Noxious weeds

The South American spongeplant is a candidate to be listed as a Class A weed in Washington. The designation would oblige landowners to root out the aquatic plant.

An aquatic plant that has invaded Northern California and has been found in a southwest Washington county is a candidate to be put on Washington’s banned weed list.

The State Weed Board is scheduled to decide Nov. 6 whether to oblige landowners to eradicate the South American spongeplant. The plant has been found in one place in Pacific County, according to the weed board’s staff.

It’s the only candidate this year for designation as a Class A weed. Class A weeds are those that are new to Washington. There is still hope of preventing them from becoming widespread.

The board also will consider expanding where 13 Class B weeds must be controlled. Class B weeds are established in some places, so control efforts are meant to keep them out of uninfested counties.

California listed the South American spongeplant as a noxious weed in 2015. It was first detected in small ponds in Redding and Arcata in 2003, according to the California Invasive Plant Council.

The spongeplant has spread to the San Joaquin River and the Sacramento-San Joaquin River Delta. The plant forms thick mats on water and causes problems for fish, boaters and irrigators, according to the council.

A report by the USDA’s Animal and Plant Health Inspection Services rated the invasive weed as a “high risk” and able to thrive along the West Coast.

The plant is native to Mexico, the Caribbean, and Central and South America. It’s scientific name is Limnobium laevigatum.

The proposed changes to where Class B weeds must be controlled are:

• Eurasian watermilfoil (Myriophyllum spicatum) in Kitsap, Kittitas and Whitman counties.

• Bohemian knotweed (Polygonum x bohemicum) in San Juan, Stevens, Whitman and Yakima counties.

• Japanese knotweed (Polygonum cuspidatum) in Stevens County.

• Himalayan knotweed (Persicaria wallichii) in Clark and Stevens counties.

• Lesser celandine (Ficaria verna) in all counties except for King and Whatcom counties.

• Leafy spurge (Euphorbia virgata) in Whitman and Garfield counties.

• Purple loosestrife (Lythrum salicaria) in Pierce and Benton counties.

• Wand loosestrife (Lythrum virgatum) in Mason, Pierce and Benton counties.

• Poison hemlock (Conium maculatum) in Douglas County.

• Policeman’s helmet (Impatients glandulifera) in Pacific and Pierce counties.

• Ravenna grass (Saccharum ravennae) in Grant County.

• Rush skeletonweed (Chondrilla juncea) in Kitsap County.

• European coltsfoot (Tussilago farfara) in Grant County.

The deadline to comment on proposed changes to the weed list is Nov. 4.

Comments can be sent by email to or by mail to WSNWCB, P.O. Box 42560, Olympia, WA 98504-2560.

The board will have a public hearing at 1 p.m. Nov. 5 at the Coast Wenatchee Center Hotel, 201 N. Wenatchee, in Wenatchee. The board will meet at 9 a.m. Nov. 6 at the same hotel to vote on the changes.

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