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HomeMy WebLinkAboutMASON STREET INFRASTRUCTURE PROJECT - FDP230016 - SUBMITTAL DOCUMENTS - ROUND 5 - Supporting Documentation (2) Mason Street Infrastructure Weed Management Plan March 2024 PO Box 272150 Fort Collins, CO 80527 i Table of Contents 1.0 Introduction ................................................................................................................................ 1 2.0 Existing Conditions ...................................................................................................................... 2 3.0 Noxious Weeds............................................................................................................................ 3 4.0 Weed Management ...................................................................................................................... 5 4.1 Best Management Practices .................................................................................................... 5 4.2 Weed Treatment Options and Recommendations ..................................................................... 5 4.2.1 List B Species ........................................................................................................ 6 4.2.1.1 Leafy Spurge ........................................................................................................ 6 4.2.1.2 Canada Thistle ...................................................................................................... 8 4.2.2 Invasive Weeds ..................................................................................................... 9 5.0 Weed Monitoring and Adaptive Management ............................................................................... 10 6.0 Literature Cited and Data Sources .............................................................................................. 11 Mason Street Development Weed Management Plan 1.0 INTRODUCTION North College 1311, LLC has proposed the Mason Street Infrastructure development project (“site”) within 3 lots totaling approximately 13.13 acres. The City of Fort Collins (City) has also proposed a future detention basin (“Hickory Pond”) within portions of Lot 1 and 2 within the site. The site is located within parcels 9702100007 and 9702100918 and is situated between Willox Lane and Hickory Street to the north/south, with Mason Street to the east and railroad to the west. An Ecological Characterization Study (ECS) was performed in September 2022 as required by Article 3, Section 3.4.1 of the City Land Use Code (LUC) (Cedar Creek 2023). The ECS informed the City’s determination that the site contains Dry Creek and will require the implementation of a Natural Habitat Buffer Zone (NHBZ) to mitigate potential impacts from development on ecological character and quality. This Weed Management Plan provides a framework control noxious and invasive weeds in a restoration project. Effectively controlling or managing noxious and invasive weeds is vital to achieve desirable vegetative outcomes. Noxious and invasive weeds can fill niches and outcompete desirable species for limited resources, such as plant available water and sunlight. The goal of this Weed Management Plan is to provide guidance on specific weed treatments. 2.0 EXISTING SITE CONDITIONS The site primarily consists of upland grassland, containing a mixture of native, invasive, and noxious species, dominated by smooth brome (Bromus inermis). Other species include leafy spurge (Euphorbia esula), Canada thistle (Cirsium arvense), Western wheatgrass (Pascopyrum smithii), orchard grass (Dactylis glomerata), alfalfa (Medicago sativa), and prickly lettuce (Lactuca serriola). Dry Creek traverses the site from the northwest to the southeast. Dry Creek appears to contain no active surface hydrology and shows little signs of conveying ephemeral flow. The Dry Creek riparian area is dominated by Siberian elm (Ulmus pumila), crack willow (Salix fragilis), and white poplar (Populus alba), with a herbaceous layer dominated by smooth brome. Other species include showy milkweed (Asclepias speciosa), horse tail (Equisetum sp.), rose (Rosa woodsii), wild licorice (Glycyrrhiza lepidota), and narrowleaf willow (Salix exigua). The southeast portion of Dry Creek (across Mason Street) is dominated by cottonwood (Populus deltoides) and contains no herbaceous layer. 3.0 NOXIOUS WEEDS Noxious weeds are characterized into three categories, in accordance with the Colorado Noxious Weed Act. • List A species are not well established in Colorado, are potentially a large problem to this state, and require mandatory eradication by local governing agencies. Prescribed techniques for management of List A species are hand pulling, digging, or herbicide application. Mowing, grazing, and insect bio-control are not acceptable forms of management for these species. • List B species are common enough in parts of the state that eradication is not feasible, though the species are still recommended for eradication, suppression, or containment depending on distribution and densities around the state. Prevention of seed disp ersal may be accomplished by mowing, hand pulling, tillage, grazing, or herbicide application. • List C species are widespread and well established. Control of List C species is recommended but not required by the state. However, local governing bodies, such as the County or City of Johnstown, may require management. For the purposes of this report, an invasive weed is a non-native (or alien) whose introduction can cause economic or environmental harm. Invasive weeds are typically annual or biennial plant species which produce large quantities of seed, thrive on disturbed soil, have aggressive root systems and often grow so densely that they smother the root systems of surrounding vegetation. The establishment and persistence of invasive species can be a significant obstacle to restoration success. The field survey revealed the presence of the following species: • List A Species o None • List B Species o Leafy spurge (Euphorbia esula) o Canada Thistle (Cirsium arvense) • List C Species o Siberian elm (Ulmus pumila) • Invasive Weeds o Prickly Lettuce (Lactuca serriola) o Smooth brome (Bromus inermis) o Several other annual and biennial weedy species This plan will focus on the management of leafy spurge and Canada thistle. Although Siberian elm is listed as a noxious species, it provides wildlife habitat and serves as a wildlife corridor along the Dry Creek riparian corridor. 4.0 WEED MANAGEMENT 4.1 Best Management Practices Noxious weeds are common in urban and developed areas, and construction -related ground disturbance creates ideal conditions for the spread of noxious weeds. Noxious and invasive weeds are opportunistic and take advantage of open niches to flourish. The best way to prevent establishment and persistence of weedy species is to limit their opportunities by implementing best management practices and ensuring that disturbed ground is not left fallow so that weedy species can take hold. Pre-Construction Phase • Treat existing noxious weed populations that could be spread by construction activities, especially individual plants and small infestations. Aggressive treatment of existing weed populations greatly reduces the ability of the weeds to rebound in post-construction conditions. • Appropriately handle all soils during any salvaging of topsoil or subsoil. Construction Phase • Wash all construction equipment prior to arriving at the site. • Utilize only certified weed free materials for any BMPs. • Minimize amount of bare ground and reseed bare ground as soon as possible. • Continue to monitor and manage any weed populations that are establishing on bare ground or stockpiles. Seeding, Planting, and Post-construction Phases • Obtain soil components, amendments, seed mixes, and mulches from weed -free sources. • Establish and maintain vigorous, desirable vegetation to discourage weeds. • Mulch any non-vegetated surfaces to minimize the amount of noxious weed seeds that will reach the soil surface and germinate. • Monitor all seeded areas for any weed infestations post -construction and to inform subsequent weed management activities. 4.2 Weed Treatment Options and Recommendations Each year weed management and treatment approaches should be tailored to on the ground conditions. Noxious and invasive weed inventory and mapping can provide vital information for developing a control strategy. Site conditions along with project goals must be considered when developing, implementing, and adapting an effective weed management plan. A qualified herbicide applicator will be used to apply herbicide to control noxious and invasive weeds on the site. The qualified herbicide applicator will perform the application in accordance with applicable laws and regulations and permit stipulations. All herbicide applications must follow US Environmental Protection Agency label instructions, including taking proper precautions (proper storage, following spill clean -up procedures, and proper disposal of containers). Application of herbicides will be suspended when any of the following conditions exists: • Wind velocity exceeds 6 miles per hour (mph) during application of liquids or 15 mph during application of granular herbicides. • Snow or ice covers the foliage of noxious weeds. • Precipitation is occurring or is imminent. Vehicle-mounted sprayers (e.g., handgun, boom, and injector) will be used mainly in open areas that are readily accessible by vehicle. Hand application methods (e.g., backpack spraying, hose and wand spraying) that target individual plants will be used to treat small or scattered weed populations in rough terrain. Calibration checks of equipment will be conducted at the beginning of spraying and periodically to ensure that proper application rates are achieved. Specific treatment plans (as well as herbicide recommendations) for the noxious weeds present on the site are described below. All noxious weeds are expected to require multiple years of treatment to effectively control populations. 4.2.1 List B Species 4.2.1.1 Leafy Spurge Leafy spurge emerges early in the spring and flower clusters develop one to two weeks following stem emergence, typically from mid-April to late May. A combination of management methods and long-term management and monitoring is required to successfully eradicate the root system and soil seed bank. • Chemical Control - Table 1 displays herbicide recommendations which could be used for chemical control. • Mechanical Control – Pulling of the species is not viable, due to an extensive root system. Mowing can be effective at reducing seed production if repeated every 2 to 4 weeks during the growing season but may not provide long-term control. • Biological Control – Flea beetles from the genus Aphthona and grazers such as sheep and goats are both effective controls. A combination of both is recommended. • Other Management Considerations: o Establishment of healthy stands of desirable vegetation to out -compete the species. Seeding of native grasses will provide competition for resources. o Mulching exposed, non-seeded areas to prevent germination of seed or vegetative re- growth. 4.2.1.2 Canada Thistle Aspects of Canada thistle’s phenology can be exploited to a land manager’s benefit, with the goal being to stress the plant to the point that root stores of nutrients and energy are exhausted. The plants draw on root stores for the first spring flush, and the plants should be allowed to grow to the bud stage but then killed to prevent seed production. Additional treatment of top growth should be implemented midsummer as the plants recover from the initial spring treatment to further stress the plant and to prevent seed set. The most critical step is the fall treatment with a translocating herbicide, in which the herbicide is applied to top growth but is transported to the root system as the plant stores nutrients and energy in the roots in preparation for the spring. • Chemical Control - Table 2 displays herbicide recommendations which could be used for chemical control. • Mechanical Control - Mowing of large populations, prior to seed set, can help prevent the expansion of existing populations. Hand pulling of Canada thistle may be appropriate if only a single or very few individuals are observed. All flowerbuds and heads must be collected, bagged, and disposed of or destroyed; seeds will mature and germinate if left on the ground. • Biological Control – A host-specific pathogenic rust fungus (Puccinia punctiformis) has been shown to effective. • Other Management Considerations: o Establishment of healthy stands of desirable vegetation to out -compete Canada thistle. Seeding of native grasses will provide competition for resources . o Mulching exposed, non-seeded areas to prevent germination of seed or vegetative re- growth. 4.2.2 Invasive Weeds Control of invasive weeds, such as aggressive, non -native annual and biennial species, is very difficult because chemical control methods typically have collateral damage to native species establishment. Cultural control, through the establishment of competitive and desired vegetation, prevents or slows down invasion by weedy species and is a key component of successful weed management. Weeds are typically opportunistic and readily invade disturbed sites. Controlling weeds on such sites can be futile withou t vegetative restoration, as weeds will readily re -invade the disturbed area. In certain situations, mowing may be useful, especially when invasive weeds are so dominant that they are outcompeting desirable species for limited resources, such as sunlight and plant available water. However, use of mowing should be carefully considered prior to implementation since there are potential implications on establishing desirable vegetation. Application of the herbicide dicamba can be used if invasive weeds become dominant. Dicamba is a selective herbicide used for post-emergent control of broadleaf weeds. Dicamba is a highly volatile chemical that can damage non-target plant species through spray drift, so it should only be used in appropriate situations. 5.0 WEED MONITORING AND ADAPTIVE MANAGEMENT Noxious and invasive weed monitoring is vital to an effective weed management plan. Therefore, site inspections for weed inventory and mapping will occur in the spring, peak of growing season, and fall visit during construction and continuing into the post -construction period (in conjunction with restoration plan monitoring). This information will be used to evaluate the effectiveness of control and develop a weed management workplan for the coming months. The workplan will be based on site specific conditions and prioritize weed management strategies based on overall risk to restoration goals. In order to complete effective weed control, the recommendations presented in the workplans should be fully implemented. Over the span of the monitoring period, the weed mapping efforts will show whether weed control efforts are effective. If requested, an annual report describing weed management activities can be provided to the City by the end of the year. 6.0 LITERATURE CITED AND DATA SOURCES Cedar Creek Associates, Inc. 2023. 1311 North College Ecological Characterization Study. February 2023. Colorado Department of Agriculture (CDA) – Conservation Services. Noxious Weed Factsheets. 2015. Fort Collins, City of. 2020. Guidance for Weed Management Plans in the City of Fort Collins. October 2020. Siegel, S. and Donaldson, S. 2003. Measures to prevent the spread of noxious and invasive weeds during construction activities. University of Nevada Cooperative Extension, Fact Sheet FS -0359.