8-Reference A Weed Management Plan 06.15.22.pdf

Mueller and North Canyon Trail Network Noxious Weed and Invasive Plant Management Plan

JUNE 2022

PREPARED FOR

Bountiful City

PREPARED BY

SWCA Environmental Consultants

MUELLER AND NORTH CANYON TRAIL NETWORK

NOXIOUS WEED AND INVASIVE PLANT

MANAGEMENT PLAN

Prepared for

Bountiful City 795 South Main Street Bountiful, Utah 84010 Attn: Todd Christensen

Prepared by

SWCA Environmental Consultants 257 East 200 South, Suite 200

Salt Lake City, Utah

(801) 322-4307 www.swca.com

June 2022

Mueller and North Canyon Trail Network Noxious Weed and Invasive Plant Management Plan i

CONTENTS

1 Introduction

1.1 Project Description and Background

1.2 Goals and Objectives

2 Noxious and Invasive Weed Inventory

3 Treatment Priorities

4 Noxious and Invasive Weed Management

4.1 Effective Treatment Methods

4.1.1 Common Burdock

4.1.2 Dalmatian Toadflax

4.1.3 Dyers Woad

4.1.4 Houndstongue

4.1.5 Whitetop (hoary cress)

4.2 Preconstruction Management

4.3 Active Construction Management

4.4 Postconstruction Management

5 Literature Cited

Appendices

Appendix A. Infestation Treatment Maps

Appendix B. Suggested Treatment Schedule and Methods

Appendix C. Proposed Seed List

Tables

Table 1. Noxious and Invasive Weed Species Inventory Results

Table 2. Treatment Priority Status Table 3. Herbicide Controls for Noxious and Invasive Weed Species ii

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1 INTRODUCTION

1.1 Project Description and Background

Bountiful City, in collaboration with the U.S. Forest Service (USFS), is proposing to expand and maintain a recreational trail network approximately 5.50 miles southeast of Bountiful, Utah. The project includes the construction of 13.64 miles of new trails through the Uinta-Wasatch-Cache National Forest where preconstruction noxious weed surveys are necessary to inform U.S. Forest Service management policies.

The proposed new trails comprise segments in Mueller Canyon, in the Mueller Canyon picnic area, in

North Canyon, and near the Summerwood Estates neighborhood.

The purpose of the noxious and invasive weed surveys is to identify and locate weed species within a specified geographic area. The inventory data collected during these surveys are used to inform the USFS invasive species management plan (USFS 2011).

Under Forest Service management (FSM) policy 2900 - Invasive Species Management, the USFS defines the term invasive species as “any exotic species (including plants, pathogens, algae, fungi, vertebrates, and invertebrates) which causes harm to the environment, the economy, or human health. The USFS recognizes 53 weed species as invasive (USFS 2019). The policy also applies to 54 species of noxious weeds defined by the State of Utah as “any plant the commissioner determines to be especially injurious to public health, crops, livestock, land, or other property” (Utah Department of Agriculture and Food

2019).

1.2 Goals and Objectives

The purpose of this noxious weed and invasive plant management plan (hereafter referred to as the plan) is to identify treatment locations and methods along the proposed trail network, and to provide effective management and monitoring strategies to mitigate the spread of noxious weeds before, during, and after construction of the Mueller and North Canyon trail network. The plan is informed by noxious weed survey data collected by SWCA Environmental Consultants (SWCA) in May 2022 and regional data provided by the USFS.

2 NOXIOUS AND INVASIVE WEED INVENTORY

SWCA conducted noxious and invasive weed surveys from May 23 through May 26, 2022, to identify the presence and/or absence of noxious and invasive weed infestations within the disturbance corridor of the proposed trail network. The total survey area was 148.5 acres and included 13.6 miles of proposed trails plus an additional 50-foot buffer on either side of the centerline of the trails to account for trailside disturbance. Four species of noxious weeds—houndstongue (Cynoglossum officinale), Dalmatian toadflax

(Linaria dalmatica), Dyers woad (Isatis tinctoria), and whitetop (hoary cress) (Cardaria draba)—were identified in the survey area. One species of invasive weed—common burdock (Arctium minus)—was identified in the survey area. The survey area comprised four distinct segment locations— Mueller

Canyon, the Mueller Canyon picnic area, North Canyon, and the Summerwood Estates. The survey methods and results (including maps of the infestation locations) are included in the technical memorandum Noxious and Invasive Weed Inventory Surveys for the Proposed Mueller Canyon and North

Canyon Trail Network (SWCA 2022). A summary of the results is provided in Table 1.

Table 1. Noxious and Invasive Weed Species Inventory Results

Species Number of Infestations Total Acres of Infestation* Total Acres of Treatment*

Common burdock 10 1.90 0.81

Dalmatian toadflax 8 3.97 2.39

Dyers woad 1 1.35 0.69

Houndstongue 5 49.01 17.5

Whitetop (hoary cress) 8 6.24 2.18

Total 32 62.47 23.57

Source: SWCA (2022).

* These numbers represent the total number of acres present within the survey area. Some weed infestations extended beyond the survey area. The full extent spatial polygons are provided in the geodatabase packaged provided with SWCA 2022. The treatment area includes a 30-foot treatment corridor surrounding containment priority species infestations and a 50-foot treatment corridor surrounding control priority species infestations.

3 TREATMENT PRIORITIES

Management priorities should be directed at controlling dalmatian toadflax, whitetop (hoary cress), and dyers woad populations within the survey area. These infestations occur in smaller and more concentrated populations, making them relatively easier to manage or eradicate.

Houndstongue is prolific and widespread throughout the survey area; however, the species is listed as low priority status by the USFS. Control efforts are best targeted near areas of disturbance to mitigate the spread of the species into undisturbed areas.

Common burdock is an invasive weed species that is not recognized by the State of Utah as being noxious; however, the Uinta-Wasatch-Cache Forest Service recognizes it as a species of management concern. Although it is not listed as a priority for USFS due to its prolific nature throughout the state, infestations of common burdock should be treated and managed where feasible. Common burdock occurs in small, isolated populations throughout Mueller Canyon, making it relatively manageable to treat these infestations. The largest infestation is currently present within the Mueller Park picnic area, which should be prioritized because of the assumed high-volume pedestrian use.

The State of Utah and USFS treatment priorities are listed by species in Table 2.

Table 2. Treatment Priority Status

Species Species Designation Uinta-Wasatch-Cache Priority Status

State Priority Status

Common burdock Invasive * Containment*

Dalmatian toadflax Noxious High Class 2 - Control

Dyers woad Noxious Medium Class 2 - Control

Houndstongue Noxious Low Class 3 - Containment

Whitetop (hoary cress) Noxious High Class 3 - Containment

Source: USFS (2019).

* Priority not listed.

4 NOXIOUS AND INVASIVE WEED MANAGEMENT

4.1 Effective Treatment Methods

Mechanical (also known as physical) treatment methods rely on cutting roots with a shovel or other hand tools, hand pulling, or employing equipment that can be used to mow or disc weed populations. Common burdock, dalmatian toadflax, dyers woad, and houndstongue are all effectively targeted by mechanical treatment. However, mechanical treatment is most useful for removing smaller or isolated populations of these species.

When considering chemical treatment, consider weed species, the site on which the herbicide will be applied, method and timing of application, and desired result when selecting the herbicide for treatment and control of noxious or invasive weeds. Ensure that selected herbicides are approved for weed(s) that are to be controlled, and ensure that chemical label applications are followed to ensure environmental and human safety, chemical efficacy, and cost-effectiveness of treatment. All species identified within the survey area can be effectively targeted by chemical treatment; however, chemical treatment is especially recommended for whitetop due to the regular intensity required for manual removal. Table 3 lists potential herbicides and how well they are expected to work on site-specific weed species. Ratings are presented when available and were obtained from Dewey et al. (2006), Colorado State University (2000), U.S. Environmental Protection Agency Pesticide Product and Label System (2018), and specific herbicide labels. All herbicides should be applied by a certified commercial applicator.

Table 3. Herbicide Controls for Noxious and Invasive Weed Species

Common Name 2,4-D Dicamba Glyphosate Imazapic Imazapyr Chlorsulfuron Aminopyralid Metsulfuron

Common burdock X F, G F – – – – F, G

Dalmatian toadflax F, P G, P G G – G – F

Dyers woad G E, F G G – G – E

Houndstongue F G X X – – – –

Whitetop F G G, F G – E – E

Notes: E = excellent, G = good, F = fair, P = poor, X = unrated, – = not applicable or no data.

Infestation treatment area maps are provided in Appendix A, and a suggested treatment schedule is provided in Appendix B for the species identified below. The herbicide label should be consulted prior to application because the timing of application may differ slightly from the proposed treatment schedule.

4.1.1 Common Burdock

Common burdock is a biennial weed species that is most effectively targeted by chemical treatment in its first year of development. However, once established, the species develops a large taproot that is more effectively managed by mechanical removal. Mechanical treatment should be targeted during the growing season before the species goes to seed. If necessary, a combination of mechanical and chemical treatments may be used to target new rosettes the following spring.

4.1.2 Dalmatian Toadflax

Dalmatian toadflax is a perennial that reproduces mainly from seeds. Seeds can remain viable in the soil for up to 10 years. Severed roots of this species can re-sprout. Mechanical and chemical applications are both effective at controlling the species. However, timing is extremely important for herbicide application because the heavy waxy cuticle on the mature Dalmatian toadflax leaves prevents herbicides from the entering plant.

4.1.3 Dyers Woad

Established dyers woad plants begin growth early in the year and reproduce mainly by seed; however, the seeds do not remain viable in the soil for long periods of time. The plant has a deep taproot as well as roots near the soil surface. Dyers woad is most effectively targeted with mechanical treatment by targeting rosettes in the early spring, but it can also be controlled with chemical application. When feasible, dyers woad should be bagged and removed from the site to limit seed dispersal.

In areas where dyers woad is removed, reseeding efforts are recommended to re-establish the desired vegetation community, stabilize exposed soils, and help prevent the re-introduction of noxious weeds within disturbed areas. The seed mix should be site specific and approved by the USFS. A proposed seed list is provided in Appendix C. The species on the provided list are tailored toward the Rocky Mountain

Gambel Oak-Mixed Montane Shrubland community, which is the dominant vegetation class within the treatment areas (LANDFIRE 2020). Seeding with perennial grasses will allow continued spot spraying with broad-leaf herbicides if necessary to maintain weed control. Other areas of temporary disturbance such as staging zones should be reseeded on an as-needed basis. SWCA recommends reseeding the treatment and temporary disturbance areas immediately following completion of the project in early fall

(estimated September 15 through October 15) prior to the first snow fall.

4.1.4 Houndstongue

Houndstongue is a biennial that reproduces entirely from seed. Seeds can remain viable for up to 3 years if left on the plant and 1 to 2 years in the soil. Therefore, the key to controlling houndstongue is to prevent it from flowering or setting seed. This species is a poor competitor with native perennials and requires disturbed or bare areas to establish. Control efforts are best targeted near areas of disturbance to mitigate the spread of the species into undisturbed areas. Mechanical removal is most effective by targeting rosette removal in the spring. Hand pulling or digging is effective for smaller populations; however, a combination of mechanical and chemical application may be required for species removal because of the widespread nature of houndstongue within the survey area.

4.1.5 Whitetop (hoary cress)

Whitetop is a perennial weed that primarily reproduces from adventitious buds that sprout from the lateral rhizomes. Seeds remain viable in the soil for up to 3 years. Though mechanical treatment is viable, it must be conducted at regular intervals to be effective (every 7 to 10 days throughout the growing season).

Whitetop is also effectively treated by herbicide application during the bud or flowering stage (May–

June). Additional applications may be required in the fall if new growth occurs.

4.2 Preconstruction Management

Prior to construction, apply the appropriate herbicide to each species at the recommended rates on the label. Target actively growing green foliage between flower bud and flowering stages. If feasible, remove and bag dead biomass 30 days after herbicide application. This will remove any seeds remaining on plants and eliminate the potential fire hazard from dead, standing biomass, but will allow enough time for the herbicide to be translocated to the roots to kill the plants.

If preferred, volunteers can target small infestations of Dalmatian toadflax, dyers woad, and common burdock within disturbance areas. Repeated removal of these plants over 2 to 3 years has completely eliminated small infestations, and continued removal along the completed trails will reduce spread by seed.

4.3 Active Construction Management

Before arriving at the construction site, clean all vehicles and equipment using high-pressure wash equipment and at designated wash stations. Wash stations are typically located in project disturbance areas or in areas that have previously been disturbed. Cleaning activities should concentrate on the tracks, feet, or tires of machinery and the undercarriage with special emphasis on axles, frame, cross members, motor mounts, underneath steps, running boards, and front bumper/brush guard assemblies.

Where feasible, construction should begin in weed-free areas before operating in weed-infested areas. All vehicles and equipment should also be inspected and washed after finishing construction in a weed-infested area and before moving to weed-free areas. During construction, operation, and maintenance activities of the project, removal of excess vegetation should be minimized wherever possible.

All contractors or personnel conducting weed and invasive plant management actions will be trained in weed and invasive plant identification and management before beginning work on the project.

Herbicide applicators will either hold a commercial applicator license and be certified in the state of Utah or work under the direct supervision of a certified/licensed applicator, as required by the State of Utah.

4.4 Postconstruction Management

In the fall immediately following the completion of the project, temporary disturbance areas that resulted from the impacts of the project should be reseeded where appropriate and on an as-needed basis. For infested areas that require fall herbicide treatment, it is recommended to reseed the infested areas with the appropriate seed mix 30 to 45 days after herbicide application.

Postconstruction monitoring should occur on an annual basis during the growing season, to the extent practicable, or as soon as weed species are easily identifiable. Monitoring time may take into consideration the treatment windows for target weed and invasive plant species, which include species more readily detected prior to peak growing season (April–May) or later in the growing season (after

July). Growing seasons will vary from year to year, and consequently the timing of seasonal monitoring and treatment will vary as well.

Qualitative data such as population density, distribution, and overall treatment effectiveness may be collected as part of the annual monitoring efforts. Additional treatments may be necessary in the spring and/or fall to maintain weed management efforts for a minimum of 3 consecutive years.

5 LITERATURE CITED

Colorado State University. 2000. Division of Plant Industry. In Creating an Integrated Weed

Management Plan: A Handbook for Owners and Managers of Lands with Natural Values.

Caring for the Land Series, Vol. IV. Colorado Department of Agriculture.

Dewey, S.A., S.F. Enloe, F.D. Menalled, S.D. Miller, R.E. Whitesides, and L. Johnson. 2006. Weed

Management Handbook, 2006-2007, Montana, Utah, Wyoming. Cooperative Extension Services

(Montana State University, Utah State University, and the University of Wyoming).

SWCA Environmental Consultants. 2022. Noxious and Invasive Weed Inventory Surveys for the

Proposed Mueller Canyon and North Canyon Trail Network. Prepared for Bountiful City.

U.S. Environmental Protection Agency. 2018. Pesticide Product and Label System. Available at:

https://iaspub.epa.gov/apex/pesticides/f?p=PPLS:1. Accessed June 1, 2022.

U.S. Forest Service (USFS). 2011. National Forest System Invasive Species Management Policy.

Available at: https://www.federalregister.gov/documents/2011/12/05/2011-31090/national-forest-system-invasive-species-management-policy. Accessed June 1, 2022.

———. 2021. Uinta-Wasatch-Cache Noxious Weed List 2019. Provided by email to SWCA

Environmental Consultants, November 24, 2021.

U.S. Geologic Survey and U.S Department of Agriculture. LANDFIRE: LANDFIRE Existing Vegetation

Type layer. Available at: http://landfire.cr.usgs.gov/viewer/. Accessed June 1, 2022.

Utah Department of Agriculture and Food. 2022. State of Utah Noxious Weed List. Available at:

http://ag.utah.gov/divs-progs/50-plants-and-pests/hay-grain-seed/599-noxious-weed-list.html.

Accessed June 1, 2022.

https://iaspub.epa.gov/apex/pesticides/f?p=PPLS:1 https://www.federalregister.gov/documents/2011/12/05/2011-31090/national-forest-system-invasive-species-management-policy https://www.federalregister.gov/documents/2011/12/05/2011-31090/national-forest-system-invasive-species-management-policy http://landfire.cr.usgs.gov/viewer/

APPENDIX A

Weed Treatment Area Maps

A-1

Figure A-1. Weed treatment areas (map 1 of 5).

A-2

Figure A-2. Weed treatment areas (map 2 of 5).

A-3

Figure A-3. Weed treatment areas (map 3 of 5).

A-4

Figure A-4. Weed treatment areas (map 4 of 5).

A-5

Figure A-5. Weed treatment areas (map 5 of 5).

A-6

APPENDIX B

Suggested Treatment Schedule and Methods

B-1

Table B-1. Treatment Schedule and Methods

Species Treatment Method 2022 2023–2025

J u n e

J u ly ly

A g u s t 1 g u s t 1

S e p te m b e r 1 p te m b e r 1

O c to b e r 1 to b e r 1

N o v e m b e r 1 v e m b e r 1

D c e m b e r 1 c e m b e r 1 p ril 1 p ril 1

M a y

M a y n e n e ly ly g u s t 1 g u s t 1 p te m b e r 1 p te m b e r 1 to b e r 1 to b e r 1 v e m b e r 1 v e m b e r 1 c e m b e r 1 c e m b e r 1

Dalmatian Toadflax

(Linaria dalmatica)

Manually remove (hand pull) individuals at the root. For most effective treatment, repeat annually each summer for 3 consecutive years.

Apply herbicide at the rosette stage (spring through fall) to small patches of Dalmatian toadflax.*

Seed areas, as needed, where Dalmatian toadflax was manually removed or treated with herbicide.

Dyer’s Woad

(Isatis tinctoria)

Manually remove small patches of Dyers woad before seed set.

Apply herbicide to large patches of Dyer’s woad before seed set.

Apply to rosettes in spring and fall and during the pre-bloom period.

Whitetop (Hoary cress)

(Cardaria draba)

Apply herbicide to rosettes and early flowering individuals.

Herbicide can also be applied at the late flower and post-flower stage. Annual treatments recommended.

Manually remove any individuals that were missed by herbicide treatment.

Seed areas where hoary cress was manually removed or treated with herbicide.

Houndstongue (Cynoglossum officinale)

Apply herbicide between rosette and bloom stages.

Manually remove houndstongue using a shovel to pry up the tap root prior to seed production.

Common burdock (Arctium minus)

Apply herbicide before or at flowering (early spring) prior to seeding efforts.

Hand-pull, cultivate, or dig below the crown before seed production is very effective. Must remove crown to prevent resprouting.

Note: Consult herbicide label for recommended product-specific application timing. Application timing and directions for use may vary between products. Information about herbicide application timing provided in this schedule is a general recommendation.

* Any herbicide use must be conducted by a licensed applicator, and the applicator must read, understand, and adhere to the label requirements for the use, application rate, and application method and timing of each herbicide.

† See Appendix C for the proposed seed mix.

B-2

APPENDIX C

Proposed Seed Mix

C-1

Table C-1. Proposed Seed Mix Species

Species Vegetation Type Percentage of Mix Broadcast Rate (Pure Live Seed lb/acre)

Bluebunch wheatgrass Pseudoroegneria spicata spp.

spicata

Grass 20 2

Bottlebrush squirreltail Elymus elymoides

Grass 15 1.5

Sandberg bluegrass

Poa secunda

Grass 10 0.5

Indian ricegrass Achnatherum hymenoides

Grass 15 1.5

Slender wheatgrass Elymus trachycaulus spp.

trachycaulus

Grass 15 1

Western wheatgrass Pascopyrum smithii

Grass 15 1.5

Lewis flax

Linum lewisii

Forb 8 0.25

Western yarrow Achillea millefolium var.

occidentalis

Forb 2 0.25

Note: seed mix is based on species current availability and cost.