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Weeds can be alluring invaders When pretty plants jump the garden fence, they can wage war on 's native flora

By DONNA FREEDMAN Anchorage Daily News

(Published: June 29, 2006)

It wasn't the fireweed's hue that was unusual. It was the timing. The bright, purply splash of color showed up on a Westchester Lagoon island last October.

Fireweed doesn't bloom that late in the year. Purple loosestrife does. Seeds from the vividly colored flower had escaped someone's garden and made their way to the island, according to Jamie Snyder of the University of Alaska Fairbanks Cooperative Extension Service. And purple loosestrife (Lythrum salicaria, Lythrum virgatum) is considered extremely invasive; its sale has been banned in more than a dozen states.

Most people don't know this. All they know is that it's pretty and Mary Walker joined the municipality- they want it in their gardens. But Snyder and other people sponsored Weed Warriors group on involved with Alaska Weed Awareness Week are asking Monday at Westchester Lagoon to gardeners to be more careful about plant choices. pull invasive weeds including bird vetch, center, which climbs and smothers natural vegetation. (Photo They'd also like folks to be aware of what's growing in public by BILL ROTH / Anchorage Daily spaces and what's "volunteering" on their own property. You News) may not have planted those charming little faux snapdragons known as butter-and-eggs (Linaria vulgaris), but they'll show up sooner or later. When they do, pull them up right away. If you see garlic mustard (Alliaria petiolata) along the bike trail, pull it up and drive a stake through its heart.

The word "weed" means any plant that's unwanted in a particular place. A garden flower that establishes itself where it shouldn't be is a weed. And if it shows up in a foreign area and has no natural enemies to keep it under control, it is considered invasive.

Not all invasives jump the garden fence. They can get to new places in commercial seed and grass mixes or move with help from animals, wind, a hiker's boot, a bulldozer's track. The leaves of hempnettle (Galeopsis bifida) are covered with bristly hairs. Understand this: Weed watchers are not saying that all non- These plants form dense stands on native plants are bad. disturbed lands and prevent the return of native species. (Photo by JAMIE SNYDER / UAF Cooperative "The vast majority of our ornamentals are not invasive," Snyder Extension Service) said. "It's when a plant can move into wild areas that it becomes a problem."

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Allowed to grow unchecked, invasives can have major impacts on local ecosystems. They compete with native plants for light, space, nutrients and water. They add plant litter to the ground and waterways at unusual times, affecting everything from insect populations to water quality to plant diseases.

Smooth-rooted invasives that crowd out denser-rooted plants don't hold on to soil as well, encouraging erosion. A plant like white sweet clover (Meliotus alba) fixes nitrogen, which may disturb native species adapted to native soil. Plants such as ornamental jewelweed (Impatiens glandulifera) are so nectar- rich that they lure bees away from native plants, reducing pollination of those varieties. Some invasives even have Skin contact with tansy ragwort (Senecio jacobea) may cause allelopathic tendencies -- they emit toxins to keep other plants irritation. A single plant can produce from growing or reproducing. up to 150,000 seeds, which are easily dispersed by wind and animals But don't blame the plants. They're just doing what they're and remain viable for six years. programmed to do: establish territory and reproduce by any (Photo by MICHAEL RASY / UAF means necessary. It's up to humans to keep them under Cooperative Extension Service) control.

Herbicides are not considered a priority in Alaska, for a couple of reasons. If it doesn't kill the targeted weed, an herbicide may actually encourage its growth by wiping out the competition (including native species). Additionally, some people worry about potential health and environmental risks from these chemicals.

Prevention is the best method, according to "Invasive Plants of Alaska," a book produced by the Alaska Soil and Water Conservation District, the University of Alaska Fairbanks Cooperative Extension Service and other state and federal Orange hawkweed's creeping stems agencies. It also notes that manual control -- hand-pulling and eventually create a dense ground digging -- is a very effective way of dealing with invasives once cover that chokes out native species. they are identified. (Photo by JAMIE SNYDER / UAF Cooperative Extension Service) Early identification is crucial, since invasives often seed impressively (a mature purple loosestrife can produce more than 100,000 seeds) and may also spread vegetatively above or below the ground.

Local native plants expert has been watching bird vetch (Vicia cracca) march south along the Seward Highway for years. The climbing plant with bluish-violet flowers probably arrived in a revegetation mix applied after the highway was widened, Pratt said. Now it's also in the Potter Marsh area, again probably from seed mix, and out in the Valley, where farmers used it as a cover crop. Bird vetch (Vicia cracca) has been "It's probably one of the worst weeds and one of the hardest to spreading south along the Seward eradicate," Pratt said. Highway for years, says native plants expert Verna Pratt. Its vining tendrils climb fencing, trees, bushes and Another stinker is western salsify (Tragopogon dubius), a other vegetation. The plant is native yellow-flowered biennial that even Pratt admits is "gorgeous" to and . (Photo by

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but which robs native plants of nutrients and is rapidly taking over. JAMIE SNYDER / UAF Cooperative Extension Service)

"The Native Plant Society has been pulling that for four years now. We haven't begun to get rid of it," she said. "There are some places down on the Seward Highway where (salsify) is the only thing."

Pratt has given invasive-plants talks around Anchorage, and audiences aren't always receptive. One "very irate" man took offense at her dislike for bird vetch, saying, "That's a pretty flower. Why wouldn't you just let it be?"

Margaret Timmerman, who runs the municipality's new Weed Warriors volunteer program, understands that kind of reaction. Spotted knapweed (Centaurea She loves the Mayday tree (Prunus padus), also known as biebersteinii) has spread throughout European bird cherry, for its fragrance, its growth pattern, its since its accidental attractiveness to birds. But Timmerman also knows that it has introduction from Europe in the late become very invasive in Anchorage. In Valley of the Moon Park, 1800s. These examples were for example, more than 90 percent of younger "understory" photographed along Turnagain Arm trees are Mayday trees, where there should be willows and on the Seward Highway. (Photo by alders. MICHAEL RASY / UAF Cooperative Extension Service) Recently, she noticed a Prunus padus volunteer in her yard. "Because of its ability to spread, I will pull it," Timmerman said.

The act is a metaphor for the invasive-weed situation in Alaska: Take care of it while it's small. Unlike other states, which have spent millions of dollars trying (and failing) to control invasives, Alaska's problem is still relatively minor, according to Snyder.

"Invasive plants are going to find their way up here. The question is, are we going to make wise decisions from the get- go?" she said. "It's a lot less expensive and a lot easier to take care of this in the early stages." Orange hawkweed's blooms are attractive to gardeners, but the European native (Hieracium aurantiacum) is unwelcome in Daily News reporter Donna Freedman can be reached at Alaska, say native plant defenders. [email protected]. (Photo by MICHAEL SHEPHARD / U.S. Forest Service)

What you can do

• A free, pocket-sized publication called Selected Invasive Plants of Alaska is available at Alaska Cooperative Extension, 2221 E. Northern Lights Blvd. The guide has color photos of some of the most common invasives and a list of Web sites that offer more information.

• COMMUNITY 'PULLS': Weed Warriors will host weed pulls from 4:30 to 7:30 p.m. today at Earthquake Park and 4:30 to 7:30 It's not fireweed. Purple loosestrife p.m. July 6 at Kincaid Park. Volunteers should wear long-

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sleeved shirts, long pants, sturdy shoes and gloves. For more (Lythrum salicaria, Lythrum information, call 343-4217. The Cooperative Extension Service virgatum) is of Eurasian origin and will host a pull along Seward Highway at 6 tonight. Meet at was well-established in North Potter Section House for carpooling. America by the early 1800s. It quickly spreads in wetlands, where it • A pair of free public programs can help gardeners make replaces native grasses and plants smarter plant decisions. Jamie Snyder will present "Invasive that provide better nutrition for Weeds" at 7 p.m. July 12 at the Campbell Creek Science Center, wildlife. More than a dozen states (Photo 6865 Abbott Loop Road; for more information, call 267-1247. prohibit its sale to gardeners. by JIM LAVRAKAS / Daily News Invasive Weeds Identification workshop will take place noon to archive 2005) 2:30 p.m. July 13 at Alaska Cooperative Extension; to register, call 786-6300.

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A free, pocket-sized publication called Selected Invasive Plants of Alaska is available at Alaska Cooperative Extension Service. ( )

http://www.adn.com/life/gardening/v-printer/story/7913676p-7807284c.html 6/29/2006