Transcript Aquatic Noxious Weeds in King County King County Noxious Weed Control Program www.kingcounty.gov/weeds

Aquatic Noxious
Weeds in King County
King County Noxious Weed Control Program
www.kingcounty.gov/weeds
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
Impacts of Aquatic Weeds
• Clog waterways
• Impede recreation
• Foul motors
• Replace native plants
• No wildlife value
• Alter water chemistry
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
Two Lists: Growing vs.
Selling Noxious Weeds
• 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
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 Ragwort
Giant Hogweed
Purple
Loosestrife
Garden
Loosestrife
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
Class B Noxious Weed
2-10 foot tall perennial of
wetlands and shorelines
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
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)
Garden Loosestrife Lysimachia vulgaris
Class B Noxious Weed
9’
Shade
Flora of China
2-4 ft
University of Wisconsin
to 3.3 ft
Connecticut Botanical Society 2-4 ft
England
2-4 ft
Germany
1.4-4.9 ft
Australia
to 4.9 ft
Flora of Europe
to 4 ft
6’6”
Full sun
Snohomish County
King County
Garden
loosestrife
distribution in
King County
Duvall
Kirkland
Matthews Beach
S no
Magnuson Park
qu
Redmond
203
a lm
ie
Ri
ve
r
405
Union Bay
202
520
ashing
to n
Montlake Park
90
5
Rutherford
Slough
La
Seward Park
h
Sammamis
e
k
Bellevue
eW
Lak
Lk Wash. Blvd
Issaquah
Lake
Burien
Raging
River
Fall City
Lake
Alice
Renton
4
0
4
8 Miles
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
Garden loosestrife Impacts
Outcompetes other aggressive plants
Purple loosestrife
Common cattail
Himalayan
blackberry
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 loosestrife
Douglas spirea
(hardhack)
Fireweed
Purple loosestrife
distribution in
King County
Snohomish County
King County
Duvall
405
Redmond
520
Bellevue
Seattle
Issaquah
90
Renton
18
Vashon
Island
5
167
Federal
Way
Auburn
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
Myriophyllum spicatum
Eurasian watermilfoil – Class B non-designate
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
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
Brazilian
elodea
usually
has 4
leaflets
Native
usually has
3 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
www.kingcounty.gov/weeds
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 98104
206-296-0290 (program line)
www.kingcounty.gov/weeds