Noxious Weed of the Month: Garlic Mustard

by Kate Yturri, Judy Winer and Gwen Stamm, MG Class of 2013

NOXIOUS Garlic Mustard 1Garlic mustard (Alliaria petiolata) is a flowering herb that was introduced to North America from Europe as a food and medicinal plant. Although edible for humans, it is not eaten by local wildlife or insects. It is a fast growing, damaging invasive that once established is difficult to eradicate. It is a biennial or winter annual herb that spreads prolifically by seed. It can cross-pollinate or self-pollinate and quickly out competes native vegetation. Garlic mustard grows well under many different conditions and has the ability to produce chemicals that inhibit the growth of other plants and mychorrizal fungi needed for healthy tree seedling survival and tree growth. Garlic mustard is a Class A noxious weed with a limited distribution in Washington, and eradication is required state-wide. It is also on the Washington quarantine or prohibited plants list and is prohibited to transport, buy, sell, offer for sale or to distribute. It has been found overtaking a private garden near Eastsound on Orcas Island.
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Noxious Weed of the Month: Scotch Broom

by Kate Yturri, Judy Winer and Gwen Stamm, San Juan County Master Gardeners Class of 2013

Noxious Scotch Broom 1Scotch Broom (Cytisus scoparius) is an invasive, many-branched shrub with green stems and bright yellow flowers, typically blooming from April to June and visible to us all from county roads. It is classified as a Class B noxious weed in Washington State and control is required, because it is a serious fire hazard and is crowding out native and beneficial plants, causing loss of grasslands and degrading open space. Seeds are toxic to livestock and horses and can remain viable up to 80 years.

Now is a good time to remove Scotch Broom, before the pods mature to produce additional seeds. Broom is easily identified by its 5-angled stems, small deciduous leaves (each with three narrow leaflets), and, of course, by the bright yellow flowers, each about ¾-inch long with 5 petals. The similar looking shrub, gorse (Ulex europaeus) also is selected for control county-wide and is distinguished by round stems and prominent spines on mature stems instead of leaves.
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Noxious Weed of the Month: Yellow Archangel

by Kate Yturri, Judy Winer and Gwen Stamm, San Juan County Master Gardeners Class of 2013

Yellow Archangel (Lamiastrum galeobdolon) is an attractive ornamental ground cover found in San Juan County. It is classified as a Class B noxious weed in Washington State, and control is required county-wide. It is a noxious weed because it easily becomes invasive, forming dense patches that out-compete native plant species and provides little or no food or shelter for native wildlife. Yellow archangel groundcover has escaped gardens to naturalize in county forestlands and has taken over the county park’s Eagle Cove streambed. Once established, it is exceedingly difficult to control.

    Yellow Archangel infestation nwcb   Yellow Archangel infestation nwcb 2

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The Myth of Well-Behaved Ornamentals

by Linda Chalker-Scott, Ph.D., Extension Horticulturist and Associate Professor,
Puyallup Research and Extension Center, Washington State University

happy-flowers-day - CopyThe Myth: “Garden plants do not become invasive.”
We’re all familiar with weeds in our landscapes: Calystegia sepium (hedge bindweed), Equisetum arvense (horsetail), Taraxacum officinale (dandelion), and Cirsium arvense and C. vulgare (Canadian and bull thistle) are but a few of the weeds we battle in Pacific Northwest gardens. Larger herbaceous and woody perennials such as Hedera helix (English ivy), Ulex europaeus (gorse), Cytisus scoparius (Scots broom), Rubus discolor (Himalayan blackberry), and Polygonum cuspidatum (Japanese knotweed) are ubiquitous in parks and along roadsides. These species have cost countless hours of labor and gallons of herbicide in our quest to restore impacted landscapes to a more natural and diverse state.
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The Dirt on Noxious Weeds

Weed Cartoon 2 Planning this year’s garden also means gearing up to battle weeds — and noxious weeds in particular will keep us constantly vigilant. Get a head start with these FAQs from the Washington State Noxious Weed Control Board.

What makes a plant a weed?
The classic gardener’s definition of a weed is ‘a plant out of place’ – that is, any plant that’s growing where it’s not wanted.

What makes a plant a noxious weed?
‘Noxious weed’ is the traditional, legal term for invasive, non-native plants that are so aggressive they harm our local ecosystems or disrupt agricultural production. These plants crowd out the native species that fish and wildlife depend on. They also cost farmers, orchardists and ranchers millions of dollars in control efforts and lost production – and that can make the food we buy more expensive.

So while ordinary weeds may be annoying, noxious weeds are a genuine threat to the natural resources, ecology and economy of our state.
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Noxious Weed of the Month: Thistle!

by Kate Yturri, Judy Winer and Gwen Stamm, MG Class of 2013

Thistles are common, recognizable weeds in the San Juan Islands, yet there are several thistles that are native to the US, one of which is located in the county.

NW native Cirsium brevistylum.

NW native C. brevistylum.

Our local native is known as Indian, short-style or clustered thistle (Cirsium brevistylum) and can be confused with bull thistle (C. vulgare). Both are up to 6 or more feet tall but the native, short-style thistle lacks spiny wings on the upper stems. It can also be distinguished from bull thistle by its hairy stem, and less deeply cut leaves that are arranged more symmetrically on the stem. Indian thistle’s stem is usually single and coated with hairs and webby fibers giving it a softer appearance. If you try to pull out a mature Indian thistle, its stem and leaves are relatively soft to the touch, whereas bull thistle is quite painful due to its spines. Thick leather gloves may be needed. It is more shade tolerant than bull thistle and provides food for native butterflies and birds.
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Noxious Weed of the Month: Tansy Ragwort

by Kate Yturri, Judy Winer and Gwen Stamm, MG Class of 2013

Tansy Ragwort Img 1 - Edit
Tansy ragwort (Senecio jacobaea) is a winter annual, biennial, or short-lived perennial that can grow up to 6 feet tall. It is easily recognized by its bright yellow flower heads, with each flower bearing about 13 petals (ray florets), and by its soft, deeply lobed leaves. It is easy to spot when it is in bloom around this time of year. You can also see smaller plants setting up for next year’s bloom as seen in the photo below.

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