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HomeMy WebLinkAboutFORT COLLINS NISSAN-KIA - PDP210017 - SUBMITTAL DOCUMENTS - ROUND 3 - ENVIRONMENTAL REPORT 937 Mallard Drive, Ft. Collins, CO 80521 • (970) 224-0851 • www.bluemountainenvironmental.com April 13, 2022 Cathy Mathis, APA TB Group 444 Mountain Avenue Berthoud, CO 80513 RE: Fort Collins Nissan-Kia Upland Revegetation and Restoration Plan Ms. Mathis: This restoration plan is intended to be used for revegetation of contoured/graded uplands and ecological restoration of the Natural Habitat Buffer Zone (NHBZ) at Fort Collins Nissan-Kia. The approximate locations of areas that will be disturbed are illustrated on the Fort Collins Nissan-Kia Project Development Plan dated October 6, 2021 (here incorporated by reference). Areas to be restored occur principally on the western, northwestern and northern perimeter of the proposed development. Our recommended approach to revegetation of contoured/graded and NHBZ upland areas includes guidelines for exotic grass and noxious weed management, soil treatment, planting of cover crop and native vegetation, erosion control, monitoring, irrigation, and maintenance of the seeded areas. Recommended restoration activities, as well as success criteria, are outlined on the following pages. This plan was prepared by Craig Severn, Amy Randell and Matt Tobler. Feel free to contact me with questions. Sincerely, Matt Tobler Natural Resource Specialist, Certified Ecologist Blue Mountain Environmental Consulting, LLC Ft. Collins Nissan – Kia Upland Restoration Plan Pre-construction Vegetation Vegetation in the project area is dominated by the exotic grass species including smooth brome (Bromus inermis) and crested wheatgrass (Agropyron cristatum). Other exotic species include kochia (Bassia scoparia), Russian thistle (Salsola iberica), yellow salsify (Tragopogon dubius), prickly lettuce (Lactuca serriola), yellow sweet clover (Melilotus officinalis), pennycress (Thlaspi arvense), and flixweed (Descurainia sophia). On-site species listed on the Colorado Noxious Weeds list include leafy spurge (Euphorbia esula), musk thistle (Carduus nutans), Dalmatian toadflax (Linaria dalmatica), field bindweed (Convolvulus arvensis), downy brome (Bromus tectorum), and common mullein (Verbascum thapsus). Native vegetation is a minor component of the total cover on the property. Existing Soils The majority of the project area is mapped as Kim-Thedalund loams, 3-15 percent slopes. Upland Restoration Plan This upland restoration plan encompasses portions of the project area to be revegetated with native upland vegetation. This includes contoured and graddedareas and the Natural Habitat Buffer Zone (NHBZ) ecological restoration areas. This plan does not include landscaped areas. Note: This upland restoration plan includes areas immediately adjacent to bioretention swales. The actual timing of project implementation is unknown, so only general temporal guidelines are provided. This plan includes guidelines for exotic grass and noxious weed management, soil treatment, planting of cover crop and native vegetation, erosion control, monitoring, irrigation, and maintenance of the seeded areas. Table 1 outlines restoration activities for each year. Table 1. Summary of upland restoration activities for contoured/graded and Natural Habitat Buffer Zone areas at Fort Collins Nissan-Kia. Year Reference Section Contoured/Graded Uplands Natural Habitat Buffer Zone (NHBZ) 1 fall Exotic Grass Control Apply herbicide to smooth brome within 10 days after first hard or killing frost. Apply herbicide to smooth brome within 10 days after first hard or killing frost. 1-6 Soil Treatment N/A Protect area from unnecessary soil disturbance and compaction during the construction period. 2 spring Noxious Weed and Exotic Grass Control Continue herbicide treatment(s) to eradicate non-native grasses and noxious weeds through growing season. Continue herbicide treatment(s) to eradicate non-native grasses and noxious weeds through growing season. Ft. Collins Nissan – Kia Upland Restoration Plan 2 fall Exotic Grass Control If necessary apply herbicide to remaining smooth brome within 10 days after first hard or killing frost. If necessary apply herbicide to remaining smooth brome within 10 days after first hard or killing frost. 3 early Soil Treatment Remove 6 inches of topsoil and stockpile. Contour and grade. N/A 3 early Plant Topsoil Piles if Necessary Seed with sterile triticale or native seed mix depending on storage period. N/A 3 spring Plant Temporary Cover Crop N/A Plant cover crop of sterile sorghum in spring. Allow cover crop to grow through summer. 3 spring- summer Irrigation Irrigate topsoil piles if necessary to promote seed germination and plant growth. Irrigate cover crop if necessary to promote seed germination and plant growth. 3 late Soil Treatment Replace topsoil and allow to settle and firm. N/A 3 late fall Plant native seed mix Drill native seed mix into firm seed bed in late fall to early spring. Mow if necessary before planting. Drill native seed mix in late fall to early spring. 3 after seeding Mulch Application All seeded areas shall be mulched within 24 hours of seeding. All seeded areas shall be mulched within 24 hours of seeding. 4-6 spring-fall Monitoring and Maintenance Monitor seeded areas for weeds, irrigation needs, erosion, and bare areas. Implement need maintenance. Monitor seeded areas for weeds, irrigation needs, erosion, and bare areas. Implement need maintenance. 4-6 spring- summer Irrigation Irrigate if necessary to promote seed germination and plant growth. Irrigate if necessary to promote seed germination and plant growth. 4 summer Noxious and Annual Weed Control If annual weeds are present, mow monthly with mowing heights no less than 4 to 6 inches. Manage noxious weeds. If annual weeds are present, mow monthly with mowing heights no less than 4 to 6 inches. Manage noxious weeds. 5-6 summer Noxious and Annual Weed Control If annual weeds are present, mow monthly with mowing heights no less than 10 inches. Manage noxious weeds. If annual weeds are present, mow monthly with mowing heights no less than 10 inches. Manage noxious weeds. 6 Determine Success Criteria Determine if success criteria for vegetative cover has been met. If success criteria have not been met, maintain growth for additional Determine if success criteria for vegetative cover has been met. If success criteria have not been met, maintain growth for additional year. Ft. Collins Nissan – Kia Upland Restoration Plan year. Year 1 Fall - Exotic Grass Control Contoured/Graded and NHBZ Begin control of smooth brome within 10 days after the first hard or killing frost in the fall. A killing frost would occur if the temperature is 27º F or colder for three consecutive hours or more. Applying glyphosate within 10 days after the frost is ideal, because the grass is beginning to pull all the moisture and nutrients in the leaves down into the root system to store energy and water during the dormant period. The Larimer County Weed District recommends treating exotic perennial grasses with Rodeo near wetlands and Roundup on uplands. Year 1-6 - Soil Treatment NHBZ Protect the NHBZ from all unnecessary soil disturbance and compaction during the construction period. Fencing or other barriers may be necessary to exclude vehicles from the area. Year 2 Spring - Noxious Weed and Exotic Grass Control Contoured/Graded and NHBZ Continue control of exotic grasses and noxious weed species. It is anticipated that three to four treatments may be necessary through the growing season. It is important to continue control of smooth brome as this exotic perennial grass can have an extensive root system. If smooth brome is entirely eliminated before topsoil removal, underground roots and rhizomes will not be viable to compete with the seeded native species after topsoil is replaced. Herbicides will be used at appropriate rates and timing. Year 2 Fall – Exotic Grass Control Contoured/Graded and NHBZ If necessary continue control of smooth brome within 10 days after the first hard or killing frost in the fall. Year 3 Early – Soil Treatment Contoured/Graded Area Remove 6 inches of topsoil from areas that are to be contoured and graded. Stockpile topsoil away from all drainage system components including swales and storm sewer inlets. Where practical, choose stockpile locations that that will remain undisturbed for the longest period of time as the phases of construction progress. Place sediment control structures around the perimeter of the topsoil stockpile. This may include sediment control logs, rock socks, silt fence, straw bales or sand bags. Soil stockpiles shall not exceed 10 feet in height to preserve soil Ft. Collins Nissan – Kia Upland Restoration Plan microbes that will aid in plant establishment. Stockpiles shall be kept loose, not compacted, and watered as needed to prevent dust migration. Additional stockpile management practices are provided in the Fort Collins Fort Collins Stormwater Criteria Manual dated September 2018. Avoid piling anything, including subsoil, construction debris, etc. on the topsoil stockpile. Avoid handling topsoil when soil is wet. Store upland and wetland top soils in separate piles. Stockpiles should be monitored for signs of erosion displacement and sediment accumulation and if conditions warrant it, stockpiles shall be covered if stored less than 30 days Year 3 Early – Plant Topsoil Piles if Necessary Contoured/Graded Area If topsoil is not going to be redistributed within 30 days within one growing season, plant a cover crop on the topsoil stockpile. We recommend QuickGuard Sterile Triticale to minimize colonization of non-native species. Broadcast QuickGuard Sterile Triticale at a rate of 40 pounds pure live seed (PLS) per acre followed by raking to incorporate seed into soil to a depth of ½ to ¾ inch. Seeding should be conducted after May 15 or after the last frost. Cover with weed-free straw mulch or hydro mulch. Seed in anticipation of natural precipitation. If soil is to be stored for more than one growing season, seed with a native prairie seed mix presented in Table 2. The seed mix may be purchased from Pawnee Buttes Seed Company, Arkansas Valley Seed, or Western Native Seed. Year 3 Spring – Plant Temporary Cover Crop NHBZ Planting a temporary cover crop of sterile sorghum in spring of year three allows for an additional growing season to deplete the seed bank and control undesirable species. The cover crop will also prevent erosion and conditions the soil for planting of the native seed mix in the late fall. Seed bed preparation such as mowing or tilling is not necessary before seeding the cover crop. A no-till grain drill shall be used to plant sterile sorghum at a rate of 5 pounds pure live seed (PLS) per acre after May 15 or after the last frost when soil temperatures are above 65 degrees F. Plant seeds ½ to ¾ inch deep in rows 7 to 12 inches apart. Allow the cover crop to grow throughout the summer. Allow cover crop to grow through the summer. Year 3 Spring – Irrigation Contoured/Graded and NHBZ If dry conditions persist after seeding, sprinkler irrigation may be necessary for successful seed germination. If dry conditions exist during the growing season, irrigation may be necessary for adequate plant establishment. Year 3 Fall – Replace Topsoil Contoured/Graded Area When grading and contouring operations are complete, distribute approximately two to six inches of topsoil to graded areas. This portion of the upland restoration plan applies to all areas Ft. Collins Nissan – Kia Upland Restoration Plan that were graded and contoured including all areas immediately adjacent to bioretention swales. Following topsoil application, allow soil to settle (ideally with rainfall) for 7 days prior to upland seeding. At the time of seeding, a human footprint should compact the soil ¼ to ½ inch. Soil compaction with a cultipacker is not recommended on clay/loam soils because this treatment will result in soils that are too firm. Once the soil is settled, seed with the native seed mix. Year 3 Fall – Plant Native Seed Mix Contoured/Graded Area This portion of the upland restoration plan applies to all areas that were graded and contoured including all areas immediately adjacent to bioretention swales. Once the soil is settled no till grain drill to seed the native seed mix presented in Table 2. Plant the native seed mix between November 15 and April 15. The mix may be purchased from Pawnee Butts Seed Company, Arkansas Valley Seed or Western Native Seed. Confirm the size of the area needed to be seeded. The native seed mix should be planted at 24.5 pounds PLS per acres. Plant seeds ¼ to ½ inch deep in rows 7 to 12 inches apart. Final drilling pass must occur on the contour, to create subtle ridges perpendicular to the flow of energy. Table 2. Native prairie seed mix. Common Name Scientific Name Growth Form* PLS/lbs. (x1000) PLS/SF PLS lbs./ac. sideoats grama Bouteloua curtipendula g 190 10 2.29 blue grama Bouteloua gracilis g 825 10 0.53 buffalo grass Buchloe dactyloides (burr) g 56 2 1.56 purple prairie clover Dalea purpurea f 293 3 0.45 Canada Wildrye Elymus canadensis g 115 10 3.79 thickspike wheatgrass Elymus lanceolatus g 154 5 1.41 annual sunflower Helianthus annuus g 115 5.5 2.08 hairy goldenaster Heterotheca villosa hs 330 3 0.40 gayfeather Liatris punctata f 168 3 0.78 blue flax Linum lewisii f 293 3 0.45 western wheatgrass Pascopyrum smithii g 120 10 3.63 mountain goldenbanner Thermposis rhombifolia f 30.6 5 7.12 Total 69.5 24.5 * g=grass, f=forb, hs=halfshrub; PLS = Pure Live Seed; SF = Square Foot Year 3 Fall – Plant Native Seed Mix NHBZ If growth of the sterile sorghum crop is determined to be too tall and/or dense for effective use of the no-till grain drill, mow the sterile sorghum before seeding. Other seed bed preparation such Ft. Collins Nissan – Kia Upland Restoration Plan as tilling is not necessary before seeding. A no -till grain drill shall be used to plant the native seed mix presented in Table 2. Plant native seed mix between November 15 and April 15. The mix may be purchased from Pawnee Butts Seed Company, Arkansas Valley Seed or Western Native Seed. Confirm the size of the area needed to be seeded. The native seed mix should be planted at 24.5 pounds PLS per acres. Plant seeds ¼ to ½ inch deep in rows 7 to 12 inches apart. Final drilling pass must occur on the contour, to create subtle ridges perpendicular to the flow of energy. Year 3 After Planting – Mulch Application Contoured/Graded and NHBZ All seeded areas shall be mulched within 24 hours of seeding, and the mulch shall either be adequately crimped and or tackified. Apply weed-free straw mulch to seeded areas at a rate of 2 tons per acre with 50 percent of the straw by weight should be 10 inches or more in length. Spread straw uniformly over seeded areas and crimp into the soil. Avoid spreading mulch when wind is in excess of 10 miles per hour. Hydro mulch application is also suitable. On slopes 3:1 or steeper we recommend Rolled Erosion Control Products (RECP). It is best to avoid thick straw or excelsior blankets because they can impede grass establishment. It is recommended to use only biodegradable RECPs, such as coconut straw composite blankets or jute netting. Plastic netting will not be used as it may trap snakes, deer and other wildlife that may utilize the area. Erosion control fabric containing plastic mesh is also prohibited. RECPs must be installed in accordance with the manufacturer’s recommendations. Years 4-6 – Monitoring and Maintenance Contoured/Graded and NHBZ Seeded areas shall be monitored several times a year for three or more years to ensure that success criteria will be met. Monitoring may require that adaptive management be employed as site conditions dictate. Conditions affecting the timing and frequency for monitoring include temperature, precipitation, plant phenology, timing of site activities, etc. Monitoring will include the following: presence and abundance of weeds; irrigation needs; erosion issues; trash removal and bare areas needing reseeding. Site conditions shall be communicated to the project team with appropriate action(s) taken as necessary. Weed issues should be addressed, irrigation shall be provided as seasonal trends dictate, additional erosion control measures may also be necessary, and bare areas should be reseeded. Years 4-6 Spring and Summer - Irrigation Contoured/Graded and NHBZ If dry conditions persist in the spring, sprinkler irrigation may be necessary for successful seed germination. If dry conditions exist during the growing season, irrigation may be necessary for adequate plant establishment and growth. The decadent cover crop of sterile sorghum in the NHBZ will moderate microclimate conditions of the seed bed helping to reduce moisture loss Ft. Collins Nissan – Kia Upland Restoration Plan from the soil profile. In the contoured and graded area, soil profile moisture will likely be lost more quickly due to the lack of cover crop plant residue. Assuming that the project is seeded in fall or early spring, irrigation shall be initiated in the first year after planting after springtime moisture is no longer available. Seeded areas shall be irrigated in the morning once per day until seed have germinated and grown past the three leaf stage. Irrigation shall be sufficient to moisten the top 1-2 inches of soil without generating runoff. Irrigation shall continue throughout the first summer and fall after planting at a rate of two to four times per week depending on site conditions. Irrigation will likely be necessary one to three times per week in the summers of year five and six. Year 4 Summer– Noxious and Annual Weed Control Contoured/Graded and NHBZ If annual weeds are present, mow monthly with mowing heights no less than 4 to 6 inches. Use of a narrow blade spade shovel for removing large tap roots, hand pulling, or spot herbicide application via a wick or spray applicator can be used to control other undesirable species as necessary. Digging or hand pulling undesirable plants when soil is moist will be the most effective means of control provided sufficient labor is available. Apply spot-control herbicide with a hand-held, backpack sprayer or wick applicator. Herbicide application is to be conducted by a licensed commercial applicator. It is important note that many herbicides are toxic in aquatic ecosystems and may cause significant risks to human health. Herbicides can enter waterbodies either directly through spray or spray drift, or they can move into waterbodies via surface water run-off or leaching and sub-surface draining. Several State-listed noxious weed species are present on the property and should be actively managed to prevent their establishment in restored areas including leafy spurge (Euphorbia esula), musk thistle (Carduus nutans), Dalmatian toadflax (Linaria dalmatica), field bindweed (Convolvulus arvensis), and mullein (Verbascum thapsus). Other undesirable species include cheatgrass (Bromus tectorum), kochia (Bassia scoparia), Russian thistle (Salsola iberica), yellow salsify (Tragopogon dubius), prickly lettuce (Lactuca serriola), yellow sweet clover (Melilotus officinalis), pennycress (Thlaspi arvense), and flixweed (Descurainia sophia). Noxious weed management guidelines are provided in Appendix A. Years 5-6 – Noxious and Annual Weed Control Contoured/Graded and NHBZ If annual weeds are still present, mow monthly with mowing heights no less than 10 inches. Use methods described in Year 4 above to control noxious and other weeds. Year 6 – Measure Success Criteria Contoured/Graded and NHBZ The Contoured/Graded and NHBZ will be surveyed twice a year on the following schedule: Ft. Collins Nissan – Kia Upland Restoration Plan 1. In the spring, a qualified ecologist will traverse the entirety of the Site to assess noxious weed populations. 2. At the peak of growing season, a qualified ecologist will implement quantitative measurements to evaluate ground cover within the NHBZ. Quantitative measurements will consist of two permanent photo points and five ground cover sampling points. At each sample point, ground cover will be measured using ocular estimates in a 1 meter by 1 meter quadrat, where the ecologist will estimate and record vegetative ground cover by species to the nearest 1%. All species, including noxious and invasive species, and their respective percent ground cover will be recorded. Annual monitoring will continue for a total of three years following restoration of the NHBZ. A brief memo containing survey findings and recommendations will be provided to the City of Fort Collins by September 30th of each year. During the third year of annual monitoring, a determination of successful establishment in the NHBZ will be made by City Environmental Planning Department based on a Site surveys and vegetative performance compared to the following success criteria: 1. 70% total vegetative cover (excluding noxious weeds) is reached with no bare spots larger than one square-foot. 2. Noxious weeds do not exceed 10% total cover. 3. Deemed acceptable by City Environmental Planning Department and erosion control. Monitoring and Maintenance Seeded areas shall be monitored several times a year for three or more years to ensure that success criteria are met. Monitoring and adaptive management shall be employed as site conditions dictate. Conditions affecting the timing and frequency of site visits include temperature, precipitation, plant phenology, timing of site activities, etc. Site conditions shall be communicated to the project team with appropriate redirection taken as necessary. Bare areas should be reseeded, additional erosion control measures may also be necessary and irrigation shall be provided as seasonal trends dictate. Monitoring results shall be communicated to the project manager who will inform the City of Ft. Collins regarding on the ground conditions and adaptive management strategies. Ft. Collins Nissan – Kia Upland Restoration Plan Appendix A: Noxious Weed Management Ft. Collins Nissan – Kia Upland Restoration Plan HERBICIDE MANAGEMENT OF SMOOTH BROME (Bromus inermis) From: Habitat Management Fact Sheet-Nebraska Pheasants Forever http://conservationtoolbox.org/wp-content/uploads/2015/09/Smooth-Brome- Management.pdf Chemical Application & Timing Smooth brome is considered a cool season grass, meaning its active growing seasons are in the spring and fall (see graph below). Removal of cover should be timed so that regrowth occurs during an active growth period. Optimal effectiveness with chemical application occurs when timing can coincide with the first “hard freeze.” When the temperature has reached 30° F for four hours it elicits a chemical response in the plant to begin putting energy reserves into the roots rather than foliar growth. Nebraska fall temperatures fluctuate from day-to-day and even hour-to-hour, which is why it is im- important to diligently watch for the weather to warm up after fall’s christening freeze. Wait for proper wind conditions and temperatures in the fifties or higher for two to three days consecutively to allow time for smooth brome to “wake up” from the freeze and start transferring foliar energy to the roots. Treatments in the fall or early spring allow time to evaluate effectiveness and return with follow-up treatments where needed. Glyphosate is the most common herbicide used to control smooth brome. Canada Thistle Cirsium arvense is an exotic perennial forb that can spread by seed, but is more of a problem due to its ability to spread rapidly from vigorous rhizomes that can extend 15 feet from the parent plant and 6-15 feet deep (Beck 2013). It is an erect plant that can grow up to 5 feet tall. Flowers are small, ranging from white to deep purple. Leaves are usually deeply incised with spiny margins. Infestations often begin on disturbed sites such as ditches, overgrazed pastures, or waste areas (Beck 2013). Canada thistle is a problem weed in riparian areas, but is also found in upland sites. Seeds are able to germinate within 8 to 10 days of pollination. Canada thistle begins growth as a rosette from mid-April to May. It flowers in June, but produces seed sparingly, relying on its extensive root system for spread. Seeds can remain viable in the soil for up to 22 years (Beck 2013). The key to managing this thistle is to stress the plant, forcing it to use its stored root nutrients (Beck 2013). Biological control: The weevil Ceutorhyncus litura is currently being used in Colorado as a biocontrol agent, and another biocontrol insect, Urophora cardui, has also been used (Beck 2013). Biological controls alone are not effective and must be used in conjunction with other strategies such as cultural and chemical practices. Mechanical control: Mowing decreases plant vigor and seed set. However, mowing may not be viable given the plant's dispersal in riparian areas. Hand pulling is effective to control small populations, but is not practical for large populations due to the deep and extensive network of underground rhizomes. When seed heads are encountered they should be clipped well below the apex, bagged, and disposed of in a dumpster. Mowing is effective only if conducted at one- month intervals over several growing seasons, or used with chemical practices (Beck 2013). Chemical control: Herbicides should be used only per label directions, and caution should be taken since the weed occurs near water where many chemicals can harm aquatic life. Herbicides should be applied by licensed commercial applicators. Research from Colorado State University shows that picloram, aminopyralid, clopyralid, aminocyclopyrachlor + chlorsulfuron, dicamba, and chlorsulfuron are effective in pastures, natural areas, and non-crop settings (Beck 2013). Re- treatment for 1-3 years is common. Cultural control: Increase competition with native perennial grasses and alfalfa. Keep moisture at optimum levels to favor grass or alfalfa growth (Beck 2013). Integrated management: Control efforts should target plants in high-quality areas first. Management strategies should be adjusted to reflect weather conditions. For example, drought stress reduces the effectiveness of most herbicides but increases the effectiveness of mechanical controls. It takes at least two years of control to determine if a method is effective. Cheatgrass Bromus tectorum is an exotic winter annual grass that is one of the most widely distributed weeds in the western U.S. Cheatgrass has been shown to significantly alter the fire regime of ecosystems (D’Antonio and Vitousek 1992). It is an erect-stemmed, annual grass that grows 8-25 inches tall. The flowering part of the grass is generally nodding with slender, straight awns. It germinates in the fall or early spring and sets seed from May to June. Cheatgrass flourishes in moderately to highly disturbed upland sites such as roadways, overgrazed areas, and waste sites. It initiates early spring growth and aggressively uses deep soil resources. Seeds are dispersed by animals and people who transport seeds in fur, socks, boots, muddy tires, etc. Because seeds remain viable for up to five years, control measures that reduce seed are most effective. Biological control: Intense grazing can reduce seed production by 90%. Cattle find cheatgrass highly palatable in early spring before seed set occurs. Once seed set occurs, plants drop in palatability and quality. Where infestations are large and dense, prescribed spring grazing repeated for 3 to 5 years by livestock can be effective, and indeed may be the only option in areas where it is difficult or impractical to implement other prescriptions (Shoderbek 2015). Mechanical control: Mechanical control efforts are not recommended unless they are followed by an aggressive revegetation and chemical control program. When mechanical control is used, it should be done in early spring before seed heads are fully developed (early to mid-May) and repeated for at least 5 years. For small infestations, hand-pull weeds. For larger infestations, mow before seed set, repeating every 2 to 3 weeks until flowering is complete (USFS 2014). Chemical control: Rejuvra is a pre-emergence herbicide that works to stop cheatgrass while it’s germinating by inhibiting normal root growth. If applying after germination, mix with a post- emergence herbicide such as Plateau or Rimsulfuron (mid-August to mid-October), or Roundup Pro Concentrate or Rimsulfuron + NIS (late-October through April) as per label instructions. It is not recommended to allow cattle to graze immediately after application (Learn about Rejuvra [date unknown]; D. Sebastian, e-mail message, October 29, 2021). Cultural control: Due to the broad distribution of this plant, tilling and seeding operations are not practical. In areas where revegetation efforts have not produced a healthy stand of perennial grass cover, inter-seeding with native perennial grasses, following cheatgrass spot-control, can be effective. Prescribed burns in areas with mixed shrub and grasses during late spring to early summer have been used with some success, but burning is most effective when used in combination with chemical methods and rigorous reseeding of native perennials (USFS 2014). Integrated management: Lasting control of cheatgrass requires a combination of chemical and mechanical control, reseeding with native perennials, and proper livestock management where land is grazed. This method keeps plants under stress, reducing their ability to spread. Common Mullein Common mullein (Verbascum thapsus) is a biennial forb that can easily be identified by its yellow flowers grouped in a "corn cob" shaped flowering raceme. The leaves are light green and densely wooly. Mature plants have a single, erect stem that can grow 6 to 8 feet in height. Seeds germinate in the early spring, forming a rosette that continues to grow into late autumn and over winter. A tall stem topped with the flowering raceme is produced the following spring. Common mullein can be hard to control due its prolific seed production. The seeds can germinate after lying dormant for several decades. Mullein is easily outcompeted in areas with a densely vegetated ground cover but readily grows in disturbed sites, such as areas that have high human activity or an abundance of bare ground. Mullein prefers dry coarse-textured soils, and is common throughout Colorado in pastures, meadows, waste areas, and along river bottoms. Biological control: The European curculionid (Gymnetron tetrum) feeds on the seeds and has some success in reducing seed production, though there is little recent research on the subject (Gross and Werner 1978). Mechanical control: Mullein plants have shallow tap roots and are easily hand-pulled. They should be pulled as soon as they are large enough to grasp but before they produce seeds. Mullein stems can be cut or mowed to prevent flower and seed production, but stems must be cut below the root crown or rosettes will re-bolt (CNAP 2000). We recommend planting native perennials after mechanical control because mullein favors bare soil. Chemical control: Herbicide application is most effective during the rosette stage. Due to the wooly nature of the leaves, herbicides should be mixed with a surfactant to facilitate uptake. Effective herbicides include metsulfuron at 0.6 oz. ai/acre, tebuthiuron at 4-6 lb. ai/acre (CNAP 2000). Cultural control: Minimize disturbance and seed dispersal, eliminate seed production and maintain healthy native communities. Mullein is often an early invader of burned areas. Integrated management: Management efforts must include the elimination of seed production and the depletion of the seed bank. Combine herbicide or mechanical removal of rosettes with removal of seed heads from any plants that have bolted as well as reseeding bare areas with native perennials. Dalmatian Toadflax Linaria dalmatica is an exotic perennial forb that easily invades natural ecosystems, thereby displacing native vegetation. It has yellow flowers with an orange lip. The leaves are heart-shaped and clasp the stem. Dalmatian toadflax germinates from mid-March to May, and flowers from May to June and given sufficient moisture, can continue flowering into the fall. By initiating early top growth from underground roots (which can reach a depth of 6 feet or more), it effectively competes with native plants for light, soil moisture, and other nutrients. It spreads efficiently from seed as well as from root buds that can travel underground up to 10 feet. In wet years, these plants reproduce abundantly from seed. However, since seedling root development is slow, this represents a life stage vulnerable to control. All toadflax species are difficult to control, so it is recommended to integrate as many management strategies as possible for successful management (Beck 2014). Biological control: Several biocontrol agents have been used to control toadflax but the success of these agents has not been sufficient. A defoliating moth (Calophasia lunula), an ovary-feeding beetle (Brachypterolus pulicarius), and two seed capsule-feeding weevils (Gymnaetron antirrhini and G. netum) have been used in the U.S. and Canada. These flower- and seed-feeding beetles should help decrease seed production. Mecinus janthinus, a stem-boring weevil, and a root-boring moth, Eteobalea intermediella, were also released in Canada and the U.S. to control all species of toadflax. These species help to control shoots and seed production as well as decrease root vigor, but research is lacking (Beck 2014). Mechanical control: Disturbance promotes the invasion of toadflax and it may be necessary for plant establishment. Mowing combined with spraying was not found effective in a study from Colorado (Beck 2014). Chemical control: Tordon 22K at 2 pints/acre sprayed at the time of flowering or in the fall has proven successful in Colorado. Spraying as well as planting native perennial grasses is more effective than spraying alone (Beck 2014). Cultural control: There is very little research supporting cultural controls being effective against this weed in Colorado. Integrated management: Successful management requires integrating as many control tactics as possible. Control can be obtained by pulling or killing the plants with herbicide before seed production begins. This process must be repeated every year for at least 10 years to completely remove a stand. Competitive perennial grasses and forbs should be planted to utilize water and nutrients that would otherwise be readily available to toadflax. Field Bindweed Field bindweed (Convolvulus arvensis) is a perennial forb identifiable by its leaves, which are the shape of arrowheads, and its white to pink funnel-shaped flowers. It favors areas with drought- stress and poor irrigation coverage. Flowers appear from June to September, and seeds mature within two weeks after pollination during hot summer days. Germination can occur in the fall or spring. Field bindweed can be a serious threat to native plant communities because of its high capacity for regeneration. Its seeds can easily live for 50 years in the soil, and its tremendous root system and rhizomes have the potential to produce large numbers of new shoots. It is highly competitive in most areas. However, field bindweed cannot tolerate shade, and it is unlikely that it would persist in later stages of community succession (CNAP 2000). Biological control: A small mite, Aceria malherbae, has been found to be somewhat effective in controlling bindweed in conjunction with other management practices. The mites infest the new growth of the plant by forming a leaf gall. This reduces flowering and stunts stem growth. The mites will overwinter on the root buds and emerge again in the spring. The mites should be released in a thick infestation that will not be sprayed with chemicals or receive heavy watering (Field Bindweed Biocontrol [date unknown]). Mechanical control: Mowing or hoeing may be an effective tool to manage bindweed and it may help spread Aceria malherbae to new locations, though mowing may be hard because of the plant’s low growth habit (Field Bindweed Biocontrol [date unknown]). Remove as many deep horizontal rhizomes as possible. Apply repeated mechanical treatments when plants are young. Chemical control: Pre-emergence herbicides are not recommended because of bindweed’s extensive root system; systemic post-emergence products must be used. Foliar application of glyphosate at 1.5 lb. ai/acre or picloram at 0.25-0.5 lb. ai/acre or 2-4 D at 1lb. ai/acre can be effective. Repeated applications are recommended. Quinclorac is highly effective at controlling bindweed. The chemical can be found in some commercial products. These herbicides are labeled to only be used in lawns and cannot be legally or safely used in landscape beds or vegetable gardens (Bindweed Control in Lawns [date unknown]). Cultural control: Maintain a healthy cover of native perennial plants to discourage field bindweed establishment. Integrated management: Field bindweed requires active management once it is established because of its potential to regenerate rapidly. Successful treatment of bindweed can result in significant damage to desirable vegetation. Leafy Spurge Euphorbia esula is an aggressive, long-lived perennial weed that displaces native plants in many habitats (Biesboer 1998). Leafy spurge produces a large number of seeds and has extensive lateral root systems with which it can reproduce vegetatively. These two reproductive strategies allow this plant to rapidly form monocultures. Large nutrient reserves in root systems allow this plant to re-establish in treated areas; it also produces an allelopathic compound that inhibits growth of other plants (Butterfield et al. 1996). Spurge can grow in a wide variety of habitats, but is best adapted to semi-arid settings. It typically occurs in untilled rangelands and is most abundant on coarse textured soils. Leafy spurge emerges early in the spring (mid April to late May), flowering ends in June to mid July. Photo from Whitson et al. (1996). Biological control: The Division of Plant Industry’s Biological Pest Control Section has released eight species to control leafy spurge. The most effective biological control agents are six species of root and foliage feeding beetles in the genus Aphthona, and a stem and root boring beetle Obera erythrocephala (Lajeunesee et al. 1999). Mechanical control: Tillage is not practical in many areas, mowing can increase plant density and may not be effective when combined with herbicide. Hand pulling is ineffective due to extensive root systems. Burning is moderately effective when it is combined with herbicide application after five weeks. Chemical control: Herbicide applications can be successful but successive treatments are required due to the extensive root systems of this plant. A combination of picloram and 2,4-D (1- 1.5 pints of picloram with 1-1.5 quarts of 2,4-D) has shown to provide best control when applied in the spring when flowers emerge (Beck 1996). Picloram at 1 quart/acre for two to three consecutive years is also effective, but costly. An annual combination of dicamba plus 2,4-D (4- 8 ounces with 0.5 to 1 quart per acre) also provided good control (Beck 1996). Glycoghosate is most effective when applied sequentially at 1 quart/acre at one month intervals, coupled with fall grass seeding (Beck 1996). Cultural control: Long-term control requires the establishment of competing vegetation. Seed mixtures should contain plants with early, mid and late growth as well as shallow, intermediate and deep roots. Integrated management: Leafy spurge is extremely difficult to control by chemical means and almost impossible to control with cultural or mechanical means. Therefore a management scheme that combines control methods over four to five years is recommended (Beck 1996). Musk Thistle Carduus nutans is an exotic winter annual or biennial that flowers from July to late September. It has bright purple flowers (3 inches wide) that are nodding (State Designated Noxious Weeds). The leaves are dark green with light-colored, spiny and deeply lobed margins (State Designated Noxious Weeds). It generally invades areas that are overgrazed or are experiencing poor perennial grass cover; establishment is favored by high levels of moisture and light. The average plant produces more than 10,000 seeds that are readily dispersed by the wind, thereby infesting large areas within two growing seasons, and are viable for up to 10 years in the soil (State Designated Noxious Weeds). Control can be obtained by reducing seed set and depleting the seed bank. Biological control: The musk thistle rosette weevil, or crown weevil, (Trichosirocalus horridus), is the only biological control agent released by the Colorado Department of Agriculture Insectary. The weevil occurs in the developing root tissue of the plant, stunting the growth and number of stems C. nutans can produce. The plant stem and foliage will start to yellow as the weevil damage accumulates (Musk Thistle Biocontrol [date unknown]). Mechanical control: Mowing with a weed whip or scythe can be a useful mechanical control when plants are just beginning to flower to reduce seed set. Repeat treatments are necessary because individual plants of C. nutans do not bloom at the same time. Grubbing or digging, being sure to get the root, can be effective as well. Mechanical control should be combined with biological methods. Chemical control: Effective chemical control has been achieved in the past using picloram (Tordon 22K), clopyralid (Transline, Stinger), clopyralid plus 2, 4-D (Curtail), chlorsulfuron (telar), glyphosate (Roundup/Rodeo), dicamba (Banvel), and 2, 4-D. Applications should be made in late spring/early summer and again in the fall. Cultural control: We recommend inter-seeding disturbed sites to prevent the spread of this plant. If competitive vegetation is not established, re-invasion is likely. Integrated management: Prevent seed production. Most control methods have a detrimental effect on other plants and may cause a disturbance that favors other exotic species. Dense musk thistle stands along roadsides and in degraded areas can be treated by spot use of herbicides, and in high quality areas by persistent pulling or cutting. Up to 10 years of control may be needed to completely eliminate a stand. References Beck, G.B. 1997. Musk Thistle. Colorado State University Cooperative Extension. No. 3.102. Fort Collins, CO. Beck KG. 2013 Nov. Canada Thistle. Colorado State University Extension [Internet]. [cited 2021 Oct 21]. Available from: https://extension.colostate.edu/topic-areas/natural- resources/canada-thistle-3-108/ Beck KG. 2014 Dec. Biology and Management of the Toadflaxes. Colorado State University Extension [Internet]. [cited 2021 Oct 22]. Available from: https://extension.colostate.edu/topic-areas/natural-resources/biology-and-management-of- the-toadflaxes-3-114/ Bindweed Control in Lawns. [date unknown]. Colorado State University Extension [Internet]. [cited 2021 Oct 22]. Available from: https://planttalk.colostate.edu/topics/lawns/1552- bindweed-control-lawns/ Biesboer, D.D. 1998. Element stewardship abstract for Euphorbia esula. The Nature Conservency. Wildland Weeds Management and Research Program. Cheatgrass, downy brome Bromus tectorum L. [date unknown]. Invasive Plant Atlas of the United States [Internet]. [cited 2021 Oct 20]. Available from: https://www.invasiveplantatlas.org/subject.html?sub=5214 Colorado Natural Areas Program (CNAP). 2000. Creating an Integrated Weed Management Plan: A Handbook for Owners and Managers of Lands with Natural Values. Colorado Natural Areas Program, Colorado State Parks, Colorado Department of Natural Resources; and Division of Plant Industry, Colorado Department of Agriculture. Denver, Colorado. 349 pages. D'Antonio, C.M., P.M. Vitousek. 1992. Biological invasions by exotic grasses, the grass/fire cycle, and global change. Annual Review of Ecology and Systematics 23:63-87. Field Bindweed Biocontrol. [date unknown]. Colorado Department of Agriculture [Internet]. [cited 2021 Oct 22]. Available from: https://ag.colorado.gov/conservation/biocontrol/field-bindweed Gross, K.L. and P.A. Werner. 1978. The biology of Canadian weeds: Verbascum thapsus and V. blatteria. Can. J. Plant Science 58:401-413. Lajeunesse, S.E., R.L. Sheley, R. Lym, and C. Duncan. 1999. Leafy spurge. In R.L. Sheley and Petroff, eds. Biology and Management of Noxious Rangeland Weeds. Oregon State University Press, Corvallis, OR. Learn about Rejuvra herbicide Stewardship. [date unknown]. Bayer United States Vegetation Management [Internet]. [cited 2021 Oct 22]. Available from: https://www.environmentalscience.bayer.us/vegetation-management/range-and- pasture/portfolios-and-solutions/rejuvra/stewardship#Application Musk Thistle Biocontrol. [date unknown]. Colorado Department of Agriculture [Internet]. [cited 2021 Oct 22]. Available from: https://ag.colorado.gov/conservation/biocontrol/musk- thistle Musk Thistle (Carduus nutans L.). Adams County Colorado State University Extension. [Internet] [cited 2021 Oct 22]. Available from: http://adams.colostate.edu/ag/muskthistle.htm Shoderbek D. 2015 Jul 15. How to beat the ‘cheat.’ Livestock & Range Colorado State University Extension [Internet]. [cited 2021 Oct 20]. Available from: https://rangemanagement.extension.colostate.edu/land-and-livestock/invasive- plants/how-to-beat-the-cheat/ United States Forest Service (USFS). 2014 Sep. Field Guide for Managing Cheatgrass in the Southwest. 1-12. Whitson, T.D. (ed.), L.C. Burrill, S.A. Dewey, D.W. Cudney, B.E. Nelson, R.D. Lee, R. Parker. 1996. Weeds of the West. Western Society of Weed Science, in cooperation with the Western United States Land Grant Universities Cooperative Extension Services, Newark, CA.