King County Noxious Weed Program helping Bellevue fight tough forest invader

Seasonal battle begins against garlic mustard, giant hogweed, other invaders

Bellevue Parks employee Isaac Cunningham knew the source of the garlic smell wafting through the trees in the Coal Creek Natural Area, which connects to King County’s Cougar Mountain Regional Wildland Park.

As part of the team fighting garlic mustard in nearby Forest Park, Cunningham knew the fragrant smell was a telltale sign that the noxious weed had secured a roothold in the forest. Quickly out-competing native vegetation, garlic mustard also reduces beneficial forest soil fungi.

Cunningham’s investigation revealed a large infestation of garlic mustard – one of several noxious weeds that the King County Noxious Weed Program is battling as the weed season gets under way.
 
County weed specialists are working closely with dozens of homeowners to fight back against garlic mustard infestations in more than 180 city parks, roadsides and backyards.

Bellevue and King County staff recently started to control the large garlic mustard patch, and plans are in place for area “weed warrior” volunteers to pull any surviving weeds in May.

“This kind of rapid response and tenacious effort is our only hope again this fast-spreading noxious weed,” said King County noxious weed specialist Ben Peterson, who is leading the county’s effort to help Bellevue control this site.

According to Steven Burke, King County Noxious Weed Program manager, every known garlic mustard site is checked closely each year, some many times, so that every plant can be removed before it seeds.

“It is very likely there are more garlic mustard sites scattered about the county, and we need the public’s help in locating new sites,” Burke said.

Garlic mustard is one of 48 state-listed noxious weeds that the King County Noxious Weed Program is working actively with landowners to control. Noxious weeds are non-native plants introduced to Washington that cause damage to the natural or economic resources of the state.

The county noxious weed program is part of a statewide effort to detect and respond to noxious weeds such as garlic mustard that harm natural and economic resources. To help protect the state’s resources, the Washington State Noxious Weed Control Board adopts a statewide noxious weed list each year.

Each county’s weed board then adopts a county noxious weed list that establishes which weeds require control by property owners and public agencies. King County’s Noxious Weed Control Board places a priority on preventing new infestations of the most serious noxious weeds, and encourages property owners to work together in stopping the spread of established noxious weeds.

Starting this month and continuing through the growing season, specialists will work throughout the county to locate and follow up on infestations of listed noxious weeds, including giant hogweed.

Feared not only for its invasiveness but for a toxic sap that causes painful, watery blisters and burns, giant hogweed has leaves that are up to five feet wide and a central flowering stem that reaches 15 feet tall, topped by an impressive umbrella-shaped flower-head, stretching two feet across.

The county’s noxious weed program has found more than 1,000 giant hogweed sites since they began looking in 1996. Today, through landowner and staff control efforts, known infestations are down 80 percent – to roughly 200 active sites.

“By watching for new sites, returning to known sites every year and helping landowners control it where needed, we have kept giant hogweed from spreading and are even hopeful that it can be eradicated,” Burke said. “The hardest part of fighting uncommon noxious weeds such as giant hogweed is finding them, and this is where the public can really help.”

The public is encouraged to report sightings of high priority weeds to help find new infestations while there is still a chance to stop them. To see photos of targeted noxious weeds, and report noxious weeds, visit www.kingcounty.gov/weeds.

Community groups are encouraged to contact the county weed program if they would like to schedule a presentation on noxious weeds or an information booth at their event. For more information, contact Sasha Shaw, the weed program’s education specialist, at 206-296-0290 or by e-mail at sasha.shaw@kingcounty.gov.

Related information

Noxious Weeds

King County Water and Land Resources