King County fights invasive weed threatening Snoqualmie Valley
May 5, 2010
By Dan Catchpole
King County weed-control officials pulled up garlic mustard near North Bend in late April. One of the aggressive, invasive plants can produce thousands of seeds, which stay in the soil for years before sprouting. (Photo contributed by King County)
NEW — 1:16 p.m. May 5, 2010
King County officials responsible for fighting invasive weeds recently attacked an outbreak of an aggressive non-native plant discovered in the agriculturally important Snoqualmie Valley.
Garlic mustard, a plant that crowds out native vegetation and depletes soil nutrients, was found growing on several adjacent properties in North Bend near a creek that drains into the South Fork Snoqualmie River. Like other noxious weeds, the plant is not native to the region and can cause ecological and economic damage.
Officials pulled out all plants they could find in the area of the outbreak, said Sasha Shaw, a noxious weed specialist with King County.
“We hope not to find any more in North Bend or the area, but we are fearful that we will since this plant has a way of escaping notice until there is a large population,” Shaw said.
The plant’s seeds can survive in soil for many years before sprouting, making it difficult to control.
The county will monitor the situation with follow-up visits in coming years.
It is the first confirmed infestation of garlic mustard in the Valley. Another infestation was found earlier in Bellevue near Cougar Mountain Regional Wildland Park.
King County and Bellevue officials are working to eradicate that outbreak.
Shaw said it’s possible the plant could have been introduced to the area in gravel dropped recently by a visitor from the Midwest.
“This forest invader is already a widespread problem across much of the eastern and Midwestern United States, and it is on the move in the Pacific Northwest,” she said.
The outbreak in North Bend was reported by a resident who is familiar with garlic mustard from Portland, where it is a problem, Shaw said.
Residents are being urged by the county to contact the Noxious Weed Program in its Water and Land Resources Division if they think they have found garlic mustard on their property or in their neighborhood.
“It can be hard to identify because it looks like a lot of other plants and weeds that grow out there in the woods,” said Doug Williams, spokesman for King County Department of Natural Resources and Parks.
At one point during its development, the plant produces a smell similar to garlic. Photos and descriptions of the plant are available on the county’s website.
The plant spreads by seeds. One stand can produce more than 62,000 seeds per square meter, quickly pushing out local flora and changing the make up of plant communities on the forest floor.
Fighting weeds across the state
The state Department of Ecology recently awarded grants worth $412,000 for 12 weed-control projects, including two in King County.
A $28,750 grant was given to King County Department of Natural Resources to fight garden loosestrife in Marymoor Park in Redmond.
King County Water and Land Resources received nearly $20,000 to produce a weed-control plan for Eurasian watermilfoil in Bass Lake, a 24-acre lake north of Enumclaw.
Dan Catchpole: 392-6434, ext. 246, or editor@snovalleystar.com.
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