Crop Areas
Option#1 Cultural and Chemical Control: A herbicide application
using short residual herbicides, such as glyphosate and/or.2,4-D,can
be made followed by reseeding in the fall with a competitive sod
forming grass mix:
Option#2 Chemical Control Only :Herbicide can be used the
flower stage,typically in June and July,and in the fall, but before a
hard freeze. Only the herbicides labeled for roadsides and other non
cropland areas will be used.
c. Cropland Sites: Field Bindweed is found in almost every crop grown
in Weld County. Prescription weed management measures developed
by Colorado State University weed scientists and the Weld County
Extension Agronomist can be used.
C. PREVENTION MEASURES
Preventive control means using measures which will stop or forestall weeds from
contaminating an area. Establishing preventive measures are often the most practical
and cost effective means of weed control.
The preventive measures which seem most practical for Weld County are as follows:
1. establishing weed free seed and mulch requirements for reclamation of
disturbed sites,
2. promoting the Colorado Weed Free Hay and Forage program,
3. prioritizing weed management areas along routes of dispersal, and
4. identifying noxious weed species in counties bordering Weld County.
Revised 1995
Undesireable Plant Management Plan
Page 22
1. Weed Free Seed and Mulch Standards
Where the ground is disturbed by activities, such as road preparation for road
resurfacing, sand and gravel lot operations and oil and gas well operations,
weeds will be the first plants to colonize or re-vegetate the site. It is important
that these sites be reclaimed so that noxious weeds do not become established.
Weld County will should establish standards within two to four years for using
weed free seed and mulch on all county operations concerned with the
reclamation of disturbed sites, such as on roadside resurfacing projects and
sand and gravel lot operations. Additional regulations may be considered for
similar operations being carried out on private land.
2. Weed Free Hay and Forage Program
Standards cw1ti11tl, L:116 have been developed that will enable growers the
ability to have their hay and forage certified as noxious weed free. These
standards will encourage growers to produce noxious weed free hay and forage
so that it can be shipped and used anywhere in the U.S. (particularly where
noxious weed free standards currently exist).
The Weld County Vegetation Management Specialist will provide an
i11i h n and-i.citificatio11 service and will promote the Colorado Weed Free
Forage Standards through the use of seminars, radio spots and newspaper
articles.
3. Prioritizing Weed Management Areas Along Routes of Dispersal
Weeds are spread rapidly through the dispersal of weed seeds in air and water.
Consequently, high weed seed dispersal areas are associated with right-of-
ways, such as along all roads and railroads and along waterways, i.e., along the
Poudre, South Platte, St. Vrain and Little Thompson Rivers and irrigation
canals.
The County Pest and Wccd Department Public Works Department will carry
out a noxious weed controlprogram on all county roads from May through
September. The noxious weeds targeted for control include: Canada, Musk,
Scotch and Bull Thistle; Leafy Spurge; Russian, Diffuse and Spotted
Knapweed; Field Bindweed; whitetop; and wild proso millet. In addition,
contact will continue:to be made with the Colorado Department of IIighways
Department of Transportation, all irrigation and ditch companies in the county,
and the Union Pacific, Burlington Northern and Great Western Railroad
companies, and the oil and gas companies operating within the county.
Revised 1995
Undesireable Plant Management Plan
Page 23
Information regarding the Undesirable Plant Management Act will be
distributed and their cooperation will be encouraged. Assistance in helping
them develop their integrated weed management programs will be offered. In
working with landowners on private property, all lands bordering the rivers in
the county will be considered high priority areas. Landowner compliance with
the Undesirable Plant Management Act will be encouraged.
4. Identifying Noxious Weeds in Bordering Counties That Do Not Occur in
Weld County
Contact will continue to be made with the weed control departments in the
bordering counties to identify the noxious weed species which occur in each
county that would threaten Weld County. Plans have been developed to
monitor the borders of Weld County, as necessary.
D. EDUCATIONAL PROGRAMS
Education of the public is one of the most important components of a Weed
Management program. Emphasis will be placed on continuing a multifaceted
educational program. The following programs have been instituted in the past and
will continue to be conducted every year.
1. Timely newspaper articles concerned with weed identification and
management.
2. Timely radio broadcasts following the information in the newspaper articles.
3. Conducting landowner weed management seminars and calibration workshops.
4. Having an educational booth at the Colorado Farm Show.
5. Utilizing brochures and CSU Service in Action brochures to hand out to
individual landowners.
Revised 1995
Undesireable Plant Management Plan
Page 24
E. MAPPING
Establishing an accurate baseline map of the existing noxious weed infestations in the
county is extremely important for the ongoing evaluation of the effectiveness of the
county weed management program. Therefore, a computerized mapping program will
be established that will map the noxious weeds established in Weld County.
County roadsides will be mapped using a computer and printer/ datalogger on the
spray equipment. Private and state land will be mapped by
Public Works Department personnel taking aerial maps from the county assessor's
office into the field and mapping on site. Through the use of the Design auto CADD
computer mapping program and-a-digitizer, the noxious weed infestations will be
mapped. All mapping information will be stored in the county IBM computer systems
and can be retrieved for future evaluation.
F. ESTABLISHING COOPERATIVE INTERGOVERNMENTAL AGREEMENTS
Contact will be made with the following agencies concerning compliance with the
Colorado Undesirable Plant Management Act.
1. Colorado Department of T ansporta'tiOn
2. Colorado State Department of Parks and Recreation
3. Colorado Division of Wildlife
4. Colorado State Land Board
5. U.S. Forest Service
Assistance will be offered in helping each agency develop integrated weed
management plans for their lands. Actual assistance in carrying out the weed control
programs on their properties will also be offered. Cooperative intergovernmental
agreements can be established if Weld County is asked to assist in implementing the
weed control measures.
G. ADOPT A ROADSIDE PROGRAM
An "Adopt a Roadside" program will be established which will give landowners the
ability to take the responsibility to manage the noxious weeds on the county rights-of-
way that borders their property.
Revised 1995
Undesireable Plant Management Plan
Page 25
Landowners who are chemically sensitive or for some reason do not want chemicals
sprayed or mowing activities carried out along their property, can take the
responsibility for managing the noxious weeds on the roadside right-of-way.
Landowner agreements with specific requirements for compliance will be established.
H. Enforcement on Private and Public Property
Cooperation from all landowners (private and state) will be encouraged through
positive communication by mail and through personal contact. When weed control
measures are not carried out by a landowner, enforcement measures may have to be
instituted. All procedures as established by the Undesirable Plant Management Law,
CRS 35-5.5-109, the Pest Control Districts Law, CRS 35-5-108, Weld County
Ordinance 169-A,and any and all federal, state,and local regulations will be followed,
prior to any enforcement activities being carried out on private or public property.
Integrated weed management plans will be requested from certain landowners, as
determined by the county vegetation management specialist and the Undesirable Plant
Management Advisory Board.
Work priorities must be established due to the size of the county and the number of
landowners with existing noxious weed problems. The following list prioritizes where
enforcement activities will be carried out in ranking order of importance.
1. Lands bordering all waterways (rivers and irrigation ditches).
2. Complaint properties.
3. Landowners identified as negligent in the past.
4. Landowners with fivc or more acres of noxious weeds. Landowners with
twenty percent(20%)or more of their property infested with noxious weeds.
V. EVALUATION OF PROGRAM
The goals and the plan of work established in chapters 3 and 4 of this document will be
reviewed and evaluated at the end of every year. A written evaluation will be prepared
establishing additions or changes in the plan of work for the following year. Any additions
or changes shall be approved by the Undesirable Plant Management Advisory Board and the
Board of County Commissioners.
The Weld County Undesirable Plant Management Plan shall be reviewed and amended, as
needed, at least every three years (CRS 35-5.5-107(4a)).
Revised 1995
Undesireable Plant Management Plan
Page 26
VI. NO WAIVER OF IMMUNITIES/NO CREATION OF DUTIES, STANDARD OF
CARE, OR RIGHTS FOR THIRD PARTIES
No portion of this Undesirable Plant Management Plan shall be deemed to constitute a waiver
of any immunities which Weld County, Colorado, by and through the Board of County
Commissioners of Weld County, or any pest control districts and/or their Boards, or the Weld
County Undesirable Plant Management Advisory Commission or their officers or employees
may possess, nor shall any provision of this Plan be construed to create any duty, standard of
care or rights in favor of any third parties with the respect to any obligation created by this
Plan.
Revised 1995
vigor it / J '
ORDINANCE NO. 169-A
IN THE MATTER OF REPEALING AND REENACTING ORDINANCE 169, THE UNDESIRABLE
PLANT MANAGEMENT PLAN FOR THE COUNTY OF WELD, STATE OF COLORADO
BE IT ORDAINED BY THE BOARD OF COUNTY COMMISSIONERS OF THE COUNTY OF
WELD, STATE OF COLORADO:
WHEREAS, the Board of County Commissioners of the County of Weld, State of Colorado,
pursuant to Colorado statute and the Weld County Home Rule Charter, is vested with the authority
of administering the affairs of the County of Weld, State of Colorado, and
WHEREAS, on May 4, 1992, the Board of County Commissioners adopted Weld County
Ordinance 169, which became effective May 12, 1992, and which provides for the adoption and
enforcement of an undesirable plant management plan in Weld County, and
WHEREAS, said Ordinance 169 designates five (5) weed species as undesirable and
mandated for management in Weld County, those being: Leafy Spurge (Euphorbia esula), Russian
Knapweed (Centaruea repens), Diffuse Knapweed (Centaurea diffusa), Spotted Knapweed
(Centaurea maculosa), Canada Thistle (Cirsium arvense), and Musk Thistle (Carduus nutans), and
WHEREAS, upon the recommendation of the Weld County Undesirable Plant Management
Advisory Board, the Board of County Commissioners hereby finds and determines that there is a
need to add two weed species to the list of those currently designated as undesirable and
mandated for management in Weld County, the two additions being: Field Bindweed (Convolvulus
arvensis) and Scotch Thistle (Onopordum acanthium), thereby requiring, at a minimum, an
amendment to said Ordinance 169, and
WHEREAS, upon further recommendation of the Weld County Undesirable Plant
Management Advisory Board, the Board of County Commissioners hereby finds and determines
that there is a need to make other revisions to the Weld County Undesirable Plant Management
Plan, thereby requiring the repeal and reenactment of said Ordinance 169.
NOW, THEREFORE, BE IT ORDAINED, by the Board of County Commissioners of the
County of Weld, State of Colorado, that Weld County Ordinance Number 169, adopted May 4,
1992, be, and hereby is, repealed and, by and through this Ordinance 169-A, be, and hereby is,
reenacted, as follows:
ARTICLE 1 --WELD COUNTY
UNDESIRABLE PLANT MANAGEMENT PLAN
I. INTRODUCTION
A. DESCRIPTION OF THE COLORADO UNDESIRABLE PLANT MANAGEMENT ACT
The Colorado Undesirable Plant Management Act, CRS §35-5.5-101, et. seq.,
(flit tgr "the Act") states that certain undesirable plants pose a threat to the
_ -7 960121
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PAGE 2
continued economic and environmental value of the land in Colorado and that they
must be managed by all landowners in the state. The undesirable plants
designated for mandatory management statewide are: Leafy Spurge (Euphorbia
esula), Russian Knapweed (Acroptilon repens), Diffuse Knapweed (Acroptilon
diffuse) and Spotted Knapweed (Centaurea maculosa). Additional weed species
may be added to the state list by each local jurisdiction: The Act states such that
local governments (cities and counties) are directed to take the necessary steps to
manage the undesirable plants in their respective jurisdictions. They are further
directed to appoint an advisory commission whose responsibilities are threefold:
1. Develop recommended management criteria and
integrated weed management plans for managing the
designated undesirable plants;
2. Recommend the addition, if necessary, of undesirable
plants that shall be subject to integrated management;
3. Recommend to the county commissioners the names of
those landowners who shall be required to submit
integrated weed management plans for managing the
undesirable plants on their property.
The Act further states that by January 1, 1992, each local governing body is to have
developed and adopted an Undesirable Plant Management Plan for all lands within
its jurisdictional boundaries.
II. DESCRIPTION OF THE COUNTY OF WELD WEED PROBLEM
A. WEED SPECIES IN WELD COUNTY TO BE CONTROLLED, PURSUANT TO WEED CONTROL
LAWS
The Pest Control Districts Law (CRS 35-5-104) enabled landowners in each county
the ability, through a lengthy petitioning and balloting process, to establish weed
control districts. Within each weed district, designated species are mandated to be
controlled. In Weld County, nine such weed districts exist. The districts occur in the
lower two-thirds of the County, and the weed species designated for control range
from three to seven species, depending upon the weed district. The weed species
that are currently being managed in at least a part of Weld County are as follows:
i Leafy Spurge (Euphorbia Esula),
Canada Thistle (Cirsium arvense),
Musk Thistle (Carduusnutans),
Field Bindweed (Convolvolus arvensis),
Whitetop (Cardaria draba),
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PAGE 3
Russian Knapweed (Acroptilon repens)
Wild Proso Millet(Panicum miliaceum)
Under the Act(CRS§35-5.5-101, et seq.),there are four weed species which are mandated
for county-wide management. They are Leafy Spurge, and Russian, Diffuse and Spotted
Knapweed. Canada Thistle, Musk Thistle, Scotch Thistle and Field Bindweed are added
to the county-wide undesirable plant list by this Ordinance 169-A, in accordance with
CRS §35-5.5-108(3).
Of the weed species listed previously, Canada Thistle, Field Bindweed, Leafy Spurge, Musk
Thistle, Russian Knapweed, Whitetop and Wild Proso Millet cover the most acreage in Weld
County and pose the greatest economic and environmental threat to the county. Diffuse
Knapweed is currently localized to a few drainages and rights-of-way in the southwest part
of the County, and there are no known Spotted Knapweed infestations in the County.
III. OBJECTIVES AND GOALS
A. STATEMENT OF OBJECTIVES
The objectives of the Weld County Public Works Department with respect to weed
management in Weld County are fourfold:
1. Develop and carry out a comprehensive noxious weed control
program on all county right-of-way and other county property, such
as in sand and gravel mining operations, grader shed lots and open
space areas.
2. Establish an educational program, by using mailings and holding
educational and calibration seminars, that will effectively
communicate weed management information to the landowners in
the County.
3. Identify non-informed or negligent landowners who are not carrying
out weed management programs on their property and provide
technical support for establishing weed management plans or
enforce on properties, if necessary.
4. Work with all state and federal agencies, through intergovernmental
agreements, if necessary, towards establishing effective weed
management programs on their property.
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PAGE 4
B. SHORT TERM GOALS —(January 1995 to December 1998)
1. Map all the County roads for noxious weed infestations.
2. Map on a computer program at least half of the landowners that
have Leafy Spurge, Canada Thistle and Russian Knapweed
infestations.
3. Continue to establish contact with landowners on the South Platte
and Poudre Rivers who have noxious weed infestations.
4. Establish educational/calibration seminars (annually) that work
directly with 150-200 landowners each year.
5. Have established contact with the Colorado Department of
Highways, Department of Parks and Recreation, Colorado Land
Board, Division of Wildlife and U.S. Forest Service. Help them
develop Weed Management Plans and where appropriate enter into
cooperative intergovernmental agreements.
6. Have established six to eight biological control release sites
throughout the county in cooperation with the Colorado Department
of Agriculture and private landowners.
7. By 1995 have reduced the noxious weed acreage sprayed on
county right-of-way by 15-20%.
C. LONG TERM GOALS— ( January 1999 to December 2002)
1. Have mapped on the computer program most noxious weed
infestations county-wide, including private, state and federal lands.
2. Have reduced the noxious weed acreage sprayed on county right-of-
way by 40-50%.
3. Have contacted and worked with most landowners county-wide who
have a noxious weed infestation.
4. Have established 30-50 biological control release sites in the county.
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PAGE 5
V. PLAN OF WORK - IMPLEMENTATION
A. DESCRIPTION OF INTEGRATED WEED MANAGEMENT TECHNIQUES
The weed species designated as undesirable and mandated for management are
Leafy Spurge (Euphorbia Esula), Russian Knapweed ( Acroptilon repens), Diffuse
Knapweed (Centaurea diffusa), Spotted Knapweed (Centaurea maculosa), Canada
Thistle (Cirsium arvense) Musk Thistle (Carduus nutans), Scotch Thistle
(Onopordum acanthium) and Field Bindweed (Convolvulus arvensis). Integrated
weed management methods are to be used in managing these weed species (CRS
§35-5.5-107). Integrated management techniques include education; preventive
measures; and control measures including cultural, mechanical, biological and
chemical control. For the purposes of this plan the following definitions for the
control measures will be used.
1. Cultural Control means those methodologies or management
practices conducted to favor the growth of desirable plants over
undesirable plants, including, but not limited to, maintaining an
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 an area.
2. Mechanical Control means those methodologies or management
practices that physically disrupt plant growth, including, but not
limited to, tilling, mowing, burning, flooding, mulching, hand-pulling
and hoeing.
3. Biological Control means the use of organisms such as sheep,
goats, cattle, insects and plant diseases to disrupt the growth of
undesirable plants.
4. Chemical Control means the use of herbicides or plant growth
regulators to disrupt the growth of undesirable plants.
Management of the various undesirable plants will vary depending upon the site
where the plant is located. Management options for each weed species will be
developed for each site. The integrated management options listed below are meant
to provide various management techniques for controlling the noxious weeds in the
various environmental sites they are found. By no means are all the management
options mentioned. Additional combinations of management techniques are
possible which may be submitted by private landowners. The integrated weed
management plans submitted by individual landowners will be evaluated by the
Weld County Vegetation Management Specialist and the Integrated Weed
Management Advisory Commission on a case by case basis.
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PAGE 6
B. INTEGRATED WEED MANAGEMENT OPTIONS FOR EACH WEED SPECIES
LEAFY SPURGE: Leafy Spurge is a deep rooted perennial plant that spreads by
seeds and creeping roots. It has a vast underground root system which makes it
difficult to control with any one control technique. Leafy Spurge is found primarily
in riparian sites (along waterways such as the Poudre and South Platte Rivers) in
Weld County and also along irrigation ditches, range and pastures, roadsides and
other non-cropland sites.
1. Control Measures
a. Cultural Control: Seeding perennial grasses and forbs can be an
effective management tool. Early emerging plant species that utilize
early season moisture such as Smooth Brome (Bromus inermis) or
Crested Wheatgrass (Agropyron cristatum) have reduced Leafy
Spurge density and limited the spread and establishment of new
infestation. Sequential glyphosate applications followed by a
seeding of Luna Pubescent Wheatgrass, Ephraim Crested
Wheatgrass, Intermediate Wheatgrass, Sherman Big Bluegrass or
Bozoisky Russian Wild Rye has shown to be very effective in
reducing an existing stand of Leafy Spurge.
b. Mechanical Control: Mechanical control of Leafy Spurge is difficult
at best; however, repeated mowing every 14-21 days throughout the
summer, starting before flowering stage, will at least keep the plants
from going to seed and may reduce the underground root reserve.
Research results are not available to indicate whether stand
reduction or eradication could be achieved through use of this
technique.
c. Biological Control: Grazing with sheep and goats throughout the
spring, summer, and fall will keep Leafy Spurge from going to seed
and may reduce the underground root reserve. This practice may
also weaken the plants to make them more susceptible to chemical
control.
Several insect species that have been released by the USDA in the
United States are showing some control of Leafy Spurge. Two
species of flea beetles, Apthona flava and Apthona nigriscutis feed
on Leafy Spurge. Adults feed on the foliage during the summer and
the larvae burrow through the soil and mine the roots and fine root
hairs. These insects used alone may not control Leafy Spurge.
When used along with other insects such as Spurgia Esula, a gall
960121
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•
PAGE 7
midge which feeds on the flowers preventing seed production, they
will weaken the plant and make it more susceptible to other control
methods, particularly chemical control.
d. Chemical Control: There are a number of herbicides labeled for
use on Leafy Spurge. Those that can be used independently or in
combination with each other are: picloram (Tordon®); dicamba
(Banvel®); 2,4-D (many different formulations); glyphosate
(Roundup® and Rodeo®); fosamine (Krenite®) and any EPA
approved chemicals labeled for use on Leafy Spurge.
2. Integrated Management Options by Site:
a. Range, Pasture and Riparian Sites
Option#1 Biological and Chemical Control: Grazing with sheep
or goats from early April through late August or early September,
followed by a herbicide treatment in late September or early
October.
Option #2 Biological and Chemical Control: The release of
insects such as Apthona nigriscutis, Apthona flava, Spurgia Esula,
and other species conducive to the area can be made. A herbicide
treatment can then be made during the true flower stage (where
insects were not released) and in the fall where insects were
released. Herbicide applications should only be carried out in the fall
where insects are used. Use of herbicides at different times if the
growing season can be instituted as additional IPM research is
conducted and recommendations are developed.
Option #3 Mechanical and Chemical Control: Mowing can be
carried out throughout the season with the first mowing cycle at the
bud stage. Mowing should stop during late August followed by a
herbicide treatment during late September or early October (before
a hard freeze).
Option #4 Biological or Mechanical Control Only: The use of
sheep or goats or mowing should be used all season to keep Leafy
Spurge from going to seed. Whether this method will keep the
existing infestation from spreading by underground root growth is
uncertain.
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Option #5 Chemical Control Only: Herbicides should be used in
the spring, early summer during the true flower stage and in the fall
just before a hard freeze. Only the herbicides labeled for the site
intended will be used.
b. Along Irrigation Ditches
Option #1 Biological and Chemical Control: The release of
insects such as Apthona nigriscutis, Apthona (lava, Spurgia Esula
and other species conducive to the area could be made. A herbicide
treatment should be carried out at the true flower stage (if the
Spurgia Esula has not kept the plants from going to seed) and/or in
the fall just before a hard freeze.
Option#2 Chemical Control Only: Herbicides can be used in the
spring or early summer during the true flower stage and in the fall
just before a hard freeze. Only the herbicides labeled for the site
intended will be used.
c. Road Right-of-Ways and Other Non-Crop Areas
Option#1 Mechanical and Chemical Control: One mowing cycle
can be carried out at the bud to early flower stage. A herbicide
application should be made at the true flower stage.
Option #2 Chemical Control Only: Herbicides can be used in the
spring or early summer during the true flower stage and in the fall
just before a hard freeze. Only the herbicides labeled for use on
roadsides and other non-cropland areas would be used.
RUSSIAN KNAPwEED: Russian Knapweed is a non-native perennial plant that
spreads by seeds and creeping roots. It has the ability to release chemicals into the
environment as foliage decays which inhibit the growth of surrounding vegetation
(allelopathic properties). Thus, once established, Russian Knapweed can colonize
an area rapidly. Russian Knapweed is found primarily in range and pastures,
roadsides and other non-cropland sites in Weld County.
1. Control Measures
a. Cultural Control: Seeding perennial grasses such as Smooth
Brome (Bromus inermis) will help to compete with Russian
Knapweed and slow its spread. In addition, stimulating grass growth
by fertilizing and/or irrigation should increase grass competition.
Due to the allelopathic properties of Russian Knapweed, other
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PAGE 9
•
control techniques such as judicious chemical control would have to
be implemented in order to give grasses a chance to compete.
b. Mechanical Control: Mechanical control of Russian Knapweed
could be carried out throughout the summer with repeated mowing
every 14-21 days. This would at least keep Russian Knapweed from
going to seed. Whether this control technique will reduce the root
mass and subsequently reduce an existing stand is not known.
c. Biological Control: There are currently no biological control agents
available for Russian Knapweed.
d. Chemical Control: There are a number of herbicides labeled for
use on Russian Knapweed. Those that can be used independently
or in combination with each other are: chlorsulfuron (Telar®);
picloram (Tordon®); 2,4-D (many different formulations); glyphosate
(Roundup®and Rodeo®) and any EPA approved chemical labeled
for use on Russian Knapweed.
2. INTEGRATED MANAGEMENT OPTIONS BY SITE
a. Range and Pastures:
Option #1 Mechanical and Chemical: Mowing can be carried out
throughout the season with the first and successive mowing cycles
carried out at the bud stage. A herbicide treatment can then be
made in the fall before a hard freeze.
Option #2 Cultural and Chemical: A herbicide application, using
short residual herbicides such as glyphosate and/or 2,4-D can be
made followed up by reseeding with a competitive grass such as
smooth brome or other sod forming species. In addition, fertilization
or irrigation could be instituted to stimulate increased grass growth.
Option#3 Chemical Control Only: Herbicide applications can be
made to Russian Knapweed during the bud stage, bloom to post-
bloom and/or in the fall, depending upon herbicide used.
b. Road Right-of-Way and other Non-Crop Areas.
Option #1 Mechanical and Chemical: One mowing cycle can be
carried out at the bud to early flower stage. A herbicide application
can be made during the bud stage, bloom to post-bloom and/or in
the fall, depending upon the herbicide used.
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Option #2 Cultural and Chemical Control: Use of short residual
herbicides such as glyphosate and/or 2,4-D can be used in the early
summer during the bud stage. Seeding with perennial grasses such
as Smooth Brome, Luna Pubescent Wheatgrass, Ephraim Crested
Wheatgrass, Intermediate Wheatgrass, Sherman Big Bluegrass or
Bozoisky Russian Wild Rye can than be carried out later in the
summer, at the appropriate time.
Option #3 Chemical Only: Herbicide applications can be made
during the bud stage, bloom to post bloom and/or in the fall,
depending upon the herbicide used.
DIFFUSE KNAPWEED: Diffuse Knapweed is a non-native, biennial to short lived
perennial forb that reproduces by seed. It spreads rapidly by the mature plant
breaking off at ground level and being blown with the wind, dispersing seed. It is
a pioneer species that will quickly invade disturbed, dry sites. Diffuse Knapweed
is found in the southwest part of Weld County along rights of way, dry pasture sites
and in gravelly riparian sites, such as along Boulder Creek and the St. Vrain and
South Platte Rivers.
1. Control Measures
a. Cultural Control: Cultural Control of Diffuse Knapweed is similar
to Russian Knapweed in that seeding with perennial grasses such
as smooth brome and crested wheatgrass will help to compete with
Diffuse Knapweed and slow its spread. Seeding alone in infested
sites will not, however, control the existing stand.
b. Mechanical Control: Mowing Diffuse Knapweed when it is in the
bud stage and again when it is flowering can significantly reduce
seed production. Keeping Diffuse Knapweed from going to seed
over a number of years can eventually eliminate an infestation, once
the seed source in the soil is depleted.
c. Biological Control: Two species of picture-winged flies, Urophora
affinis and U. quadrifasciata have demonstrated the ability to reduce
the seed production of diffuse and Spotted Knapweed. The flies lay
eggs on the developing seed heads. As a result of the larvae
feeding on the flowering heads, the plants produce galls which
reduces seed production. The Colorado insectory is currently
rearing these two flies and has made releases in the state the last
three years.
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d. Chemical Control: There are a few herbicides labeled for use on
Diffuse Knapweed. Those that can be used independently or in
combination with each other are: picloram (Tordon®); dicamba
(Banvel®); glyphosate (Roundup®); 2,4-D (many different
formulations) and any EPA approved chemical labeled for use on
Diffuse Knapweed.
2. Integrated Management Options by Site
a. Pasture and Riparian Areas
Option#1 Cultural and Chemical Control: A herbicide application
can be made in early summer when Diffuse Knapweed is in the
rosette through bolting stage. Reseeding with competitive perennial
grasses such as smooth brome and crested wheatgrass can be
followed later in the summer depending upon the herbicide used and
rate of application.
Option #2 Biological and Chemical Control: The release of
insects such as Urophora affinis and U. quadrifasciata can be made.
A herbicide treatment can then be made from the rosette through
bolting stage (where insects were not released) and in the fall where
insects were released. Herbicide applications should only be carried
out in the fall, where insects are used. The use of herbicides at
different times of the growing season can be instituted as additional
IPM research is conducted and recommendations are developed.
Option #3 Mechanical and Chemical Control: Mowing can be
carried out when Diffuse Knapweed is in the bud stage and again at
flowering. A herbicide application can then be made to any plants
that have re-bolted, if necessary.
Option #4 Mechanical Control Only: Mowing can be carried out
throughout the season which will reduce seed set.
Option #5 Chemical Control Only: Herbicide application can be
made during the rosette stage, spring or fall, and while bolting.
b. Right-of-Ways and Other Non-Crop Areas
Option#1 Cultural and Chemical Control: Same as for Option#1
in pasture and riparian areas.
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Option #2 Mechanical and Chemical Control: One mowing
operation can be carried out when Diffuse Knapweed is in the bud
stage. If necessary, a herbicide application can be made to plants
that have re-bolted.
Option #3 Mechanical Control Only: Same as for Option #4 in
pasture and riparian areas.
Option #4 Chemical Control Only: Same as for Option #5 in
pasture and riparian areas.
SPOTTED KNAPWEED: Spotted Knapweed is a non-native, perennial forb that
reproduces by seed. It is a highly competitive plant in rangeland sites that will
exclude most grasses and forbs with time. There is limited Spotted Knapweed
infestations currently along the South Platte River drainage in Weld County.
1. Control Measures
a. Cultural Control: Cultural control of Spotted Knapweed is similar
to such control of Russian and Diffuse Knapweed in that seeding
with perennial grasses such as Smooth Brome and crested
wheatgrass will help to compete with Spotted Knapweed and slow
its spread. Seeding infested sites will not, however, control the
existing stand. In range and pasture conditions, good grazing
management practices will help to reduce the spread of the
knapweeds in general.
b. Mechanical Control: Mechanical control of Spotted Knapweed
could be carried out throughout the summer with repeated mowing
every 14-21 days. This would at least keep Spotted Knapweed from
going to seed. Whether this control technique will reduce the root
mass and subsequently reduce an existing stand is not known.
c. Biological Control: The same as what was developed under
biological control for Diffuse Knapweed.
d. Chemical Control: There are a few herbicides labeled for use on
Spotted Knapweed. Those that can be used independently or in
combination with each other are: picloram (Tordon®), dicamba
(Banvel®), 2,4-D (many different formulations and clopyrald and 2,4-
D (Curtail®).
CANADA THISTLE: Canada Thistle is an aggressive, creeping perennial that
reproduces by seed and vegetative buds in the root system. It is a difficult plant to
control because of its extensive root system. Vertical roots may grow 6-15 foot
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deep and horizontal roots may extend 15 feet or more. Canada Thistle is the most
widespread noxious weed in Weld County. It can be found in most habitat types,
including: pastures, riparian sites (along waterways such as the Poudre, South
Platte, St. Vrain and Big Thompson Rivers), irrigation ditches, along roadside
rights-of-way and in the various crop and non-cropland sites.
1. Control Measures
a. Cultural Control: Plant competition from various grasses and from
alfalfa can be an effective management tool. Early emerging grass
species such as Smooth Brome and Crested Wheatgrass can be
used to compete with Canada Thistle and slow the spread and
establishment of new infestations. Competition alone, however, is
seldom effective on Canada Thistle.
b. Mechanical Control: Mechanical Control of Canada Thistle could
be carried out throughout the summer with repeated mowing every
14 days. Such method keeps Canada Thistle from going to seed;
however, mowing has shown to stimulate new shoot growth from
roots. Consequently, mowing alone may increase shoot density in
an established stand. Whether consistent mowing for consecutive
years (two to three years) will reduce the root mass and
subsequently reduce an existing stand is unknown.
c. Biological Control: There is one insect species, a weevil, called
Ceutorynchus litura, that is currently being used as a biological
control agent on Canada Thistle in Colorado. The female lays eggs
on the underside of the leaves in early spring and then the larvae
bore into the main leaf vein and migrate down to the crown of the
plant. The holes created by the larvae open up Canada Thistle to
secondary infection. Where high numbers of the larvae occur death
of Canada Thistle can occur.
d. Chemical Control: There are a number of herbicides labeled for
use on Canada Thistle, depending upon where the thistle is found.
The herbicides that can be used independently or in combination
with other compounds are: picloram (Tordon®); dicamba (Banvel®);
2,4-D (many different formulations); chlorsulfuron (Telar®);
clopyralid (Curtail®, Stinger®, Transline®); glyphosate (Roundup®,
Rodeo®) and any EPA approved chemicals labeled for use on
Canada Thistle.
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2. Integrated Management Options by Site
a. Range, Pasture and Riparian Sites
Option #1 Biological and Chemical: Release of the insect
Ceutorynchus litura can be made during the early summer. A
herbicide application can then be made at the bud stage (where
insects were not released) and in the fall where insects were
released. Herbicide applications should only be carried out in the
fall, where insects were directly released. Use of herbicides at
different times of the growing season can be instituted as additional
IPM research is coordinated and recommendations are developed.
Option#2 Mechanical and Chemical: Mowing can be carried out
throughout the season with the first mowing cycle at the bud stage.
Mowing should stop during late August followed by a herbicide
treatment during late September through October, before a hard
freeze.
Option #3 Cultural and Chemical Control: A herbicide
application, using short residual herbicides such as glyphosate
and/or 2,4-D can be made followed up by reseeding with a
competitive grass such as smooth brome or other sod forming
species. In addition, fertilization or irrigation could be instituted to
stimulate increase grass growth.
Option#4 Chemical Control Only: Herbicide applications can be
made to Canada Thistle from rosette to the bud stage, and/or in the
fall, depending upon the herbicide used.
b. Road Right-of-Ways and Other Non-Crop Areas
Option#1 Mechanical and Chemical: One mowing cycle can be
carried out at the bud to early flower stage. A herbicide application
can be made from rosette to bud stage and/or in the fall, depending
upon the herbicide used.
Option #2 Cultural and Chemical Control: A herbicide application
can be made in early summer when Canada Thistle is in the rosette
through bud stage. Reseeding with competitive perennial grasses
such as smooth brome and crested wheatgrass can be followed later
in the summer depending upon the herbicide used and rate of
application.
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Option#3 Chemical Control Only: Herbicide applications can be
made from rosette to bud stage, and/or in the fall, depending upon
the herbicide used.
c. Cropland Sites
Canada Thistle is found in almost every crop grown in Weld County.
Prescription weed management measures developed by Colorado
State University weed scientists and the Weld County Extension
Agronomist will be used.
MUSK THISTLE: Musk Thistle is a biennial plant that reproduces only by seed.
Rosettes (clump of leaves on the ground) are formed during the first year of growth
and the plant bolts and sets seed the second year. It is a prolific seed producer with
a single plant producing up to 20,000 seeds. Musk Thistle is found primarily in
pastures and riparian sites (along waterways such as the South Platte, St. Vrain,
Big Thompson, and Little Thompson drainages and Boulder Creek) and along
irrigation ditches, roadside rights-of-way and other non crop areas.
1. Control Measures
a. Cultural Control: Maintaining pastures and riparian sites in good
condition is the primary method of culturally managing Musk Thistle.
Promoting good grass growth by proper grazing management and
fertilizing according to soil testing recommendations will prevent
establishment of Musk Thistle.
b. Mechanical Control: Musk Thistle can be effectively controlled
mechanically. Severing the roots below ground with a shovel or hoe
or mowing Musk Thistle every time it reaches early flower stage will
reduce, if not eliminate seed production. If mowing occurs mid to
late flower stage, the thistle should be gathered and burned to
destroy any seed that has developed.
c. Biological Control: Two species of weevils, Rhinocyllus conicus
(seed head weevil) and Trichosirocalus horridus, attack two different
sites of Musk Thistle. The seed head weevil, as its name implies,
attacks the seeds of Musk Thistle. Eggs are laid by the female on
the back of developing flowers and then the larvae bore into the
flower, destroying the developing seed. The seed head weevil can
reduce seed production by as much as 50%. Use of this weevil as
the sole means of controlling Musk Thistle is not very effective.
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Trichosirocalus horridus attacks the crown area of Musk Thistle
rosettes, killing or weakening the plant before it bolts. Use of both
weevil species together may prove to be an effective biological
control program.
d. Chemical Control: There are a number of herbicides labeled for
use on Musk Thistle, depending upon where the thistle is found.
The herbicides that can be used independently or in combination
with other compounds are: picloram (Tordon®); dicamba (Banvel®);
2,4-D (many different formulations); chlorsulfuron (Telar®);
clopyralid (Curtail®, Stinger®, Transline®); glyphosate (Roundup®,
Rodeo®) and any EPA approved chemical labeled for use on Musk
Thistle.
2. Integrated Management Options by Site
•
a. Pasture and Riparian Sites
Option #1 Biological and Chemical: Release of Trichosirocalus
borridus can be made at the appropriate time of the summer.
Rhinocyllus conicus is well established in Weld County and should
already be infesting the stand. A herbicide application can then be
made to Musk Thistle at the flower stage. Telar or Escort should be
used when treating Musk Thistle in the flower stage. Herbicide
applications should only be carried out in the flower stage in order to
allow the seed head weevil to complete its life cycle. Use of
herbicides to rosettes in the spring or fall should not be carried out
where Trichosirocalus horridus was released. Use of herbicides at
different times of the growing season can be instituted as additional
IPM research is conducted and recommendations are developed.
Option #2 Mechanical and Chemical Control: Mowing can be
carried out throughout the summer when Musk Thistle is in the bud
to early flower stage. A herbicide application can than be made in
October to the fall rosettes and any bolted plants.
Option #3 Mechanical Control Only: Multiple mowings (two to
four) can be carried out throughout the summer when Musk Thistle
is in the bud stage, keeping it from producing seed. If mowing
occurs mid to late flower stage, the thistle should be gathered and
burned to destroy any seed that has developed.
Option #4 Chemical Control Only: Herbicides can be used in the
spring and fall when the plant is in the rosette stage. Only the
herbicides labeled for the site intended will be used.
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b. Road Right-of-Ways and other Non Crop Areas
Option#1 Biological and Chemical Control: Same as for Option
#1 in pasture and riparian sites.
Option#2 Mechanical and Chemical Control: One mowing pass
can be made when Musk Thistle is in the bud stage. A herbicide
application can be made in the fall to the rosettes and re-bolted
plants.
Option#3 Chemical Control Only: Herbicides can be used in the
spring and the fall when the plant is in the rosette stage. Only the
herbicides labeled for the site intended will be used.
SCOTCH THISTLE: Scotch Thistle is a biennial plant that reproduces only by seed.
Rosettes are formed during the first year of growth and the plants bolt and set
seeds the second year. The leaves are densely covered with hair, giving the plant
a grayish-green color. Scotch Thistle is primarily found in pastures and riparian
sites (South Platte River Drainage) and along roadside rights of way and other non-
crop areas in southern Weld County.
1 . Control Measures
a. Cultural Control: Maintaining pastures and riparian sites in good
condition is the primary method of culturally managing Scotch
Thistle. Promoting good grass growth by proper grazing
management and fertilizing according to soil testing
recommendations will help prevent establishment of Scotch Thistle.
b. Mechanical Control: Scotch Thistle can be efficiently controlled
mechanically. Severing the roots below ground with a shovel or
hoe or mowing Scotch Thistle every time it reaches bud to early
flower stage will reduce, if not eliminate seed production. If mowing
occurs mid to late flower stage, the thistle should be gathered and
burned to destroy any seed that has developed.
c. Biological Control: No biological control agents are available for
Scotch Thistle. One weevil species, Rhinocyllus conicus, will
move from Musk Thistle to Scotch Thistle; however, effective control
of Scotch Thistle has not been demonstrated.
d. Chemical Control: There are a number of herbicides labeled for
use on Scotch Thistle, depending upon where the thistle is found.
The herbicides that can be used independently or in combination
with other compounds are: picloram (Tordon®); dicamba
(Banvel®); 2,4-D (many different formulations); chlorsulfuron
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(Telar®); metsulfuron (Escort®); clopyralid (Curtail®); Stinger®;
Transline® and glyphosate (Roundup®, Rodeo®) and any other
EPA approved chemical labeled for use on Scotch Thistle.
2. Integrated Management Options By Site
a. Pastures and Riparian Sites
Option #1 Mechanical and Chemical Control: Multiple mowings
(two to four) can be carried out throughout the summer when Scotch
Thistle is in the bud stage, keeping it from producing seed. A
herbicide application can than be made in October to the fall rosettes
and any bolted plants.
Option #2 Mechanical Control Only: Multiple mowings (two to four)
can be carried out throughout the summer when Scotch Thistle is in
the bud stage, keeping it from producing seed. If mowing occurs mid
to late flower stage, the thistle should be gathered and burned to
destroy any seed that has developed.
Option #3 Chemical Control Only: Herbicides can be used in the
spring and fall when the plant is in the rosette stage. Only the
herbicides labeled for the site intended will be used.
b. Road Rights of Way and Other Non Crop Areas
Option#1 Mechanical and Chemical Control: One mowing pass can
be made when Scotch Thistle is in the bud stage. A herbicide
application can be made to rebolted plants in the bud stage and/or to
fall regrowth.
Option #2 Chemical Control: Herbicides can be used in the spring
and the fall when the plant is in the rosette stage. Only the herbicides
labeled for the site intended will be used.
FIELD BINDWEED: Field Bindweed is a deep rooted creeping perennial plant that
reproduces by seed and horizontal roots. Bindweed seed can survive in soil up to 40
years; therefore, it is important that bindweed be kept from going to seed. Field
Bindweed is found throughout Weld County in most habitat types including:
rangeland, pastures, along roadside rights of way and in various crop and non-
cropland sites.
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1. Control Measures
a. Cultural Control: Seeding perennial grasses can be an effective
management tool in providing plant competition against bindweed.
Selecting the proper native grass and/or improved cultivar grass seed
mix for a site specific location is important. For site specific reseeding
recommendations the Natural Resource Conservation Service and the
CSU Extension Office can be contacted.
b. Mechanical Control: Mechanical control of Field Bindweed can only
realistically be carried out in cultivated cropland by discing and
cultivating every 3 weeks. This would keep Field Bindweed from
producing seed and would start to reduce root reserves. Mowing is
not effective due to the creeping nature of bindweed. Discing in
range, pasture or roadside is not environmentally sound.
c. Biological Control: There are currently no biological control agents
on Field Bindweed that are cleared for release in the United States;
however, research is in process. Grazing with livestock (cattle or
sheep), with proper stocking rates, can be an effective means of
keeping bindweed from going to seed in range and pasture sites.
d. Chemical Control: There are a number of herbicides labeled for use
on Field Bindweed, depending upon where the bindweed is found.
The herbicides that can be used independently or in combination with
other compounds are: picloram (Tordon®); dicamba (Banvel ®); 2, 4-
D(many different formulations); glyphosate (Roundup®, Rodeo®) and
any other EPA approved chemicals labeled for use on Field
Bindweed.
2. Integrated Management Options by -Site
a. Range and Pasture land
Option #1 Cultural and Chemical Control: A herbicide application
using short residual herbicides such as glyphosate and/or 2,4-D, can
be made, followed by reseeding in fall with a competitive sod forming
grass mix. In addition, fertilization according to soil tests or irrigation
could be instituted to stimulate increased grass growth.
Option #2 Biological Control: Grazing with cattle and sheep
throughout the summer and fall will keep Field Bindweed from going
to seed and may reduce the underground root reserve.
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Option#3 Biological and Chemical Control: Grazing with cattle or
sheep from May through early September followed by a herbicide
treatment in late September or early October.
Option #4 Chemical Control Only: Herbicides can be used during
the flower stage typically in June and July, and in the fall prior to a
hard freeze. Only the herbicides labeled for the site intended will be
used.
b. Road Rights of Way and Other Non Crop Areas
Option #1 Cultural and Chemical Control: A herbicide application
using short residual herbicides, such asglyphosate and/or 2,4-D, can
be made followed by reseeding in the fall with a competitive sod
forming grass mix.
Option #2 Chemical Control Only : Herbicide can be used during
the flower stage, typically in June and July, and in the fall just before
a hard freeze. Only the herbicides labeled for roadsides and other
non cropland areas will be used.
c. Cropland Sites: Field Bindweed is found in almost every crop grown
in Weld County. Prescription weed management measures
developed by Colorado State University weed scientists and the Weld
County Extension Agronomist can be used.
C. PREVENTION MEASURES
Preventive control means using measures which will stop or forestall weeds from
contaminating an area. Establishing preventive measures are often the most
practical and cost effective means of weed control.
The preventive measures which seem most practical for Weld County are as
follows:
1. establishing weed free seed and mulch requirements for reclamation
of disturbed sites,
2. promoting the Colorado Weed Free Hay and Forage program,
3. prioritizing weed management areas along routes of dispersal, and
4. identifying noxious weed species in counties bordering Weld County.
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1. Weed Free Seed and Mulch Standards
Where the ground is disturbed by activities, such as road preparation for road
resurfacing, sand and gravel lot operations and oil and gas well operations,
weeds will be the first plants to colonize or re-vegetate the site. It is important
that these sites be reclaimed so that noxious weeds do not become
established.
Weld County plans to establish standards within two to four years for using
weed free seed and mulch on all county operations concerned with the
reclamation of disturbed sites, such as on roadside resurfacing projects and
sand and gravel lot operations. Additional regulations may be considered for
similar operations being carried out on private land.
2. Weed Free Hay and Forage Program
Standards have been developed that enable growers the ability to have their
hay and forage certified as noxious weed free. These standards will
encourage growers to produce noxious weed free hay and forage so that it
can be shipped and used anywhere in the U.S. (particularly where noxious
weed free standards currently exist).
The Weld County Vegetation Management Specialist will promote the
Colorado Weed Free Forage Standards through the use of seminars, radio
spots and newspaper articles.
3. Prioritizing Weed Management Areas Along Routes of Dispersal
Weeds are spread rapidly through the dispersal of weed seeds in air and
water. Consequently, high weed seed dispersal areas are associated with
right-of-ways, such as along all roads and railroads and along waterways, i.e.,
along the Poudre, South Platte, St. Vrain and Little Thompson Rivers and
irrigation canals.
The County Public Works Department will carry out a noxious weed control
program on all county roads from May through September. The noxious
weeds targeted for control include: Canada, Musk, Scotch and Bull Thistle;
Leafy Spurge; Russian, Diffuse and Spotted Knapweed; Field Bindweed;
whitetop; and wild proso millet. In addition, contact will continue to be made
with the Department of Transportation, all irrigation and ditch companies in
the county, the Union Pacific, Burlington Northern and Great Western
Railroad companies, and the oil and gas companies operating within the
county. Information regarding the Weld County Undesirable Plant
Management Act will be distributed and their cooperation will be encouraged.
Assistance in helping them develop their integrated weed management
programs will be offered. In working with landowners on private property, all
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lands bordering the rivers in the county will be considered high priority areas.
Landowner compliance with the Undesirable Plant Management Act will be
encouraged.
4. Identifying Noxious Weeds in Bordering Counties That Do Not Occur in
Weld County
Contact will continue to be made with the weed control departments in the
bordering counties to identify the noxious weed species which occur in each
county that would threaten Weld County. Plans have been developed to
monitor the borders of Weld County, as necessary.
D. EDUCATIONAL PROGRAMS
Education of the public is one of the most important components of a Weed
Management program. Emphasis will be placed on continuing a multifaceted
educational program. The following programs have been instituted in the past and
will continue to be conducted every year.
1. Timely newspaper articles concerned with . weed identification and
management.
2. Timely radio broadcasts following the information in the newspaper articles.
3. Conducting landowner weed management seminars and calibration
workshops.
4. Having an educational booth at the Colorado Farm Show.
5. Utilizing brochures and CSU Service in Action brochures to hand out to
individual landowners.
E. MAPPING
Establishing an accurate baseline map of the existing noxious weed infestations in
the county is extremely important for the ongoing evaluation of the effectiveness of
the county weed management program. Therefore, a computerized mapping
program will be established that will map the noxious Weeds established in Weld
County.
County roadsides will be mapped using a computer and printer/datalogger on the
spray equipment. Private and state land will be mapped by Public Works Department
personnel taking aerial maps from the county assessor's office into the field and
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mapping on site. Through the use of the auto CADD computer mapping program, the
noxious weed infestations will be mapped. All mapping information will be stored in
the county IBM computer systems and can be retrieved for future evaluation.
F. ESTABLISHING COOPERATIVE INTERGOVERNMENTAL AGREEMENTS
Contact will be made with the following agencies concerning compliance with the
Colorado Undesirable Plant Management Act:
1. Colorado Department of Transportation
2. Colorado State Department of Parks and Recreation
3. Colorado Division of Wildlife
4. Colorado State Land Board
5. U.S. Forest Service
Assistance will be offered in helping each agency develop integrated weed
management plans for their lands. Actual assistance in carrying out the weed control
programs on their properties will also be offered. Cooperative intergovernmental
agreements can be established if Weld County is asked to assist in implementing the
weed control measures.
G. ADOPT A ROADSIDE PROGRAM
An "Adopt a Roadside" program will be established which will give landowners the
ability to take the responsibility to manage the noxious weeds on the county rights-of-
way that borders their property.
Landowners who are chemically sensitive or for some reason do not want chemicals
sprayed or mowing activities carried out along their property, may take the
responsibility for managing the noxious weeds on the roadside right-of-way.
Landowner agreements with specific requirements for compliance will be established.
H. ENFORCEMENT ON PRIVATE AND PUBLIC PROPERTY
Cooperation from all landowners (private and state) will be encouraged through
positive communication by mail and through personal contact. When weed control
measures are not carried out by a landowner, enforcement measures may have to
be instituted. All procedures as established by the Undesirable Plant Management
Law, CRS §35-5.5-109, the Pest Control Districts Law, CRS §35-5-108, Weld County
Ordinance 169-A, and any and all federal, state, and local regulations will be followed,
prior to any enforcement activities being carried out on private or public property.
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Integrated weed management plans will be requested from certain landowners, as
determined by the Weld County Vegetation Management Specialist and the
Undesirable Plant Management Advisory Board.
Work priorities must be established due to the size of the county and the number of
landowners with existing noxious weed problems. The following list prioritizes where
enforcement activities will be carried out in ranking order of importance:
1. Lands bordering all waterways (rivers and irrigation ditches).
2. Complaint properties.
3. Landowners identified as negligent in the past.
4. Landowners with twenty percent (20%) or more of their property infested with
noxious weeds.
V. EVALUATION OF PROGRAM
The goals and the plan of work established in Sections III. and IV. of this Ordinance 169-A
will be reviewed and evaluated at the end of every year. A written evaluation will be prepared
establishing additions or changes in the plan of work for the following year. Any additions
or changes must be recommended by the Undesirable Plant Management Advisory Board
and approved by the Board of County Commissioners.
The Weld County Undesirable Plant Management Plan shall be reviewed and amended, as
needed, at least every three years (CRS §35-5.5-107(4)(a)).
ARTICLE 2 -- ENFORCEMENT OF
UNDESIRABLE PLANT MANAGEMENT PLAN
AUTHORIZED AGENT FOR ENFORCEMENT
Pursuant to CRS §35-5.5-105(2), the Weld County Vegetation Management Specialist, his
employees and agents, are hereby authorized to enforce the above-stated Undesirable Plant
Management Plan in the unincorporated areas of County of Weld, State of Colorado, by
utilizing those procedures set forth in CRS §§35-5-108, 35-5-109, and 35-5.5-108, and any
other applicable State and Federal Statutes, rules, regulations, and ordinances, including the
remaining provisions of this Ordinance No. 169-A.
II. RIGHT OF ENTRY
•
Prior to entering private lands for the purpose of enforcing the Weld County Undesirable
Plant Management Plan as set forth herein, the Weld County Vegetation Management
Specialist shall first obtain a "right of entry"from the Board of County Commissioners, no less
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than ten days after a Notice to Control Identified Undesirable Plants has been sent to the
owner or occupant of the private lands and said owner or occupant has failed to comply with
said notice.
III. MAILING OF ASSESSMENTS
All assessments for the whole cost of any enforcement work performed by the Weld County
Vegetation Management Specialist or his designee(s) upon private lands, including up to
15% for inspection and other incidental costs in connection therewith, shall be mailed to the
landowner or occupant by certified mail. Failure to receive said assessment shall not act as
a defense to said assessment.
V. 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 Weld County
Vegetation Management Specialist or his designee(s) have 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 Weld County Treasurer's Office to
be collected in the same manner as provided for collection of taxes upon the private lands
in accordance with CRS §§35-5-108 and 35-5.5-109(5)(a).
ARTICLE 3 -- SEVERABILITY
If any section, subsection, paragraph, sentence, clause or phrase of this Ordinance No. 169-A is,
for any reason, held or decided to be invalid or unconstitutional, such decision shall not affect the
validity of the remaining portions. The Board of County Commissioners, Weld County, Colorado,
hereby declares that it would have passed this Ordinance No. 169-A, and in each and every section,
subsection, paragraph, sentence, clause and phrase thereof irrespective of the fact that any one or
more sections, subsections, paragraphs, sentences, clauses, or phrases might be declared to be
unconstitutional or invalid.
•
ARTICLE 4 -- LIABILITY
This Ordinance No. 169-A shall not be intended to create a civil cause of action against the Board
of County Commissioners, Weld County, Colorado, or any other person that may administer this
Ordinance No. 169-A in any manner.
ARTICLE 5 -- EFFECTIVE DATE
This Ordinance No. 169-A shall become effective five (5) days after its final public notice, in
accordance with Section 3-14(2) of the Weld County Home Rule Charter.
960121
ORD169
RE: ORDINANCE NO. 169-A
PAGE 26
ARTICLE 6 -- COMPLIANCE WITH NOTICE REQUIREMENTS
The Board of County Commissioners hereby states and affirms that by following the reading and
publication schedule set forth below, it has and hereby does comply with the notice requirements of
CRS §35-5.5-108.
ARTICLE 7 -- NO WAIVER OF IMMUNITIES/NO CREATION OF DUTIES. STANDARD OF
CARE. OR RIGHTS FOR THIRD PARTIES
No portion of this Ordinance 169-A shall be deemed to constitute a waiver of any immunities which
Weld County, Colorado, by and through the Board of County Commissioners of Weld County, or any
pest control districts and/or their Boards, or the Weld County Undesirable Plant Management
Advisory Board or their officers or employees may possess, nor shall any provision of this Ordinance
169-A be construed to create any duty, standard of care or rights in favor of any third parties with
the respect to any obligation created by this Ordinance 169-A.
BE IT FURTHER ORDAINED by the Board, if any section, subsection, paragraph, sentence,
clause, or phrase of this Ordinance is for any reason held or decided to be unconstitutional, such
decision shall not affect the validity of the remaining portions hereof. The Board of County
Commissioners hereby declares that it would have enacted this Ordinance in each and every
section, subsection, paragraph, sentence, clause, and phrase thereof irrespective of the fact that any
one or more sections, subsections, paragraphs, sentences, clauses, or phrases might be declared
to be unconstitutional or invalid.
The above and foregoing Ordinance Number 169-A was, on motion duly made and
seconded, adopted by the following vote on the * day of , A.D., 1996.
BOARD OF COUNTY COMMISSIONERS
WELD COUNTY, COLORADO
ATTEST:
Barbara J. Kirkmeyer, Chair
Weld County Clerk to the Board
George E. Baxter, Pro-Tem
BY:
Deputy Clerk to the Board
Dale K. Hall
APPROVED AS TO FORM:
Constance L. Harbert
County Attorney
W. H. Webster
960121
ORD169
RE: ORDINANCE NO. 169-A
PAGE 27
Initial Publication: February 1, 1996, in the North Weld Herald
First Reading: March 4, 1996
Publication: March 7, 1996, in the North Weld Herald
Second Reading: March 18, 1996
Publication: March 21, 1996, in the North Weld Herald
Final Reading: April 1, 1996
Publication: April 4, 1996, in the North Weld Herald
Effective Date: April 9, 1996
960121
ORD169
AFFIDAVIT OF PUBLICATION
THE NORTH WELD HERALDLEGAL PAGE 8 THURSDAY,FEBRUARY 1,1996 STATE OF COLORADO
ss.
ORDINANCE NO.169-A COUNTY OF WELD
I, Bruce J. Bormann, of said County of Weld,being duly
IN THE MATTER OF REPEALING AND REENACTING ORDINANCE 169,THE UNDESIRABLE PLANT MANAGEMENT PLAN FOR
THE COUNTY OF WELD,STATE OF COLORADO sworn,say that I am Publisher of
BE IT ORDAINED BY THE BOARD OF COUNTY COMMISSIONERS OF THE COUNTY OF WELD,STATE OF COLORADO: THE NORTH WELD HERALD
WHEREAS,the-Board of County Commissioners of the County of Weld,State of Colorado,pursuant to Colorado statute
and the Weld County Home Rule Charter,is vested with the authority of administering the affairs of the County of Weld,State of a weekly newspaper having a general circulation in said
Colorado,and
WHEREAS,on May 4,1992,the Board of County Commissioners adopted Weld County Ordinance 169,which became County and State,published in the Town of Eaton, in said
effective May 12,1992,and which provides for the adoption and enforcement o1 an undesirable plant management plan in Weld County and State;and that-the notice,of which the annexed is
County,and
WHEREAS,said Ordinance 169 designates five(5)weed species as undesirable and mandated for management in Weld a true copy,has been published in said weekly newspaper for
County,those being:Leafy Spurge(Euphorbia esu/a),Russian Knapweed(Centaruea repens),Diffuse Knapweed(Centaurea diffuse), -2,,n
Spotted Knapweed(Centaurea maculosa),Canada Thistle(Cirsium arvense),and Musk Thistle(Carduus nutans),and C, `'�-- successive weeks,that the notice was published
WHEREAS,upon the recommendation of the Weld County Undesirable Plant Management Advisory Board,the Board of in the regular and entire issue of every number of the paper
County Commissioners hereby finds and determines that there is a need to add two weed species to the list of those currently
designated-as undesirable and mandated for management in Weld County,the two additions being:Field Bindweed(Convolvulus during the period and time of publication, and in the
arvensis)and Scotch Thistle(Onopordum acanthium),thereby requiring,at a minimum,an amendment to said Ordinance 169,and
newspaper proper and not in a supplement,and that the
WHEREAS,upon further recommendation of the Weld County Undesirable Plant Management Advisory Board,the Board
of County Commissioners hereby finds and determines that there is a need to make other revisions to the Weld County Undesirable publication of said notice:
Plant Management Plan,thereby requiring the repeal and reenactment of said Ordinance 169. (n �y f,\ /_
NOW,THEREFORE,BE 1T ORDAINED,by the Board of County Commissioners of the County of Weld,State of Colorado, A(„l1i-•IMa'r'-.k`. /`ro /6 9-A-F"VSf igtikv` 6,O
that-Weld County Ordinance Number 169,adopted May 4,1992,be,end hereby is,repealed and,by and through this Ordinance 169-
A,be,and hereby is,reenacted,as follows:
was in said newspaper bearing the date(s) of:
ARTICLE 1—WELD COUNTY iS f
UNDESIRABLE PLANT MANAGEMENT PLAN Thursday,the day of 47.1J.,24.L.I.4.,1 ,1996
I. INTRODUCTION cr
A. DESCRIPTION OF THE COLORADO UNDESIRABLE PLANT MANAGEMENT ACT Thursday,the day of ,1996
The Colorado Undesirable Plant Management Act,CRS§35-5.5-101,et.seq.,(hereinafter"the-Act")states that Thursday, dayof ,1996
certain undesirable plants pose a threat to the continued economic and environmental value of the land in y
Colorado and that they must be managed by all landowners in the state. The undesirable plants designated for
mandatory management statewide are:Leafy Spurge(Euphorbia esula),Russian Knapweed(Acroptilon
repens),Diffuse Knapweed(Acroptilon diffuse)and Spotted.Knapweed(Centaurea maculosa). Additional weed Thursday,the day of ,1996
species may be added to the state list by each local jurisdiction. The Act states such that local governments
cities and co-unties)
are directeda the s steps to ee the sasirable e ants in ir
respecive jursdctions. Theare further directed toappont an advisoryommisi whose responsibilities
are threefold: and that the said THE NORTH WELD HERALD has been
1. Develop recommended management criteria and Integrated weed management plans for managing the designated undesirable plants; published continuously and uninterruptedly for the period of 52
2. Recommend the addition,if necessary,of undesirable plants that shall be subject to consecutive weeks,in said County and State,prior to the date
Integrated management; of first publication of said notice,and the same is a newspaper
3. Recommend to the county commissioners the names of those landowners who shall be within the meaningof an Act to regulate printingof legal
required to submit integrated weed management plans for managing the undesirable9 9
plants on their property. notices and advertisements,approved May 18,1931,and all
The Act further states that by January 1,1992,each local governing body is to have developed and adopted an
Undesirable Plant Management Plan for all lands within its Jurisdictional boundaries. prior acts so far force.
II. DESCRIPTION OF THE COUNTY OF WELD WEED PROBLEM A
A. WEED SPECIES IN WELD COUNTY TO BE CONTROLLED,PURSUANT TO WEED CONTROL LAWS ,,U `` r-7
The Pest Control Districts Law(CRS 35-5-104)enabled landowners in each county the ability,through a lengthy B E J.BORMANN,PUBLISHER
petitioning and balloting process,to establish weed control districts. Within each weed district,designated
species are mandated to be controlled. In Weld County,nine such weed districts exist. The districts occur in
the lower two-thirds of the County,and the weed species designated for control range from three to seven
species,depending upon the weed district. The weed species that are currently being managed in at least a
pad of Weld County are as follows:
Leafy Spurge(EuppborblaEsule),
Canada Thistle(Ciralum arvense), Subscribed a i C c 1t�1. \,t-this / day
Musk Thistle(Carduusnutans),
Field Bindweed(Convolvolus arvensis), i /C,11
Whiletop(Cardada drabs), of %, s' j f
1y 9 -
Russian Knapweed(Acroptilon repens) , ,
Wild Proso Millet(Panicum miliaceum)
Under the Act(CRS§35-5.5-101,et seq.),there are four weed species which are mandated for county-wide management. It , BA • k ,f'
They are Leafy Spurge,and Russian,Diffuse and Sported Knapweed. Canada Thistle,Musk Thistle,Scotch Thistle and rr..c•s
Field Bindweed are added to the county-wide undesirable plant list by this Ordinance 169-A,in accordance with CRS§35- 'Q NOTARY PUBLIC
5.5-108(3). i 4 ,.. `.QQ_
Of the weed species listed previously,Canada Thistle,Field Bindweed,Leafy Spurge,Musk Thistle,Russian Knapw:',-,d, 11%\c OF C��.0
Whitetop and Wild Proso Millet cover the most acreage in Wald County and pose the greatest economic vId \\\\,• ��►. �yti qc C
environmental threat to the county. Diffuse Knapweed is currently localized to a few drainages and rights-of-way in the My commission explr• y // /,
southwest part of the County.and there are no known Spotted Knapweed infestations in the County.
\�.:.
III. OBJECTIVES AND GOALS
A. STATEMENT OF OBJECTIVES
The objectives of the Weld County Public Works Department with respect to weed management in Weld
County are fourfold:
1. Develop and carry out a comprehensive noxious weed control program on all county
right-of-way and other county property, such as In sand and gravel mining operations,
grader shed lots and open space areas.
2. Establish an educational program, by using mailings and holding educational and
calibration seminars,that will effectively communicate weed management information to
the landowners in the County.
3. Identify non-informed or negligent landowners who are not carrying out weed •
management programs on their property and provide technical support for establishing
- weed management plans or enforce on properties,if necessary.
4. Work with all state and federal agencies, through Intergovernmental agreements, if
necessary,towards establishing effective Weed management programs on their property.
B. SHORT TERM GOALS—(January 1995 to December 1998)
1. Map all the County roads for noxious weed infestations.
2. Map on a computer program at least half of the landowners that have Leafy Spurge,
Canada Thistle and Russian Knapweed infestations.
3. Continue to establish contact with landowners on the South Platte and Poudre Rivers
who have noxious weed Infestations.
4. Establish educational/calibration seminars(annually) that work directly with 150-200
landowners each year.
5. Have established contact with the Colorado Department of Highways, Department of
Parks and Recreation, Colorado Land Board, DI ision of Wildlife and U.S. Forest
Service. Help them develop Weed Management Plans and where appropriate enter Into
• cooperative.Intergovernmental agreements.
6. Have established six to eight biological control release sites throughout the county in
cooperation with.the Colorado Department of Agriculture and private landowners.
7. By 1995 have reduced the noxious weed acreage sprayed on county right-of-way by 15-
20%.
C. LONG TERM GOALS—(January 1999 to December 2002)
1. Have mapped on the computer program most noxious weed infestations county-wide,
including private, state and federal lands.
2. Have reduced the noxious weed acreage sprayed on county right-of-way by 40-50%.
3. Have contacted and worked with most landowners county-wide who have a noxious
weed Infestation.
4. Have established 30-50 biological control release sites in the county.
V. PLAN OF WORK-IMPLEMENTATION '
A. DESCRIPTION OF INTEGRATED WEED MANAGEMENT TECHNIQUES Leafy
The
R Russian species
weed(dAcrouptilonrrippens),Diffuse Knapweed (r Cen auree dis ),Spottted(Knapweed
(Centaurs. meculosa), Canada Thistle (Cirsium ervense) Musk Thistle (Carduus nutans), Scotch Thistle
. (Onopordurn acanthlum)and Field Bindweed(Convolvulus arvensls). Integrated weed management methods
are to be-used In managing these weed species (CRS $35-5.5-107). Integrated management techniques
include education; preventive measures' and control measures including cultural, mechanical, biological and
chemical control. For the purposes of this plan the following definitions for the control measures will be used.
1. - Cultural Control means those methodologies or management practices conducted to
favor the growth of desirable plants over undesirable plants, including,but not limited to,
maintaining an optimum 1eRXhy and plant moisture status in an area,planting at optimum
density and spatial arrangement in an area,and planting species most suited to an area.
2. Mechanical Control means those methodologies or management practices that
physically disrupt plant growth, including, but not limited to, tilling, mowing, burning,
flooding,mulching,hand-pulling and hoeing.
3. Biologicaldismerupt the growth of undesirablela
the
pntsheep, goats, cattle, insects
andplant diseases to
4. Chemical Control means the use of herbicides or plant growth regulators to disrupt the
growth of undesirable plants.
Management of the various undesirable plants will vary depending upon the site where the plant is located.
Management options for each weed species will be developed for each site. The integrated management
options listed WOW are meant to provide various management techniques for controlling the noxious weeds in
• the various environmental sites they are found. By no means are all the management options mentioned.
Additional combinations of management techniques are possible which may be submitted by private
landowners. The integrated weed management plans submitted by individual landowners will be evaluated by
the Weld County Vegetation Management Specialist and the integrated Weed Management Advisory
Commission on a case by case basis.
B. INTEGRATED WEED MANAGEMENT OPTIONS FOR EACH WEED SPECIES
LEAFY SPURGE: Leafy Spurge is a deep rooted perennial plant that spreads by seeds and-creeping roots. It
hags a vast underground root system which makes It difficult to control with any one control technique. Leafy
S is found
d primarily
(along
as the Poudre
Rivers) inWeld County analoalng Ir In rigation ditchrian sites es, and pastures,roadsides and other non-cropland sites.
1. Control Measures
a. Cultural Control: Seeding perennial grasses and forbs can be an effective management
tool. Early emerging plant species that utilize early season moisture such as Smooth
Brome (Bromus aermrs) or Crested Wheatgrass (Agropyron cnstatum) have reduced
Leafy Spurge density and limited the spread and establishment of new infestation.
Sequential glyphosate applications followed by a seeding of Luna Pubescent
Wheatgrass, Ephraim Crested,Wheatgrass, intermediate Wheatgrass, Sherman Big
Bluegrass or Bozoisky Russian Wild Rye has shown to be very effective in reducing an
existing stand of Leafy Spurge.'
b. repeatedee mowingteve Mechanical
4-21(days throughout a ul of t thessummee r,starting beflt at ore flowering
stae, will at leagst keep the plants from going to seed and may reduce the underground
root reserve. Research results are not available to indicate whether stand reduction or
eradication could be achieved through use of this technique.
c. Biological Control:.Grazing with sheep and goats throughout the spring,summer, and
ICES
fall will keep Leafy Spurge from going to seed and may reduce the underground root
reserve. This practice may also weaken the plants to make them more susceptible to
chemical control.
Several insect species that have been released by the USDA In the United States are
showing some control of Leafy Spurge. Two species of flea beetles,Apthona (lava and
Apthona nigdscutis feed on Leafy Spurge. Adults feed on the foliage during the summer
and the larvae burrow through the soil and mine the roots and fine root hairs. These
insects used alone may not control Leafy Spurge. When used along with other insects
such as Spurgia Esula, a gall midge which feeds on the flowers"preventing seed
production,"they will weaken the plant and make it more susceptible to other control
methods,particularly chemical control.
d. Chemical Control: There are a number of herbicides labeled for use on Leafy Spurge.
Those that can be used independently or in combination with each other are: picloram
(Tordon®); dicamba (Banvele); 2,4-D (many different formulations); glyphosate
(Roundup®and Rodeo®);fosamine(Krenae®)and any EPA approved chemicals labeled
for use on Leafy Spurge.
2. Integrated Management Options by Site:
a. Range,Pasture end Riparian Sites•
Option s1 Biological end Chemical Control: Grazing with sheep or goats from early April ,
through late August or early September, followed by a herbicide treatment in late
September or early October.
Option e2 Biological and Chemical Control: Th0 release of insects such as Apthona
Mgr/sculls,Apthona (lava, Spurgia Esula, and other species conducive to the area can
be made. A herbicide treatment can then be made during the true flower stage(where
insects were not released) and in the fall where insects were released. Herbicide
applications should only be carried out in the fall where Insects are used. Use of
herbicides at different times If the growing season can be instituted as additional IPM
research is conducted end recommendations are developed.
Option e3 Mechanical and Chemical Control: Mowing can be carried out throughout the
season with the first mowing cycle at the bud stage. Mowing should stop during late
August followed by a herbicide treatment during late September or early October(before a
hard freeze).
Option 44 Biological or Mechanical Control Only: The use of sheep or goats or mowing
should be used all season to keep Leafy Spurge from going to seed. Whether this
method will keep the existing infestation from spreading by underground root growth is
uncertain.
Option s5 Chemical Control Only: Herbicides should be used in the spring, early
summer during the true flower stage apdin the fall just before a hard freeze. Only the
herbicides labeled for the site intended will be used.
b. Along Irrigation Ditches
Option e1 Biological and Chemical Control: The release of insects such as Apthona
nrgnacutis, Apthona(lava, Spurgia Esula and other species conducive to the area could
be made. A herbicide treatment should be carried out at the true flower stage (If the
Spurgia Esula has not kept the plants from going to seed)and/or in the fall just before a
hard freeze.
Option a2 Chemical Control Only: Herbicides can be used In the spring or early summer
during the true flower stage and in the fall just before a hard freeze. Only the herbicides
labeled for the site intended will be used.
e. Road Right-of-Ways end Other Non-Crop Areas
Option e1 Mechanical and Chemical Control: One mowing cycle can be carried out at
the bud to early flower stage. A herbicide application should be made at the true flower
stage.
Option 02 Chemical Control Only: Herbicides can be used in the spring or early summer
during the true flower stage and in the fall just before a hard freeze. Only the herbicides
labeled for use on roadsides and other non-cropland areas would be used.
RUSSIAN KNAPWEED: Russian Knapweed is a non-native perennial plant that spreads by seeds and
creeping roots. It has then ability to release chemicals into the environment as foliage decays which inhibit the
growth of surrounding vegetation (allelopathic properties). Thus, once established, Russian Knapweed can
colonize an area rapidly. Russian Knapweed is found primarily in range and pastures, roadsides and other
non-cropland sites In Weld County.
1. ' Control Measures
a. Cultural Control: Seeding perennial grasses such as Smooth Brome(Bromus inermis)
will help to compete with Russian-Knapweed and slow Its spread. In addition,
stimulating grass growth by fertilizing and/or irrigation should increase grass
competition. Due to the allelopathic properties of Russian Knapweed, other control
techniques such as judicious chemical control would have to be Implemented in order to
' give grasses a chance to compete.
b. Mechanical Control: Mechanical control of Russian Knapweed could be carried out
throughout the summer with repeated mowing every 14-21 days. This would at least
keep Russian Knapweed from going to seed. Whether this control technique will reduce
the root mass and subsequently reduce an existing stand is not known.
e. Biological Control: There are currently no biological control agents available for Russian
Knapweed.
d. Chemical Control: There are a number of herbicides labeled for use on Russian
Knapweed. Those that can be used independently or in combination with each other are:
chiorsulfuron (Telar®); picloram (Tordon®); 2,4-D (many different formulations);
glyphosate(Roundup®and Rodeo®)and any EPA approved chemical labeled for use on
Russian Knapweed.
2. INTEGRATED MANAGEMENT OPTIONS BY SITE
a. Range and Pastures:
Option el Mechanical and Chemical: Mowing can be carried out throughout the season
with the first and successive mowing cycles carried out at the bud stage. A herbicide
treatment can then be made in the fall before a hard.freeze.
Option e2 Cultural and Chemical: A herbicide application, using short residual
herbicides such as glyphosate and/or 2,4-D can be made followed up by reseeding with
a.competitive grass such as smooth brome or other sod forming species. In addition,
fertilization or irrigation could be instituted to stimulate increased grass growth.
• Option e3 Chemical Control Only: Herbicide applications can be made to Russian
Knapweed during the bud stage,bloom to post-bloom and/or in the fall,depending upon
herbicide used.
b. Road Flight-of-Way and other Non-Crop.Areas.
Option e1 Mechanical and Chemical: One mowing cycle can be carried out at the bud to
early flower stage. A herbicide application can be made during the bud stage, bloom to
post-bloom and/or in the fall,depending upon the herbicide used.
Option e2 Cultural and Chemical Control: Use of short residual herbicides such as
glyphosate and/or 2,4-D can be used in the early summer during the bud stage. Seeding
with perennial grasses such as Smooth Brome, Luna Pubescent Wheatgrass, Ephraim
Crested Wheatgrass, Intermediate Wheatgrass, Sherman Big Bluegrass or Bozoisky
Russian Wild Rye can than be carried out later in the summer,at the appropriate time.
Option e3 Chemical Only: Herbicide applications can be made during the bud stage,
bloom to post bloom and/or in the fall,depending upon the herbicide used.
DIFFUSE KNAPWEED: Diffuse Knapweed is a non-natIVe, biennial to short lived perennial forb that
• reproduces by seed. It spreads rapidly by the mature plant breaking off at ground level and being blown with
the wind, dispersing seed. It Is a pioneer species that will quickly invade disturbed, dry sites. Diffuse
Knapweed is found in the southwest pert of Weld County along rights of way,dry pasture sites and In gravelly
riparian sites,such as along Boulder Creek and the St.Vraln and South Platte Rivers.
1- Control Measures
a. Cultural Control: Cultural Control of Diffuse Knapweed is similar to Russian Knapweed
in that seeding with perennial grasses such as smooth brome and crested wheatgrass
will help to compete with Diffuse Knapweed and slow its spread. Seeding alone in
infested sites will not,however,control the existing stand. -
b. Mechanical Control: Mowing Diffuse Knapweed when It is in-the bud stage and again
when it is flowering can significantly reduce seed production. Keeping Diffuse
Knapweed from going to seed over a number of years can eventually eliminate an
infestation,once the seed source In the soil is depleted.
c. Biological Control: Two species of picture-winged flies, Urophora a/inis and U.
quadnfasciata have demonstrated the ability to reduce the seed production of diffuse and
Spotted Knapwoed. The flies lay eggs on the developing seed heads. As a result of the
larvae feeding on the flowering heads, the plants produce galls which reduces seed
production. The Colorado insectory is currently rearing these two flies and has made
releases In the state the last three years.
d. Chemical Control: There are a few herbicides labeled for use on Diffuse Knapweed.
Those that can be used independently or in combination with each other are: picloram
(Tordon®); dicemba (Banvel®); glyphosate (Roundup®); 2,4-D (many different
formulations)and any EPA approved chemical labeled for use on Diffuse Knapweed.
2. Integrated Management Options by Site
a. Pasture and Riparian Areas
Option e1 Cultural and Chemical Control: A herbicide application can be made in early
summer when Diffuse Knapweed is in the rosette through bolting stage. Reseeding with
competitive perennial grasses such as smooth Moms and crested wheatgrass can be
followed later in the summer depending upon the herbicide used and rate of application.
Option e2 Biological and Chemical Control: The release of insects such as Urophora
aNMls and U. quadrrfasciata can be made. A herbicide treatment can then be made from
the rosette through bolting stage(where Insects were not released)and in the fall where
insects were released. Herbicide applications should only be carried out in the fall,
where insects are used. The use of herbicides at different times of the growing season
can be instituted as additional IPM research is conducted and recommendations are
developed.
Option e3 Mechanical and Chemical Control: Mowing can be carried out when Diffuse
Knapweed is in the bud stage and again at.flowering. A herbicide application can then
be made to any plants that have re-bolted,if necessary.
Option e4 Mechanical Control Only: Mowing can be carried out throughout the season
which will reduce seed set.
Option e5 Chemical Control Only: Herbicide application can be made during the rosette
stage,spring or fall,and while bolting.
b. Right-el-Ways and Other Non-Crop Areas
Option e1 Cultural and Chemical Control: Same as for Option#1 in pasture and riparian
areas.
Option e2 Mechanical and Chemical Control: One mowing operation can be carried out
when Diffuse Knapweed is in the bed stage. if necessary, a herbicide application can
be made to plants that have re-bolted. •
Option e3 Mechanical Control Only: Same as for Option e4 In pasture and riparian areas.'
Option e4 Chemical Control Only: Same as for Option#5 in pasture and riparian areas.
SPOTTED KNAPWEED: Spotted Knapweed is a non-native,perennial forb that reproduces by seed. It Is a
highly competitive plant in rangeland sites that will exclude most grasses and fobs with time. There is limited
Spotted Knape/sad infestations currently along the South Platte River drainage in Weld County.
Ordinance No. 169-A Continued to next page
A
1. Control Measures
a. Cultural Control: Cultural control of Spotted Knapweed is similar to such control of
Russian and Diffuse Knapweed in that seeding with Perennial grasses such as Smooth
Brome and crested wheatgrass will help to compete with Spotted Knapweed and slow its
spread. Seeding infested sites will not, however, control the existing stand. In range
and pasture conditions, good grazing management practices will help to reduce the
spread of the knapweeds in general.,-
b. Mechanical Control: Mechanical control of Spotted Knapweed could be carried out
throughout the summer with repeated mowing every 14-21 days. This would at least
keep Spotted Knapweed from going to seed. Whether this control technique will reduce
the root mass and subsequently reduce an existing stand is not known.
c. Biological Control: The same as what was developed under biological control for Diffuse
Knapweed.
d. Chemical Control: There are a few herbicides labeled for use on Spotted Knapweed.
Those that can be used independently or in combination with each other are: picloram
(Tordon®),dicamba(Banvel®),2,4-D(many different formulations and clopyrald and 2,4-
D(Curtail®).
CANADA THISTLE: Canada Thistle is an aggressive, creeping perennial that reproduces by seed and
vegetative buds In the root system. It Is a difficult plant to control because of its extensive root system.
Vertical roots may grow 6-15 foot deep and horizontal roots may extend 15 feet or more. Canada Thistle is the
most widespread noxious weed in Weld County. It can be found in most habitat types, including: pastures,
riparian sites (along waterways such as the Poudre, South Platte, St. Vrain and Big Thompson Rivers),
irrigation ditches,along roadside rights-of-way and in the various crop and non-cropland sites.
1. • Control Measures
a. Cultural Control: Plant competition from various grasses and from alfalfa can be an
effective management tool. Early emerging grass species such as Smooth Brome and
Crested Wheatgrass can be used to compete with Canada Thistle and slow the spread
and establishment of new infestations. Competition alone, however, is seldom effective
on Canada Thistle.
b. Mechanical Control: Mechanical Control of Canada Thistle could be carried out
throughout the summer with repeated mowing every,14 days. Such method keeps
Canada Thistle from going to seed;however, mowing has shown to stimulate new shoot
growth from roots. Consequently, mowing alone may increase shoot density in an
established stand. Whether consistent mowing for consecutive years (two to three
years)will reduce the root mass and subsequently reduce an existing stand is unknown.
c. Biological Control: There is one insect species,a weevil,called Ceutorynchus litura,
that is currently being used as a biological control agent on Canada Thistle in Colorado.
The female lays eggs on the underside of the leaves in early spring and then the larvae
bore into the main leaf vein and migrate down to the crown of the plant. The holes
created by the larvae open up Canada Thistle to secondary infection. Where high
numbers of the larvae occur death of Canada Thistle can occur. ,
d. Chemical Control: There are a number of herbicides labeled for use on Canada Thistle,
depending upon where the thistle is found, The herbicides that can be used
independently or in combination with other compounds are: picloram(Tordon®1 dicamba
(Banvel®);2,4-D(many different formulations);chlorsulfuron(Telai®);clopyralid(Curtail®,
Stinger®, Transline®); glyphosate (Roundup®, Rodeo®) and any EPA approved
chemicals labeled for use on Canada Thistle.
2. Integrated Management Options by Site
a. Range,Pasture and Riparian Sites
Option e1 Biological and Chemical: Release of the insect Ceutorynchus inure can be
made during the early summer. A herbicide application can then be made at the bud
stage (where insects were not released) and in the fall where insects were released.
Herbicide applications should only be carried out In the fall,where Insects were directly
released. Use of herbicides at different times of the growing season can be instituted as
additional IPM research is coordinated and recommendations are developed.
Option e2 Mechanical and Chemical: Mowing can be carried out throughout the season
with the first mowing cycle at the bud stage. Mowing should stop during late August
followed by a herbicide treatment during late September through October, before a hard
freeze.
Option e9 Cultural and Chemical Control: A herbicide application,using short residual
herbicides such as glyphosate and/or 2,4-D can be made followed up by reseeding with
a competitive grass such as smooth brome or other sod forming species. In addition,
fertilization or Irrigation could be instituted to stimulate increase grass growth. p,
Option e4 Chemical Control Only: Herbicide applications can be made to Canada
Thistle from rosette to the bud stage, and/or in the fall, depending upon the herbicide
used.
b. Road RlgMof-Ways and Other Non-Crop Areas'
Option e1 Mechanical and Chemical: One mowing cycle can be carried out at the bud to
early flower stage. A herbicide application can be made from rosette to bud stage and/or
in the fall,depending upon the herbicide used.
Option*2 Cultural and Chemical Control: A herbicide application can be made in early
summer when Canada Thistle is In the rosette through bud stage. Reseeding with
competitive perennial grasses such as smooth brome and crested wheatgrass can be
followed later In the summer depending upon the herbicide used and rate of application.
Option.a3 Chemical Control Only: Herbicide applications can be made from rosette to
bud stage,and/or in the fail,depending upon the herbicide used.
e. Cropland Sites
Canada Thistle is found in almost every crop grown in Weld County. Prescription weed
management measures developed by Colorado State University weed scientists and the
- Weld County Extension Agronomist will be used.
MUSE THISTLE: Musk Thistle is a biennial plant that reproduces only by seed. Rosettes(clump of leaves on
the ground)are formed during the first year of growth and the plant bolts and sets seed the second year. It 1s a
prolific seed producer with a single plant producing up to 20,000 seeds. Musk Thistle is found primarily in
pastures and riparian sites (along waterways such as the South Platte, St. Vrain, Big Thompson, and Little
Thompson drainages and Boulder Creek)and'atbng irrigation ditches,roadside rights-of-way and other non crop
areas.
1. Control Measures
a. Cultural Control: Maintaining pastures and riparian sites in good condition is the primary
method of culturally managing Musk Thistle. Promoting good grass growth by proper
grazing management and fertilizing,according to soil testing recommendations will
prevent establishment of Musk Thistle.
b. Mechanical Control: Musk Thistle can be effectively controlled mechanically. Severing
the roots below ground with a shovel or hoe or mowing Musk Thistle every time h
reaches early flower stage will reduce, if not eliminate seed production. If mowing
occurs mid to late flower stage,the thistle should be gathered and burned to destroy any
seed that has developed. I
c. Biological Control• .Two'species of weevils, Rhinocyllus conicus (seed head weevil)
and Trichosirocalus horridus,attack two different sites of Musk Thistle. The seed head
weevil, as its name implies, attacks the seeds of Musk Thistle. Eggs are laid by the
female on the back of developing flowers and then the larvae bore into the flower,
destroying the developing seed. The seed head weevil can reduce seed production by
as much as 50%. Use of this weevil as the sole means of controlling Musk Thistle is not
very effective.
Trichosirocalus horridus attacks the crown area of Musk Thistle rosettes; killing or
weakening the plant before it bolts. Use of both weevil species together may prove to be
an effective biological control program.
d. Chemical Control: There are a number of herbicides labeled for use on Musk Thistle,
depending upon where the thistle is found. The herbicides that can be used
independently or in combination with other compounds are: picloram(Tordon®);dicamba
(Banvelb);2,4-0(many different formulations);chlorsulfuron(Telar®);clopyralid(Curtail®,
Stinger®,Transline®);glyphosate(Roundup®,Rodeo®)and any EPA approved chemical
labeled for use on Musk Thistle.
s
2. Integrated Management Options by Site
a. Pasture end Riparian Sites
Option e1 Biological and Chemical: Release of Trichosirocalus borridus can be made at
the appropriate time of the summer. Rhinocyllus conicus is well established in Weld
County and should already be infesting the stand. A herbicide application can then be
made to Musk Thistle at the flower.stage.Telar or Escort should be used when treating
Musk Thistle In the flower stage. Herbicide applications should only be carried out in the
flower stage in order to allow the seed head weevil to complete its life cycle. Use of
herblcides_to rosettes in the spring or fall should not be carried out where Trichosirocalus
horridus was released. Use of herbicides at different times of the growing season can be
instituted as additional IPM research is conducted and recommendations are developed.
Option 02 Mechanicaland Chemical Control: Mowing can be carried out throughout the
summer when Musk Thistle is In the bud to early flower stage. A herbicide application
can than be made In October to the fall rosettes and any bolted plants.
Option e3 Mechanical Control Only; Multiple moorings(two to four)can be carried out
throughout the summer when Musk Thistle is m the bud stage,keeping it from producing
seed. If mowing occurs mid to late flower stage, the thistle should be gathered and
burned to destroy any seed that has developed.
Option 04 Chemical Control Only: Herbicides can be used In the spring and fall when
the plant is in the rosette stage. Only the herbicides labeled for the site intended will be
used,
Road Right-of-Ways and other Non Crop Areas
Option e1 Biological and Chemical Control: Same as for Option #1 In pasture and
riparian sites.
• Option e2 Mechanical and Chemical Control: One mowing pass can be made when
Musk Thistle is in the bud stage. A herbicide application can be made in the fall to the
rosettes and re-bolted plants.
Option e3 Chemical Control Only: Herbicides can be used in the spring and the fall
when the plant Is in the rosette stage. Only the herbicides labeled for the ate Intended
will be used.
SCOTCH THISTLE:Scotch Thistle is a biennial plant that reproduces only by seed. Rosettes are formed during
the first year of growth and the plants bolt and set seeds the'second year. The leaves ate densely covered with
hair, giving the plant a grayish-green color. Scotch Thistle Is primarily found in pastures and riparian sites
(South Platte River Drainage) and along roadside rights of way and other non-crop areas in southern Weld
County.
1 . Control Measures
a. CulturalControl:Maintaining pastures and riparian sites in good
condition is the primary method of culturally managing Scotch Thistle. Promoting good
grass growth by proper grazing management and fertilizing according to soil testing
recommendations will help prevent establishment of Scotch Thistle.
b. Mechanical Control: Scotch Thistle can be efficiently controlled mechanically.Severing
the roots below ground with a shovel or
hoe or mowing Scotch Thistle every time it reaches bud to early flower stage will reduce,
if not eliminate seed production. If mowing occurs mid to late flower stage, the thistle
should be gathered and burned to destroy any seed that has developed.
c. Biological Control:No biological control agents are available for •
Scotch Thistle. One weevil species, Rhinocyllus conicus, will move from Musk Thistle
• to Scotch Thistle; however, effective control of Scotch Thistle hes not been
demonstrated.
d. Chemical Control:There are a number of herbicides labeled for use on Scotch Thistle,
depending upon where the thistle Is found.
The herbicides that can be used Independently or in combination
with other compounds are:picloram(Tordon®);dicamba -
(Banvel®);2,4-D(many different formulations);chlorsulfuron
(Telar(0);metsuifuron(Escort®);clopyralid(Curtail®);Stinger®;
1 THE NORTH WELQ HERALD
D THURSDAY, FEBRUARY 1, 1996 PACE 9
transline®and glyphosate(Roundup®,Rodeo®)and any other
EPA approved chemical labeled for use on Scotch Thistle.
2. Integrated Management Options By Site
a. Pastures and Riparian Sites
Option#1 Mechanical and Chemical Control:Multiple mowings(two to four)can be carried
out throughout the summer when Scotch.Thistle is in the bud stage, keeping it from
producing seed. A herbicide application can than be made in October to the fall rosettes
and any bolted plants.
Option #2 Mechanical Control Only: Multiple mowings (two to four)can be carried out
throughout the summer when Scotch Thistle is in the bud stage,keeping it from producing
seed. If mowing occurs mid to late flower stage,the thistle should be gathered and burned
to destroy any seed that has developed.
Option#3 Chemical Control Only: Herbicides can be used In the spring and fall when the
plant is in the rosette stage. Only the herbicides labeled for the site intended will be used.
b.. Road Rights of Way and Other Non Crop Areas
Option#1 Mechanical and Chemical Control:One mowing pass can be made when Scotch
Thistle is in the bud stage. A herbicide application can be made to rebolted plants in the
bud stage and/or to fall regrowth.
Option#2 Chemical.Control: Herbicides can be used In the spring and the fall when the
Matte Is in the stage. Only the herbicides labeled for the site intended will be used.
FIELD BINDWEED: Field Bindweed is a deep rooted creeping perennial plant that reproduces by seed and
horizontal roots. Bindweed seed can survive In soil up to 40 years; therefore, it is Important that bindweed be
kept from going to seed. Field Bindweed is found throughout Weld County in most habitat types including:
rangeland,pastures,along roadside rights of way and in various crop and non-cropland sites.
1. Control Measures a. Cultural Control: Seeding perennial grasses can be an effective management tool in
providing plant competition against bindweed. Selecting the proper native grass and/or
improved cultivar grass seed mix for a site specific location is important. For site specific
reseeding recommendations the Natural Resource Conservation Service and the CSU
Extension Office can be contacted.
b. Mechanical Control:Mechanical control of Field Bindweed can only realistically be carried
out in cultivated cropland by discing and cultivating every 3 weeks. This would keep Field
Bindweed from producing seed and would start to reduce root reserves. Mowing is not
effective due to the creeping nature of bindweed. Discing in range, pasture or roadside is
not environmentally sound.
c. aBiological
e Ic eared Control:
n releasehere in there United States;no bihowever,ical,rresearcntrol h is s on Field in process. indweed that
Grazing with
livestock (cattle or sheep), with proper stocking rates, can be an effective means of
keeping.bindweed from going to seed in range and pasture sites.
d. Chemical Control: There ere a number of herbicides labeled for use on Field Bindweed,
depending upon where the bindweed is found. The,herbicides that can be used
independently or in combination with other compounds are: picloram (Tordon®); dicamba
(Banvel it);2,4-D(many different formulations);glyphosate(Roundup®,Rodeo®)and any
other EPA approved chemicals labeled for use on Field Bindweed.
2. Integrated Management Options by-Site
a. Range and Pasture land
• Option#1 Cultural and Chemical Control: A herbicide application using short residual
herbicides such as glyphosate and/or 2,4-D, can be made, followed by reseeding In fall
with a competitive sod forming grass mix. In addition,fertilization according to soil tests or
irrigation could be instituted to stimulate increased grass growth.
Option#2 Biological Control:Grazing with cattle and sheep throughout the summer and fall
will keep Field Bindweed from going to seed and may reduce the underground root reserve.
' Option 03 Biological and Chemical Control:Grazing with cattle or sheep from May through
early September followed by a herbicide treatment in late September or early October.
Option#4 Chemical Control Only:Herbicides can be used during the flower stage typically
in June and July,and in the fall prior to a hard freeze. Only the herbicides labeled for the
site intended will be used.
b. Road Rights of Way and Other Non Crop Areas
Option #1 Cultural and Chemical Control: A herbicide application using short residual
herbicides,such asglyphosate and/or 2,4-D,can be made followed by reseeding in the fall
with a competitive sod forming grass mix.
Option#2 Chemical Control Only:Herbicide can be used during the flower stage,typically
in June and July,and in the fall just before a hard freeze. Only the herbicides labeled for
roadsides and other non cropland areas will be used.
c. Cropland Sites: Field Bindweed is found in almost every crop grown in Weld County.
Prescription weed management measures developed by Colorado State University weed
scientists and the Weld County Extension Agronomist can be used.
C. PREVENTION MEASURES
Preventive control means using measures which will stop or forestall weeds from contaminating an area.
Establishing preventive measures are often the most practical and cost effective means of weed control.
The preventive measures which seem most practical for Weld County are as follows:
1. establishing weed free seed and mulch requirements for reclamation of disturbed sites,
2. promoting the Colorado Weed Free Hay and Forage program,
3. prioritizing weed management areas along routes of dispersal,and
4. identifying noxious weed species In counties bordering Weld County,
1.
Weed Free Seed and Mulch Standards
•
Where the ground Is disturbed by activities, such as road preparation for road resurfacing,sand and
gravel lot operations and oil and gas well operations,weeds will be the first plants to colonize or re-
vegetate the site. It is important that these sites be reclaimed so that noxious weeds do not become
established.
Weld County plans to establish standards within two to four years for using weed free seed and mulch
on all county operations concerned with the reclamation of disturbed sites, such as on roadside
resurfacing projects and sand and gravel lot operations. Additional regulations may be considered for
similar operations being carried out on private land.
2. Weed Free Hay and Forage Program
Standards have been developed that enable growers the ability to have their hay and forage certified
as noxious weed free. These standards will encourage growers to produce noxious weed free hay and
forage to that It can be shipped and used anywhere in the U.S. (particularly where noxious weed free
standards currently exist).
The Weld County Vegetation Management Specialist will promote the Colorado Weed Free Forage
Standards through the use of seminars,radio spots and newspaper articles.
3. Prioritizing Weed Management Areas Along Routes of Dispersal
Weeds are spread rapidly through the dispersal of weed seeds in air and water. Consequently, high
weed seed dispersal areas are associated with right-of-ways, such as along all roads and railroads
and along waterways, i.e., along the Poudre, South Platte, St. Vrain and Little Thompson Rivers and
irrigation canals.
The County Public Works Department will carry out a noxious weed control program on all county
roads from May through September.Spurge;
noxious weeds targeted for control include: Canada,Musk,
eld Bindweed;
whitetop; and wild protch and Bull so meet SIn addition, contact willscontinue e and Spotted
made withdthe�Department of
Transportation, all irrigation and ditch companies in the county, the Union Pacific, Burlington Northern
and Great Western Railroad companies, and the oil and gas companies operating within the county.
Information regarding the Weld County Undesirable Plant Management Act will be distributed and their
cooperation will be encouraged. Assistance in helping them develop their Integrated weed
management programs will be offered. In working with landowners on private property, all lands
bordering the rivers in the county will be considered high priority areas. Landowner compliance with
the Undesirable Plant Management Act will be encouraged.
4. Identifying Noxious Weeds In Bordering Counties That Do Not Occur in Weld County
Contact will continue to be made with the weed control departments in the bordering counties to
identify the noxious weed species which occur in each county that would threaten Weld County.
Plans have been developed to monitor the borders of Weld County,as necessary.
D. EDUCATIONAL PROGRAMS
' Education of the public is one of the most important components of a Weed Management program. Emphasis
will be placed on continuing a multifaceted educational program. The following programs have been instituted in
the past and will continue to,be conducted every year..
1. Timely newspaper articles concerned with weed identification and management.
2. Timely radio broadcasts following the information in the newspaper articles.
3. Conducting landowner weed management seminars and calibration workshops.
4. Having an educational booth at the Colorado Farm Show.
5. Utilizing brochures and CSU Service in Action brochures to hand out to individual landowners.
E. MAPPING
Establishing an accurate baseline map of the existing noxious weed infestations in the county is extremely
important for the ongoing evaluation of the effectiveness of the county weed management program. Therefore,a
computerized mapping program will be established that will map the noxious weeds established in Weld County.
County roadsides will be mapped using a computer and printer/datalogger on the spray equipment. Private and
state land will be mapped by Public Works Department personnel taking aerial maps from the county assessor's
office Into the field and mapping on site. Through the use of the auto CADD computer mapping program, the
noxious weed Infestations will be mapped. All mapping Information will be stored in the county IBM computer
systems and can be retrieved for future evaluation.
F. ESTABUSHING COOPERATIVE INTERGOVERNMENTAL AGREEMENTS
Contact will be made with the following agencies concerning compliance with the Colorado Undesirable Plant
. Management Act:
1. Colorado Department of Transportation
2. Colorado State Department of Parks and Recreation
3. Colorado Division of Wildlife
4. Colorado State Land Board
5. U.S. Forest Service
Assistance will be offered in helping each agency develop integrated weed management plans for their lands.
Actual assistance in carrying out the weed control programs on their properties will also be offered. Cooperative
intergovernmental agreements can be established if Weld County Is asked to assist in implementing the weed
control measures.
ADOPT A ROADSIDE PROGRAM
An "Adopt a Roadside' program will be established which will give landowners the ability to take the
responsibility to manage the noxious weeds on the county rights-of-way that borders their property.
Landowners who are chemically sensitive or for some reason do not want chemicals sprayed or mowing
activities carried out along their property,may take the responsibility for managing the noxious weeds on the
roadside right-of-way. Landowner agreements with specific requirements for compliance will be established.
Oddinance No. 169-A Continued,to next page
H. ENFORCEMENT ON PRIVATE AND PUBLIC PROPERTY
Cooperation from all landowners(private and state)will be encouraged through positive communication by mail
and through personal contact. When weed control measures are not carded out by a landowner,enforcement
measures may have to be Instituted. All procedures as established by the Undesirable Plant Management Law,
CRS§35.5.5-109,the Pest Control Districts Law,CRS§35d-l0s,Weld County Ordinance 169-A,and any and all
federal,state,and local regulation will be tollow@d,prior to any enforcement activities being carried out on
private or public properly. integrated weed management plane wilt be requested from certain landowners,as
determined by the Weld County Vegetation Management Specialist and the Undesirable Plant Management
Advisory Board.
Work priorities must be established due to these of the county and the number of landowners with existing
noxious weed problems. The following list prioridzes where enforcement activities will be carried out In ranking
order of importance:
1. Lands bordering all waterways(rivers and irrigation ditches)'.
2. Complaint properties. •
3. Landowners identified as negligent In the past.
4. Landowners with twenty percent(20%)or more of their property infested with noxious weeds.
V. EVALUATION OF PROGRAM
The goals and the plan of work established In Sections III.and IV.of this Ordinance 169•A will be reviewed and evaluated at
the end of every year. A written evaluation will be prepared establishing additions or changes in the plan of work for the
following year. Any additions or changes must be recommended by the Undesirable Plant Management Advisory Board and
approved by the Board of County Commissioners.
The Weld County Undesirable Plant Management Plan shall be reviewed and amended,as needed,at least every three
years(CRS§35-8.5-107(4)(a)).
ARTICLE 2—ENFORCEMENT OF
UNDESIRABLE PLANT MANAGEMENT PLAN
I. AUTHORIZED AGENT FOR ENFORCEMENT
Pursudnt to CAS§35-5.5-105(2),the Weld County Vegetation Management Specialist,his employees and agents,are
hereby authorized to enforce the above-stated Undesirable Plant Management Plan in the unincorporated areas of County of
Weld„State of Colorado,by utilizing those procedures set forth In CRS§§35-5.108,35-5-109,and 35-5.5-I08,and any other
applicable State and Federal Statutes,rules,regulations,and ordinances,including the remaining provisions of this
Ordinance No.169-A.
II. RIQHT OF ENTRY
Prior to entering private lands for the purpose of enforcing the Weld County Undesirable Plant Management Plan as set forth
herein,the Weld County Vegetation.Managemem Specialist shall first obtain a'right of entry'from the Board of County
Commissioners,no less than ten days after a Notice to Control Identified Undesirable,Plants has been sent to the owner or
occupant of the private lends and sold owner or occupant has failed to comply with said notice.
111. MAILING OF ASSESSMENTS
All assessments for the whole cost of any enforcement work performed by the Weld County Vegetation Management
Specialist or his designee(s)upon private lands,Incidig up to 15%for inspection and other incidental costs in connection
therewith,shall be mailed to the landowner or occupant by certified mail. Failure to receive said assessment shall not act
as a defense to said assessment. -
V. FAILURE TO PAY ASSESSMENT
Any assessment which is not paid within thirty-three(33)days after the date of mailing by certified mall to the landowner or
occupant of private lands upon which the Weld County Vegetation Management Specialist or his designee(s)have
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 Weld County Treasurers Office to be collected in the same manner
as provided for collection of taxes uflon the private lands in accordance with CRS§§35-5-108 apd 35-5.5-109(5)(a).
ARTICLE 3—SEVERABILITY
If any section,subsection,paragraph,sentence,clause or phrase of this Ordinance No.169-A is,for any reason,held or decided to be
invalid or unconstitutional,such decision shell not affect the validity of the remaining portions.The Board of County-Commissioners,
Weld County,Colorado,hereby declares that it would have passed this Ordinance No.169-A,and in each and every section,
subsection,paragraph,sentence,clause and phrase thereof irrespective'of the tact that any one or more sections,subsections,
paragraphs,sentences,clauses,or phrases might be declared to be unconstitutional or invalid,
ARTICLE 4—LIABILITY
This Ordinance No.169-A shall not be Intended to create a civil cause of action against°the Board of County Commissioners,Weld
County,Colorado,or any other person that may administer this Ordinance No.169-A in any manner.
ARTICLE 5,—EFFECTIVE DATE
This Ordinance No.169-A shall become effective five(5)days after Its final public notice,In accordance with Section 3-14(2)of the
Weld County Home Rule Charter.
ARTICLE 6—COMPLIANCE WITH NOTICE REQUIREMENTS
The Board of County Commissioners hereby states and affirms that by following the reading and publication schedule set forth below,it
has and hereby does comply with the notice requirements of CRS§35-5.5-108.
ARTICLE 7-NO WAIVER OF IMMUNITIESMO CREATION OF DUTIES.STANDARD OF CARE.OR RIGHTS FOR THIRD PARTIES
No portion of this Ordinance 189-A shall be deemed to constitute a waiver of any Immunities which Weld County,Colorado,by and
through the Board of County Commissioners of Weld County,or any pest control districts and/or their Boards,or the Weld County
Undesirable Plant Management Advisory Board or their officers or employees may possess,nor shall any provision of this Ordinance
169-A be construed to create any duty,standard of care or rights in favor of any third parties with the respect to any obligation created
by this Ordinance 169-A.
BE IT FURTHER ORDAINED by the Board,If any section,subsection,paragrapohh,�sentence,clause,or phrase of this
Ordinance is for any reason hejq:on decided to be unconstitutional,such decision shall not effect'the validity of the remaining portions
hereof. The Board of County Commissioners hereby declares that it would have enacted this Ordinance in each and every section,
subsection,paragraph,sentence,clause,and phrase thereof Irrespective of the fact that any one or more sections,subsections,
paragraphs,sentences,clauses,or phrases might be declared to be unconstitutional or invalid.
The above and foregoing Ordinance Number 169-A was,on motion duly made and seconded,adopted by the following vote
on the day of',A,D.,1996.
BOARD OF COUNTY COMMISSIONERS
WELD COUNTY,COLORADO
ATTEST: • -
Barbara J.Kirkmeyer,Chair
Weld County Clerk to the Board
George E.Baxter,Pro-Tern
BY:
Deputy Clerk to the Board •
Dale K.Hall
APPROVED AS TO FORM:
Constance L.Harbert
County Attorney • .
W.H.Webster
Initial Publication: February 1,1996,in the North Weld Herald
First Reading: March 4,1996
Publication:March 7,1996,in the North Weld Herald
Second Reatling: March 18,1996
Publication: March 21,1996,in the North Weld Herald
Final Reading: April 1,1998 .
Publication: April 4,1996,In the North.Weld Herald
Effective Dater April 9,1996
AFFIDAVIT OF PUBLICATION
STATE OF COLORADO
ss.
COUNTY OF WELD
I, Bruce J. Bormann, of said County of Weld, being duly
sworn, say that I am Publisher of
THE NORTH WELD HERALD
a weekly newspaper having a general circulation in said
County and State, published in the Town of Eaton, in said
County and State; and that the notice, of which the annexed is
a true copy, has been published in said weekly newspaper for
(T>.Q successive weeks, that the notice was published
in the regular and entire issue of every number of the paper
during the period and time of publication, and in the
newspaper proper and not in a supplement, and that the
publication of said notice:
Ot c(i nu Ice 4W/1,9—/-� T, sF R
was in said newspaper bearing the daate(s))of:
Thursday,the iti" day of /14 tt" ' , 1996
Thursday,the day of , 1996
Thursday,the day of , 1996
Thursday,the day of , 1996
and that the said THE NORTH WELD HERALD has been
published continuously and uninterruptedly for the period of 52
consecutive weeks, in said County and State, prior to the date
of first publication of said notice, and the same is a newspaper
within the meaning of an Act to regul printing of legal
notices and advert ents, approved 16, 1931, and all
prior acts so far force.
BR E J. BORMANN, PUBLISHER
Subscribed and sworn to before me this ZO 4_ day
U'
CRY PUB
• h of s"l , 19 96
-�`�= ��i' ue „
&&ka- e .
i EPoKA C. (J N Ai Y PUBLIC
% BAGLEY •'
1 q '••• .� Qo� My commission expires Actabv1 2/ /999
" (0F•COL
�\`, \r ,
ORDINANCE NO. 189-A
IN THE MATTER OF REPEALING AND REENACTING ORDINANCE NO. lee, THE UNDESIRABLE PLANT MANAGEMENT PLAN
FOR TIE COUNTY OF WELD, STATE OF COLORADO •
BE IT ORDAINED BY THE BOARD OF COUNTY COMMISSIONERS OF THE COUNTY OF WELD, STATE OF COLORADO:
WHEREAS,the Board of County Commissioners of the County of Weld,State of Colorado,pursuant to Colorado statute and the Weld
County Home Rule Charter,is vested with the authority of administering the affairs of the County of Weld,State of Colorado,and
which
1992,and wWHEREAS,on hich provides for the ado992,the Board of ption and enforcement of an undesirable plant management plan Iners adopted Weld County nlWeald County,and became effective May 12.
WHEREAS,said Ordinance 169 designates five(5)weed species as undesirable and mandated for management in Weld County,those
being: Leafy Spurge(Euphorbia eaula), Russian Knapweed (AcropNlon repent), Diffuse Knapweed(Centaurea diffuse), Spotted Knapweed
(Centeurea meculosa),Canada Thistle(Cirsium ervense),and Musk Thistle(Carduue nutens),and.
WHEREAS, upon the recommendation of the Weld County Undesirable Plant Management Advisory Board,the Board of County
Commissioners hereby finds and determines that there Is a need to add two weed species to the list of those currently designated as undesirable and
mandated for management In Weld County,the two additions being: Field Bindweed(Convolvulus amensls)and Scotch Thistle(Onopordum
acanmium),thereby requiring,at a minimum,an amendment to said Ordinance 169,and
WHEREAS,upon further recommendation of the Weld County Undesirable Plant Management Advisory Board,the Board of County
Commissioners hereby finds and determines that there is a need to make other revisions to the Weld County Undesirable Plant Management Plan,
thereby requiring the repeal and reenactment of said Ordinance 169.
NOW,THEREFORE,BE 1T ORDAINED,by the Board of County Commissioners of the County of Weld,State of Colorado,that Weld
County Ordinance Number 169,adopted May 4,1992,be,end hereby is,repealed and,by and through this Ordinance 169-A,be,and hereby Is,
reenacted,as follows:
ARTICLE 1 — WELD COUNTY
UNDESIRABLE PLANT MANAGEMENT PLAN
I. INTRODUCTION
A. DESCRIPTION OF THE COLORADO UNDESIRABLE PLANT MANAGEMENT ACT
The Colorado Undesirable Plant Management Act,CRS §35-5.5-101, et. seq., (hereinafter'the Acr) states that certain
undesirable plants 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 undesirable plants designated for mandatory management statewide
are:Leafy Spurge(Euphorbia aside),Russian Knapweed(Acroptllon repens),Diffuse Knapweed(Centeurea diffuse)and
Spotted Knapweed(Centeurea maculose). Additional weed species may be added to the state list by each local jurisdiction.
The Act states such that local governments(cities and counties)are directed to take the necessary steps to manage the
undesirable plants in.their respective jurisdictions. They are further directed to appoint an advisory commission whose
responsibilities are threefold:
1. Develop recommended management criteria and integrated weed management plans for managing the
designated undesirable plants;
2 Recommend the addition,if necessary,of undesirable plants that shall be subject to integrated management;
Recommend to the county commissioners the 3 integrated weed management plans for names m agingthe undesirable plantsbe required to submit
on their property,
The Act further states that by January 1,1992,each local governing body is to have developed and adopted an
Undesirable Plant Management Plan for all lands within Its jurisdictional boundaries.
II. DESCRIPTION OF THE COUNTY OF WELD WEED PROBLEM
A. WEED SPECIES IN WELD COUNTY TO BE CONTROLLED,PURSUANT TO WEED CONTROL LAWS
The Pest Control Districts Law(CRS 35-5-104)enabled landowners in each county the ability,through a lengthy petitioning
and balloting process,to establish weed control districts. Within each weed district,designated species are mandated to be
controlled. In Weld County,nine such weed districts exist. The districts occur in the lower two-thirds of the County,and the
Mee are designatedcurrently being m for
rcod in control
range netfr part of Weld County are species,as depending upon the weed district. The weed species
Leidy Spurge (Euphoria!" saute),
Canada Thistle (Clrelum crvanes),
Musk Thistle (Carduus matins),
Field Bindweed (Convolvelus arvanais),
Whitetop (Curtails drabs),
Russian Knapweed (Acroptllon ripens)
Wild Proso Millet(Penleum mitlaesum)
Under the Act(CRS§35-5.5-101,et seq.),there are our weed species which are mandated for couny-woe management. They are Leafy
Spurge,and Russian,Diffuse and Spotted Knapweed. Canada Thistle,Musk Thistle,Scotch Thistle and Field Bindweed are added to the
county-wide undesirable plant list by this Ordinance 169-A,in accordance with CRS§35-5.5-108(3).
Of the weed species listed previously,Canada Thistle,Field Bindweed Leafy Spurge,Musk Thistle,Russian Knapweed,Whitetop and
Wild Proso Millet cover the most acreage in Weld County and pose the greatest economic and environmental threat to the county., Diffuse
Knapweed is currently localized to a few drainages and rights-of-way in the southwest part of the County,and there is one known Spotted
Knapweed infestation In the County.
III. OBJECTIVES AND GOALS
A. STATEMENT OF OBJECTIVES
The objectives of the Weld County Public Works Department with respect to weed management In Weld County are fourfold:
1. Develop and carry out a comprehensive noxious weed control program
sam on all county ed lots and open space of-way and other
county property,such as in sand and gravel mining operations,grader
2. Establish an educational program,by using mailings and holding educational and calibration seminars,that will
effectively communicate weed management Informatlion to the landowners in the County.
a identify non-Informed or negligent landowners who are not carrying out weed management programs on their
property and provide technical support for establishing weed management plans or enforce on properties, if
necessary.
Work with all state and
raprograms on their
agreements, if necessary, towards
establishing effective weedmanagement
B. SHORT TERM GOALS — (January 1995 to December 1995)
1. Map all the County roads for noxious weed Infestations.
2 Map on a computer program at least half of the landowners that have Leafy Spurge,Canada Thistle and Russian
Knapweed infestations.
3 Continue to establish contact with landowners on the South Platte and Poudre Rivers who have noxious weed
infestations.
4. Establish educationaVcalibration seminars(annually)that work directly with 15O200 landowners each year.
5 Have established contact with the Colorado Department of Highways, Department of Parks and Recreation,
. Colorado Land Board,Division of Wildlife and U.S.Forest Service. Help them develop Weed Management Plans
and where appropriate enter Into cooperative Intergovernmental agreements.
fi Have established six to eight biological control release sites throughout the county in cooperation with the Colorado
' Department of Agriculture and private landowners.
7. By 1995,have reduced the noxious weed acreage sprayed on county rights-of-way by 15-20%.
C. LONG TERM GOALS—(January 1909 to December 2002)
1. Have mapped on the computer program most noxious weed infestations county-wide,including private,state and
federal lands.
2 Have reduced the noxious weed acreage sprayed on county rights-of-way by 40-50%.
3 Have contacted and worked with most landowners county-wide who have a noxious weed infestation.
4. Have established 30-50 biological control release sites in the county.
IV. PLAN OF WORK - IMPLEMENTATION
A. DESCRIPTION OF INTEGRATED WEED MANAGEMENT TECHNIQUES
The weed species designated as undesirable and mandated for management are Leafy Spurge(Euphorbie saute),Russian
Knapweed(Acroptilon repens),Olffuse'Knapweed(Centaurea diffuse),Spotted Knapweed(Censures meculosa),Canada
Thistle(Cirsium anions')Musk Thistle(Cerduus nutans), Scotch Thistle(Onopordum acanthium) and Field Bindweed
(Convolvulus arvensis). Integrated weed management methods are to be used in managing these weed species(CRS 535-
5.9.107). Integrated management techniques Include education; preventive measures; and control measures including
cultural,mechanical,biological and chemical control. For the purposes of this plan the following definitions for the control
measures will be used.
1. Culture! Control means those methodologies or management practices conducted to favor the growth of
desirable plants over undesirable plants,Including,but not limited to,maintaining an 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 an area.
2 Mechanical Control means those methodologies or management practices that physically disrupt plant growth,
including,but not limited to,tilling,mowing,burning,flooding,mulching,hand-pulling and hoeing.
3 Biological Control means the use of organisms such as sheep, goats, cattle, Inflects and plant diseases to
disrupt the growth of undesirable plants.
4. Chemical Control means the use of herbicides or plant growth regulators to disrupt the growth of undesirable
plants.
Management of the various undesirable plants will vary depending upon the site where the plant is located. Management
options for'each weed species will be developed for each site.The integrated management options listed below are meant to
provide various management techniques for controlling the noxious weeds in the various environmental sites they are found.
By no means are all the management options mentioned. Additional combinations of management techniques are possible
which may be submitted by private landowners. The Integrated weed management plans submitted by individual landowners
will be evaluated by the Weld County Vegetation Management Specialist and the Integrated Weed Management Advisory
Commission on a case by case basis.
B. INTEGRATED WEED MANAGEMENT OPTIONS FOR EACH WEED SPECIES
LEAFY SPURGE: Leafy Spurge is a deep rooted perennial plant that spreads by seeds and creeping roots. It has a vast
underground root system which makes It difficult to control with any one control technique. Leafy Spurge Is found primarily in
riparian sites(along waterways such as the Poudre and South Platte Rivers)in Weld County and also along irrigation ditches,
range and pastures,roadsides and other non-cropland sites.
1. Control Measures
a. Cultural Control: Seeding perennial grasses and forbs can be an effective management tool- Early
emerging plant species that utilize early season moisture such as Smooth Brome(Bromus inermis)or
Crested Wheagrasa(Agropyron clistatum)have reduced Leafy Spurge density and limited the spread
and establishment of new Infestation. Sequential glyphoaate applications followed by a seeding of
Luna Pubescent Wheagrass,Ephraim Crested Wbestgraea,Intermediate Wheatgrass,Sherman Big
Bluegrass or Bozoisky Russian W9d Rye has shown fo be very effective in reducing an existing stand of
Leafy Spurge.
b. Mechanical Control: Mechanical control of Leafy Spurge le difficult at best; however, repeated
mowing every 14-21 days throughout the summer,staring before flowering stage, will at least keep
the plants from going to seed and may reduce the underground root reserve. Research results are not
available to indicate whether stand reduction or eradication could be achieved through use of this
technique.
a Biological Control: Grazing with sheep and goats throughout the spring,summer,and fall will keep
Leafy Spurge from going to seed and may reduce the underground root reserve. This practice may
also weaken the plants to make them more susceptible to chemical control.
Several insect spades that have been released by the USDA in the United States are showing some
control of Leafy Spurge. Two species of flea beetles,Apthona have and Apthona nignscuts feed on
Leafy Spurge. Adults feed on the foliage during the summer and the larvae burrow through the soil and •
mine the roots and fine root hairs. These insects used alone may not control Leafy Spurge. When used
• along with other insects such as Spurgia Esula,a gall midge which feeds on the flowers preventing
seed production,they will weaken the plant and make It more susceptible to other control methods,
particularly chemical control.
d. Chemical Control: There are a number of herbicides labeled for use on Leafy Spurge. Those that
can be used independently or In combination with each other are: picloram (Tordon®): dicamba
(Benvel®); 2,4-D (many different formulations); glyphoeate (Roundup® and Rodeo®); fosamine
(Krsnaet)and any EPA approved chemicals labeled for use on Leafy Spurge.
2. Integrated Management Options by Site
a. Range, Pasture and Riparian Sites
Option 01 Biological and Chemical Control: Grazing with sheep or goats from early April through
late August or early September,followed by a herbicide treatment in late September or early October.
Option a2.B1ological and Chemical Control: The release of insects such as Apthona nigriscutis,
Apthona (lava, Spurgia Esula,and other species conducive to the area can be made. A herbicide
treatment can then be made during the true flower stage(where Insects were not released)and In the
fall where insects were released.Herbicide applications should only be carried out in the tall where
insects are used. Use of herbicides at different times if the growing season can be instituted as .
additional IPM research is conducted and recommendations are developed.
Option a3 Mechanical and Chemical Control; Mowing can be carried out throughout the season
with the first mowing cycle at the bud stage. Mowing should stop during late August followed by a
herbicide treatment during late September or early October(before a herd freeze).
Option a4 Biological or Mechanical Control Only: The use of sheep or goats or mowing should
be used all season to keep Leafy Spurge from going to seed. Whether this method will keep the
existing infestation from spreading by underground root growth is uncertain.
Option a5 Chemical Control Only: Herbicides should be used in the spring,early summer during
the true flower stage and in the fall just before a hard freeze. Only the herbicides labeled for the site
intended will be used.
b. Along Irrigation Ditches
Option 01 Biological and Chemical Control: The.release of insects such as Apthona nigriscutis,
• Apthona(lava,Spurgia Esula and other species conducive to the area could be made: An herbicide
treatment should be carried out at the true flower stage(if the Spurgia Esula has not kept the plants
from going to seed)and/or in the fall just before a hard freeze.
Option e2 Chemical Control Only: Herbicides can be used in the spring or early summer during
the true flower stage and in the fall just before a hard freeze. Only the herbicides labeled for the site
Intended wit be used.
c. Road Rights-of-Way and Other Non-Crop Areas
Option e1 Mechanical and Chemical Control: One mowing cycle can be carried out at the bud to
early flower stage. A herbicide application should be made at the true flower stage.
Option a2 Chemical Control Only: Herbicides can be used in the spring or early summer during
the true flower stage and in the fall just before a hard freeze. Only the herbicides labeled for use on
roadsides and other non-cropland areas would be used.
•
RUSSIAN KNAPWEED: Russian Knapweed is a non-native perennial plant that spreads by seeds and creeping roots. It has
the ability to release chemicals into the environment as foliage decays which inhibit the growth of surrounding vegetation
(allelopathlc properties). Thus,once established,Russian Knapweed can colonize an area rapidly. Russian Knapweed Is
found primarily in range and pastures,roadsides and other non-cropland sites in Weld County.
1. Control Measures
a. Cultural Control: Seeding perennial grasses such es Smooth Brome(Bromus inermis)wit help to
compete with Russian Knapweed and slow its spread. In addition,stimulating grass growth by fertilizing
r and/or Irrigation should Increase grass competition. Due to the allelopathic properties of Russian
Knapweed,other control techniques such as judicious chemical control would have to be implemented
in order to give grasses a chance to compete.
b. Mechanical Control: Mechanical control of Russian Knapweed could be carried out throughout the
summer with repeated mowing every 14-21 days. This would at least keep Russian Knapweed from
going to seed. Whether this control technique will reduce the root mass and subsequently reduce an
existing stand is not known.
c. Biological Control: There are currently no biological control agents available for Russian Knapweed.
d Chemical Control: There are a number of herbicides labeled for use on Russian Knapweed. Those
that can be used independently or in combination with each other are: chlorsulfuron(Telar®);picloram
(Tordon®);2,4-D(many different formulations);glyphosate(Roundup®and Rodeo®)and any EPA
approved chemical labeled for use on Russian Knapweed.
2. Integrated Management Options by Site •
a. ' Range and Pastures
Option a1 Mechanical and Chemical: Mowing can be carried out throughout the season with the
first and successive mowing cycles carried out at the bud stage. A herbicide treatment can then be
made in the tall before a hard freeze.
Option 72 Cultural and Chemical: An herbicide application, using short residual herbicides such
as glyphosate and/or 2,4-D can be made followed up by reseeding with a competitive grass such as
smooth brome or other sod forming species. In addition,fertilization or irrigation could be instituted to
stimulate increased grass growth.
Option *3 Chemical Control Only: Herbicide applications can be made to Russian Knapweed
during the bud stage,bloom to post-bloom and/or in the fall,depending upon herbicide used.
b. Road Rights-of-Way and other Non-Crop Areas
Option *1 Mechanical and Chemical: One mowing cycle can be carried out at the bud to early
flower stage. An herbicide application can be made during the bud stage,bloom to post-bloom and/or
In the fall,depending upon the herbicide used.
Option 42 Cultural and Chemical Control: Use of short residual herbicides such as glyphosate
and/or 2,4-D can be used In the early summer during the bud stage. Seeding with perennial grasses
such as Smooth Brome, Luna Pubescent Wheatgrass, Ephraim Crested Wheatgrass, Intermediate
Wheatgrass,Sherman Big Bluegrass or Bozoisky Russian Wild Rye can than be carried out later In the
summer,at the appropriate time.
Option 43 Chemical Only: Herbicide applications can be made during the bud stage,bloom to post
bloom and/or in the fall,depending upon the herbicide used.
DIFFUSE KNAPWEED: Diffuse Knapweed is a non-native,biennial to short-lived perennial forb that reproduces by seed. It
spreads rapidly by the mature plant breaking off al ground levet and being blown with the wind,dispersing seed. It is a pioneer
species that will quickly invade disturbed,dry sites. Diffuse Knapweed is found in the southwest part of Weld County along
rights-of-way,drypasture sites and in gravely riparian sites,such as along Boulder Creek and the St.Vraln and South Platte
Rivers.
1• Control Measures
a. Cultural Control: Cultural Control of Diffuse Knapweed is similar to Russian Knapweed in that
• seeding with perennial grasses such as smooth brome and crested wheatgrass will help to compete
with Diffuse Knapweed and slow its spread. Seeding alone in Infested sites will not,however,control
the existing stand.
b. Mechanical Control: Mowing Diffuse Knapweed when it Is in the bud stage and again when It is
flowering can significantly reduce seed production.'Keeping Diffuse Knapweed from going to seed over
a number of years can eventually eliminate an infestation,once the seed source in the soil is depleted.
e• Biological dentrol: Two species of picture-winged flies,Urophore e#lhis end U.quaddfesclete have
demonstrated the ability to reduce the seed production of diffuse and Spotted Knapweed. The flee lay
eggs on the developing seed heads. As a result of the larvae feeding on the flowering heads,the plants
produce galls which reduces seed production The Colorado Insectory Is currently rearing these two
flies and has made releases in the state the last three years.
d• - Chemical Control: There are a few herbicides labeled for use on Diffuse Knapweed.
be used independently or in combination with each other art picloram(Toron®o imba(BBanvel®
glyphosate(Roundup®);2,4•D(many different formulations)and any EPA approved chemical labeled
for use on Diffuse Knapweed.
2. Integrated Management Options by Slte
a. Pasture and Riparian Areas
Option#1 Cultural and Chemical Control: A herbicide application can be made in early summer
when Diffuse Knapweed is in the rosette through bolting stage. Reseeding with competitive perennial
grasses such as smooth brome and crested wheatgrass can be followed later in the summer
depending upon the herbicide used and rate of application.
Option#2 Biological and Chemical Control: The release of insects such as Urophore affin/s and
U. quadr/fasciete can be made. A herbicide treatment can then be made from the rosette through
bolting stage(where Insects were not released)and In the fall where insects were released. Herbicide
applications should only be carried out In the fall,where insects are used. The use of herbicides at
different times of the growing season can be instituted as additional IPM research is conducted and
recommendations are developed.
XOption #3 Mechanical and Chemical Control: Mowing can be carried out when Diffuse
e�ee nain�ee��stag,if e�eaagain at flowering. A hetblgdeappli ration can then be made tosny
Option#4 Mechanical Control Only: Mowing can be carried out throughout the season which will
reduce seed set.
Option#5 Chemical Control Only: Herbicide application can be made during the rosette stage,
spring or fall,and while bolting.
b. Rights-of-Way and Other Non-Crop Areas
Option#1 Culture!and Cfhemleal Contrel: Same as for Option#1 In pasture and riparian areas.
Option#2 Mechanise!and Chemical Control: One mowing operation can be carded out when .
ha Diffuse Meweed k In the bud siege. Ifneosrery,a herbicide application can be made to plants that
Option 13 Mechanical Control Only: Same as for Option#4 In pasture and riparian areas.
Option#4 Chemical Control Only: Same as for Option#5 in pasture end riparian areas.
SPOTTED KNAPWEED: Spotted Knapweed is a non-native, perennial forb that reproduces by seed. It Is a highly
competitive plant in rangeland sites that will exclude most grasses and forts with time. There is limited Spotted Knapweed
infestations currently along the South Platte River drainage in Weld County.
1• Control Measures
a. Cultural Control: Cultural control of Spotted Knapweed is similar to such control of Russian and
Diffuse Knapweed in that seeding with perennial grasses such as Smooth Brome and crested
wheatgrass will help to compete with Spotted Knapweed and slow Its spread. Seeding infested sites will
not,however,control the existing stand. In range and pasture conditions,good grazing management
practices will help to reduce the spread of the knapweeds in general.
b. Mechanics Control: Mechanical control of Spotted Knapweed could be carried out throughout the
summer with repeated mowing every 14-21 days. This would at least keep Spotted Knapweed from
going to seed. Whether this control technique will reduce the root mass and subsequently reduce an
existing stand Is not known.
c. Biological Control: The same as what was developed under biological control for Diffuse Knapweed.
d. Chemical Control: There are a few herbicides labeled for use on Spotted be used Independently or in combination with each other are: don®),Knapw Those that can
2,4-D(many different formulations and clopyraldu picloramj (Tortlon®),dicamba(Barrel®),
and z,a-o(curtan®).
CANADA
the root systemSlIis•a difficult plant Thistle
control begcause of Its extensive perennial
root system. Vertical rootreproduces s m y and vegetative deep aid
horizontal roots may extend 15 feet or more. Canada Thistle is the most widespread noxious weed In Weld County. It can be
found in most habitatY grow 6-15 foot and
and Big Thompson Riv ),types,rrigatioin ditches,alonpastures, g roadside righarian sites ts-of-way way end waterways the vario s cop and noncopland sites.
such as the Poudre,South Platte,St Vraln
1. Control Measures
a. Cultural Control: Plant competition from various grasses and from alfalfa can be an effective
be used to management tool. Early emerging grass species such as Smooth Brome and Created Wheatgrass can
compete
weCesda Thistle and slow
anead and establishment of new infestations.Competition alone,hoers seldom effective on Canada Thistle.
b. Mechanical Control: Mechanical Control of Canada Thistle could be carried out throughout the
summer with repeated mowing every 14 days. Such method keeps Canada Thistle from going to seed;
however,mowing has shown to stimulate new shoot growth from roots. Consequently,mowing alone
may Increase shoot density in an established stand. Whether consistent mowing for consecutive years
(two to three years)will reduce the root mass and subsequently reduce an existing stand Is unknown.
-c• Biological Control: There Is one Insect species,a weevil,called Ceutorynchs/Itura,that is currently
being used as a biological control agent on Canada Thistle in Colorado. The female lays eggs on the
underside of the leaves in early spring and then the larvae bore into the main leaf vein and migrate
down to the crown of the plant. The holes created by the larvae open up Canada Thistle to secondary
infection. Where high numbers of the larvae occur death of Canada Thistle can occur.
d. Chemical Control: There are a number of herbicides labeled for use on Canada Thistle,depending
upon where the thistle is found. The herbicides that can be used independently or in combination with
• other compounds are: picloram(Tordon®);dicamba(Banat®);2.4-D(many different formulations);
chlorsulfuron(Toler®);clopyralid(Curtail®,Stinger®,Transline®);glyphosate(Roundup®,Rodeo®)
and any EPA approved chemicals labeled for use on Canada Thistle.
2. Integrated Management Options by Site
a. Range, Pasture and Riparian Sites
Option k1 Biological and Chemical: Release of the insect•Ceuturynchus Ilfura can be made during
the early summer. A herbicide application can then be made at the bud stage(where insects were not
released)and In the fall where insects were released. Herbicide applications should only be carried out
in the fall,where insects were directly released. Use of herbicides at different times of the growing
season can be instituted as additional IPM research is coordinated and recommendations are
developed. -
Option 02 Mechanical and Chemical: Mowing can be carried out throughout the season with the
first mowing cycle at the bud stage. Mowing should stop during late August followed by a herbicide
treatment during late September through October,before a hard freeze.
Option e3 Cultural end Chemical Control: A herbicide application,using short residual herbicides
such as glyphosate and/or 2,4-D can be made followed up by reseeding with a competitive grass such
as smooth brome or other sod forming species. In addition,fertilization or irrigation could be instituted
to stimulate Increase grass growth.
Option k4 Chemical Control Only: Herbicide applications can be made to Canada Thistle from
rosette to the bud stage,and/or in the fell,depending upon the herbicide used.
b. Road Rights-of-Way and Other Non-Crop Areas
Option i1 Mechanical and Chemical: One mowing cycle can be carried out at the bud to early
_ --, - flower stage.. A herbicide-application can be made from rosette tb bud stage and/or in the fall,
• ,.. depending upon the herbs ideused.
Option k2 Cultural and Chemical Control: A herbicide application can be made in early summer
when Canada Thistle is in the rosette through bud stage. Reseeding with competitive perennial
grasses such as smooth brome and crested whealgrase can be followed later in the summer
depending upon the herbicide used and rate of application.
Option k3 Chemical Control Only: Herbicide applications can be made from rosette to bud stage,
and/or in the fall,depending upon the herbicide used.
c. Cropland Sites
Canada Thistle is found in almost every crop grown in Weld County. Prescription weed management
measures developed by Colorado State University weed scientists and the Weld County Extension
Agronomist will be used.
MUSK THISTLE: Musk Thistle is a biennial plant that reproduces only by seed. Rosettes(clump of
leaves on the ground)are formed during the first year of growth and the plant bolts and sets seed the
second year. It is a prolific seed producer with a single plant producing up to 20,000 seeds. Musk
Thistle is found primarily in pastures and riparian sites.(along waterways such as the South Platte,St.
Vrain,Big Thompson,and Utile ThompsoiRlrainages and Boulder Creek)and along Irrigation ditches,
roadside rights-of-way and other non crop areas.
1. Control Measures
a. Cultural Control: Maintaining pastures and riparian sites in good condition Is the primary method of
culturally managing Musk Thistle. Promoting good grass growth by proper grazing management and
fertilizing according to soil testing recommendations will prevent establishment of Musk Thistle.
b. Mechanical Control: Musk Thistle can be effectively controlled mechanically. Severing the roots
below ground with a shovel or hoe or mowing Musk Thistle every time it reaches early flower stage will
reduce,if not eliminate seed production. If mowing occurs mid to late flower stage,the thistle should be
gathered and burned to destroy any seed that has developed.
c Biological Control: Two species of weevils, Rhinocyllus conicus (seed head weevil) and
Trichosirocalus horndus,attack two different sites of Musk Thistle. The seed head weevil,as its name
Implies,attacks the seeds of Musk Thistle. Eggs are laid by the female on the back of developing
flowers and then the larvae bore into the flower,destroying the developing seed. The seed head weevil
can reduce seed production by as much as 50%. Use of this weevil as the sole means of controlling
Musk Thistle is not very effective.
Trichosirocalus horridus attacks the crown area of Musk Thistle rosettes,killing or weakening the plant
before it bolts. Use of both weevil species together may prove to be an effective biological control
program.
d. Chemical Control: There are a number of herbicides labeled for use on Musk Thistle,depending
upon where the thistle is found. The herbicides that can be used independently or in combination with
other compounds are: picloram(Tordon®);dicamba(Banal®);2,4-D(many different formulations);
chiorsulfuron(Tatar®);clopyralid(Curtail®,Stinger®,Transline®);glyphosate(Roundup®,Rodeo®)
and any EPA approved chemical labeled for use on Musk Thistle.
2. Integrated Management Options by Site
a. Pasture and Riparian Sites
Option k1 Biological and Chemical: Release of Trichosirocalus borridus can be made at the I
appropriate time of the summer. Rhinocyllus conicus is well established in Weld County and should
already be infesting the stand. A herbicide application can then be made to Musk Thistle at the flower
stage.Telar or.Escort should be used when treating Musk Thistle In the flower stage. Herbicide
applications should only be carried out in the flower stage in order to allow the seed head weevil to
complete its life cycle. Use of herbicides to rosettes in the spring or fall should not be carried out where
Trichosirocalus horr/dus was released.Use of herbicides at different times of the growing season can
be Instituted as additional IPM research is conducted and recommendations are developed.
Option 412 Mechanical and Chemical Control: Mowing can be carried out throughout the summer
when Musk Thistle Is in the bud to early flower stage. A herbicide application can than be made in
October to the fall rosettes and any bolted plants.
Option k3 Mechanical Control Only: Multiple mowings(two to four)can be carried out throughodt
the summer when Musk Thistle is in the bud stage,keeping it from producing seed. If mowing occurs
mid to late flower stage„the thistle should be gathered and burned to destroy any seed that has
developed.
Option k4 Chemical Control Only: Herbicides can be used in the spring and fall when the plant is in
the rosette stage. Only the herbicides labeled for the site intended will be used.
•
b. Road Rights-of-Way and other Non Crop Areas
Option#1 Biological and Chemical Control: Same as for Option#1 in pasture and riparian sites.
Option #2 Mechanical and Chemical Control: One mowing pass can be made when Musk
Thistle is in the bud stage. A homicide application can be made in the fall to the rosettes and re-bolted
plants.
Option#3 Chemieel Control Only: Herbicides can be used in the spring and the fall when the plant
is in the rosette stage. Only the herbicides labeled for the site intended will be used.
SCOTCH THISTLE:Scotch Thistle is a biennial plant that reproduces only by seed. Rosettes are formed during the first year
of growth and the plants bolt and set seeds the second year. The leaves are densely covered with hair,giving the plant a
grayish-green color. Scotch Thistle is primarily found in pastures and riparian sites(South Platte River Drainage)and along
roadside rights-of-way and other non-crop areas in southem Weld County.
1. Control Measures
a Cultural Control: Maintaining pastures and riparian sites in good condition is the primary method of
culturally managing Scotch Thistle.Promoting good grass growth by orooer grazing management and
fertilizing according to soil testing recommendations will help prevent establishment of Scotch Thistle.•
• Mechanical Control: Scotch Thistle can be efficiently controlled mechanically. Severing the roots
below ground with a shovel or hoe or mowing Scotch Thistle every time it reaches bud to early flower
stage will reduce,if not eliminate seed production.If mowing occurs mid to late flower stage,the thistle
should be gathered and bumed to destroy any seed that has developed.
• Biological Control: No biological control agents are available for Scotch Thistle. One weevil species,
Rhinocyflus conicus,will move from Musk Thistle to Scotch Thistle;however,effective control of Scotch
Thistle has not been demonstrated.
d Chemical Control: There are a number of herbicides labeled for use on Scotch Thistle,depending•
upon where the thistle is found. The herbicides that can be used Independently or in combination with
other compounds are:picloram(Tordon®);dicamba(Banvel®);2,4-D(many different formulations);
chlorsulfuron (Telar®); metsulfuron (Escort®); clopyralid (Curtail®); Stinger®; Translihe® and
glyphosate(Roundup®,Rodeo®)and any other EPA approved chemical labeled for use on Scotch
Thistle.
2 Integrated Management Options By Site
a Pastures and Riparian Sites
Option#1 Mechanical and Chemical Control: Multiple mowings(two to four)can be carried out
throughout the summer when Scotch Thistle is In the bud sage,keeping it from producing seed. A
herbicide application can than be made in October to the fall rosettes and any bolted plants.
Option k2 Mechanical Control Only:Multiple mowings(two to four)can be carried out throughout
the summer when Scotch Thistle is in the bud stage,keeping it from producing seed. If mowing occurs
mid to late flower stage,the thistle should be gathered and burned to destroy any seed that has
developed.
Option#3 Chemical Control Only:Herbicides can be used in the spring and fall when the plant is In
the rosette stage. Only the herbicides labeled for the site intended will be used.
Road Rights-of-Way and Other Non Crop Areas
Option#1 Mechanical and Chemical Control:One mowing pass can be made when Scotch Thistle/Is
in the bud stage. A herbicide application can be made to rebolted plants in the bud stage and/or to fall
regrowth.
Option#2 Chemical Control: Herbicides can be used in the spring and the fall when the plant is in
the rosette stage. Only the herbicides labeled for the site intended will be used.
FIELD BINDWEED:Field Bindweed is a deep rooted creeping perennial plant that reproduces by seed and horizontal roots.
Bindweed seed can survive in soil up to 40 years;therefore,it is important that bindweed be kept from going to seed. Field
Bindweed is found throughout Weld County In most habitat types including:rangeland,pastures,along roadside rights-of-way
and in various crop and non-cropland sites.
1. Control Measures
a Cultural Control:Seeding perennial grasses can be an effective management tool in providing plant , a
competition against bindweed. Selecting the proper native grass and/or improved cuitivar grass seed
mix for a site specific location is important. For site specific reseeding recommendations the Natural'
Resource Conservation Service and the CSU Extension Office can be contacted.
b Mechanical Control:,Mechanical control of Field Bindweed can only realistically be carried out in
cultivated cropland by discing and cultivating every 3 weeks. This would keep Field Bindweed from
producing seed and would start to reduce root reserves. Mowing is not effective due to the creeping
nature of bindweed. Discing in range,pasture or roadside is not environmentally sound.
c. Biological Control: There are currently no biological control agents on Field Bindweed that are
cleared for release in the United States; however,research is in process. Grazing with livestock(cattle
or sheep),with proper stocking rates,can be an effective means of keeping bindweed from going to
seed in range and pasture sites. -
d Chemical Control:There are a number of herbicides labeled for use on Field Bindweed,depending
upon where the bindweed is found. The herbicides that can be used independently or in combination
with other compounds are: picloram (Tordon®); dicamba (Banvel ®); 2,4-D (many different
formulations);glyphosate(Roundup®.Rodeo®)and any other EPA approved chemicals labeled for
use on Field Bindweed.
2 integrated Management Options by Site
a Range and Pasture land
Option 81 Cultural and Chemical Control:A herbicide application using short residual herbicides
.such as glyphosate and/or 2,4-D,can be made,followed by reseeding In fall with a competitive sod
forming grass mix. In addition,fertilization according to soil tests or irrigation could be Instituted to
stimulate Increased grass growth.
Option 42 Biological Control:Grazing with cattle and sheep throughout the summer and fall will
keep Field Bindweed from going to seed and may reduce the underground root reserve.
Option e3 Biological and Chemical Control:Grazing with cattle or sheep from May through early
September followed by a herbicide treatment in late September or early October.
•
Option 14 Chemical Control Only:Herbicides can be used during the flower stage typically in June
and July,and in the fall prior to a hard freeze. Only the herbicides labeled for the site Intended will be
used.
b Road Rights-of-Way and Other Non Crop Areas
Option a1 Cultural and Chemical Control:A herbicide application using short residual herbicides,
such asglyphosate and/or 2,4-D.can be made followed by reseeding In the fall with a competitive sod
forming grass mix.
Option s2 Chemical Control Only: Herbicide can be used during the flower stage,typically in Jury
and July,and in the fall just before a hard freeze. Only the herbicides labeled for roadsides and othe
non cropland areas will be used.
c. Cropland Sites: Field Bindweed Is found in almost every crop grown in Weld County. Prescription
weed management measures developed by Colorado State University weed scientists and the Weld
County Extension Agronomist can be used.
C. PREVENTION MEASURES
Preventive control means using measures which will stop or forestall weeds from contaminating an area. Establishing
preventive measures are often the most practical and cost effective means of weed control.
The preventive measures which seem most practical for Weld County are as follows: _
1. establishing weed tree seed and mulch requirements for reclamation of disturbed sites,
2 promoting the Colorado Weed Free Hay and Forage program,
a prioritizing weed management areas along routes of dispersal,and
4. Identifying noxious weed species in counties bordering Weld County.
1. Weed Free-Seed and Mulch Standards
Where the ground is disturbed by activities,such as road preparation for road resurfacing, sand and gravel lot
operations and oil and gas well operations,weeds will be the first plants to colonize or re-vegetate the site.It is
important that these sites be reclaimed so that noxious weeds do not become established.
Weld County plans to establish standards within two to four years for using weed free seed end mulch on all county
operations concerned with the reclamation of disturbed sites,such as on roadside resurfacing projects and sand
and gravel lot operations. Additional regulations may be considered for similar operations being carried out on
private land.
2 Weed Free Hay and Forage Program
Standards have been developed that enable growers the ability to have their hay and forage certified as noxious
weed free. These standards will encourage growers to produce noxious weed free hay and forage so that it can be
shipped and used anywhere in the U.S.(particularly where noxious weed free standards currently;exist).
The Weld County Vegetation Management Specialist will promote the Colorado Weed Free Forage Standards
through the use of seminars,radio spots and newspaper articles.
3. Prioritizing Weed Management Areas Along Routes of Dispersal •
Weeds are spread rapidly through the dispersal of'weed seeds in air and water. Consequently,high weed seed
dispersal areas are associated with rights-of-way,such as along all roads and railroads and along waterways,i.e.,
along the Poudre,South Platte,St.Vrain and Utile Thompson Rivers and irrigation canals.
The County Public Works Department will carry out a noxious weed control program on all county roads from May
through September. The noxious weeds targeted for control include: Canada,Musk,Scotch and Bull Thistle;Leafy
Spurge;Russian,Diffuse and Spotted Knapweed;Field Bindweed;whitetop;and Wild proso millet. In addition,
contact will continue to be made with the Department of Transportation,all irrigation and ditch companies in the
county,the Union Pacific, Burlington Northern and Great Western Railroad companies, and the oil and gas
companies operating within the county. Information regarding the Weld County Undesirable Plant Management
Act will be distributed and their cooperation will be encouraged. Assistance in helping them develop their
integrated weed management programs will be offered.In working with landowners on private property,all lands
bordering the rivers in the county will be considered high-priority areas. Landowner compliance with the
Undesirable Plant Management Act will be encouraged.
4. Identifying Noxious Weeds in Bordering Counties That Do Not Occur in Weld County
Contact will continue to be made with the weed control departments in the bordering counties to identify the
noxious weed species which occur in each county that would threaten Weld County. Plans have been developed to
monitor the borders of Weld County,as necessary.
D. EDUCATIONAL PROGRAMS
• Education of the public is one of the most important components of a Weed Management program. Emphasis will be placed on
continuing a multifaceted educational program. The following programs have been instituted in the past and will continue to
be conducted every year.
1. Timely newspaper articles concerned with weed identification and management.
2. ' Timely radio broadcasts following the information in the newspaper articles.
3. Conducting landowner weed management seminars and calibration workshops.
4. Having an educational booth at the Colorado Farm Show. •
5 Utilizing brochures and CSU Service in Action brochures to hand out to individual landowners.
E. MAPPING •
Establishing an acerbate baseline map of the existing noxious weed infestations in the county is extremely important for the
ongoing evaluation of the effectiveness of the county weed management program. Therefore, a computerized mapping
program will be established that will map the noxious weeds established in Weld County.
•
County roadsides will be mapped using a computer and printer/datalogger on the spray equipment. Private and state land will
be mapped by Public Works Department personnel taking aerial maps from the county assessor's office into the field and
mapping on site. Through the use of the Auto CADD computer mapping program, the noxious weed infestations will be
mapped. All mapping information will be stored in the county IBM computer systems and can be retrieved for future evaluation.
F. ESTABLISHING COOPERATIVE INTERGOVERNMENTAL AGREEMENTS
Contact will be made with the following agencies concerning compliance with the Colorado Undesirable Plant Management
Act:
•
1. Colorado Department of Transportation
2. Colorado State Department of Parks and Recreation
3. Colorado Division of Wildlife
4. Colorado State Land Board
5. U.S.Forest Service
Assistance will be offered in helping each agency develop integrated weed management plans for their lands. Actual
assistance in carrying out the weed control programs on their properties will also be offered. Cooperative intergovernmental
agreements can be established if Weld County is asked to assist in implementing the weed control measures.
G. ADOPT A ROADSIDE PROGRAM
An'Adopt a Roadside'program will be established which will give landowners the ability to take the responsibility to manage
the noxious weeds on the county rights-of-way that borders their property.
Landowners who are chemically sensitive or for some reason do not want chemicals sprayed or mowing activities carried out
along their property,may take the responsibility for managing the noxious weeds on the roadside rights-of-way. Landowner
agreements with specific requirements for compliance will be established.
•
H. ENFORCEMENT ON PRIVATE AND PUBLIC PROPERTY
Cooperation from all landowners(private and state)will be encouraged through positive communication by mail and through
personal contact. When weed control measures are not carried out by a landowner,enforcement measures may have to be
Instituted. All procedures as established by the Undesirable Plant Management Law, CRS§35-5.5-109, the Pest Control
• Districts Law,CRS§35-5-108,Weld County Ordinance 169-A,and any and all federal, state, and local regulations will be
followed,prior to any enforcement activities being carried out on private or public property. Integrated weed management
plans will be requested from certain landowners,as determined by the Weld County Vegetation Management Specialist and
the Undesirable Plant Management Advisory Board.
• Work priorities must be established due to the size of the county and the number of landowners with existing noxious weed
problems. The following list prioritizes where enforcement activities will be carried out in ranking order of importance:
1. Lands bordering all waterways(rivers and irrigation ditches).
• 2 — Complaint properties.
3 Landowners identified as negf2 ent in the past.
4. Landowners with twenty percent(20%)or more of their property infested with noxious weeds.
EVALUATION OF PROGRAM
The goals and the plan of work established in Sections III.and IV.of this Ordinance 169-A will be reviewed and evaluated at the end of
every year. A written evaluation will be prepared establishing additions or changes in the plan of work for the following year. Any additions
or
• oommngsi s must be recommended py the Undesirable Plant Management Advisory Board and approved by the Board of County
ers.
•
The Weld County Undesirable Plot Management Plan shall be reviewed and amended,as needed,at least every three years(CRS§35-
5.5-107(4)(a)).
•
ARTICLE 2 — ENFORCEMENT OF
UNDESIRABLE PLANT MANAGEMENT PLAN
AUTHORIZED AGENT FOR ENFORCEMENT
Pursuant to CRS§35-5.5-105(2),the Weld County Vegetation Management Specialist,his employees and agents,are hereby authorized
• to enforce the above-stated Undesirable Plant Management Plan in the unincorporated areas of County of Weld,State of Colorado,by
utilizing those procedures set forth In CRS§§35-5-108,35-5-109,and 35-5.5-108,and any other applicable State and Federal Statutes,
•
rules,regulations,and ordinances,including the-remaining provisions of this Ordinance No.169-A.
II. RIGHT OF ENTRY •
•
Prior to entering private lands for the purpose of enforcing the Weld County Undesirable Plant Management Plan as set forth herein,the
Weld County Vegetation Management Specialist shall first obtain aright of entry'from the Board of County Commissioners,no less than
ten days after a Notice to Control Identified Undesirable Plants has been sent to the owner or occupant of the private lands and said owner
or occupant has failed to comply with said notice.
lit. MAILING OF ASSESSMENTS
All assessments for the whole cost of any enforcement work performed by the Weld County Vegetation Management Specialist or his
designee(s)upon private lands,Including up to 15%for inspection and other incidental costs in connection therewith,shall be mailed to the
landowner or occupant by certified mail.Failure to receive said assessment shall not ad as a defense to said assessment
IV. 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 Weld County Vegetation Management Specialist or his designee(s)have performed enforcement work,shall
constitute a lien against each lot or tract of land until paid and may be certified by tesoluton of the Board of County Commissioners to the
Weld County Treasurer's Office to he collected In the same manner as provided for collection of taxes upon the private lands in
• accordance with CRS§§35-5.106 and 35-5.8-109(5)(a).
ARTICLE 3— SEVERABILITY •
.any section,subsection,paragraph,sentence,clause or phrase of this Ordinance Na.169-A is,for any reason,held or decided to be invalid or
unconstitutional,such decision shall not affect.the validity of the remaining portions.The Board of County Commissioners,Weld County,Colorado,
hereby declares that it would have passed this Ordinance No.169-A,and in each and every section,subsection,paragraph,sentence,clause and
phrase thereof irrespective of the fact that any one or more sections,subsections,paragraphs,sentences,clauses,or phrases might be declared to
be unconstitutional or invalid.
ARTICLE 4-- LIABILITY
•
This Ordinance No.169-A shall not be intended to crests a civil cause of action against the Board of County Commissioners,Weld County,Colorado,
or any other person that may administer this Ordinance No.169-A in any manner. •
ARTICLE 5•- EFFECTIVE DATE
•
This Ordinance No.169-A shall become effective five(5)days after its final public notice,in accordance with Section 3-14(2)of the Weld County Home
Rule Charter.
•
•
ARTICLE 6--COMPLIANCE WITH NOTICE REQUIREMENTS
The Board of County Commissioners hereby states and affirms that by following the reading and publication schedule set forth below,it has and
hereby does comply with the notice requirements of CRS§35-5.5-108.
ARTICLE 7--NO WAIVER OF•IMMUNITIES/NO CREATION OF DUTIES.STANDARD OF CARE.OR RIGHTS FOR THIRD PARTIES
No portion of this Ordinance 169-A shall be deemed to constitute a waiver of any immunities which Weld County,Colorado,by and through the Board
of County Commissioners of Weld County,or any pest control districts and/or their Boards,or the Weld County Undesirable Plant Management
Agiasory Board or their officers or.employees may possess,nor shall any'provislon of this Ordinance 169-A be construed to create any duty,standard
are or rights in favor of any third parties with the respect to any obligation created by this Ordinance 169-A. -
BE IT FURTHER ORDAINED by the Board,if any section,subsection,paragraph,sentence,clause,or phrase of this Ordinance is for
any reason held or decided to be unconstitutional,such decision shall not affect the validity of the remaining portions hereof.The Board of County
Commissirntars hereby declares that it would have enacted this Ordinance in each and every section,subsection,paragraph,sentence,clause,and
phrase thereof irrespective of the fact that any one or more sections,subsections,paragraphs,sentences,clauses,or phrases might be declared to
be unconstitutiorrel or . ,.
The above end fororego)f rdinance Number 169-A was,on motion duly made and seconded,adopted by the following vote on the'day
of,A.D.;1996.
BOARD OF COUNTY COMMISSIONERS
•
WELD COUNTY,COLORADO
ATTEST:
Weld County Clerk to the Board Barbara J.Kirkmeyer,Chair
•
•
-�: George E.Baxter,Pro-Tem
Deputy Clerk to the Board •
Dale K.Hall
APPROVED AS TO FORM:
Constance L.Harbert
County Attorney •
W.H.Webster
•
Initial Publication:February 1,1996,in the North.Weld Herald •
First Reading:March 4,1996
Publication:March 7,1996,in the North Weld Herald
Second Reading:March 18,1996
Publication:March 21,1996,in the North Weld Herald
Final Reading:April 1,1996
Publication:April 4,1996,in the North Weld Herald
Effective Date:April 9,1996
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