Vegetation Management and Maintenance Plan - Watsonville ...

Draft 

Watsonville Wetlands Trail System 

Vegetation Management and Maintenance Manual 

Biotic Resources Group 

Biotic Assessments Resource Management Permitting


Biotic Assessments Resource Management Permitting 

Draft 

Watsonville Wetlands Trail System 


Prepared for: 

City of Watsonville 

Attn: Bob Geyer 

Michelle Templeton 

Prepared by: 


Kathleen Lyons, Plant Ecologist 

With 

George McMenamin 

Restoration Ecologist 

July 27, 2007 

2551 S. Rodeo Gulch Road #12 Soquel, CA 95073 (831) 476-4803 Fax (831) 476-8038

TABLE OF CONTENTS 

1.0 INTRODUCTION 

1.1 Study Methodology 1 

2.0 INTRODUCTION TO WEEDS 

2.1 State Noxious Weeds and Threats 7 

2.2 Cal-IPC Invasive Plants and Threats 8 

2.3 Problems for Trail Maintenance and Land Stewardship 8 

2.4 Invasive Weeds Within the VMMM Project Area 8 

3.0 INVASIVE WEED MANAGEMENT 

3.1 Invasive Weed Control Techniques 14 

3.2 Priority Treatment Areas 29 

3.3 Implementation Schedule and Adaptive Management 31 

4.0 RIPARIAN AND WETLAND MITIGATION/RESTORATION AREA 

MAINTENANCE 

4.1 Riparian and Wetland Mitigation and Restoration Sites 39 

4.2 Maintenance Activities 41 

TABLES 

1. Ratings and Guidelines for Action for California Noxious Weeds 7 

2. Categories of Invasive Plants, California Invasive Plant Inventory 8 

3. Invasive Weeds of Management Concern 10 

4. Levels of Invasive Weed Infestations and Potential Control Techniques 21 

5. Typical Flowering Period of Invasive Weeds 27 

6. Plant Species Suitable for Revegetation within VMMM Project Area 28 

7. Invasive Weed Treatment – Yearly Implementation Schedule 32 

8. Upper Struve Slough Mitigation Plantings 39 

9. Upper Watsonville Slough Mitigation Plantings 40 

10. Middle Watsonville Slough Restoration Plantings 40 

11. Lower Struve Slough Mitigation Plantings 40 

FIGURES 

1. Watsonville Slough Trails – Project Area 3 

2. Vegetation Types, 1 of 3 4 



5. Distribution of Invasive Weeds, 1 of 3 11 



8. Priority Treatment Areas, 1 of 3 36 



________________________________________________________________________ 


Draft i July 27, 2007

APPENDICES 

A. Invasive Weeds within the VMMM Project Area 

B. Native Plants within the VMMM Project Area 

C. Volunteer Projects 

D. Mitigation Area Maps 

E. Bucket Watering System 

________________________________________________________________________ 


Draft ii July 27, 2007

CHAPTER 1.0 

INTRODUCTION 

The Watsonville Wetlands Trail System encompasses approximately six miles of multi-use 

recreational trails in the City of Watsonville. The trails traverse portions of Watsonville Slough 

and Struve Slough and abut multiple urban land uses, including residential areas, commercial 

developments, school facilities, and City recreational areas. The trail system and slough areas 

addressed in this manual are depicted on Figure 1. 

The Watsonville Wetlands Trail Vegetation Management and Maintenance Manual (VMMM) 

identifies the location and treatment methods to be used by the City’s maintenance personnel, 

contractors, and/or volunteer groups to remove and/or control the growth of weeds and invasive, 

non-native plant species within the trail system project area. The manual also outlines strategies 

to encourage native plant growth that will reduce the need for long-term weed control. 

The City of Watsonville has implemented several riparian and wetland plantings along the slough 

trails, providing mitigation for bridge and trail improvement projects. The VMMM identifies 

these areas and the specific maintenance and monitoring requirements that are applicable to these 

mitigation plantings. 

1.1 STUDY METHODOLOGY 

1.1.1 Existing Vegetation Types and Management Areas 

The existing vegetation types in the VMMM project area were mapped during the City’s 

preparation of the Trail Plan (Swanson Hydrology & Geomorphology, 2002). Nine plant 

community types were observed within the trail study area. These plant communities are nonnative 

grassland, blackberry scrub, ruderal (weedy) scrub, coyote brush scrub, non-native 

trees/tree groves, willow riparian woodland, freshwater marsh, and seasonal wetlands. Field 

surveys conducted for the VMMM confirmed the current distribution of these habitat types and 

identified recent City-designated riparian and wetland mitigation and enhancement areas; the 

distribution of the vegetation types and mitigation/enhancement areas is shown on Figures 2, 3, 

and 4. 

1.1.2 Existing Invasive Weeds, Infestation Areas, and Threat Rankings 

The occurrence of invasive weeds (i.e., invasive, non-native species) within the project area was 

identified and mapped during field surveys conducted in February, March, May, and June 2007. 

The infestations were mapped as line features, polygons, or spot locations by GPS or hand drawn 

onto aerial photos. The GPS and hand drawn data was supplied to the City’s GIS coordinator to 

develop a GIS data layer (i.e., “distribution of invasive weeds”). Potential vegetation management 

or maintenance areas were also identified, such as vegetation types or plant species that may 

require periodic maintenance (e.g., willow riparian woodland that abuts a trail and pruning or 

other maintenance may be required now or in the future). 

Based on the type and extent of invasive weeds in the project area, the species/species locations 

were categorized as high, moderate, or low threat. A species growth pattern, extent within the 

project area, effect on native vegetation, and ability to spread into uninfected areas were used to 


Draft 1 July 27, 2007

determine a species ranking. Information on the invasive weed species and their ranking and 

threat is described in Chapter 2.0. Appendix A identifies, using photographs, the invasive weeds 

that are currently of management concern in the VMMM project area. 

1.1.3 Prioritize Vegetation Management and Weed Removal/Control Treatment Areas 

Using information gathered in Tasks 1.1.1 and 1.1.2, above, areas within the VMMM project area 

were identified for vegetation management action. Various management methods were evaluated 

as to their potential use in the VMMM project area, such as seasonal mowing, hand removal, 

solarization, periodic thinning or pruning, and allowing and/or encouraging conversion of areas to 

other vegetation types (i.e., conversion of grassland/ruderal areas to scrub). Threat rankings used 

by the USDA, Cal-IPC, and field observations were used to identify areas/species with a high 

priority for removal. This information was marked on maps as priority treatment areas. 

1.1.4 Development of Maintenance and Management Treatments 

Vegetation management and/or maintenance treatments were identified for the VMMM project 

area. Short-term weeding activities, as well as long-term strategies to encourage native plant 

growth that can reduce long-term maintenance, were evaluated. Preferred maintenance operations 

were also identified, such as the time and intensity of mowing/weed whipping, hand removal, 

solarization, flaming and selective herbicide application. Chapter 3.0 of the VMMM outlines 

these recommended invasive weed control techniques and grassland/ scrub management actions. 

A yearlong schedule outlining the optimum time for implementing treatment is also provided in 

this chapter. 

The VMMM outlines short-term and long-term vegetation management goals and objectives. An 

example of a short-term goal is to reduce the extent of high priority weeds within the project area 

over the next five years. An objective to reach this goal is to remove 100% of pampas grass from 

the project area in Year 1 and reduce the extent of yellow star thistle to less than two occurrences 

in Year 2. A long-term goal may be to allow natural colonization of competitive native plant 

species, such as coyote brush (Baccharis pilularis), within select areas that are currently infested 

with poison hemlock (Conium maculatum) and wild radish (Raphanus sativa). 

Chapter 4.0 outlines maintenance and monitoring requirements for the City’s riparian and 

wetland mitigation and enhancement areas. Activities include repair of browse protectors, replanting 

techniques, and plant survival monitoring techniques. The maintenance activities follow 

regulatory agency permit requirements, including a 5-year monitoring period and plant survival 

requirements. Maintenance of planted trees and shrubs, such as mulch replacement, irrigation 

requirements, and any specific restrictions imposed on the site by regulatory agencies (e.g., 

restriction on herbicide use in/around waterways supporting special status amphibians) are 

identified. To aid maintenance personnel, the VMMM includes photographs of all native trees 

and shrub species planted within the mitigation areas. These photos are found in Appendix B. 

Appendix B also includes other native plants that occur in the VMMM project area that, in most 

instances, should be retained. 

The VMMM identifies maintenance activities that are suitable for volunteer and/or school groups. 

The VMMM includes “volunteer” packages for these activities. Each package includes a map of 

the work area, tasks to be implemented, the optimum period for the work, and expected level of 

effort. These volunteer packets are presented in Appendix C. 



CHAPTER 2.0 

INTRODUCTION TO WEEDS 

Weeds, in general, are defined as plants growing in an area where they are not indigenous. Some 

botanists and land managers also refer to these plants as non-native. Many weeds are of European 

origin having entered the United States with early European explorers. In California, many weed 

species were also introduced during the Spanish and Mexican occupation periods, particularly at 

coastal sites and around settlements (Brossard, Randall and Hoshovsky 2000). Non-native plants 

came into California on grazing animals, in livestock feed, ship ballast, and through the transport 

of ornamental and crop plants. Non-native plants continue to enter California from the 

international transport of economic goods, the global plant trade, and tourism. 

Currently, it is estimated that over 1,800 non-native plant species have become established in 

California, with a minority of these species (approximately 200) having escaped cultivation and 

invaded into natural areas (Cal-IPC 2006). In instances where a plant to found to be 

“troublesome, aggressive, intrusive, detrimental, or destructive to agriculture, silviculture, or 

important native species, and difficult to control or eradicate” the plant has been identified by the 

California Department of Food and Agriculture (CDFA) as a noxious weed (CDFA 2007). The 

CDFA rates each species based on its statewide importance, the likelihood of successful 

control/eradication, and the species distribution in the state. 

In a similar manner, the California Invasive Plant Council (Cal-IPC) has identified plant species 

that displace native species and negatively affect natural systems as invasive species. Cal-IPC has 

developed it own ranking system that identifies a species invasive qualities as well as its negative 

effect on native ecosystems. 

2.1 STATE NOXIOUS WEEDS AND THREATS 

The state’s Noxious Weed List identifies plant species that are currently considered a pest 

according to laws/regulations in the California Food and Agriculture Code. Plants are rated as A, 

B, C, or Q, to give guidance on the most appropriate action to take against the weed species, as 

depicted on Table 1. Presently, there are 134 plant species considered noxious weeds in 

California. 

Table 1. Rating and Guidelines for Action for California Noxious Weeds 

Pest Rating Appropriate Action Number of Plant 

Species Listed 

A Eradication, containment, rejection or other holding action at the 

45 

state-county level; quarantine possible. 

B Eradication, containment, control or other holding action at 

54 

discretion of County Agricultural Commissioner. 

C State endorsed holding action and eradication if plant found in a 

24 

nursery; action to retard spread of plant outside nursery at 

discretion of County Agricultural Commissioner. 

Q Temporary A action outside of nurseries pending determination of 11 

a permanent rating; This rating includes al List 2, Federal Noxious 

Weed Regulations. 

D No action 0 

Total 134 

Source: CDFA 2007 



2.2 Cal-IPC INVASIVE PLANTS AND THREATS 

Cal-IPC has identified plant species that they consider to be invasive in natural areas, have an 

aggressive growth pattern that adversely competes with native species, and have potential to 

change plant community structure and reduce habitat values. In 2006 the California Invasive 

Plant Inventory was developed as a scientific and education report to provide information to those 

working on habitat restoration, land managers, and the public. The Cal-IPC inventory has no 

regulatory authority. 

Table 2 identifies the inventory categories developed by Cal-IPC. These categories (high, 

moderate, or limited) reflect the level of a species negative ecological impact in California. This 

information can be useful to land managers in evaluating management actions. Presently, there 

are 193 invasive plants listed in the Inventory. Forty-one of these species are also listed as 

noxious weeds by the CDFA. 

Table 2. Categories of Invasive Plants, California Invasive Plant Inventory 

Ranking Meaning of Ranking Number of Plant 

Species Listed 

High Plant species pose severe ecological impacts on physical 

39 

processes, plant and animal communities and vegetation structure, 

plants have moderate to high rates of dispersal and establishment. 

Moderate Plant species have substantial ecological impacts; plants have 

65 

moderate to high rates of dispersal yet establishment is generally 

dependent on ecological disturbance. 

Limited Plant species are invasive, but ecological impacts are minor on 

89 

statewide level; reproductive biology result in low to moderate 

rates of spread, but species may be locally persistent and 

problematic. 

Total 193 

Source: Cal-IPC 2006 

2.3 PROBLEMS FOR TRAIL MAINTENANCE AND LAND STEWARDSHIP 

Both noxious weeds and invasive species can hinder natural habitats, degrade visual features of 

public spaces, and increase fire hazards on public lands. Within the Watsonville Wetlands Trail 

System, invasive weeds can also adversely affect the progress of riparian and wetland 

revegetation efforts. 

Typically, invasive weeds are successful in out competing native plants for growing space, soil 

moisture, and nutrients. These weeds may also contribute to a fire hazard, thus threatening trail 

users as well as adjacent lands. 

2.4 INVASIVE WEEDS WITHIN THE VMMM PROJECT AREA 

The VMMM addresses plant species considered to be of management concern within the 

Watsonville Wetlands Trail System. Most of the plant species found within the project area are 

listed by the CDFA and Cal-IPC, as noxious weeds and invasive species. This manual provides 

field identification for 22 plant species considered to be of management concern. Table 3 lists 

these species, segregated as to their growth habit (herbaceous [non-woody] or woody shrub/tree) 

and the typical habitat where they are found. Table 3 also identifies the invasive threat ranking 



assigned to each species. This ranking is based on the CDFA ranking, Cal-IPC ranking, and field 

observations. 

In general, noxious weeds and invasive plants are adapted to establish on previously disturbed 

conditions, such as loose soils exposed by grading or on sites that have experienced a substantial 

habitat change from previous agriculture, grazing or other activity. 

The plants can be annual/biennial species, such as Italian thistle, that grow quickly and produce 

large amounts of seed. The seeds from annual plants are often easily dispersed by wind or by 

animals. Perennial herbaceous plants, such as Harding grass, reproduce by seed but can also 

spread by spreading roots. The woody plant species within the VMMM project area are fast 

growing; they produce copious amount of seed, which are viable for decades (e.g., French 

broom). The growth habitat of the VMMM invasive weed species is listed on Table 3. 

Field identification features of each species are presented in Appendix A. This appendix provides 

the user with information on how to recognize the plant, where would one typically find it 

growing, and what problems it causes for trail and habitat maintenance. Photographs are included, 

depicting the species in flower as well as in summer when the plants are commonly observed. 

Figures 5, 6, and 7 show the current distribution of invasive weeds within the VMMM project 

area. 



Table 3. Invasive Weeds of Management Concern, Typical Habitats Where they are Found, and Invasive Rankings, Watsonville Wetlands 

Trail System Project Area 

Common Name Scientific Name Freshwater 

Marsh 

Aquatic 

Areas 

Seasonal 

Wetland, 

Edge of 

Slough 

Dry 

Grassland 

Scrub Riparian 

and Tree 

Groves 

Cal-IPC 

Ranking 

HERBACEOUS PLANTS 

Wild Mustard Brassica spp. X 1 X 1 Moderate Annual 

Biennial 

Iceplant Carpobrotus edulis 

X X X Moderate Perennial 

Italian thistle 

Slender flowered thistle 

Carduus pycnocephalus 

Carduus tenuiflorus 

1 

X X 1 X Moderate 2 Annual 

Biennial 

Yellow star thistle Centaurea solstitialis 

1 

X 

High 2 Annual 

Bull thistle Cirsium vulgare 

X X X Moderate Annual 

Biennial 

Poison hemlock Conium maculatum 

X X X X Moderate Annual 

Biennial 

Jubata and pampas grass Cortederia jubata, C. selloana 

X X X High Perennial 

Cape ivy Delaireia odorata 

X X High Perennial 

Fennel Foeniculum vulgare 

X X X X High Perennial 

English and Algerian ivy Hedera helix and H. canariensis 

X High Perennial 

Kikuyu grass Pennisetum clandestinum 

X X X 

2 

Limited Perennial 

Harding Grass/Canary Grass Phalaris aquatica/ P. 


arundinacea 

Bristly ox-tongue Picris echioides 

X X 1 X 1 Limited Biennial 

Bermuda buttercup Oxalis pes-caprae 

X X X X Moderate Perennial 

Wild Radish Raphanus sativa X 1 X 1 X Limited Annual 

Himalaya Berry Rubus discolor 

X X X X High Perennial 

Curly Dock Rumex crispus X X 1 X Limited Perennial 

SHRUBS AND TREES 

French broom Genista monspessulana 

X X X High 2 Perennial 

Acacia Acacia spp. 

X Limited Perennial 

Eucalyptus Eucalyptus sp. 


1 - species may also occur along disturbed road and trail edges 

2 - species has a pest rating of “C” by CDFA. 

Growth 

Habit 



CHAPTER 3.0 

INVASIVE WEED MANAGEMENT 

The management of invasive weeds within the VMMM project area refers to the removal/control 

of invasive, non-native plant species that have been considered a threat to recreational uses of the 

trail system and/or significantly degrade habitat resource values. The desired manner for the 

control of these species is for City maintenance personnel to check the sites frequently, and in 

most instances, control infestations manually such that new, larger and more difficult to control 

infestations are prevented. However, the VMMM project area currently supports large 

infestations of hard to treat invasive weeds that will require considerable effort to remove/control. 

This chapter describes the various weed management techniques that can be used and identifies 

the most effective techniques for each species. 

3.1 INVASIVE WEED CONTROL TECHNIQUES 

Invasive weeds within the VMMM project area can be controlled through hand removal/cutting, 

mechanical weed whipping/mowing, solarization, flaming, grazing/browsing, and herbicide 

application. Active and passive revegetation is also a viable control technique for some species 

and locations. 

The most effective control techniques must take into account a species growth pattern, its 

reproductive characteristics, and its occurrence or level of infestation with the project area. Table 

4 identifies the growth patterns and the potential control techniques for each invasive weed 

species currently found within the VMMM project area. The invasive ranking of each species 

within the project area is also identified. This ranking is based on the species CDFA ranking, Cal- 

IPC ranking, and observations of its occurrence/infestation within the project area. 

The VMMM project area supports large infestations of poison hemlock, Harding grass, and 

bristly ox-tongue; often these species overlap in their distribution. These species are present 

throughout the project area, in varying degrees of density. Management actions for these species 

will require a combination of grubbing, hoeing, seasonal mowing/weed-whipping, solarization, 

select herbicide applications, animal browsing, and passive revegetation, as described in more 

detail below. Control and eradication techniques must also take into account a species growing 

cycle, particularly the flowering period and seed production/release periods. Table 5 displays the 

typical flowering period of the invasive weeds currently found with the VMMM project area. 

3.1.1 Field Training 

Although supervision as to timing, technique and general location for invasive plant management 

can be provided for personnel performing invasive plant fieldwork, the personnel performing the 

work will need to be capable of operating independently. Untrained personnel can cause negative 

impacts on plant management results. Therefore, a certain level of field training is required for 

success. Such training should also be provided so that the methods and skills are readily 

transferable to future workers. 

Training should include, but not be limited to, the follow skills and abilities: 

• The ability to identify the key invasive plant species likely to be encountered within the 

VMMM project area. This could be achieved by disseminating a booklet of major 

invasive plants (as presented in Appendix A) and field training sessions. 



• The ability to identify the key native plants species likely to be encountered within the 

VMMM project area. This could be achieved by disseminating a booklet of major native 

plants (as presented in Appendix B) and field training sessions. 

• The ability to identify areas of potential special status species/habitat, both flora and 

fauna. A brief training session, conducted by qualified personnel, could be provided to 

workers to achieve a limited recognition of such habitat/species. Species of concern 

within the VMMM project area include Santa Cruz long-toed salamander, California redlegged 

frog, and Santa Cruz tarplant. 

• Although field personnel often have a high degree of skill with various types of 

equipment, details of proper techniques should be provided to achieve maximum 

efficiency and success. 

• A discussion and presentation of the potential positive and adverse effects of various 

management techniques, focusing on the goals of field activities and the VMMM. 

• Instructions if field personnel encounter plants, animals or situations outside of their 

scope of training, including the proper course of action when these situations occur. 

General guidance should be provided to workers to limit harm to sensitive or protected 

habitats, including guidelines to employ that would limit the disruption of work. 

• Provide workers with project goals and objectives to facilitate their “buy in” with the 

management program. Some of the field techniques may require subtle changes in their 

work effort (i.e., low weed-whipping/mowing, bagging flowering heads), therefore a 

change of their perspective on a task may be critical for project success. Project success 

may increase if workers are encouraged to be knowledgeable about their work 

environment, have a change in outlook related to scale (slower and correct weed 

eradication effort often proves more efficient and effective), and to ask questions if field 

techniques or eradication/control goals are not clear. 

• Use adaptive management strategies. Field personnel may have useful and efficient ideas 

and methods for doing a given task. Field supervisors should be encouraged to consider 

new ideas and potential improvements. “I may not use an idea, but I will listen and 

considered it”, is a concept that not only increases effectiveness but also increases “buy 

in” by field personnel. 

3.1.2 Grubbing 

Within the VMMM project area, grubbing, both with tools and by hand, is a suitable treatment 

for infestations of cape ivy, English ivy, thistles (Italian thistle, slender-flowered thistle, bull 

thistle), bristly ox-tongue, wild radish and most other invasive weeds found in isolated small 

patches. Grubbing is often used during the Bradley Method. The Bradley Method is a technique 

where invasive plants are completely removed around the perimeter of desirable, existing native 

plants to create noncompetitive growth patches for the native plants. 

Additionally, hand grubbing may be used to create controllable perimeters around large patches 

of poison hemlock and Himalaya berry. In some cases, all biomass created by grubbing should be 

bagged and removed for proper disposal. Plants that should be carefully bagged and removed for 

disposal include species that re-sprout from spreading rhizomes or stems, such as Cape ivy, 

English ivy, Kikuyu grass, and Harding grass. Table 4 provides specific details for grubbing 

individual plant species. 

Grubbing should be followed by revegetation with appropriate native plants. Appropriate erosion 

control practices and techniques should also be implemented prior to grubbing, and applied as 

needed during or immediately after the work is completed. 



General Rules for Grubbing 

• If the plant has gone to flower, the floral heads should be bagged and removed for proper 

disposal. 

• If the plant has runners (rhizomes or stolens) all parts of the plant should be bagged and 

removed for disposal. 

• If plants are to be root cut, they should be cut below the root crown (greater than 2” 

below the surface) and prior to flowering. 

• Small to moderate woody stem plants may be girdled, if it is safe to do so and you are 

unable to efficiently dig them up. 

• If you are not sure if a plant is an invasive species, do not remove it until it has been 

identified. 

• If you see an animal in the area that you suspect may be protected (e.g., Santa Cruz longtoes 

salamander, California red-legged frog), do not work in the immediate area until the 

animal has been identified. 

There are a number of hand tools that are widely used for grubbing specific types of invasive 

plants. Commonly used tools include: 

• Weed Wrench - This tool is used to remove woody-stemmed plants with minimal soil 

disturbance. Examples include French broom, young acacias and young eucalyptus. 

• Rakes - Rakes may be used to remove lose biomass, establish clear perimeters or remove 

dense non-woody spreading plants or vines. Examples include cape ivy and iceplant. 

• McLeod/fire rake - These tools are used to clear areas to bare earth for controllable 

perimeters or when utilizing the Bradley Method. 

• Pulaski/hand pick - These tools can be used like an axe, hoe, small shovel, or pick to cut 

large or woody plants, clear earth, dig holes, or girdle trees. 

• Round-pointed shovel - Depending on type, shovels are efficient for cutting roots, 

exposing rhizomes, establishing perimeters, or making hole for plantings. 

• Soil knife- A soil knife is useful for exposing and cutting the roots of individual plants or 

small patches of plants. This tool can be easily carried in a pouch. 

• Scythe/hand scythe - The scythe is not commonly used, as it requires proper training in 

both use and sharpening. However, the scythe is increasingly being used to cut grasses, as 

it is proving to be faster, quieter, and more effective than weed whipping when the proper 

technique is developed. The hand scythe is useful for small areas of grass, in sensitive 

areas. Use of the hand scythe does not require any training. 

• Axes, saws, loppers and pruners - These tools are used to remove woody-stemmed plants 

or large/tough stemmed herbaceous plants, such as late season thistles. 

• Serrated knife- Knives can be carried at all times and used to cut, saw, or girdle small 

woody-stemmed plants or tough stemmed herbaceous plants. 

• Strapping or chains- These can be used with vehicles, come-alongs, or winches to pull 

plants such as pampas grass out of the ground. 

• Hoes- Discussed below. 

3.1.3 Hoeing 

Hoeing invasive weeds is an effective technique to remove small groups of plants and/or 

individual occurrences. 

Typically, hoeing should occur prior to flowering, with the plant cut 2-4” below the ground 

surface. If flowers are on the plant, the cut/removed material should be bagged and removed from 

the site. If no flower heads have formed, the cut material can be left on site, with the possible 

exception of poison hemlock. Hoeing can be used at all times of the year, although plant removal 



efore the flowering season (typically spring) is usually the most effective as a means of reducing 

weed seeds in the project area. 

Within the VMMM project area, hoeing is a suitable treatment for all species where they occur as 

individual occurrences or small infestations. Plants that can re-sprout from spreading rhizomes or 

stems, such as cape ivy, English ivy, Kikuyu grass, and Harding grass should be removed in a 

controlled, careful manner such that hoeing does not encourage the species growth. Table 4 

identifies species suitable for hoeing. Table 5 displays the typical flowering period for the 

invasive weeds currently found within the VMMM project area; this table should be consulted 

such that hoeing is conducted prior to flowering. 

3.1.4 Mowing and Weed Whipping 

The City currently has a mowing program for the area immediately adjacent to the trails (2-foot 

wide strip) and other areas. This program involves seasonal mowing of herbaceous plants and 

small shrubs (primarily coyote brush). As depicted on Table 4, many invasive weed species, 

including poison hemlock and bristly ox-tongue, can be controlled with a properly timed mowing 

program. 

To be an effective invasive weed control technique, a mowing or wee -whipping program needs 

to be timed to mow in the spring (prior to flowering and seed set – see Table 5), then again in 

summer and/or early fall, depending upon the rainfall year. This mowing program will adequately 

control most invasive weed species. This mowing program, however, is only feasible on the flat 

and gently sloping portions of the project area and will not be a suitable treatment for the steeper 

slopes that abut the sloughs. 

Within the VMMM project area, mowing and weed whipping is a suitable treatment for thistles 

(Italian thistle, slender-flowered thistle, bull thistle), bristly ox-tongue, and poison hemlock. 

Specifications for each of these species are listed in Table 4. 

The following general rules apply to weed whipping poison hemlock, bristly ox-tongue, and 

poison hemlock: 

• Equipment heads should be limited to string or plastic blades. Metal blades are 

discourages since they may start fires and create a wind effect that limits their 

effectiveness. Because plastic tri-blades provide the highest level of control, plastic 

blades are recommended when working in areas with desirable native plants or grasses. 

Additionally, late in the flowering season when plants have tough fibrous stems, plastic 

blades are more effective than string. 

• The invasive weeds should be whipped as close to the ground as possible without causing 

erosion or damaging desirable plant species. 

• Table 5 provides a general timeline on the correct timing for the initial weed whipping. 

• Weed whipping should be timed to deplete the root reserves of invasive plants, to the 

maximum extent possible. 

• All flower heads that have gone to seed should be bagged and removed from the site. If 

noted for specific species (Table 4), all biomass should also be bagged and removed from 

the site. 

Thistles (Italian thistle, slender-flowered thistle, bull thistle) - The general techniques for weed 

whipping these three species of thistles are similar. The idea is to whip the thistles when their root 

reserves are depleted to the maximum extent. This limits re-growth of individual plants and 

reduces the number and size of repeat treatments required. The timing of the initial weed 



whipping is critical. However, local conditions require site inspections to determine the exact 

timing. The initial weed whipping should occur soon after the thistle has bolted (the main stem 

has risen from the basal leaf grouping) and during the period when the flower buds are forming, 

but have not yet opened. As bull thistles flower later in the season than Italian and slender thistle, 

the initial weed whipping for bull thistle may occur at a different time. However, it is likely that 

the initial bull thistle treatment will correspond with a secondary treatment for the Italian and 

slender thistle species. Additionally, for maximum effectiveness, as all thistles in an area do not 

bolt at the exact same time, several sessions over a period of a couple weeks may be required. If 

funding or labor availability is limited, the initial weed whipping should occur when the majority 

of thistles have bolted and are creating buds. If the timing is correct, only one or two retreatments 

should be necessary. A periodic inspection of the thistle sites will be required to 

determine the number and timing of re-treatments. Any thistle flowers that have opened or about 

to open should be bagged and removed from the site 

Bristly ox-tongue - Bristly ox-tongue should be weed-whipped prior to flower opening and seed 

formation, in the late spring (see Table 5). Bristly ox-tongue should be weed-whipped as close to 

the ground as possible without causing erosion or causing damage to desirable plant species. 

String heads should prove effective, except late in the season, although plastic blades provide 

greater control. As bristly ox-tongues flower over a long period of time, periodic site inspections 

should occur during the flowering cycle and multiple treatments are likely. Any flowers that have 

opened should be bagged and removed from the site. 

Poison hemlock - Weed-whipping is most efficient if it occurs after the stalk has formed and 

before the flowers have opened. If weed whipping occurs after the flowers have opened, it should 

occur prior to seed formation. If poison hemlock is weed-whipped after the flowers have opened, 

the flower heads should be separated from the major mass of the stem and root and be bagged and 

removed from the site. 

Although string heads are effective in the spring and early summer, plastic blades may be 

required later in the season. Repeated treatments will be required, as poison hemlock can have 

large root reserves. In some locations, poison hemlock can grow year-round and may require 

periodic site inspections, throughout the year. Multiple spring and fall mowing/weed-whipping 

should be done at the lowest height possible, without disturbing the soil (approximately 2-3 

inches, depending upon equipment). 

As poison hemlock is an annual/biennial species, with seed viability of three or four years, the 

mowing/whipping regime needs to occur intensively for 3-5 years. Weed-whipping plants that 

have dropped their seed is of limited usefulness for control, as the plant dies after seeding. The 

entire poison hemlock plant is toxic and all above ground biomass should be removed from site if 

animals or people may eat it. 

3.1.5 Solarization 

There are two types of solarization used to control weeds. Within the VMMM project area, only 

one type of solarization is applicable for weed management, due to factors such as cost and 

human disturbance. Within the VMMM project area, solarization is a suitable treatment for 

Kikuyu grass, Harding/canary grass and potentially, poison hemlock (Table 4). For these species, 

a minimum thickness 10mm black plastic needs to be in place for one or more years to effectively 

kill the plant/plant roots and the successional weed seeds. Additionally, treatment by solarization 

may be suitable for isolated large patches of many other invasive weeds, depending on location, 

slope and proximity to desirable native plants. The use of City-supplied 30mil landfill liner 



plastic would be suitable. 

3.1.6 Spot Application of Herbicide and Organic Sprays 

The use of herbicides and organic sprays may also be suitable for some of the invasive species; 

the City currently uses herbicides along some portions of the trail. If herbicide use is proposed in 

close proximity to slough waters, the herbicide should be used in a manner that will not 

negatively impact the riparian and wetland habitats, including special status wildlife (i.e., 

California red-legged frog and/or Santa Cruz long-toed salamander). Although herbicide use can 

prove economically attractive, the VMMM recommends the use of herbicides only where other 

management techniques would prove impractical or are not economically viable. 

Within the VMMM project area, spot application of herbicide may be a suitable treatment for 

biennial thistles (spot spray on rosettes), iceplant, poison hemlock, jubata/pampas grass, fennel, 

Harding/canary grass, bristly ox-tongue, English ivy, and cut stumps of acacia and eucalyptus. 

Herbicide use is typically effective when combined with mechanical cutting/removal techniques 

and/or applied to coincide with plant growth/uptake, such that the least amount of herbicide is 

needed. Methods of application should be limited to those with the lowest probability of damage 

to surrounding habitat, such as painting and selective, targeted foliar spray. In many cases, 

multiple applications will be required. Strict adherence to manufacturing and agency guidelines 

should be observed at all times. A formal herbicide use plan should be created and discussed by 

appropriate personnel, prior to the use of any herbicides. A licensed herbicide applicator with 

extensive experience in wetland and riparian habitats should be consulted regarding herbicide use 

within the VMMM project area. 

California has approved a limited number of herbicides for use in or near aquatic environments. 

Several possibilities are mentioned here as examples, but may not be acceptable for all 

applications: 

• Aquamaster R (an aquatic formula previously marketed as Rodeo R ) contains glyphosate 

and water, but does not contain any surfactant. Aquamaster R is approved for use in and 

around water. Glyphosate is a nonselective, broad-spectrum herbicide. The timing and 

methods of application are critical and should be carefully monitored. This herbicide can 

damage desirable native plants and care is required to avoid drift. As surfactants aid the 

ability of the herbicide to penetrate vegetation, if allowed, some use of acceptable 

surfactants may be added in upland areas, along the sloughs. 

• Habitat R is an herbicide that was approved for use in California in 2005. It is labeled for 

use with aquatic and other wetland vegetation. Whether it is approved for use in Santa 

Cruz County is unknown, but it may be an option. 

• Roundup Pro R is an herbicide that contains glyphosate, water and a surfactant. It may be 

useful in some upland areas, away from water. As glyphosate is a nonselective, broadspectrum 

herbicide, any used of this herbicide should be restricted around desirable 

native vegetation and it should not be used within 25 feet of water. Methods of 

application should be restricted. 

In recent years, several organic, contact-type herbicide products have appeared on the market. 

These organic sprays include the soap-based product, Scythe, (produced by Mycogen), clove 

oil products, Matran II (produced by EcoSmart), and acetic acid/citric acid products, AllDown 

(produced by Summerset) (UC Davis, 2007). These products damage any green vegetation 

contacted, though they are safe as directed sprays against woody stems and trunks. Because these 

herbicides only kill contacted tissue, good coverage is essential. Adding an organically acceptable 

surfactant is also recommended. Because these materials lack residual activity, repeat 



applications will be needed to control new flushes of weeds. Recent work has also examined 

essential oils as potential herbicides. It was found that clove oil or cinnamon oil at concentrations 

of 1 to 5% controlled most small weeds. The use of organic sprays could be evaluated for use 

within the VMMM project area as part of a pilot project. 

3.1.7 Flaming/ Selective Burning 

Within the VMMM project area, flaming/selective burning is a suitable treatment for many 

invasive weeds during the seedlings stage or growth of new shoots. This management option 

should prove effective with French broom, Harding grass, and some annual weeds. Flaming or 

selective burning should be done under strict guidelines related to safety, moisture and the life 

history stage of target species. Larger scale prescribed burning is an option unlikely to be 

acceptable, due to the limited number of isolated large patches of invasive weeds and the 

extensive effort required to coordinate a prescribed burn. 

3.1.8 Selective Grazing/Browsing 

Within the VMMM project area, selective grazing/browsing is a suitable treatment for Harding 

and canary grass. Potentially effective grazing animal species may be limited, due to several 

factors. Sheep are adversely affected by Harding grass and goats are browsers, rather than 

grazers. However, due to the fencing/containment needs for grazing animals, the aquatic nature in 

which the Harding/canary grass is found, animal-safety concerns, and existing recreational uses, 

grazing as an invasive weed control treatment may be limited. One potentially suitable area is the 

relatively confined area along Middle Struve Slough, immediately downstream of Main Street. 

Although goats are browsers, they may prove helpful in reducing the amount of poison hemlock, 

wild radish, fennel, and Harding grass. They remove biomass, thereby lowering green waste 

removal costs. Additionally, they increase the ability of personnel to access areas and roots of 

some invasive plants. Revegetation will be required in all cases where goats are utilized. Because 

goats do not kill many invasive plant species, re-infestations by aggressive, surviving invasive 

plants may limit the success of revegetation, unless secondary control methods are utilized in 

conjunction with the use of goats. The effectiveness of goats is predicated on a number of 

additional factors, as presented below: 

• Goats should not be utilized on slopes, soils, or in habitats where erosion is likely to 

occur, unless an acceptable, effective erosion control plan is created and provided for, 

prior to the arrival of the herd. 

• Goats often require regular active management and almost always require rapid response 

capabilities, by the goat providers. Specific conditions as to management and response 

requirements should be placed into contracts to assure compliance. Proximity to more 

desirable food and delays in proper management or response may result in destruction of 

desirable vegetation, both inside and outside the fenced area, including the girdling of 

riparian trees. Increases in erosion or sedimentation may also occur. 

• Goats are much more likely to eat certain plant species. Some plants will be eaten only 

when nothing else is available, reducing the effectiveness and increasing the cost of 

utilizing goats. 

• Goats do not kill many invasive plants. The survival of many plants results in the need 

for repeated visits, over a number of years. Additionally, other methods will be needed in 

conjunction with the use of goats to achieve success. 

• Safety and health concerns must be addressed for the goats and people who may come in 

contact with them. 



Table 4. Levels of Invasive Weed Infestations and Potential Control Techniques, Watsonville Wetlands Trail System Project Area 

Common 

Name 

Scientific Name Invasive Weed 

Ranking 

Infestation 

Threshold 

Growth Pattern 

Potential Control Techniques 

HERBACEOUS SPECIES 

Wild Mustard Brassica spp. Moderate Greater than 20 

plants or patch 

greater than 25 sq. 

ft. 

Annual or Biennial 

Spread by seed 

a. Hand-pull and bag flowering plants. 

b. Shovel cut or hoe mature plants prior to flowering 


Slenderflowered 

thistle 

Iceplant 

Management Goal: Reduce number of patches to


Common 

Name 


Ranking 

Infestation 

Threshold 



Yellow star 

thistle 

Bull thistle 

Centaurea 

solstitialis 

High Greater than 25 



ft. 

Annual 

Spread by seed, 

including seed on old 

flower heads. The bristly 

seed coat attaches to 

equipment, vehicles and 

animals. 



Common 

Name 


Ranking 

Infestation 

Threshold 

Growth Pattern Potential Control Techniques 

Poison 

Hemlock 

Jubata grass 

Pampas grass 

Cape Ivy 

Conium 

maculatum 




ft. 

Annual or biennial 

Spread by seeds on 

vehicles and animals; 

basal rosettes over 

winter and crowd out 

native plants, yet 

individual plants die 

after setting seed. 



Common 

Name 


Ranking 

Infestation 

Threshold 


Fennel 

English ivy 

Algerian ivy 

Bermuda 

buttercup 

Kikuyu grass 

Foeniculum 

vulgare 




ft. 

Perennial 

Spread by seeds , 

vehicles and animals; 

sprouts from root 

crown. 



Common 

Name 


Ranking 

Infestation 

Threshold 



Harding grass 

Reed canary 

grass 

Bristly oxtongue 

Wild Radish 

Phalaris aquatica 

P. arundinacea 

High 

Patch greater 

than 100 sq. ft. 

Perennial 

Spreads by seed and 

spreading underground 

stems (rhizomes). Limited 

rhizome spread by 

Harding grass. Extensive 

rhizome spread by reed 

canary grass 

a. Avoid mechanical cutting of rhizomes and transport of 

cut pieces to new locations. 

b. Remove small patches, removing all root pieces and 

seed heads, bag and dispose. 

c. Mow close late in season to reduce vigor, repeat 

several years. Apply herbicide. 

d. Graze with geese low during the growing season to 

control. Apply herbicide. 

e. Solarization for >1 year with 10mm black plastic. 

f. A critical component to control Harding grass is: 

Revegetate treated areas with native perennial grasses; 

spot remove young Harding/canary grass seedlings. 

Management Goal: Reduce size of existing patches to


Common 

Name 


Ranking 

Infestation 

Threshold 


Himalaya 

berry 

Curly dock 

Rubus discolor Low Greater than 50 


greater than 100 

sq. ft. 

Perennial 

Spread by seeds, 

spreading vines 

a. Hand cut, remove rootstock. 

b. Establish a controllable perimeter around the edge of 

each large patch. 

c. Hoe young plants. 

Management Goal: Retain existing patches over first 5 years; reduce patch size to

Table 5. Typical Flowering Period of Invasive Weeds, Watsonville Wetlands Trail System Project Area 

Common Name Scientific Name Jan Feb Mar Apr May Jun July Aug Sept Oct Nov Dec 

Cape ivy Delaireia odorata 

English and Algerian ivy Hedera helix, H. canariensis 

Bermuda buttercup Oxalis pes-caprae 

Eucalyptus Eucalyptus ssp. 

Wild Mustard Brassica ssp. 

Wild radish Raphanus sativa 

Acacia Acacia spp. 

Harding grass/ canary grass Phalaris aquatica, P. 

arundinacea 

French broom Genista monspessulana 

Poison hemlock Conium maculatum 

Fennel Foeniculum vulgare 

Kikuyu grass Pennisetum clandestinum 

Bristly ox-tongue Picris echioides 

Himalaya berry Rubus discolor 

Curly dock Rumex crispus 

Iceplant Carpobrotus edulis 


Slender-flowered thistle 

Carduus pycnocephalus 

Carduus tenuiflorus 

Jubata and pampas grass Cortederia jubata, C. selloana 

Yellow star thistle Centaurea solstitialis 

Bull thistle Cirsium vulgare 



3.1.9 Active Revegetation 

Within the VMMM project area, active revegetation is a suitable follow-up treatment for areas 

where infestations of thistles (Italian thistle, slender-flowered thistle, bull thistle), bristly oxtongue, 

poison hemlock, and French broom have been removed. Active revegetation is a critical 

requirement for eradication and/or long-term control of Harding/canary grass. In suitable areas, 

revegetation efforts can include broadcast seeding and direct plantings of plugs and other 

container stock. Revegetation efforts should utilize native plant species that are aggressive 

competitors with invasive species. Grass species, such as blue wild rye (Elymus glaucus) are 

recommended for many post-eradication areas. Other herbaceous and woody plant species are 

also recommended, as listed in Table 6 below. 

In areas immediately adjacent to a trail, where trail user visibility is a concern, low-growing 

shrubs and herbaceous plant species are recommended. If a dense cover of native plant species 

can be established, weed recruitment in these areas will be substantially reduced. 

Vegetated buffer zones can also be established using active revegetation. The VMMM identifies 

projects to establish low-growing evergreen buffer areas between residential yards, slough trails, 

and City open space areas. Evergreen buffer plantings will reduce weed infestations, reduce grass 

cover and fire hazards, and promote native plant habitat. Low-growing evergreen shrubs suitable 

for buffer plantings are listed in Table 6. 

Table 6. Plant Species Suitable for Revegetation within the VMMM Project Area 

Common Name Scientific Name Typical Plant Typical Propagule Size 

Spacing 

Vegetated Buffer Areas 

Dwarf Coyote Brush Baccharis pilularis pilularis 6 1 gallon or Dee pot 

‘Pigeon Point’ 

Hooker’s Manzanita Arctostaphylos hookeri 6 1 gallon 

Dwarf Wild Lilac 

Ceanothus griseus 

6 Dee pot 

horizontalis 

Coffee Berry Rhamnus californica 6 1 gallon or Dee pot 

Bee’s Bliss Sage Salvia ‘Bee’s Bliss’ 6 1 gallon or Dee pot 

Low-Growing Trail Edge Revegetation 

Spreading Rush Juncus patens 4 2-inch pot 

Common Yarrow Achillea millefolium 4 2-inch pot 

Wood Strawberry Fragaria vesca 4 2-inch pot 

Creeping Wildrye Leymus triticoides 2 2-inch pot or plugs 

Foothill Sedge Carex tumulicola 2 2-inch pot or plugs 

Blue-eyed Grass Sisyrinchium bellum 4 2-inch pot 

California Meadow Sedge Carex pansa 4 2-inch pot 

Creeping Sage Salvia somomensis 6 1 gallon or Dee pot 

Scrub Revegetation Areas 

Sticky Monkey Flower Mimulus aurantiacus 6 1 gallon 

California Rose Rosa californica 6 1 gallon or Dee pot 

Snowberry Symphoricarpos rivularis 6 Dee pot 

Mugwort Artemisia douglasiana 6 Dee pot 

Coyote Brush Baccharis pilularis 6 1 gallon or Dee pot 

California Blackberry Rubus ursinus 6 Dee pot 

California Aster Aster chilensis 6 Dee pot 

Deerweed Lotus scoparius 6 Dee pot 

California Sagebrush Artemisia californica 6 2-inch pot 



Table 6. Plant Species Suitable for Revegetation within the VMMM Project Area (continued) 

Common Name Scientific Name Typical Plant Typical Propagule Size 

Spacing 

Dwarf Coyote Brush Baccharis pilularis pilularis 


6 1 gallon or Dee pot 

Hooker’s Manzanita Arctostaphylos hookeri 6 1 gallon 



6 Dee pot 

horizontalis 

Grassland Areas 

Blue Wildrye Elymus glaucus - Seed 

California Brome Bromus carinatus - Seed 

Red Fescue Festuca rubra - Seed 

3.1.10 Passive Revegetation 

Within the VMMM project area, passive revegetation is a suitable treatment for expanding stands 

of coyote brush and other desirable native plants (e.g., California rose, blackberry, willow) that 

are vigorous and have the potential to spread into areas infested by invasive weeds. The VMMM 

project area supports areas of thistles, wild mustard, wild radish, bristly ox-tongue, poison 

hemlock, and Harding/canary grass that are growing amid and/or immediately adjacent to native 

vegetation. In these areas, selective removal/control of the invasive weeds (while retaining the 

surrounding or adjoining native vegetation) will allow the native plants to spread and outcompete 

the invasive weeds. 

Where invasive weeds abut stands of native shrubs, five-foot wide bands of invasive plant species 

growing outward from the native stand should be removed/treated (Bradley method). Areas may 

need to be treated more than once, at 2-3 year intervals. Where weeds grow amid the native 

shrubs, selective removal of the weeds should be done using hand labor such that there is minimal 

impact to the native shrubs to be retained. 

3.2 PRIORITY TREATMENT AREAS 

Invasive weeds infestations within the VMMM project area have been prioritized for treatment. 

These areas have been designated as high, moderate, or low, based on the species occurrence in 

the project area, it’s ranking (based on the species ability to spread and its impact on habitat 

values), and treatment options. Figures 8, 9, and 10 depict these priority treatment areas. 

3.2.1 High Priority Treatment Areas (Years 1-5) 

Areas identified as a high priority have been divided into the following seven categories and are 

depicted on Figures 8, 9, and 10: 

H.1 –Remove Isolated Patches of Highly Invasive Species: These species occur in low 

numbers and/or are confined to a few, scattered occurrences; they have ability to quickly 

spread into un-infested areas. Level of infestation is low enough that it is feasible to eradicate 

them from project area within five years. The species are not widespread in the project area 

yet have the potential to spread into non-infested areas within next 1-5 years. Species include 

yellow star thistle, French broom, pampas grass, Bermuda buttercup, and teasel. 



In addition, isolated patches of widespread, invasive weeds that are adjacent to non-infested 

habitat or mitigation areas are included in this category. These infestations can be removed 

with moderate effort, within 1-5 years. These are select occurrences of fennel, wild mustard, 

Italian thistle, iceplant, wild radish, poison hemlock, bull thistle, and Harding/canary grass. 

Management Goal: Remove all H.1 identified occurrences before they spread; repeat 

treatments during Years 1-5 to reach management goal thresholds as listed for each species in 

Table 4. 

H.2 – Contain Existing Infestations in Select Areas: These areas support widespread 

invasive weed species that are difficult to eradicate. Identified treatment areas are somewhat 

isolated with limited ability to spread. The management strategy is to prevent these 

occurrences from spreading into adjacent un-infested areas. Treatment actions are to control 

the perimeter of the infestation (to limit an increase in patch size) depending upon resource 

availability. 

Management Goal: Keep H.2 designated occurrences from spreading; implement measures to 

contain population to existing areas by periodically removing invasive weeds within a fivefoot 

wide buffer area. 

H.3 – Encourage Spread of Native Species in Select Areas: Encourage the spread of 

vigorous native species by clearing successive bands of non-natives from the edges of the 

native stands and allowing native plant growth to occur (Bradley Method). Identified 

treatment areas occur adjacent to vigorous rose, coyote brush, and berry thickets. 

Management Goal: Within H.3 designated areas encourage spread of native thickets by 50% 

in five years. 

H.4 – Implement Pilot Projects for Removal /Control of Aggressive Invasive Weeds in 

Select Areas: Implement pilot weed eradication/control projects to control aggressive weed 

species; pilot projects to include solarization, flaming, mowing/weed-whipping, 

grazing/browsing, and herbicide application; most actions to be combined with revegetation. 

Pilot treatments are most suitable for occurrences of perennial/biennial invasive weeds that 

are widespread and where considerable effort will be required to control/reduce/remove their 

infestations, such as Harding grass/canary grass, poison hemlock, and Kikuyu grass. 

Management Goal: Within H.4 designated areas implement at least one project per year. 

H.5 – Facilitate Volunteer Buffer Plantings in Select Areas: Develop volunteer 

revegetation projects to install native buffer plantings to minimize weeds, reduce fire hazards 

and facilitate slough stewardship. Revegetation projects could include weed removal, 

installation of native low-growing shrubs, and temporary irrigation and maintenance. 

Appendix C outlines various volunteer projects. 

Management Goal: Within H.5 designated areas implement approximately 400 linear feet of 

plantings per year. 

H.6 – Maintain Mitigation Plantings: Weed, repair, mulch, and irrigate mitigation 

plantings; monitor plant survival and report to regulatory agencies as needed. Areas subject to 

maintenance are plantings along upper Struve Slough, Lower Struve Slough, Upper 

Watsonville Slough and Middle Watsonville Slough (see Chapter 4.0). 

Management Goal: Meet permit conditions each year. 

H.7 – Modify Existing Mowing Program: Modify timing, intensity and level of mowing 

along trail edges. Modified program will reduce infestations of bristly ox-tongue and Harding 

grass, and other invasive weeds over time. 



Management Goal: Reduce level of weeds along trail by 50% in five years. 

3.2.2 Moderate Priority Treatment Areas (Years 5-10) 

Areas identified as moderate priority for treatment include the following: 

• Occurrences of invasive weeds that are widespread in the project area and/or have the ability 

to spread into non-infested areas within next 1-10 years. These are occurrences of English/ 

Algerian ivy, wild mustard, bristly ox-tongue, wild radish, and acacia. 

• Occurrences of invasive weeds that are widespread, adjacent to non-infested habitat or 

mitigation areas, and considerable effort will be required to control/reduce/remove the 

infestations over a 10-year period. These are select occurrences of poison hemlock, Italian 

thistle, bristly ox-tongue, and Harding/canary grass. 

3.2.3 Low Priority Treatment Areas (After Year 10) 

Areas identified as low priority for treatment are the following: 

• Occurrences of invasive weeds that are limited to landscaped areas adjacent to trails and have 

a low potential to spread into non-infested areas within next 10 years. These are occurrences 

of eucalyptus and some non-native landscape plants. 

• Occurrences of invasive weeds that are widespread, yet their potential to adversely affect the 

value of non-infested habitat or mitigation areas is considered low over the next 10 years. 

These are occurrences of curly dock, Himalaya berry, and select areas of poison hemlock and 

bristly ox-tongue. 

3.3 IMPLEMENTATION SCHEDULE AND ADAPTIVE MANAGEMENT 

Weed control should be timed to coincide with specific weather and plant growth conditions. 

Most invasive weed infestations can be effectively controlled when treatments are implemented 

prior to plant flowering, which reduces seed formation. However, some biennial and perennial 

species are best treated after flowering, when plant nutrients are being expended and treatment 

actions can stress the plant, reduce its vigor, and inhibit its ability to reproduce. 

Table 7 presents a generalized schedule of invasive weed control and maintenance. This schedule 

should only be used as a guide, as plant growth, including timing of flowering and seed set, are be 

greatly influenced by rainfall and temperature patterns. Management actions should be updated 

and refined in response to weather patterns, plant responses, and as new information on weed 

control/treatment is gathered. 

All management actions should be monitored as to their effectiveness. Adaptive management 

techniques should be used to update, revise, amend, and improve the VMMM management 

program. A simple flowchart of adaptive management during Years 1-5 is presented below: 

Distribution of 

invasive weeds 

Implement high priority treatments 

Implement high priority pilot projects 

Modify treatments to 

increase effectiveness 

Monitor effectiveness of treatments; 

document distribution of invasive weeds 

Modify treatments to 

increase effectiveness 



Table 7. Invasive Weed Treatment – Yearly Implementation Schedule, Watsonville Wetlands Trail System Project Area 

Task Jan Feb Mar Apr May Jun July Aug Sept Oct Nov Dec 

Yearly Tasks 

Monitor plant growth and progress of flowering stalks on invasive 

weed species. Monitor project area for new infestations and any 

change in previously mapped occurrences. Update GIS data as needed. 

Prior to the spring flowering season conduct first-season mowing 

and/or weed whipping of a 1-foot wide trail edge to control plant 

growth. In summer, re-mow/weed-whip trail edges to reduce fire 

hazard and maintain trail edge. Mow/weed-whip to

Table 7. Invasive Weed Treatment – Yearly Implementation Schedule, Watsonville Wetlands Trail System Project Area (continued) 


Establish solarization plots within Kikuyu grass area; maintain 10mm 

black plastic over plot for minimum of 1 year. Periodically monitor site 

and repair fabric/plastic as needed. After treatment revegetate treated 

area with native perennial grass species. 

Establish solarization plots within Harding/canary grass areas; 10mm 

black plastic over plot for minimum of 1.5 years. Periodically monitor 

site and repair fabric/plastic as needed. After treatment revegetate 

treated area with native perennial grass species. 

Prior to flowering, mow and/or weed-whip selected high priority areas 

of poison hemlock. Conduct 3-4 more mowings/whippings into 

summer and fall. Repeat for 3-5 years. 

Establish pilot plot for alternative treatment for poison hemlock, test 

solarization for 1-2 years; test flaming 4 times per year similar to 

mowing. 

Establish pilot plot for passive revegetation areas; remove radish, 

poison hemlock and Harding grass in selected areas over 5-year period, 

allowing natural revegetation of coyote brush and rose thickets. 

Moderate Priority Treatment Areas (Years 5-10) 

Hand-pull or hoe patches of English/Algerian ivy. Remove acacias; 

treat cut stumps with herbicide to reduce suckering. 

Prior to flowering of these species, hand-pull or hoe all patches of wild 

mustard, wild radish, Italian thistle, and bull thistle. 

Continue solarization plots within Harding/canary grass patch; 

maintain 10mm black plastic over plot for minimum of 1 year. 

Periodically monitor site and repair fabric/plastic as needed. After 

treatment revegetate treated area with native perennial grass species. 

Prior to flowering, mow and/or weed-whip selected patches of poison 

hemlock. Conduct 3-4 more mowings/whippings into summer and fall. 

Repeat for 3-5 years. 



Table 7. Invasive Weed Treatment – Yearly Implementation Schedule, Watsonville Wetlands Trail System Project Area (continued) 


Continue to establish pilot plots for alternative treatment for poison 

hemlock and Harding grass, test solarization for 1-2 years; test flaming 

at 4 times per year; test goat grazing along Struve Slough, downstream 

of Main Street. 

Low Priority Treatment Areas (After Year 10) 

Remove all acacias. Remove eucalyptus trees (

This page left intentionally blank. 



CHAPTER 4.0 

RIPARIAN AND WETLAND MITIGATION/RESTORATION AREA MAINTENANCE 

4.1 RIPARIAN AND WETLAND MITIGATION AND RESTORATION SITES 

Currently there are four riparian and wetland mitigation/restoration sites within the VMMM 

project area. These sites were selected to provide mitigation for City of Watsonville projects, 

pursuant to the project environmental review and regulatory agency permits. 

The mitigation/restoration sites are: 

1) Upper Struve Slough, north of Main Street; site provides wetland and riparian 

mitigation for the Watsonville Wetlands Trail Project. Plantings installed in fall 2003 

(Table 8). 

2) Upper Watsonville Slough, upstream and downstream of Harkins Slough Road 

(Ramsey Park area); site provides wetland and riparian mitigation for the Harkins 

Slough Road Bridge at Watsonville Slough Project. Plantings installed in fall/winter 

2005 and fall/winter 2006 (Table 9). 

3) Middle Watsonville Slough, downstream of Kearney Road (Manabe site, Phase 1A); 

site provides wetland and riparian mitigation for the Manabe wetland enhancement 

project. Plantings installed in fall/winter 2006 (Table 10). 

4) Lower Struve Slough, downstream of Main Street; site provides wetland mitigation 

for the Harkins Slough Road Bridge at Struve Slough Project. Plantings installed in 

fall/winter 2006 (Table 11). 

Tables 8, 9, 10, and 11 identify the plantings that were installed at each of these sites. The 

planting plans for these areas are presented in Appendix D. 

Table 8. Upper Struve Slough Mitigation Plantings 

Common Name Scientific Name Number 

Size 

Installed 

(2003) 

Western Sycamore Platanus racemosa 8 Tree pot 

California Buckeye Aesculus californica 14 Tree pot 

Box Elder Acer negundo 14 Dee pot 

Big Leaf Maple Acer macrophyllum 24 Tree pot 

Willow Salix sp. 450 Dormant Pole Cutting 

Coast Live Oak Quercus agrifolia 7 Tree pot 

Toyon Heteromeles arbutifolia 29 Dee pot 

Sticky Monkey Flower Mimulus aurantiacus 5 1 gallon 

California Rose Rosa californica 33 Dee pot 

Snowberry Symphoricarpos rivularis 16 Dee pot 


Coyote Brush Baccharis pilularis 12 Dee pot 

California Wax Myrtle Myrica californica 30 Dee pot 

Hairy Honeysuckle Lonicera hispidula 25 Dee pot 

Wild Lilac Ceanothus thrysiflorus 21 Dee pot 

Coffee Berry Rhamnus californica 6 Dee pot 

Spreading Rush Juncus patens 200 2-inch pot 

Cattail Typha latifolia 224 Salvage transplants 

Bulrush Scirpus sp. 224 Salvage transplants 



Table 9. Upper Watsonville Slough Mitigation Plantings 


Size 

Installed 

(2005) 

Arroyo Willow Salix lasiolepis 590 Pole Cutting 

Red Willow Salix laevigata 590 Pole Cutting 

Meadow Barley Hordeum branchyantherum 23 lbs. Seed 

California Brome Bromus carinatus 23 lbs. Seed 

Box Elder Acer negundo 7 Tree pot 

Western Sycamore Platanus racemosa 8 Tree pot 

Blue Elderberry Sambucus mexicana 7 Dee pot 


Flowering Currant Ribes californicum 28 Dee pot 

Meadow Barley Hordeum branchyantherum 1.5 lbs. Seed 

California Brome Bromus carinatus 1.5 lbs. Seed 

Common Rush Juncus effusus 559 Tree band 

Santa Barbara Sedge Carex barbarae 559 Tree band 

Burreed Sparangium erectum 559 Tree band 

Spikerush Eleocharis macrostachya 559 Tree band 



Meadow Barley Hordeum branchyantherum 2.5 lbs. Seed 

California Brome Bromus carinatus 2.5 lbs. Seed 

Table 10. Middle Watsonville Slough Restoration Plantings 


Size 

Installed 

(2006) 

Arroyo Willow 

Salix lasiolepis 

255 Dormant Pole Cutting 

Red Willow 

Salix laevigata 

Black Cottonwood Populus balsamifera 

57 Dormant Pole Cutting 

trichocarpa 

Common Rush Juncus effusus 413 4” Transplant 

Burreed Sparangium erectum 413 4” Transplant 

Blue Wildrye Elymus glaucus 8 lbs./acre Seed 

California Fescue Festuca rubra 5 lbs./acre Seed 

California Brome Bromus carinatus 10 lbs./acre Seed 

Purple Needlegrass Nassella pulchra 5 lbs./acre Seed 

Yarrow Achillea millefolium 1 lb./acre Seed 

Farewell to Spring Clarkia amoena 2 lb./acre Seed 

Tidy Tips Layia platyglossa 6 lb./acre Seed 

Meadow Barley Hordeum branchyantherum 20 lbs./acre Seed 

California Brome Bromus carinatus 10 lbs./acre Seed 

Table 11. Lower Struve Slough Mitigation Plantings 


Size 

Installed 

(2006) 

Arroyo Willow Salix lasiolepis 23 Pole cutting 

Red Willow Salix laevigata 23 Pole cutting 

Blue Elderberry Sambucus mexicana 16 6” pot 

Coyote Brush Baccharis pilularis 10 6” pot 



Table 11. Lower Struve Slough Mitigation Plantings (continued) 

Pink-flowering currant Ribes sanguineum var. 

16 2.5” pot 

glutinosum 

California Blackberry Rubus ursinus 16 2.5” pot 

Nut Sedge Cyperus eragrostis 66 1.5” pot 

4.2 MAINTENANCE ACTIVITIES 

Maintenance actions are required at each of the mitigation/restoration sites to ensure the plantings 

are successful in placing/providing wetland and riparian habitat. As of December 2006, the Upper 

Watsonville Slough plantings have met their Year 1 plant survival requirements. No other plant 

survival data is currently available for the other sites; however, cursory field observations of the 

Upper Struve Slough plantings (installed in 2003) indicate that remedial maintenance is necessary 

(i.e., weeding, repair of browse protection cages, possible replanting). 

4.2.1 Weeding Within Planting Basins and Surrounding Areas 

All planting basins within the mitigation areas are to weeded during the 5-year establishment 

period (i.e., for five years after planting). All herbaceous plants should be removed from the 

basins. Weeds should be removed by hand pulling the entire plant, including the roots that are 

subject to re-rooting. For areas outside the planting basins, infestations of non-native plants 

should be reduced and controlled, throughout the 5-year establishment period, to reduce weed 

cover and competition with the newly created riparian woodland plantings. Weeds between the 

planting basins should be controlled through hand removal/cutting or mechanical weed whipping. 

The use of herbicides is prohibited. Weeds occurring between the planting basins should be less 

than 24 inches high at all times. 

4.2.2 Application and Maintenance of Mulch Around Plantings 

During Years 1-3 following planting, the planting basins for all container stock should be 

maintained with a 3-inch layer of mulch. Mulch should be free of disease, invasive weeds and 

seeds. 

4.2.4 Watering and Maintenance of Watering Basins 

The Upper Struve Slough plantings are serviced by a drip irrigation system. Hand watering is 

currently being used to irrigate the Upper Watsonville Slough plantings. 

If hand watering is used, a bucket watering system can be effective. Buckets, with specially sized 

drip holes, can be used to allow a slow, deep watering session. Depending upon the bucket size (2 

or 5-gallon) and size of the drip holes, watering times can range from six to 20 minutes. Using 

multiple buckets, a system of filling buckets, allowing them to drip, and then rotating them at set 

intervals, watering numerous plantings can be done quickly and efficiently. Details on the water 

system are presented in Appendix E. 

Where plants have basins and are to be hand-watered, the basins should be routinely inspected by 

maintenance staff and repaired expeditiously, so that hand watering is directed to plant roots and 

does not contribute to erosion. In late fall, at the onset of the rainy season, the lip of the basin 

should be opened as necessary to release excessive rain water from the basin. In the spring, plant 

basins should be rebuilt for plant species requiring continued irrigation. 



4.2.5 Remedial Planting 

The density of plant species in the wetland and riparian areas were formulated to allow for 

expected mortality rates so that supplemental planting can be kept to a minimum. Even with over 

planting, some sites may require supplemental planting, due to unforeseen events or factors, such 

as vandalism. Remedial planting needs should be assessed during the annual monitoring. 

Typically, remedial planting should occur if plant survival rates are less than 80%. The number 

of replacement plants, the species, and the propagule or container size should be determined by 

the monitor and stated in the annual monitoring reports. Substitute species may be used, if the 

original species consistently performs poorly and suitable alternative species perform well. 

However, substitute species should be consistent with the goals and objectives and be compatible 

with the criteria for success. The City is responsible for contracting with a native plant nursery (or 

similar facility) for the production of the required plants. 

Supplemental plant installation should occur in the fall, after the annual site monitoring. This 

schedule may be amended, if the necessary plants are not available, are low in quality, or 

conditions are deemed unsuitable for replanting. It is desirable to replant as soon as possible to 

minimize the extension of the establishment period maintenance. 

4.2.6 Plant Installation Techniques 

Once replacement plantings are available, they should be installed in the same manner as the 

original planting. However, the dead plant material from the original planting must first be 

removed. By the time the new plants are ready to install, the dead plant material may have 

decomposed. Each reused planting hole should be re-excavated to the specified dimensions and 

prepared to receive the replacement plant. If necessary, a root protector can be installed in the 

planting hole. The replacement plant should be carefully removed from its container to avoid any 

root damage and then should be placed in the planting hole. The planting hole is then back filled 

with the original soil and a water basin of appropriate dimension constructed. If used, a foliage 

protector can be fitted over the replacement plant. The final step is to apply a three-inch layer of 

clean mulch. 

4.2.7 Restriction of Pesticides in Aquatic Areas 

No pesticides (e.g., insecticides, herbicides or rodenticides) are to be used within or immediately 

adjacent to aquatic and wetland areas. Only chemicals approved by the Environmental Protection 

Agency (EPA) for use in aquatic environments may be used within 50 feet of the wetlands. 

The application of pesticides shall be directly supervised by a person with a Qualified 

Applicators Certificate (QAC) from the State of California Department of Pesticide Regulation. 

This person should have sufficient experience in wetlands and riparian habitat. 

4.2.8 Annual Report Required by CDFG and USACE 

Under the requirements of the City’s permits with regulatory agencies (i.e., USACE and CDFG), 

the status of City’s compliance with these permits/agreements should be reported in a yearly 

monitoring report (for a period of 5 years after planting). The yearly reports are to be submitted to 

the USACE and CDFG by December 31 of each monitoring year. 



Each year’s annual monitoring report shall contain a brief description of the project, methods 

used to collect and analyze the data, results on plant survival, conclusions regarding the present 

conditions of the site and remedial actions to be implemented. Table 12 displays the reporting 

requirements for each of the mitigation sites. 

Table 12. Reporting Requirements for Riparian and Wetland Mitigation Sites, Watsonville 

Wetlands Trail Project Area 

Mitigation Site CDFG Requirements USACE Requirements 

Upper Struve Slough Annual Report, due December 31 

each year 

80% plant survival for 5 years 

None 

(through 2008) 

Upper Watsonville Slough Annual Report, due December 31 

each year 



Middle Watsonville Slough 

(Phase 1A) 

Annual Report, due December 31 

each year 



Lower Struve Slough Annual Report, due December 31 

each year 



Annual Report, due 

December 31 each year 

80% plant survival for 5 

years (through 2011) 














APPENDIX A 

Invasive Weeds within the VMMM Project Area 






WILD MUSTARD 

Brassica ssp. 

DISTINCTIVE FEATURES Wild mustards grow as annual or biennial 

herbs. The lower leaves are deeply lobed; the upper leaves are 

toothed, often on short stalks. Plants typically grow 1- 3 feet tall. 

BLOOMS Yellow, in terminal clusters; flowers are 4-petaled, 

February - May. 

PREFERRED HABITAT Bare ground, road/trail edges and previously 

disturbed areas. Spreads rapidly from seed. 

ITALIAN THISTLE 

C. pycnocephalus 

SLENDER-FLOWERED THISTLE 

C. tenuiflorus 

DISTINCTIVE FEATURES These thistles have winged stems, are 

very spiny, and have many-branched stems. They grow as annual or 

biennial herbs from a basal rosette of spiny leaves. The leaves are 

deeply lobed; the undersides are slightly to very woolly. Plants typically 

grow 1- 4 feet tall (Italian thistles can reach 6.5 feet). Rosette is 

evident in fall and spring, distinguished by thorny patch with leaves 

that have a white midrib (center rib). 

BLOOMS Pink to purple in cylindrical heads, with either single or 

multiple flowers, May - August. 


disturbed areas. Often spreads rapidly and forms dense stands 

by chemically inhibiting the growth of other plants (allelopathy).

ICEPLANT 

Carpobrotus edulis 

DISTINCTIVE FEATURES This perennial herb grows from 

spreading stems, which easily root along the soil surface. The leaves 

are short and fleshy. Plants typically grow as dense patches, approximately 

1 foot in height. Known to hybridize with its close relative, sea 

fig (C. chilensis). 

BLOOMS Yellow to light pink; large 2-6 inch flowers, peak flowering 

season May - October. 

PREFERRED HABITAT Bare ground, road edges and previously 

disturbed areas. Often spreads rapidly and forms dense stands. 

YELLOW STAR THISTLE 

Centaurea solstitialis 

DESCRIPTION This two annual or short-lived perennial thistle is 

characterized by the sharp spines on the single flower head and tips of 

leaves. Leaves are grayish-green, divided into deep lobes. Young 

plants form distinctive basal rosettes in winter, sending up flowering 

stems in late spring or early summer. Plant height ranges from 6” to 4 

feet. 

BLOOMS Yellow (0.5-0.8 in.), June - September. 

PREFERRED HABITAT Dry grasslands, most widely distributed in 

the Sacramento and northern San Joaquin valleys and Sierra Nevada 

foothills. It is most problematic in moderately warm, exposed areas on 

drier soils and disturbed sites such as roadsides and pastures.

BULL THISTLE 

Cirsium vulgare 

DISTINCTIVE FEATURES This thistle grows as a biennial herb. 

The species has erect, highly branched, stems, arising from a basal rosette. 

The leaves are alternate and deeply lobed, with a rough, sandpaper-like 

texture and attach to the stem in awing-like pattern. The leaf 

tips have spines. The flower heads are 1-2” wide and 1-1.5” tall. 

Plants typically grow to 2-6 feet tall. 

BLOOMS Purple-pink, July - October. 

PREFERRED HABITAT Bull thistle is common in coastal grasslands 

and edges of mesic areas elsewhere in the state. Forms infestations 

in disturbed pastures, cleared areas and along roads and ditches. 

It spreads by seed, forming a rosette in year 1, with flowering and 

seed set in the 2 nd year. 

POISON HEMLOCK 

Conium maculatum 

DISTINCTIVE FEATURES This member of the carrot family typically 

grows as a biennial herb from a deep taproot. The species has 

finely divided leaves arising from an erect, yet hollow, ribbed stem. 

The stem has characteristic purple spots. The small flowers form a terminal 

flat-topped cluster on stalks that reach above the leaves. Plants 

range between 2-10 feet tall. 

BLOOMS White, April - July. 

PREFERRED HABITAT Poison hemlock occurs throughout California 

below 5,000 feet elevation. It is commonly found in meadows, 

along roadsides and riparian area, where there is moist soil during 

most of the growing season. Poison hemlock spreads by seed and can 

spread quickly in open areas. The plant is toxic to livestock, wildlife 

and humans. The plant forms flowering stalks in spring it is 2 nd year, 

with seed set by early summer. Seeds can be dispersed for several 

months and are viable for up to 5 years.

PAMPAS GRASS 

Cortederia selloana 

JUBATA GRASS 

Cortederia jubata 

DESCRIPTION A perennial grass, characterized by the tall flower 

plumes (6-12 feet tall) and dense clumps of linear leaves. Leaf blades 

have sharp edges. Tough, fibrous root system. Individual plants can 

live up to 15 years. 

BLOOMS Jubata grass has pinkish plumes. July-September; pampas 

grass plumes are white, May - June. 

PREFERRED HABITAT Widespread in coastal areas (C. jubata) 

and interior valleys, expanding in range, escaping from cultivation. 

Prefers previously disturbed areas, recently seeded areas, eroded 

slopes, and road cuts. Spreads by seed. 

CAPE IVY 

Delaireia odorata 

DISTINCTIVE FEATURES This is a perennial vine, distinguished 

by its 5-6 pointed leaves and its aggressive growth in/over riparian 

trees. The belowground stems are purple. The vine produces clusters 

of small composite flowers. 

BLOOMS Yellow, December - February. 

PREFERRED HABITAT Forms spreading patches in coastal forests 

of California, typically below 660 feet elevation. Prefers shady, disturbed 

sites with year-round moisture, such as riparian woodlands and 

moist oak woodlands. Native to the moist mountain forests of South 

Africa.

FENNEL 

Foeniculum vulgare 

DISTINCTIVE FEATURES This perennial herb plant is distinguishable 

by its strong anise scent and finely dissected, feathery 

leaves. Stems arise from a thick, deep taproot and support branches of 

the feathery leaves. The flower groups form large, rounded umbrellashaped 

clusters atop tall stems. The seeds are oblong and ribbed and 

resemble anise. Plants grow 4-10 feet tall. 

BLOOMS Yellow, April - July. 

PREFERRED HABITAT Fennel is most common in moist areas 

along the coast, typically below 2,000 feet. It also grows in the Central 

Valley as scattered occurrences in fields and along drainage channels. 

It can tolerate a wide range of soil conditions, yet most commonly 

forms dense stands on high clay soils. Fennel reproduces from 

both root crown growth and seed. Seeds form on plants 1.5-2 years 

old. 

ENGLISH IVY 

Hedera helix 

ALGERIAN IVY 

H. canariensis 

DISTINCTIVE FEATURES These aggressive perennial vines are 

evergreen, becoming woody as it ages. English ivy leaves are 3-5 

lobed, leathery and are alternately arranged along the stem. Algerian 

ivy leaves are generally 3-lobed. Young shoots and leaves often have 

hairs. The vine produces inconspicuous white flowers, followed by 

dark blue to black fruit. Some forms have variegated leaves. 

BLOOMS White, December - February. 

PREFERRED HABITAT Forms spreading patches in coastal forests 

of California. Prefers shady, disturbed sites with year-round moisture, 

such as riparian woodlands, moist oak woodlands, and redwood forests. 

English ivy is native to England, Ireland and northern Europe; it 

is very frost-hardy. Algerian ivy is native to Tunisia and Algeria and 

can be frost-damaged. 

English ivy 

Algerian ivy

BERMUDA BUTTERCUP 

Oxalis pes-caprae 

DISTINCTIVE FEATURES This herbaceous plant grows from underground 

bulbs and bulblets. Its clover-like leaves and funnel-shaped 

yellow flowers are characteristic. 

BLOOMS Yellow, November - March. 

PREFERRED HABITAT Forms spreading patches in winter-rainfall 

areas. Prefers light-textured soils and sun-to-part-shade. Bermuda buttercup 

is native to South Africa. 

KIKUYU GRASS 

Pennisetum clandestinum 

DISTINCTIVE FEATURES This is a perennial turf grass, distinguished 

by its extensive stolen and rhizome system and bright green 

leaf color. Flowering stems support leaves that are often covered with 

short hairs. The stolens are often flattened with swollen nodes. Plants 

often found in dense mats, 6-12 inches high. 

BLOOMS Bristly-spikelets, April - October. 

PREFERRED HABITAT Forms spreading patches in sunny areas 

with warm weather, primarily in disturbed areas, fields and along 

roadsides below 350 feet. Can also grow along ditches and streambeds.

HARDING GRASS 

Phalaris aquatica 

REED CANARY GRASS 

P. arundinaceae 

DISTINCTIVE FEATURES These two perennial grasses are distinguished 

by their gray-blue leaves and dense, spike-like flowering 

heads. The plant grows from deep, spreading rhizomes, forming a 

dense, waist-high thicket. 

BLOOMS Grass heads, March - September. 

PREFERRED HABITAT Forms spreading patches in wet soil conditions. 

Spreads by seed and underground stems. Native to the Mediterranean 

region, it is widespread in California since it is used for forage 

and withstands heavy grazing. 

BRISTLY OX-TONGUE 

Picris echioides 

DISTINCTIVE FEATURES This plant grows as a biennial herb, 1-3 

feet tall. The species has erect branched stems, arising from a basal 

rosette. The leaves are bristly, with a rough, sandpaper-like texture 

and clasp the. The flower heads are 1” wide in terminal heads. 

BLOOMS Yellow, April - December. 

PREFERRED HABITAT Bristly ox-tongue is common in coastal 

grasslands and previously disturbed areas, where it can forms dense 

infestations. It spreads by seed, forming a rosette in year 1, with flowering 

and seed set in the 2 nd year. Native to the Mediterranean region.

WILD RADISH 

Raphanus sativa 

DISTINCTIVE FEATURES Wild radish grows as an annual herb. 

The lower leaves are deeply lobed; the upper leaves are toothed, often 

on short stalks. Plants typically grow 2-5 feet tall. 

BLOOMS White to pink, in terminal clusters; flowers are 4-petaled, 

February - June. 


disturbed areas. Spreads rapidly from seed. Native to Europe. 

HIMALAYA BERRY 

Rubus discolor 

DISTINCTIVE FEATURES Himalaya berry is a fast-growing perennial 

vine, often forming dense thickets or mounds. The leaves are 

5-parted, which hooked prickles on the leaf stems. Flowers form at the 

end of the branches, black berries form when ripe. 

BLOOMS White, 5-petaled, April - June. 


disturbed areas, especially riparian areas. Spreads rapidly from 

seed and rooting cane tips. Native to Western Europe.

CURLY DOCK 

Rumex crispus 

DISTINCTIVE FEATURES This dock is a perennial herb that 

grows from a large taproot. The species has erect stems, often unbranched 

and tinged with red. The leaves are mostly basal with curly 

or wavy margins, 4-12 inches long. The flowers are small and form in 

clusters on tall stalks. The conspicuous brown seeds have smooth 

wings. Plants typically grow to 2-5 feet tall. 

BLOOMS Green, April - August. 

PREFERRED HABITAT Curly dock is common in seasonally wet 

areas. They often colonize previously disturbed areas. It spreads by 

seed. Curly dock is native to Europe. 

ACACIA 

Acacia spp. 

DISTINCTIVE FEATURES An evergreen tree with many species. 

Acacias within the project area are characterized by their gray, finely 

divided leaves (green wattle, A. decurrens). A. longifolia has simple 

green leaves. Both species have bright yellow flower clusters that are 

evident in the winter months. Brown-black seedpods are evident beneath 

the trees in summer. 

BLOOMS Yellow, February - March. 

PREFERRED HABITAT Previously disturbed areas, tolerating a 

wide range of soil moisture conditions. Plants native to Australia.

EUCALYPTUS 

Eucalyptus spp. 

DISTINCTIVE FEATURES An evergreen tree with many species. 

The eucalyptus trees within the project area are characterized by their 

sickle-shaped gray leaves and peeling bark. Flower clusters are evident 

in the winter months. Seeds are evident beneath the trees in summer. 

BLOOMS White, December - May. 

PREFERRED HABITAT Previously disturbed areas, tolerating a 

wide range of soil moisture conditions. Plants native to Australia. 

FRENCH BROOM 

Genista monspessulana 

DISTINCTIVE FEATURES A perennial shrub (6-10 ft.). Stem 5- 

angled in Scotch broom and round in French broom; leaves with 3 

leaflets. Bright yellow pea flowers, forming dark brown or black 

pods. 

BLOOMS Yellow, March - June. 

PREFERRED HABITAT Previously disturbed areas, recently 

seeded areas, eroded slopes, riverbanks and road cuts. French broom 

is limited to the Coast Range.

APPENDIX B 

Native Plants within the VMMM Project Area 


Draft July 27, 2007



Draft July 27, 2007

CALIFORNIA BUCKEYE 

Aesculus californica 

DISTINCTIVE FEATURES This deciduous tree is known for its 

palmate, 5-parted leaves. Flowers form on long spikes, which are followed 

by large brown chestnut-like fruits. Trees can range from 15 to 

40 feet in height. 

BLOOMS White, in large spikes, April - June. 

PREFERRED HABITAT Planted along Struve Slough, upstream of 

Main Street. Prefers summer dry soil conditions. 

BIG LEAF MAPLE 

Acer macrophyllum 

DISTINCTIVE FEATURES This is a deciduous trees, characterized 

by its large (8-14 inches wide) bright green 3-5 lobed, palmate leaves. 

The leaves turn bright yellow or orange in the fall. Drooping clusters 

of yellow-green flowers ripen into double-winged fruits (samaras). 

Mature trees can reach 80 feet tall. 

BLOOMS Yellow-green in clusters, March - May. 

PREFERRED HABITAT Along creeks; planted along upper Struve 

Slough.

BOX ELDER 

Acer negundo 

DISTINCTIVE FEATURES This is a common deciduous tree along 

creeks and sloughs. The tree supports opposite compound leaves that 

hang from slender petioles (stems). Each leaf is pale green 2-4 inches 

long, and has three leaflets, each lobed with toothed margins. Winged 

seeds (samaras) form in late summer. Trees can reach 50 to 70 feet 

tall. 

BLOOMS Small, white, in drooping clusters, March - April. 

PREFERRED HABITAT along streams and edges of sloughs; also 

planted as large garden trees. Box elder trees were planted along upper 

Struve Slough. 

WESTERN SYCAMORE 

Platanus racemosa 

DESCRIPTION The statuesque tree is characterized by the white 

and gray jigsaw-like pattern to its bark and the multiple, twisting 

branches. The deciduous leaves are 5-10 inches wide, light green, 

deeply lobed, and when young have a velvety texture. Small clusters 

of flowers hang from the stems in spring, ripening into round, spiny 

fruits. Mature trees can reach up to 100 feet tall. 

BLOOMS Whitish in small clusters, March - April. 

PREFERRED HABITAT Upper edges of creeks and rivers where 

they are subject to infrequent flooding. Sycamores have been planted 

along upper Struve Slough.

BLACK COTTONWOOD 

Populus balsamifera ssp. trichocarpa . 

DISTINCTIVE FEATURES This deciduous tree forms a broad 

crown of spreading branches. The leaves are almost triangular in 

shape, 2-4 inches long, glossy green above and whitish beneath. The 

tree bark form furrows when mature, yet the branches are often whitish. 

The trees tremble in the wind, as they are related to quaking aspen. 

Small flowers yield tufts of cottony seeds that can be seen hanging 

from the branches in summer. Trees can range from 40 to 100 feet 

tall. 

BLOOMS Small whitish in clusters, February - April . 

PREFERRED HABITAT Black cottonwood is common along 

coastal streams; it grows along upper Watsonville Slough and is colonizing 

the wetland restoration sites. 

WILLOW 

Salix ssp. 

DISTINCTIVE FEATURES Several species of willow grow within 

in the Watsonville Slough system. All trees are deciduous, growing 20 

to 45 feet in height. The leaves tend to be linear-shaped, 3-6 inches 

long, some with pointed leaves (yellow willow), others more rounded 

(arroyo willow). These fast-growing trees have hanging catkins which 

produce tiny seeds surrounded by cottony fluff. 

BLOOMS Yellowish-white, in hanging catkins February - April. 

PREFERRED HABITAT Wet areas along creeks, rivers, and along 

the edge of all sloughs in the Watsonville area; the most common tree 

species in the trail system area.

BLUE ELDERBERRY 

Sambucus mexicana 

DESCRIPTION This large shrub-small tree is distinguished by its 

pattern of compound leaves. The leaves, comprised of 6-8 leaflets 

with a final leaflet at the end, grow opposite each other along the 

stem. In spring, clusters of fragrant pale yellow flowers form, followed 

by blue-gray berries. Blue elderberries can reach 10 to 20 feet 

tall. 

BLOOMS Pale yellow in dense clusters. March - June. 

PREFERRED HABITAT Widespread within coastal range and foothills; 

planted along upper Struve Slough. 

COAST LIVE OAK 

Quercus agrifolia 

DISTINCTIVE FEATURES This common tree is evergreen. Its 

leaves are dark green and leathery, often sharply toothed and cupshaped. 

The leaves range from 1-3 inches long and are usually a paler 

green on the underside surface. Small flower clusters form in the 

spring, forming the characteristic oak acorn in fall. 

BLOOMS Whitish, in handing clusters, February - April. 

PREFERRED HABITAT Dry slopes abutting creeks and sloughs 

within the VMMM project area. Several oak species are native to 

California.

MUGWORT 

Artemisia douglasiana 

DISTINCTIVE FEATURES This perennial herb is distinguishable 

by its soft, lobed gray leaves. The leaves are aromatic and the undersides 

are whitish, with soft hairs. A member of the sunflower family, 

mugwort produces clusters of small, whitish flowers, which forms 

brown seed heads in late summer. Plants grow 3 to 5 feet tall. 

BLOOMS Whitish, June - October. 

PREFERRED HABITAT Mugwort is common in many communities, 

including coast scrub and riparian woodlands. Within the 

VMMM project area, mugwort is often found intermixing with coyote 

brush and berry thickets. 

COYOTE BRUSH 

Baccharis pilularis 

DISTINCTIVE FEATURES This evergreen shrub is common 

within the VMMM project area. The small leaves are wedge-shaped 

with small toothed edges and three noticeable veins. The species has 

both male and female plants; the female plant produces white tufts of 

seeds in spring and summer, which release in the wind. 

BLOOMS White, August - December . 

PREFERRED HABITAT Coyote brush can tolerates many soil conditions, 

yet does best on dry, well-drained soils. The shrub forms 

dense patches which can successfully compete with herbaceous weed 

species. Coyote brush seeds are used many riparian and upland bird 

species.

CALIFORNIA ROSE 

Rosa californica 

DISTINCTIVE FEATURES This deciduous shrub is characterized 

by its curved prickles and small, pink rose flower. This native rose has 

leaves composed of 5-7 leaflets, each with hairy undersides. The pink 

blossoms are about 1-inch wide and mildly fragrant. In fall, red urnshaped 

seed capsules (rose hips) are formed. 

BLOOMS Pink, April - September. 

PREFERRED HABITAT Forms spreading thickets in well-drained 

soils. The plant can form dense thickets which can successfully compete 

with herbaceous weed species. Rose hips are used many riparian 

and upland bird species. 

COFFEE BERRY 

Rhamnus californica 

DISTINCTIVE FEATURES Coffee berry is an evergreen shrub 

known for its clusters of red-purple berries. Growing 4-6 foot high, 

the plant’s leaves are light green, leathery and simply shaped. Clusters 

of greenish flowers form in late spring, ripening to black berries by 

fall. 

BLOOMS Greenish, May - July. 

PREFERRED HABITAT Grows as a hardy shrub in dry areas, often 

intermixing with coyote brush.

CALIFORNIA BLACKBERRY 

Rubus ursinus 

DISTINCTIVE FEATURES This evergreen vine is identified by its 

sprawling habit, prickly stems and its leaves, each divided into three 

leaflets. Blackberry forms white, rose-like flowers, each turning into a 

black berry in late summer. The plant can spread by rooting stem 

nodes, forming dense thickets. 

BLOOMS White, March - August. 

PREFERRED HABITAT Prefers sunny, well-drained areas. Spreads 

by seed and rooting stems; dense thickets can compete with invasive 

weeds. Common within the VMMM project area, often intermixing 

with the non-native Himalaya berry. 

CALIFORNIA ASTER 

Aster chilensis 

DISTINCTIVE FEATURES This small shrub is in the sunflower 

family. It is characterized by its clusters of small, violet to purple 

daisy-like flowers. The leaves are linear, 1-2 inches long, and attach 

closely to the stem. The shrub grows 1 to 3 feet tall and can form 

dense thickets. The flower heads are 1” wide in terminal heads. 

BLOOMS Violet - purple, January - December. 

PREFERRED HABITAT California aster prefers dry banks along 

creeks and sloughs. Within the VMMM project area a dense thicket 

grows along Watsonville Slough.

BUR-REED 

Sparangium erectum 

DISTINCTIVE FEATURES Bur-reed is in the cat-tail family; it is 

characterized by its linear strap-like leaves and round, sphere-like 

flower heads. Brown seed heads form in early fall. Bur-reed can grow 

between 5 and 7 feet tall, with its roots submerged within slough mud. 

BLOOMS White, in round clusters, April - August. 

PREFERRED HABITAT Edges of creeks and along sloughs, tolerating 

inundated clay soils and fluctuating water levels between winter 

and summer. 

CATTAIL 

Typha latifolia 

DISTINCTIVE FEATURES Cattail is a common plant growing 

along the sloughs. It has tall, strap-like linear leaves. The flowers are 

borne in tight clusters, forming a cylindrical spike; male and female 

flowers occupy separate portions of the spike. Cattails grow from vigorous 

roots, easily forming dense stands within shallow water areas. 

BLOOMS Whitish, January - June. 

PREFERRED HABITAT Edges of creeks and along sloughs, tolerating 

inundated clay soils and fluctuating water levels between winter 

and summer.

COMMON RUSH 

Juncus patens 

BOG RUSH 

Juncus effusus 

DISTINCTIVE FEATURES These two plants have narrow, rounded 

leaves, typical of all rushes. Common rush has a characteristic bluegreen 

color, while bog rush stems are bright green. Plants typically 

grow 2-3 feet tall. Small flower clusters form at the top of tall stems, 

forming brown seeds. 

BLOOMS White, in clusters, January - June. 

PREFERRED HABITAT Both species grow in wet areas, although 

common rush can also be in drier areas. Both rushes are common 

within the VMMM project area. 

BLUE WILD RYE 

Elymus glaucus 

DISTINCTIVE FEATURES Blue wild rye is a native perennial 

grass. The plant produces numerous blue-gray stems, with narrow 

clasping leaves. Densely clustered flowers grow at the ends of tall 

stems; flowering stems can reach 3 feet tall. 

BLOOMS Greenish, grass flowers, January - August. 

PREFERRED HABITAT Blue wild rye occurs on dry slopes above 

the sloughs. The species has also been planted within revegetation areas 

within the VMMM project area.

BULRUSH - CALIFORNIA TULE 

Scirpus californicus 

DISTINCTIVE FEATURES This perennial wetland plant has a tall 

stem, often reaching 8 to 12 feet in height. The stem can be round or 

triangular. Flower and seed clusters form at the ends of the stem, usually 

with 2 sharp-pointed bracts. 

BLOOMS Whitish, but inconspicuous, January – September. 

PREFERRED HABITAT Edges of sloughs and shallow ponds. 

Common along the slough edges within the VMMM project area.

APPENDIX C 

Volunteer Projects 


Draft July 27, 2007



Draft July 27, 2007

DESCRIPTION OF 

WORK 

VOLUNTEER PROJECT 

Buffer Plantings 

Installation of native shrubs in weed-treated buffer areas to 

discourage re-infestation by invasive weeds, reduce long-term 

maintenance, and fire hazard 

November - December 

SUITABLE 

SEASON 

LOCATION • On designated slopes adjacent to slough trails (H.4 treatment 

areas) 

• Upper slopes adjacent to yards within Bay Breeze, SeaView 

Ranch and Las Brisas residential developments (H.5 

treatment areas). 

SUITABLE FOR • Scout troops (middle and high school-age) 

• Homeowners association groups 

• Middle and high school classes/groups 

• Environmental groups 

MATERIALS • Planting stock (to be obtained by City), shovels, watering 

TRAINING 

buckets, gloves 

Designate planting area, provide instructions on planting 

technique, including application of mulch and construction of 

watering basin; hand watering after planting 

Plant Species Suitable for Establishing Vegetated Buffer Areas 

Common Name Scientific Name Typical Plant 

Spacing 

Typical 

Propagule Size 

Number 

of Plants 

for 400 ‘ x 

10’ strip 

23 

Dwarf Coyote Brush Baccharis pilularis pilularis 


6 1 gallon or Dee 

pot 

Hooker’s Manzanita Arctostaphylos hookeri 6 1 gallon 22 

Dwarf Wild Lilac Ceanothus griseus 

6 Dee pot 22 

horizontalis 

Coffee Berry Rhamnus californica 6 1 gallon or Dee 22 

pot 

Bee’s Bliss Sage Salvia ‘Bee’s Bliss’ 6 1 gallon or Dee 23 

pot 

Total Plants 112


WORK 


Low-Growing Trail Edge Revegetation 

Installation of native plants along weed-treated trail edge areas to 

discourage re-infestation by invasive weeds, reduce long-term 

maintenance, and fire hazard. 


SUITABLE 

SEASON 

LOCATION • On designated trail edges following eradication program (H. 

1., H.4, and H.7 treatment areas) 






TRAINING 





Plant Species Suitable for Establishing Low-Growing Trail Edge Vegetation 

Common Name Scientific Name Typical 

Plant 

Spacing 

Typical Propagule 

Size 

Number 


for 400 ‘ x 

2’ strip 

Spreading Rush Juncus patens 4 2-inch pot 10 

Common Yarrow Achillea millefolium 4 2-inch pot 10 

Wood Strawberry Fragaria vesca 4 2-inch pot 10 

Creeping Wildrye Leymus triticoides 2 2-inch pot or plugs 30 

Foothill Sedge Carex tumulicola 2 2-inch pot or plugs 30 

Blue-eyed Grass Sisyrinchium bellum 4 2-inch pot 10 

California Meadow Carex pansa 4 2-inch pot 10 

Sedge 

Creeping Sage Salvia somomensis 6 1 gallon or Dee pot 20 



WORK 


Scrub Revegetation 

Installation of native shrubs in weed-treated areas to discourage 

re-infestation by invasive weeds, reduce long-term maintenance, 

and fire hazard 


SUITABLE 

SEASON 

LOCATION • Within designated areas following eradication program (H. 

1., H.4, and H.7 treatment areas) 






TRAINING 





Plant Species Suitable for Scrub Revegetation Areas 

Common Name Scientific Name Typical Plant 

Spacing 

Typical 

Propagule 

Size 

Number 


for 400 ‘ x 

20’ strip 

Sticky Monkey Flower Mimulus aurantiacus 6 1 gallon 18 

California Rose Rosa californica 6 1 gallon or 18 

Dee pot 

Snowberry Symphoricarpos rivularis 6 Dee pot 18 

Mugwort Artemisia douglasiana 6 Dee pot 20 

Coyote Brush Baccharis pilularis 6 1 gallon or 20 

Dee pot 

California Blackberry Rubus ursinus 6 Dee pot 20 

California Aster Aster chilensis 6 Dee pot 20 

Deerweed Lotus scoparius 6 Dee pot 20 

California Sagebrush Artemisia californica 6 2-inch pot 20 

Dwarf Coyote Brush Baccharis pilularis pilularis 6 1 gallon or 20 


Dee pot 

Hooker’s Manzanita Arctostaphylos hookeri 6 1 gallon 20 



6 Dee pot 18 

horizontalis 



Remove Annual and Biennial Weeds 

DESCRIPTION OF Hand-hoe select occurrences of invasive weeds from project area 

WORK 

prior to flowering; bag flower heads if encountered 

SUITABLE Wild Radish: February – March 

SEASON 

Bristly ox-tongue: March – April 

Italian and Slender flowered thistle: April- May 

Bull thistle: May - June 

LOCATION • Within designated H.1 treatment areas) 

SUITABLE FOR • Scout troops (high school age) 


• High school classes/groups 


• Individuals 

MATERIALS • Hoes, gloves, disposal bags; plant identification sheet 

TRAINING Designate work areas, provide instructions on hoeing technique, 

and plant identification, and provide instructions on disposal of 

flower heads, if encountered.

DESCRIPTION 

OF WORK 


Remove French Broom Seedlings 

Hand-pull occurrences of French broom weeds from project area 

prior to flowering; bag seed/flower heads if encountered. 

Remove the entire plant and roots using hand pulling/wrenching 

techniques. 

February, when soil is moist 

SUITABLE 

SEASON 

LOCATION • Within designated H.1 treatment areas) 

SUITABLE FOR • Scout troops (high school-age) 


• High school classes/groups 



MATERIALS • Gloves, weed wrench, disposal bags; plant identification 

TRAINING 

sheet 

Designate work areas, provide instructions on pulling and weed 

wrench operation and plant identification, provide instructions on 

disposal of seed/flower heads, if encountered.

DESCRIPTION 

OF WORK 

SUITABLE 

SEASON 

LOCATION 

SUITABLE FOR 


Weed and Water Mitigation Plantings 

Remove herbaceous weeds from shrub and tree planting basins; 

provide summer irrigation (using buckets) to maximize plant 

survival. 

June – October, 2 times a month 

Within designated mitigation sites 

• Upper Watsonville Slough (approx. 200 plants) 

• Upper Struve Slough (approx. 206 plants) 

• Scout troops (high school-age) 




MATERIALS • Map of planting locations, watering buckets, gloves, hoe, 

weed disposal bags, mulch 

TRAINING Designate planting area and individual planting sites, provide 

instructions on weeding technique, including re-application of 

mulch and maintenance of watering basin; hand watering 

technique

APPENDIX D 

Mitigation Area Maps 


Draft July 27, 2007



Draft July 27, 2007

APPENDIX E 

Bucket Watering System 


Draft July 27, 2007



Draft July 27, 2007

Georges' Bucket Watering System 

For when an irrigation system is not practical 

All you need is some buckets and a source of water 

This system greater reduces per plant hand watering time and 

still allows a slower, deeper watering. 

Each bucket has 2 holes in it 6" apart. This is recommended to prevent blockage. 

Hole sizes and number of holes can vary. These hole sizes are given as reference points. 

The buckets were level for these references. 

Buckets of a significantly different depth will empty at a different rate. Width is not as important 

Hole sizes can be different to achieve intermediate flows or times. 

2 Gallon 5 Gallon 

Bucket 

Bucket 

(Standard white) 

Bucket size-in. 9.25"h x 8.5" dia. 13.5" x 11.4" dia 

Bucket size-cm. 23cm x 21.5 cm 34cm x 29cm 

Drill bit / Hole Approximate Approximate 

Size in inches & cm time to empty time to empty 

A 3/32 / 2mm 20 minutes 

B 7/64 /2.5mm & 1/8 /3mm 13 minutes 31 minutes 

C 1/8 / 3mm 9 minutes 24 minutes 

D Drill size 30 / 3.5mm 8 minutes 19 minutes 

E Drill size 25 / 4mm 6 minutes 14 minutes

Vegetation Management and Maintenance Plan - Watsonville ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?