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

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Presentation on theme: "Aquatic Noxious Weeds in King County King County Noxious Weed Control Program"— Presentation transcript:

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

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

3 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

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

5 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

6 Noxious Weed List (WAC 16-750) –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 16-752) –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

7 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

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

9 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

10 Meet the LOOSESTRIFES and other aquatic Noxious Weeds


12 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

13 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)

14 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 Germany1.4-4.9 ft Australiato 4.9 ft Flora of Europeto 4 ft Garden Loosestrife Lysimachia vulgaris Class B Noxious Weed

15 Bellevue Issaquah Redmond Renton Kirkland Fall City Duvall Rutherford Slough Lake Burien Sammamish River 203 202 Snohomish County King County Garden loosestrife distribution in King County 90 5 405 Raging River 520 Lake Alice Matthews Beach Magnuson Park Union Bay Montlake Park Lk Wash. Blvd Seward Park

16 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

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

18 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

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

20 Seattle Bellevue Issaquah Redmond Renton Federal Way Duvall Green River Snohomish County King County Purple loosestrife distribution in King County 5 90 405 520 167 18 Auburn Snoqualmie River Vashon Island

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

22 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

23 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

24 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

25 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

26 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

27 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

28 Egeria densa Brazilian elodea – Class B

29 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

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

31 Dozens of other submerged natives in Lake Washington

32 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

33 A Few Less Common Regulated Aquatic and Shoreline Weeds

34 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

35 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

36 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

37 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

38 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

39 Impatiens glandulifera Policeman’s Helmet – Class B

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

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

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

43 Grows so thickly that nothing can compete with it…

44 Except maybe garden loosestrife!

45 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

46 Sasha Shaw and Katie Messick King County Noxious Weed Program 201 South Jackson St, Suite 600 Seattle, WA 98104 206-296-0290 (program line)

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