HomeMy WebLinkAbout960519.tiff 6311 .44-4.-
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be, and hereby is, repealed and, by and through this Ordinance 169-A, be, and hereby is, reenacted,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
1. INTRODUCTION
A. DESCRIPTION OF THE COLORADO UNDESIRABLE PLANT MANAGEMENT ACT
The Colorado Undesirable Plant Management Ad, 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
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 diffuse) 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 goveming 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 amensis),
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 intergovemmental
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 (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.
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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 forts 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 (lava 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 Nava, 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 (Teiar®); 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 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. 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 fort 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
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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®), 2,4-0 (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 /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 (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 burned to destroy any
seed that has developed.
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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 (Banvel®);
2,4-O (many different formulations); chlorsulfuron (Telar®); clopyralid
(Curtail®, Stinger®, Transline®); glyphosate (Roundup®, Rodeo(0)
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.
ScorcH 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 bumed 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: picloram (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 ®);
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 assessors 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 conceming 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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PAGE 21
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
960121
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RE: ORDINANCE NO. 169-A
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).
960121
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RE: ORDINANCE NO. 169-A
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.
960121
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RE: ORDINANCE NO. 169-A
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
960121
ORD169
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
O.21-1-- 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: /�
t� YY,Q,ila eiCG 'Ile/69'"A — Second 4A-4 S'J`
was in said newspaper bearing the date(s) of:
Thursday,the CA 5 day of /�0,idt , 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 regulate printing of legal
notices and advert' ments, approved Ma 18, 1931, and all
prior acts so far i force.
iY
BRU J. ORMANN, PUBLISHER
Subscribed and sworn to before me this 21-5 day
�.:,. ...,.C of Q/LC/L
S ERIKA C. @ BAGLEY 074, a„Q
NA: t) NOTARY PUBLIC
C .......
QP L
My commission expires lbub 0a, 2/ /999
2C
THE NORTH WELD HELD
THURSDAY, MARCH 21R1996 PUBLIC Ni
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:
County WHEREAS,the Board of County Commissioners of the County of Weld,State of Colorado,pursuant to Colorado statute and the Weld
Home Rule Charter,is vested with the authody of administering the affairs of the County of Weld,Stale of Colorado,and
WHEREAS,on May 4,1992,the Board of County Commissioners adopted Weld County Ordinance 169,Mich became effective May
12,1992,and which provides for the adoption and erdorcement of an undesirable plant management plan in Weld County,and
those WHEREAS,said Ordinance 169 designates live(5)weed species as undesirable and mandated for management In Weld County,
(Centaurw atyiasaa)�Canada Thistle(CCa krm amenla),Russians.),
Kn.), ud k Thistle
it le a Diffuse u Knapweed(Cerllewsa a19uea),Spotted Knapweed
( rvavae),and Musk Thistle(Cats rxrlerr(,and
WHEREAS,upon the recommendation of the Weld County Undesirable Plant Management Advisory Board,the Board of County
Co nandoners hereby finds and datemnksa that there le a need to add Iwo weed species to the lb'of those coven*designated as undesirable
management in Weld County,the two additions being:Field Bkldweed(ConvolvuluS arveraist and Scotch Thistle(Otlopordum
coca is),thereby requiring,at a minimum,an amendment to said Ordinance 169,and
n WHEREAS,upon further recommendation ol the Weld County Undesirable Plant Management Advisory Board,the Board of County
hereby finds and determines that there is a need to make other revision to the Weld County Undesirable Plant Management Plan,
thereby molds roe repeal and reenactment of saki 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 ce Number 169,adopted May 4, 1992,be,and hereby Is,repealed and,by and through this Ordnance 169-A,be,and
hereby is,reenacted,as follows:
ARTICLE 1 — WELD COUNTY
IINf1FSIRARr F PI ANT MANAGEMFNT PLAN.
I. INTRODUCTION
A. DESCRIPTION OF THE COLORADO UNDESIRABLE PLANT MANAGEMENT ACT
The Colorado Undesirable Plan Management Ad,CRS§35.5.5-101,et.seq.,(hereinafter the Act"
states that contain 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 stale. The undesirable plaits designated for mandatory
management statewide are:Leafy Spurge(Euptwbla ate).Russian Knapweed(Acmpflon redone),Defuse Knapweed
(Centawrra diffuse)and Spotted Knapweed(Cstaurea 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 plaids in their respective Juradlctio s. They are further directed to appoint an
advisory commission whose responstWtles are threefold:
1. Develop recommended management criteria and integrated weed management plans for managing the
designated undesirable pane:
2 Recommend the addition,if necessary,of undesirable plants that shall be subject to integrated management;
a 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 properly.
The Act further slates that by January 1,1992,each local governing body is to have developed and
adopted an Undesirable Pan Management Plan for all lands within its Jurisictlonal boundaries.
It. 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 aunty the ability,
through a lengthy petitioning and balloting process,to establish weed control distrkts. Within each weed datrtct,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 am ditty being managed in at least a pad of Weld County are as follows:
Leafy Spurge (Euphorbla
Canada Thistle (C/rolum arvenss),
Musk Thistle (Carduus natant),
Field Bindweed (Canso/value arven:dab
Whitetop (Cardad& drabs),
Russian Knapweed (Acroptilon repent)
Wild Proso Millet(Pan/eum mlllaceum)Under She Act and Russian,Diffuse et seq.),
&Spothertted are four weed species which are mandated for county-wide management. They are
Leafy po Knapweed. Canada Thistle,Musk Thistle,Scotch Thistle and Field Bindweed are
added to the county-wide undesirable pled list by this Ordinance 169-A,in accordance with CRS§35.5.5.108(3).
Of the weed species listed previously, „WeldThistle,sh Bindweed,Leafy Spurge,Musk Thistle,Russian Knapweed,Whitetop and
Wild Prato Millet cover the mostCounty and pose the greatest economic and environmental threat to the county.
Diffuse Knapweed le currently localized to a few drainages and rights-of- In the southwest art of the County,and there is one
known Spotted Knapweed tribulation in the County. -way P
NI. OBJECTIVES AND GOALS
A. STATEMENT OF OBJECTIVES
The
fo objectives of the Weld County Public Works Department with respect to weed management in Weld County are
old:
1. Develop and carry out a comprehensive noxious weed control program on at 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.
a bendy non-informed or negligent landowners who are not carrying out weed management programs on their
propertyand provide technical support for establishing weed management plans or enforce on properties,If
ry.
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 WS County roads for noxious weed asedatlons.
2. Map on a computer program at least hag of the landowners that have Leafy Spurge,Canada Thistle and
Russian Knapweed infestations.
a 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.
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
end where appropriate enter into cooperative intergovernmental agreements.
fl Have established six to eight biological control release sites throughout the county in cooperation with the
Colorado Department of Agriagure 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)
IY.
1. Have mapped on the computer program most noxious weed infestations courtly-wide,Including private,state
and federal leads.
2 " Have reduced the noxious weed acreage sprayed on county rights-of-way by 40-50%.
a Have contacted and worked with most landowners county-wi0e who have a noxious weed Infestation.
4. Have edablsled 30-50 biological control release sues in the county.
IV. PLAN OF WORK - IMPLEMENTATION
A. DESCRIPTION OF INTEGRATED WEED MANAQEMENT TECHNIQUES
The weed spades designated as undesirable and mandated for management are Leafy Spurge(Eupbonola asula),
Russian Knapweed ( AcropWon repent), Diffuse K weed (Condone diffuse), Spotted Knapweed (Centaurea
mambas),Canada Thistle(Casbm arvense)Musk T e(Canduus nutans),Scotch Thistle(Oncpordum acanuilum)and
Field (Cawolvulus annals). Integrated management methods are to be used in managing these weed
species(Cp9 g35r55.107). Integrated management' es include education;preventive measures;and control
measures k4udag cultural,mechanical,biological and chemical control. For the purposes of this plan the following
definitions for the control measures wig be used.
1. Cultural Control means those methodologies or management practices conducted to favor the growth of
desirable pints over undesirable plants,Including,but not gilled to,manlMrrg 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,tiling,mowing,burning,Iloodiag.mulching,hand-puling and hoeing.
a Biological Control mew the use of organisms such as sheep,goats,cattle,insects and plant diseases to
disrupt the growth of undesirable putts.
4. Chemical Control means the use of herbicides or plant growth regulators to disrupt the growth of undesirable
plants.
Management of the various undesirable plaits will vary depending upon the site where the pant is located. Management ed nt
to provide vons for ararious manach weed gement techniques fdes will be or for each site.The contrdtng the noxious weedsIn the vaatous lee ions listed
m d below ntal sitesey arse
found. By no means are all the management options mentioned. Additional wMYWbns of management techniques are
dual
landownle ers will be evaluated b be submitted y theWe private landowners.
County Vegetations Management Specialist plans subrnitted and the integrated r Weed
Management Advisory Commission n a case by case basis.
B. INTEGRATED WEED MANAGEMENT OPTIONS FOR EACH WEED SPECIES
LEAFY SPURGE: Leafy Spurge is a deep rooted perennial pant that spreads by seeds and creeping roots. It has a vast
underground root system which nails t difficult to control with any one control technique. Leafy Spurge is found primary
in tartan sites(along waterways such as the Poudre and South Platte Rivera)in Weld County and also along irrigation
ditches,range and pastures,roadsides and other non-cropland alas.
1. Control Measures
a. Cultural Control: Seeding perennial grasses and?orbs can be an effective management tool.
Early emerging plant species t1Nt utilize early season moisture such as Smooth aroma(aroma
manmia)or Crested rryyq9(Agrapyron crlafatum)have reduced Leafy Spurge density and
limited the spread and plabNihmart of new infestation. Sequential glyphosate applications
followed by a seeding S Luna Pubescent Wlralgrass,Ephraim Growled W heatgreas,IMenoadiate
WNrtlprs,Shaman Big Bluegrass or Bomww Russian Maid Rye has shawl to be very effective in
reducing an existing stand of Leafy Spurge.
b. Mechanical Control: Mechanical control of Leafy Spurge is difficult al best;however,repeated
mown every 14-21 days throughout the summer,Mrsig before lowering stage, will at Mad keep
dine plants from going to seed and may reduce the underground rod reserve. Research results are
not available to indicate whether stand reduction or eradication could be achieved through use of
this technique.
,and fall will
a keep Leafy
Control: going to seed and razing with sheep and goats throughout
ilteuunderground root reserve. This practice
keep also safy Spurge s to make them more ausceptble to chemical control.
may weaken the pant ing Several treed species that have been released by the USDA kt the United new and d States are tates are shotwapeed some
control d Levy Spurge. Two species of flea beetles,AWhone
n
Leafy Spurge. Adults teed on the longs during the summer and the larvae burrow through the soil
and mina the roots and line root hairs. These insects used alone may not control Leafy Spurge.
When used edp withodu other insects ley sl we�the
and make t moreult),a gall susceptible to other which feeds on the clowers
ontrol
evamirq seed la ndemical control.
methods,peNaatl
d. Chemical Control: There area number of herbicides labeled for use on Leafy Spurge. Those that
can be used independently or in oombhatbnewith each other
Roe: picl ram and ToRord o®);dicamba
(Knelled): d (many approved
lab ediltyP glyphosate
Lady Spurge.
(Knelled)and any EPA approved
2. Integrated Management Options by Site
a. Range, Pasture and Riparian Sites
Option e/ Biological and Chemical Control: Grazing with sheep or goats from early Aprl
through late August or early September,followed by a herbicide treatment in late September or early
October.
Option 02 Biological and Chemical Control: The release of insects such as Apthona
nigzbaAa,Apthona/lava, Spurges ails,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 carded
out In the fail 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 e3 Mechanical and Chemical Control: Mowing can be canted 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 e4 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 K Chemical Control Only: Herbicides should be used in the spring,early summer
during the we flower stage and in the fall just before a hard freeze. Only the herbicides labeled for
the site intended w41 be used.
b. Along Irrigation Ditches
Option el Biological and Chemical Control: The release of insects such as Apthona
nlgdscWs,Apthona flays,Sputgla Esula and other species conducive to the area could be made.
An herbicide treatment should be carded out at the true flower stage(it the Spurgia Saute has not
kept the plants from going to seed)and/or in the tall just before a hard freeze.
Option e2 Chemical Control Only: Herbaidos can bo 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.
0. Road Rights-of-Way and Other Non-Crop Areas
Option H 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 e2 Chemical Control Only: Herbicides can be used in the spring or early summer during
the true flower stage and in the fail 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(alebpathlc properties). Thus,aloe 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 Brame(Brotnus bermes)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 aielopaak:properties of
Russian Knapweed,other control techniques such as judicious chemical control would have to be
hpemefed In order to give grasses a chance to compete.
b. Mechanical Control: Mechanical control of Russian Knapweed could be canted 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.
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(Teter®);
pobram(Tordon®);2,4-0(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 e1 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: 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 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 Rights-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. An herbicide application can be made during the bud stage,bloom to post-bloom
andeor in the fall,depending upon the herbicide used.
Option e2 Cultural and Chemical Control: Use of short residual herbicides such as glyphosate
and/or 2,4-0 can be used in the early summer during the bud stage. Seeding with perennial grasses
such as Smooth Brae,Luna Pubescent Wheatgrass,Ephraim Crested Wheatgrass,Intermediate
Wheatgrass,Sherman Big Bluegrass or Bozolsky 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
pat bloom and/or in the fall,depending upon the herbicide used.
DIFFUSE KNAPWEED: Diffuse Knapweed s a non-native,biennial to shod-lived perennial forb that reproduces by seed.
It spreads rankly by the mature plant brealdng off at ground level and being blown with the wind,dispersing seed. It is a
pioneer species that will qulcdy invade disturbed,dry sites. Diffuse Knapweed Is found in the southwest pail of Weld County
along rights-of-way,ay pasture sites and in gravelly Marian sites,such as along Boulder Creek and the St.Vrain and South
Platte Rivers.
1. Control Measures
G e rat trot: Vu...
a. ejj;; cal Control of Diffuse Knapweed Is similar to RusalasedMpweed in that
' grasses such as smooth brome and crested wheatgrasswet hip to compete
•. ..+.1 and slow is spread. Seeding alone In Iaested sites will not,however,control
IReex sW.0
b. Mechanical Control: Mowing Diffuse Knapweed when k Is in the bud Slaps and again when k is
flowering can significantly reduce seed production. Keeping Diffuse Kn pwsed from going to seed
over a number of years an eventually eliminate an infestation,once the seed source in the soil is
depleted.
c. Biological Control: Two species of picture-winged flies,Uraphora aslnis and U. quadnfasclata
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 plans produce galls which reduces seed production. The Colorado ieeclory is currently
rearing these two Dies and has made releases in the state the last three years.
d Chemical Control: There are a few herdckles labeled for use on Defuse Knapweed. Those that
can be used independently or In combination with each other are: picbram(Tordon®);dicamba
(Sanoit);yyphosete(Roundup®);2,4•D(many different fomulatbns)and any EPA approved
chemical labeled for use on Diffuse Knapweed.
2. Integrated Management Options by Site
a. Pasture and Riparian Areas
Option a1 Cultural end Chemical Control: A herbicide application can be made in early
summer when Douse Knapweed is in the rosette through bolting stage. Reseeding with ConpeBive
peremial 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 12 Biological and Chemical Control: The release of insects such as Urophora Shins
and U. quadrlfasclata can be made. A herbicide treatment can then be made from the rosette
through bolting stage(where Secs were not released)and in the fall where Insects were released.
Herbicide applications should only be carried out in the fan,where insects are used. The use of
herbicides at different tines 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 pain at flowering. A herbicide application can then be made to
any plants that have re-bolted,if necessary.
Option s4 Mechanical Control Only: Mowing can be carved out throughout the season which
sup reduce seed set.
Option 06 Chemical Control Only. Had*Ina a acdkatbn can be made during the rosette stage,
spring a lace,and whle bolting.
b. RIghte-of-Way and Other Non-Crop Areas
Option a1 Cultural and Chemical Control: Same as for Option a1 in pasture and riparian
rasa.
Option#2 Mechanical and Chemical Control: One mowing operation can be carried out when
Diffuse Knapweed is in the bud stage. lt necessary,a herbicide spplatbn an be made to plants
that have re-bolted.
Option IS Mechanical Control Only: Same as for Option#4 in pasture and Marian area.
Option 04 Chemical Control Only: Same as for Option#5 in pasture and riparian areas.
SPOTTED KNAPWEED: Spotted Knapweed Is a non-native,perennial Mb that reproduces by seed. I Is a highly
conpetkive plant in rangeland alas that wit exclude moat passes and leas with time. There is Btsted Spotted Knapweed
infestations currently along the South Platte River drama 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
wfeatgrass sell step 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 1421 days. This would at least keep Spotted Knapweed
from going to seed. Whether this control technique will reduce the root mass and subsequent&
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 i ndepenxent&or in combination with each other are: pbbram(Tordan®),dicamba
(Barwei®),2,4-D(nary different formulations and clopyrald and 2,4D(Coded®).
CANADA THISTLE: Canada Thistle is an aggressive,creeping perennial that reproduces by seed and vegetative buds In
the root system. lt is a dffbut plant to control because of its extensive root system. Vertical roots may pow 6-15 foot deep
and horizontal roots may extend 15 feet or more. Canada Thistle is the most widespread noxious weed in Weld County.. 1
can be found in mod habitat types,Including:pasta riparian sites(along waterways such as the Podre,South Platte,St.
Vraln and Big Thompson Rivers),Irrigation ditches,along roadside rights-of-way and n the various crop and non-cropland
sites. 1
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 Wheatpaa
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 ha shown to stimulate nevi shoot growth from roots. Consequetty,
mowing alone may increase shoot density in an established stand. Whether consisted 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,aled CeutoryncMu Mortar,is
currently being used as a biological control agent on Canada Thistle in Colorado. The ie ys
eggs on the underside of the leaves n early spring and then the larvae bore into the man en
and migrate down to the crown of the plant. The holes created by the larvae open up C- the
Thistle o secondary infection. Where high numbers of the larvae occur death of Canada n
occur.
d. Chemical Control: There are a number of herbicides labeled for use on Canada
depending upon where the thistle Is found. The herbicides that can be used Indepe kf
combination with other compounds are: picbram(Tordon®);dicamba(Bane*);2,4-
d lerent formulations); chlorsulfuron (Team): cbpyralld (Curial*, Stinger®, Tra 5;..
glyphosate(Roundup*,Rodeos) and any EPA approved chemicals labeled for use on
Teets.
2. Integrated Management Options by Site
a. Range, Pasture end Riparlan Sites
Option 11 Biological and Chemical: Release of the insect Ceutorynchus mum can be made
during the early summer. A herbicide application an then be made at the bud stage(where creeds
were not released)and in the tall where insects were released. Herbicide applications should only
be canted out in the fall,where insects were directly released. Use of herbicides al dNlerera times of
the growing season can be Instituted as additional 1PM research ,Is coordinated,and
recommendations are developed.
Option 12 Mechanical and Chemical: Mowing can be canted 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 03 Cultural and Chemical Control: A herbicide application, using short residual
herbicides such as gtyphosate and/or 2,43 can be made followed-up-by reseeding with a
competitive grass such as smooth brome or other sod forming species. In addition,ledlization or
irrigation could be instituted to stimulate Increase grass growth.
Option 04 Chemical Control Only: Herbicide applications can be made to Canada Thistle hem
rosette to the bud stage,anchor in the fall,depending upon the herbicide used.
b. Road Rights-of-Way and Other Non-Crop Areas
Option 11 Mechanical and Chemical: One mowing cycle can be carried out at the bud to early
flower sage. A herbicide application can be made from rosette to bud stage and/or in the fall,
depending upon the herbicide used.
Option 02 Cultural and Chemical Control: A herbicide application can be made in early
summer when Cads Thistle b kr the rosette through bud stage. Reseeding with competitive
peremial grasses such a smooth brume and crested whealgrass can be followed later In the
summer depending upon the herbicide used and rate of application.
Option 13 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 Edenslon Agronomist MN be used.
MUSK THISTLE: Music Thistle is a blervna plan that reproduces only by seed. Rosettes(dump of leaves on the ground)
are formed during the flat year of growth and the plane bolts and eels seed the second year. It is a prolific seed producer
with a single pore producing up to 20,000 seeds. Musk Thistle is found primarily in pastures and riparian ales(Song
waterways such as the South Platte,S.Vrein,Big Thompson,and Little Thompson drainages and Boulder Creek)and
along irrigation dices,roadside Milts-el-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 propel grazing management
and Waning 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 readies early flower stage
will reduce,N net 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, Rhlnocyllus con/cus (seed head weevil) and
Trohoskocalus beetles,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 weevl can reduce seed production by as much as 50%. Use MOM weevil as the sole
men of connoting Music Thistle is not very effective.
Tdchostocelus honidus Wad.the crown area of Musk Trestle rosettes,idling or weakening the
plant before It bolls. Use of both weevil species together may prove to be an effective biological
control program.
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 tie used independently or in combination
with other compounds are: picloram (Tordon®); dicarnba (Bement); 2,4-D (many different
formulations); chorsuiuron.(Telma); clopyraild (Curtail®, Stingers,Transli a®); glPhosate
(Roundup!),Rodeo®)and any EPA approved chemical labeled or use on Musk Thistle.
2. Integrated Management Options by.She
•
a. Pasture and Riparian Sites
Opion 01 Biological and Chemical: Release of Trichosirocelus bonldus can be made al the
appropriate tined the summer. Rhhmocylw con cus is well established kn Wed County and should
already be Westing the stand. A herbicide application can then be mach to Musk Thistle at the
flower stage.Teter or Escort should be used when treating Musk Thais in the flower saga.
Herbicide applications should only be canted out In the flower stage in ode to slow the seed head
weevil to complete its Me cycle. Use of MOM:ides to rosettes in the sprig or fall should not be
carried out where Tdchos/rocalus Amides was released.Use of herbicidaset dmerent times ot the
growing season can be instituted as additional IPM research Is condnctedand recommendations
are developed.
Option 42 Mechanical and Chemical Control: Mowing can be carded 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 03 Mechanical. Control Only: Multiple mowings(two to lour) can be carded out
thmuglout the summer when Musk Thistle is in the bud stage,keepig It from producing reed. N
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 thesprkg and tall when 11w plan
is in the rosette stage. Only the harbk:ides labeled for the ale knedst will be used.
b. Road Rights-of-Way and other Non Crop Areas
Option 01 Biological and Chemical Control: Same as for°Mon W hi pasture and riparian
sites.
Option 02 Mechanical and Chemical Control: One mowing taw can be ritade when Musk
Thistle le in the bud stage. A herbiclds application can be made*the fall to the rosettes and re-
bolted plants.
Option 13 Chemical Control Only: Herbicides can be used in le spring and the fall when the
plant is In to rosette stags. Only the he bicides Waled for life use intended wig be used.
SCOTCH THISTLE:Scotch Thistle indent®plant that reproduces only by seed. Rosettes n formed during the fist
year of growth end the plants boa and set seeds the second year. The eaves are densely coverid with their,giving the plant
a grayish-green color. Scotch Thistle is primarily found M pastures and riparian sites(South Platte River Drainage)and
along roadside rights-al-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
d culturally managing Scotch Thistle.Promoting good grass growth by proper grazing management
end fertilizing according to soil testing recommendations WI help prevent establishment of Scotch
HAS.
Mechanical Control: Scotch Thistle can be efficiently controlled mechanically. Severing the roots
below ground with a shovel or hoe or mowing Scotch Thistle every one 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,RMnocyllus conlcus,will move from Musk Thistle to Scotch Thistle;however,effective
control of Scotch Thistle has not been demonstrated.
Chemical Control: There are a number of herbicides labeled for use on Scotch Thistle,
depending upon where ihe4hisile is found. The herbicides that can be used independently or In
combination with other compounds are:ploloram (Tordon®);dicamba(Banal®);2,4-D(marry
different lonulalions); chlorauiuron (Telar®); metsulluron (Escort®); dopyralld (Curtail®);
Steger®;Translhe®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 It Mechanical and Chemical Control: Multiple mowing.(two to four)can be carded
out throughout the summer when Scotch Thistle is In to 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 02 Mechanical Control Only: Multiple mowings (two to four) can be carried out
throughout to summer when Scotch Thistle is in the bud stage,keeping I from producing seed. If
mowing occurs mid to late flower stage,is 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 pent
is in the rosette stage. Only the herbicides labeled for the site intended MI 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 reboped plane 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 pin is
in the rosette stage. Only the herbicides labeled for the site intended wB be used.
FIELD BINDWEED:Feld Bindweed s a deep rooted creeping perennial plant that reproduces by seed and horizontal
roots. Bindweed seed can survive in soil up to 40 years;therefore,I Is inporar 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
plot competition against bkdweed. Selecting the proper native grass and/or improved cutivar
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.
Mechanical Control:Mechanical control of Field Bindweed can only realistically be carried out in
cultivated cropland by disdng and cultivating every 3 weeks. The would keep Field Bindweed from
producing seed and would stn to reduce root reserves. Mowing Is not effective due to the creeping
nature of bindweed. Disctg In range,pasture or roadside is not environmentally sound.BiologIcal Control:There are currently no ed that are
cleared for release In the United States; however,r,�
s p research In process. Grazing l control agents on Field gwith livestock
(cattle or seed range sheep),
and pasture
with proper rates,can be an effective means of keeping bindweed from
going to
4 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 axe:plcioram
different formulations);gypheeste(Round o (Banvel
(Roundup®, odo®)and any pother EPA ch approved emlcab
labeled for use on Field Bindweed.
2. Integrated Management Options by Site
r
a Range and Pasture land
Option Si 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
competitNe
sod stimulate forming increased grass
mix grass growth.
In addition, according to soil tests or irrigation could
be instituted
keOep Field Bindwon#2 weeed fromical ntrol:going to seed and may reduce the uidergr with cattle and sheep ound root ut the summer and fall will
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 to site Intended
colt be used.
Road Rights-of-Way and Other Non Crop Areas
Option it Cultural c and Chemical
2,4•D,can be made folowed by reseeding In the fall with a
Control: A herbicide application
herbicides, asolinpgra e and/or
competitive sod fouling grass mbc.
Option#2 Chemical Control Only: Herbicide can be used during the flower stage,typically in
June end July,and in the fall lust before a hard freeze. Only the herbicides labeled for roadsides and
other non cropland areas will be used.
Cropland Sites:Feld Bindweed is found In almost every crop grown in Weld County. Prescription
weed management t 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 means are often the most practical and cost effective mesa of weed control.
The preventive measures with seem most practical for Weld County am 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,
a prioritizing weed management areas along routes of dispersal,and
♦ 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 sand and gravel lot
operations and dl and gas well operations,weeds win be t ha first preparation
plants to colonize o�egetate the site.it is
knporta t 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 tree seed and mulch on ail
county operations concerned with the reclamation of disturbed sites,such as on roadside resurfacing protects
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 edited as noxious
�,t p d These
used anywherefinatMeuS e@atlkxulacy wwers to here noxiousweednoxioufree ststan sty andards currently ex forage so ist).
The can
The Weld County Vegetation Management Specialist will promote the Colorado Weed Free Forage Standards
though the use of seminars,radio spots and newspaper asides.
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 seeddial areas are
ILe� associated
alonnng the Poudre,South Platte,St with�VmY f-way,such as along all roads and railroads and along waterways,
and Little Thompson Rivers and irrigation canals.
l roads May/through September.The County Public Works The noxious weeds targeted frtment will carry out a or control indite:s weed control program,Malusi4 Such and Bull
Thigh;
Lealy
ordSpurge;
w Russian,con s tDefo be and Spotted
the�Departmeeweed; nt of Transportation,treetop; imgation and wild�and dfedch
companies
in the county.the Union Padilla,gas companies operating within c Cocompanies,
theoounty. lydonnatlo,regarding the WeldCounty
the oil andUndesirable
Plant Management Ad wit be distributed and their cooperation
be orn will
be nc ur�with anc.in helpners ing
develop their integrated weed management programsareas. Landowner
'
property,
ans Nance with the Undesirable Plant all lands bordering the raManagement county
Act Mil encouraged. high
diy
4. Identifying Noxious Weeds in Bordering Counties That Do Not Occur in Weld County
Contact WI continue to be made with the weed control departments in the bordering counties to identity the
noxious
weed speciesthe
borders occur
In each Carat•nt 'ld threaten Weld County. Plans have been onitor developed toof
D. EDUCATIONAL PROGRAMS
Education of the public Is one of the most important components of a Weed Management program. Emphasis will be plead
on continuing a multifaceted educational program. The following programs have been IMfuted in the past and will
cone to be conducted every year.
1. Timely newspaper Midas concerned with weed IdertMlcalion and management.
2. Timely radio broadcasts blowing the information In the newspaper articles.
3. Conducting landowner weed management seminars and calibration workshops.
4. Having an educable ban al the Colorado Farm Show.
S lANztnnp brodaras end CSU Service In Action brochures to hand out b Individual landowners.
E. MAPPING
Establishing an accurate baseline map of the existing nwtbus 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 war be established that we map the noxious weeds established in Weld County.
County roadsides will be mapped using a computer and printer/datalogge.on the spray equipment. Private and stale lend
will be mapped by Public Works Department personnel taking aerial maps from the county assessor's office into the field
and mapping on site. Though 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 wit be made with the following agencies concerning compliance with the Colorado Undesirable Plant Management
Ad:
1. Colorado Department of Transportation
2. Colorado State Department of Parks and Recreation
3. Colorado Division of Wildlife
4. Colorado Slate Land Board
5. US.Forest Sella
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 an be established II 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 responsbiify 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 castled
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 al landowners private and Mate)will be encouraged through positive communication by mall and
through personal contact. When weed control measures are not carded out by a landowner,enforcement measures may
have to be instituted. AN 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 aN federal,state,and local regulations
will be followed;prior to any enforcement activities being carried out on private or public property. Integrated weed
management plane will be requested from certain landowners,as determined by the Weld County Vegetation Management
Specials and the Undesirable Plan 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. T)w folowhg list prioritizes where enforcement activities will be caned out In ranldng order of Importance:
1. Lands bordering all waterways(rivers and higaten ditches).
2 Complaint properties.
a Landowners identified as negllOent in the past.
a Landowners with twenty percent(20%)or more of their property fleeted with noxious weeds.
V. EVALUATION OF PROGRAM
The goals and the plan of work established in Sections III.and IV.of this Ordinance 109•A will be reviewed and evaluated at*ie end of
every year. A written evaluation will be prepared estabtehing addition or charges in the plan of work for the lollowing 'Ear. Any
additions or changes must be recommended by the Undesirable Pert Management Advisory Board and approved by the Board of
County Commissioners.
The Weld County Undesirable Plant Management Plan shal be reviewed and amended,as needed,a at least every three years(CRS
$35.5.5-107(4)(a)).
ARTICLE-2 —E- NFORCEMENT OF
UNDESIRABLE PI ANT MANAGEMENT PLAN
AUTHORIZED AGENT FOR ENFORCEMENT
Pursuant to CRS$35.5.5.105(2),the Weld County Vegetation Management Specialist, his em,loyeee and agents,are hereby
authorized to enforce the above-stated Undesirable Plant Management Plan in the unincorporated areas of County of Weld,State of
Federal Statutes rules,regulations,those rres set forth In and ordnances,CRS IncudYq the remaining35-5-109,
provsion+of he and 1Ord and
rance No.169-A.
applicableState and
11. 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 Spedallst shah that obtain a'nigh of entry'from the Board of County Commissioners,no less
than ten days after a Wive to Centel Identified Undesirable Plants has been sent to the owner or occupant of the pnNate lands and
said owner or navel le%clad lo campy with said notice.
IIL MAILING OF ASSESSMENTS
AN assessments for the whole oast of ay antorame t work palomed by the Weld County Vegetation Management Specialist or his
designee(the a)upon petals lands,inducing up lo 15%ter Inspelon and east laddialei cads In connection therewith,dal be mailed to
case melt Failure r said w saNa m Mid elS not as a se a defame said aaeaMnrt.
IV. FAIT URE TO PAY ASSESSMENT
Any assessment which Is rot pail within thirty-three(33)days alter the date of mailing by codified mall to the landowner or occupant of
private lands upon which the Weld Corny Vegetation Management SeedMlet x his designee(*)have performed entornement work,
shall constitute a lien against each lot ottrad of land until paid and May be called by resolution of the Board of County Commissioner*
to the Weld County Treasurers 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(Sxa). '
ARTICLE 3 — SEVERABII ITY
If any section,subsection,paragraph,sentence,clause or phrase of this Ordnance No.169-A Is,for any reason,held or decided to be Wald or
unconstitutional,such decision shall not affect the validly of the remaining portions.The Board of County Commissioners,Weld County,Colorado,
hereby thereof e irrespective r of ld theefadththatt d this
o mmooree sections,and
sub In sections,paragraphs,sentences,and every section, s,ciclaauuses or a pusses nigh declared,clause
to be unconstitutional sttutional or Invalid.
An'cLE 4 — I IABI,ITY
This Ordinance No.169-A ehal not be Intended to ante a civil cause of action against the Board of County Commissioners,Weld County,
Colorado,or any other person that may administer trs Ordinance No.18g-A in any manner.
ARTICI F 5 — FrEECTIVE DATE
Thin Ordinance No.169-A shat become effective the(5)days after Is final pudic notice,In accordance with Section 3-14(2)of the Weld County
Home Rule Charter.
ARTICLE 6 — COMP;IANCE WITH NOTICE REQUIREMENTS
The Board of County Com iesbrsa hereby Metes at Cans that by following g the reading and publication schedule set forth below,it has and
hereby does comply sib the notice requkernents ol CRS$35.5.5-108.
ARTICLE 7 — NO WAIVER OF IMMUNITIES/NO CREATION OF DUTIES_ STANDARD OF CARE OR RIGHTS FOR THIRD
EAMTIfl
No portion of the Ordinance 169-A shall be deemed to constitute a waiver of any Immunities which Weld County,Colorado,by and through the
Board of County Commissioners of Weld County,or any pest control districts and/or their Boards,or the Weld County Undesirable Plant
Management Advisory Board or MeV officers or employees may possess,nor shall any provision of INS Ordinance 169-A be construed to ante
any duty,standard of care or rights in favor of any third parties with the repect to any obligation created by this Ordnance 169-A.
•
BE IT FURTHER ORDAINED.by the Board,If any section,subsedbn,paragraph,sentence,clause,or phrase of this Ordinance is
for any reason held or decided to be unconstitutional,such decision shall not affect the v$fay of the remaining portions hereof. The Board of
County Commissioners hereby declares that it would have enacted this Ordinal ire In each and every section,subsection,paragraph,sentence,
clause,and phrase thereof irrespective of the fact that any one or more sections,subsedioms,paragraphs,senletxas,Causes,or phrases might
be declared to be unconstitutional or invalid.
The above and foregoing Ordnance Number 169-A was,on motion duty made and seconded adopted by the following vote on the•day a•,
1996.
BOARD OF COUNTY COMMISSIONERS
WELD COUNTY,COLORADO
ATTEST:
Barbara J.KNkmeyer,Chair
Weld County Clerk to the Board
George E.Batter,Pro-Tern
BY:
Deputy Clerk to the Board
Dale K.Hal
APPROVED AS TO FORM:
Constance L.Harbert
County Attorney
W.H.Webster
initial Pubacatbn: February 1,1996,in the North Weld Herald
FM Reading:March 4,1996
Publication: March 7,1996,in the North Weld Herald
Second Reading: March 18,1996
Publication: Marctt21,1990,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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