Aquatic Noxious Weeds in King County King County Noxious Weed Control Program

Agenda Overview – Definitions, Impacts, and Laws Priority Aquatic Invasive and Noxious Weeds in King County

What is an Invasive Weed?  Introduced / non-native  Ability to out-compete native plants Lack of predators or natural controls Ability to modify local ecology Aggressive ability to reproduce  Not all introduced plants are invasive but most invasive plants were brought here intentionally Fragrant water lily on Cottage Lake

Clog waterways Impede recreation Foul motors Replace native plants No wildlife value Alter water chemistry Impacts of Aquatic Weeds

How is a Noxious Weed Defined? Non-native plant that damages agriculture, wildlife, human health, land values or natural resources Defined and regulated by state law (RCW 17.10) –control required only where weed is not widespread –goal of law is to prevent spread of new invaders to un-infested areas

Noxious Weed List (WAC ) –Highest priority is where weeds are beginning to invade –List set primarily by state weed board; law enforced by county noxious weed boards –Requires property owners to prevent plants from seeding Prohibited Plants List (WAC ) –Goal is to prevent spread of new introductions –List is determined by WSDA, enforced by state Nursery Inspection Program –Prohibits sale and purchase of plants and seeds Two Lists: Growing vs. Selling Noxious Weeds

State Weed Categories Class A (39 on list; 14 found in KC) –non-native, invasive, very limited distribution –eradication required throughout state –control provides statewide benefits (sometimes even greater) Class B (51 designated in KC; 28 present) –non-native, invasive, split distribution –where limited, control required by state law –where widespread, county board decides on control –control provides regional or countywide benefits Class C (only 3 selected for control in KC, 31 on state list; most too widespread to require control) –widespread distribution, county decides on control –control provides local or site-specific benefits; more if efforts are coordinated with neighbors

Four Most Common Regulated Noxious Weeds in King County Tansy RagwortPurple Loosestrife Garden Loosestrife Giant Hogweed

Other King County Weed List Categories Non-Regulated Noxious Weeds –State-listed Class B and C weeds that are widespread in the county; control recommended but not required –For example: milfoil, knotweed Weeds of Concern –Not technically noxious weeds according to state law; considered invasive vegetation in King County; control desirable especially in natural or agricultural areas

Meet the LOOSESTRIFES and other aquatic Noxious Weeds

THE LOOSESTRIFES

Garden Loosestrife Lysimachia vulgaris Flowers: showy yellow primrose-like flowers clustered at top of stem (terminal pannicle) Flowers in July and August Leaves: opposite or whorled (in threes or fours), leaves usually have small orange or black glands visible with magnification 2-10 foot tall perennial of wetlands and shorelines Class B Noxious Weed

Produces extensive red rhizomes that will reach out up to 10 feet into the adjacent open water Stems have soft hairs and are round, occasionally flattened (fasciated)

9’ 6’6” Shade Full sun Flora of China2-4 ft University of Wisconsinto 3.3 ft Connecticut Botanical Society2-4 ft England2-4 ft Germany ft Australiato 4.9 ft Flora of Europeto 4 ft Garden Loosestrife Lysimachia vulgaris Class B Noxious Weed

Bellevue Issaquah Redmond Renton Kirkland Fall City Duvall Rutherford Slough Lake Burien Sammamish River Snohomish County King County Garden loosestrife distribution in King County Raging River 520 Lake Alice Matthews Beach Magnuson Park Union Bay Montlake Park Lk Wash. Blvd Seward Park

Garden loosestrife Impacts Ecological – displaces native plants and animals; interferes with wetland food web and habitat; clogs small streams Economic – clogs irrigation systems & water control structures; dominates wet pastures

Purple loosestrife Common cattail Himalayan blackberry Garden loosestrife Impacts Outcompetes other aggressive plants

Purple loosestrife Lythrum salicaria Class B Noxious Weed Key characteristics: perennial rhizomatous emergent with showy magenta flower spikes branched stems are square, can root at nodes leaves opposite, lanceolate up to 2.5 million tiny seeds/plant flowers July and August

Look-alikes: Purple loosestrife vs. spirea and fireweed Purple loosestrifeDouglas spireaFireweed (hardhack)

Seattle Bellevue Issaquah Redmond Renton Federal Way Duvall Green River Snohomish County King County Purple loosestrife distribution in King County Auburn Snoqualmie River Vashon Island

other common aquatic noxious weeds (and native look-alikes)

Iris pseudacorus – Yellow Flag Iris Class C non-designate Key characteristics: perennial monocot to 1.5 meters tall thick rhizomes form solid mats showy yellow flowers green seed pods with flat seeds like corn kernels that float

Nymphaea odorata Fragrant waterlily – Class C non-designate Key characteristics: floating perennial flowers white to pink on separate flexible stalks thick fleshy rhizomes round leaves

Nuphar lutea spatterdock, yellow pond lily – Native Key characteristics: very large heart-shaped leaves ball-shaped yellow flowers stems rigid enough to hold leaves out of water when water level drops

Key characteristics: 14 or more leaflet pairs leaves whorled usually red stem, branched leaves generally collapse against stem when pulled from water flower spike held above water Myriophyllum spicatum Eurasian watermilfoil – Class B non-designate

Eurasian watermilfoil – Myriophyllum spicatum vs. the native northern watermilfoil Myriophyllum sibiricum Eurasian water Milfoil has 14 or more leaflet pairs The native has fewer than 14 leaflet pairs Collapses out of water Holds shape out of water

Egeria densa Brazilian elodea – Class B Key characteristics: smooth leaf edges leaves in whorls of 4 (up to 6) relatively showy flower grows in up to 20 feet of water

Egeria densa Brazilian elodea – Class B

Elodea canadensis American waterweed – Native Key characteristics: leaves linear, whorled in 3s (sometimes 2-4) on the stem leaves sparse toward bottom of plant, more bunched together toward top branching stem

Brazilian elodea vs. our native American waterweed Elodea canadensis Native usually has 3 leaflets Brazilian elodea usually has 4 leaflets

Dozens of other submerged natives in Lake Washington

Potamogeton spp. Submerged pondweeds – Native Key characteristics: many species leaves alternate, grass-like to oval, always have at least one mid-vein stems branched, flexible, up to 3m long small flowers/seedheads on spikes held above water

A Few Less Common Regulated Aquatic and Shoreline Weeds

Glyceria maxima Reed sweetgrass – Class A Key characteristics: Emergent perennial grass, sometimes variegated Up to 2.5 m (>8 ft.) tall in up to 2 m (6 ft.) of water Leaves stiff and smooth Ligule papery, rounded and pointy Flowers in summer, inflorescense open and branched

Ludwigia peploides Floating Primrose-willow – Class A Key characteristics: prostrate or floating stems alternate, variable leaves bright yellow 5-petalled flowers in leaf axils Grows in up to 10 feet of water, can be up to 2 ½ feet tall

Myriophyllum aquaticum Parrotfeather – Class B Key characteristics: emergent up to 1 ft. above water leaves in whorls around stem leaves feathery like milfoil dense mat of brownish rhizomes

Nymphoides peltata Yellow Floating Heart – Class B Key characteristics: floating perennial small yellow flowers with distinctive fringes 2 to 5 flowers per stalk heart-shaped or round leaves, wavy margins, often purplish underneath

Phragmites australis Common Reed – Class C designate Key characteristics: 12+ foot tall rhizometous grass hollow woody stems wide stiff leaves large feathery flower head purplish when young, brown in seed Duwamish: First Avenue South

Impatiens glandulifera Policeman’s Helmet – Class B

Spotted Jewelweed - Impatiens capensis (control not required but strongly encouraged)

Invasive Knotweed – Class B Non-Designate (control not required but strongly encouraged)

Hollow, upright, bamboo like stems often reddish or red-speckled

Grows so thickly that nothing can compete with it…

Except maybe garden loosestrife!

King County Noxious Weed Control Program Website Weed Photo Page: Search by Common Name or Latin Name Or click thumbnail picture of plant for weed information and photos

Sasha Shaw and Katie Messick King County Noxious Weed Program 201 South Jackson St, Suite 600 Seattle, WA (program line)