SRRC - Cooperative Noxious Weed Program

Overview

The Salmon River Restoration Council has been involved in noxious weed management since the early 1990’s.  Our Community Noxious Weed Program promotes manual removal, mulching, and other non-chemical methods of invasive plant control throughout the watershed.

The program focuses on the inventory, mapping and removal of the following noxious weeds:

• Spotted knapweed
• Meadow knapweed
• Diffuse knapweed
• Marlahan mustard (dyer's woad)
• Yellow starthistle
• Italian thistle
• Scotch broom
• Puncture vine (goathead)
• White top (hoary cress)
• Teasel
• Tree of heaven

We employ local crews and community volunteers to treat invasive plant populations without using pesticides.

The success of the program relies on a strong community volunteer component and a commitment to chemical-free control.  Our community-based effort is recognized as one of the most effective watershed scale weed control programs in the country.

History of the Cooperative Noxious Weed Program

Beginnings

Recognizing the need for a coordinated, collaborative approach to noxious weed control in the Salmon River watershed, the SRRC initiated a community-supported program to eradicate weeds in 1994.

Initially the focus of the program was on Scotch broom, Spanish broom, and Marlahan mustard. In order to safeguard the health of aquatic ecosystems and work crews, no chemical herbicides were used.

Good progress was made on reducing populations of these weeds, especially Scotch and Spanish broom.

This early success reinforced the idea that federal land managers, private landowners and other stakeholders could work together to achieve watershed-level noxious weed control.

A New Invader: Spotted Knapweed

Two new noxious weeds, spotted knapweed and diffuse knapweed were first discovered on the Salmon River in 1997. Both probably arrived in the watershed during the wildfires of 1987, inadvertently brought in with fire fighting equipment and personnel.

Both knapweed species are rated as a Class A Pest by the State of California. This mandates eradication or containment of the weeds. At the Salmon River, local land managers planned the use of synthetic herbicides to control knapweed along roads and river bars.

The SRRC and local community was averse to the idea of spraying chemical herbicides around the river and tributaries. Many herbicides are toxic to aquatic life even at very low concentrations.

In response, the SRRC launched a very successful knapweed control program that completely avoided the use of chemical herbicides. Our program uses manual control methods to remove the weeds. Detailed inventory, tracking, monitoring, mapping, and coordination provide the structure needed to obtain results.

Knapweed has been significantly reduced or eliminated at over 260 sites throughout the watershed. A recent US Forest Service survey was unable to find any knapweed plants producing seed.

Other noxious weed control programs have been modeled after ours.

Roadside Weed Control

In 2000, SRRC started the “Drivers That Care” program to help control Marlahan mustard and other weeds along roads in the Salmon River. Drivers and cyclists are educated on weed identification and control techniques and are then encouraged to engage in spontaneous (and organized) acts of weed removal along our roads.

As a result, Marlahan mustard infestations have been significantly reduced along the county road between Etna Summit and Wooley Creek.

Formation of the Salmon River Cooperative Noxious Weed Program

To provide for even better coordination, the SRRC and its partners pulled together to form the Salmon River Cooperative Noxious Weed Program. A Comprehensive Management Plan was adopted to outline the goals and framework for achieving them.

The plan aims at the recovery of healthy native plant communities in the Salmon River watershed by prioritizing actions and developing prescriptions to manage the most aggressive and problematic invasive species.

Weed Spotlight: Spotted Knapweed

Largest Infestation in California

The Salmon River's spotted knapweed infestation is the largest in California by acreage. This invasive species from Europe and Asia is found throughout the Salmon River watershed, mostly along river bars and flood plains. 

The infestation is believed to have begun during the massive wildfires of 1987 when fire equipment and personnel brought to the Salmon River unknowingly spread knapweed seeds at fire camps and water tanker fill sites.

Despite the size of the infestation, SRRC has had great success in controlling spotted knapweed using manual control methods.

Managed Sites

Over 270 knapweed sites are currently being managed by the SRRC. These sites are spread out along 70 miles of river, over 300 miles of roads and trails, and in 400 acres of upslope habitat. A total of approximately 1,500 acres are surveyed and managed annually.

The status of each site is recorded at every visit and is tracked in a database.

Progress in Eradicating Knapweed: 99% Reduction!

In 1999, 200,000 knapweed plants were removed from the 49 sites that were managed at the time. In 2007, there were only 1,123 knapweed plants remaining at 271 managed sites! This represents a 99% reduction in the knapweed population, all without the use of herbicides!

Monitoring by the US Forest Service identified no knapweed plants reaching seed maturation at any of the managed sites.

Three Pass System

We use a three pass system to schedule and monitor ground work. 

1. First pass (February to May): crews visit all sites inventoried in the past year. Any visible knapweed is uprooted and left to dry in the sun. 
2. Second pass (May to July): crews search for new populations between known infestation areas on both sides of the river. The crews eliminate all visible adult and immature plants at both new and old sites.
3. Third pass (July to September): crews sweep both sides of the river from the North Fork to the confluence of the Salmon and Klamath Rivers, covering 36 miles. On average, 200 feet on each side of the river is surveyed.  The emphasis is on finding new populations and eliminating all plants to prevent seed maturation.

An extra pass takes place in October on the North Fork.

How to Control Spotted Knapweed on Your Property

1. Identify the extent of the infestation. You will need to remove all plants, regardless of size. Look hard!
2. Observe the individual plants. If there are old seed heads or flowering heads, carefully clip them directly into a bag. Be careful not to spill seeds. Safely burn the bagged seeds. 
3. Using a pointed metal tool such as a crow bar, grab the plant and dig around the crown to expose as much root as possible. Pull gently and follow the root as far as it goes--this may be several feet. The object of digging is to remove as much of the root as possible. Pull the plant and leave it exposed to the sun to dry.
4. Continue to monitor the area, looking for sprouts and new plants. Any remaining roots will resprout, often shooting off numerous new plants with a lush and large development of leaves.

Salmon River Noxious Weed Identification Guide

Spotted Knapweed (Centaurea maculosa)

Identifying Characteristics

• Habit: biennial or short lived perennial with a stout taproot
• Flower color: pinkish purple with fuzzy white center
• Flowers: July to September
• Plant height: 8 inches to 6 feet
• Stems: One or more, branching
• Basal leaves: feathery, lobed
• Bracts: tipped with dark tinged
• Similar to meadow knapweed
• CA State Pest Rating: Class A

Occurrence

From 400-4000' elevation, adaptable to a variety of habitats. Moist areas, river bars, dry roadsides, in the shade or sun.

Notes

Spotted and diffuse knapweed were first discovered by the USFS on the Salmon River in 1997, with concentrated populations in the Kelly Bar vicinity on the North Fork. Both species are rated "Class A Pests" by the State of California, which mandates eradication as described in county and state health codes. Public land managers originally promoted intensive herbicide applications to control knapweed. SRRC and the local community responded with a very effective chemical-free control program that has significantly reduced or eliminated knapweed plant concentrations at over 260 sites.

More Info

Photo Gallery

California Department of Food & Agriculture
www.cdfa.ca.gov/phpps/ipc/weedinfo/centaurea.htm

Wikipedia
en.wikipedia.org/wiki/Centaurea_maculosa

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Meadow Knapweed (Centaurea jacea x nigra)

Identifying Characteristics

• Flower color: white to purple
• Plant spreads via rhizomes (underground roots), that run 2-6" below soil level, and seed. Vigorous colonizer of disturbed road side areas where a seed bank of plants exist nearby
• Similar to spotted knapweed
• CA State Pest Rating: Class A

Occurrence

From 400-4000' elevation, adaptable to a variety of habitats. Moist areas, river bars, dry roadsides, in the shade or sun.

Notes

If meadow knapweed seeds make it to the water they can be transported throughout the watershed in one high water event. Automobiles passing along this road after seed heads form are also likely to transport this weed throughout the watershed.

More Info

Photo Gallery

California Department of Food & Agriculture
www.cdfa.ca.gov/phpps/ipc/weedinfo/centaurea.htm

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Diffuse Knapweed (Centaurea diffusa)

Identifying Characteristics

• Flower color: white to rose or sometimes purplish
• Flowers: margins of involucral bracts are divided like the teeth of a comb, and bracts are tipped with a slender spine
• Blooms: July to September
• Plant height: up to 2 feet
• Leaves: pinnately divided
• CA State Pest Rating: Class A

Occurrence

Diffuse knapweed infests roadsides and is highly competitive. It thrives in dry and compact soil conditions.

Notes

Rough to the touch. Depending on soil conditions, diffuse knapweed may have frail, thin roots and will need to be dug deeply to prevent resprouting. Low infestation on the Salmon River.

More Info

Photo Gallery

California Department of Food & Agriculture
www.cdfa.ca.gov/phpps/ipc/weedinfo/centaurea.htm

Wikipedia
en.wikipedia.org/wiki/Centaurea_diffusa

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Marlahan Mustard (Isatis tinctoria L.)

Identifying Characteristics

• Habit: erect biennial
• Flower color: bright yellow
• Blooms: April to June
• Plant height: up to 4 feet
• Stem leaves: alternate, sessile, broad to narrowly arrowhead-shaped
• Seed pods: black, 0.5 inches long
• CA State Pest Rating: Class B

Occurrence

There is a high infestation of Marlahan mustard throughout the Salmon River watershed, including wilderness areas and river bars. Often grows on dry, rocky or sandy soils.

Notes

Also known as dyer's woad. Marlahan mustard was cultivated for several centuries in Europe as a medicinal herb and, until trade routes with India were opened, it was the only source of blue dye. Evidence of its use by humans extends back to Neolithic times. Foliage contains compounds that appear to have insecticidal and fungicidal properties. The Scott Valley has a remarkable infestation of Marlahan mustard and is the likely origin of the populations found on the Salmon River.

More Info

Photo Gallery

California Department of Food & Agriculture
www.cdfa.ca.gov/phpps/ipc/weedinfo/isatis.htm

Wikipedia
en.wikipedia.org/wiki/Isatis_tinctoria

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Yellow Starthistle (Centaurea solstitialis L.)

Identifying Characteristics

• Habit: annual
• Flower color: bright yellow
• Flowers ringed with spines
• Blooms: May to August
• Plant height: up to 4 feet
• Stems: gray-green, rigid, branching
• Basal leaves: deeply lobed, sharply pointed
• CA State Pest Rating: Class C

Occurrence

There is a high infestation of starthistle throughout the Salmon River watershed, including wilderness areas. Starthistle came here through infested hay, vehicles, animals, and other vectors.

Notes

Starthistle grows quickly and is very competitive. It has a long tap root that enables it to thrive during dry, hot summers. It is versatile in its growth patterns, and can adapt to drought or low soil moisture content by producing smaller plants with fewer seeds during dry years.

The SRRC has begun to map locations of starthistle and we have removed satellite populations from roadsides and river bars. This is the beginning of our management of starthistle. After all known populations are mapped, we can then prioritize densities and control the population from the outside in.

Generally similar in appearance, Malta starthistle is found more rarely in the Salmon River watershed.

More Info

Photo Gallery

California Department of Food & Agriculture
www.cdfa.ca.gov/phpps/ipc/weedinfo/centaurea2.htm

Wikipedia
en.wikipedia.org/wiki/Centaurea_solstitialis

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Italian Thistle (Carduus pycnocephalus L.)

Identifying Characteristics

• Habit: annual
• Flower color: pink to purple
• Blooms: May to July
• Plant height: 8 inches to 6.5 feet
• Stems: winged with spines, glabrous to slightly woolly
• Basal leaves: 4-6 inches long, lobed
• CA State Pest Rating: Class C

Occurrence

It is found in disturbed areas, often with fertile soils or soils with a relatively high pH (> 6.5). The only known infestation of Italian thistle in the Salmon River watershed is in the immediate vicinity of Forks of Salmon.

Notes

SRRC has been working to eradicate the single population of Italian thistle in the watershed and the effort is showing great results.

More Info

Photo Gallery

California Department of Food & Agriculture
www.cdfa.ca.gov/phpps/ipc/weedinfo/carduus.htm

Wikipedia
en.wikipedia.org/wiki/Carduus_pycnocephalus

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Scotch Broom (Cytisus scoparius)

Identifying Characteristics

• Habit: perennial, leguminous shrub
• Flower color: golden yellow
• Blooms: late April to May
• Plant height: 2 to 7 feet
• Stems: up to 2 inches thick, tough
• Leaves: trifoliate leaves 0.1 to 0.5 inches long
• Seed pods: black, 1-2 inches long
• CA State Pest Rating: Class C

Occurrence

Here on the Salmon River, a low to medium infestation of Scotch Broom occurs on roadsides (where it was once planted for erosion control) and disturbed areas such as old house sites and campgrounds.

Notes

Scotch broom is a prodigious seed producer. Seeds can survive in the environment for up to 80 years. Seeds are transported from place to place in mud stuck to vehicles, equipment, shoes and the feet of animals. Seeds may be carried via runoff from roads into streams and gullies. Scotch broom burns vigorously when ignited, creating an extreme fire hazard.

More Info

Photo Gallery

California Department of Food & Agriculture
www.cdfa.ca.gov/phpps/ipc/weedinfo/brooms.htm

Wikipedia
en.wikipedia.org/wiki/Scotch_broom

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Puncture Vine (Tribulus terrestris)

Identifying Characteristics

• Habit: annual
• Flower color: bright yellow, solitary
• Flowers:  April to October
• Stems: highly branched, green to reddish-brown, prostrate and spreading radially from the crown on open ground to  erect when shaded or competing with other plants
• Leaves: opposite, even-pinnate compound, 1.5 to 2 inches long, with 3-7 leaflet pairs per leaf and a small extension at the tip
• Seeds: extremely sharp, can puncture bicycle tires and shoes

Occurrence

Disturbed places, roadsides, cultivated fields, yards, waste places, walk ways. Grows best on dry sandy soils, but tolerates most soil types. Intolerant of freezing temperatures.

Notes

Puncturevine has not been present in this area for very long. Now is the time to control the spread before the seed bank becomes unmanageable. Also known as "goathead".

More Info

Photo Gallery

California Department of Food & Agriculture
www.cdfa.ca.gov/phpps/ipc/weedinfo/tribulus-terrestris.htm

Wikipedia
en.wikipedia.org/wiki/Tribulus_terrestris

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White Top

Identifying Characteristics

• Habit: perennial
• Flower color: white
• Blooms: March to July
• Plant height: up to 2 feet
• Stems: erect, sparse to densely covered with short hairs
• Leaves: alternate, ovate to oblong, dull, scaly
• CA State Pest Rating: Class B

Occurrence

Often grows on moderately moist, alkaline to saline soils, but tolerates a wide range of soil types and moisture conditions. Prefers irrigated areas.

Notes

Also known as hoary cress. Native to Southwest Asia. It was likely introduced in multiple shipments of contaminated alfalfa seed from Turkestan. White top was first found in California in 1876 near Yreka.

More Info

Photo Gallery

California Department of Food & Agriculture
www.cdfa.ca.gov/phpps/ipc/weedinfo/cardaria.htm

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Teasel (Dipsacus laciniatus L.)

Identifying Characteristics

• Habit: annual
• Flower color: white
• Blooms: July to September
• Plant height: 2 to 8 feet
• Stems: erect, stout, rough-hairy, longitudinally ridged
• Leaves: opposite; basal leaves irregularly cleft
• Inflorescences: heads, dense, egg-shaped to cylindrical, 1 to 4 inches tall, 1 to 2 inches wide, terminal on long stalks

Occurrence

Disturbed areas, weedy fields, wet ditches, and roadsides.

Notes

Native to Europe.

More Info

Photo Gallery

Invasive.org
www.invasive.org/browse/subject.cfm?sub=5545

Program Coordinator

Shannon Flarity,

Salmon River Restoration Council
PO Box 1089
25631 Sawyers Bar Road (shipping only)
Sawyers Bar, CA 96027

phone: 530-462-4665 or 800-840-4665
fax: 530-462-4664