Invasive Knapweeds Of Washington

Day 284: While driving along one of my accustomed routes in South Hill yesterday, my eye recognized flecks of lavender on a leggy, three-foot diameter plant with sparse pale greyish-green foliage. By the time I had uttered the words, "Dammit! Was that Knapweed?" the car had travelled about 100 yards, and I found myself looking at a monoculture covering a quarter-acre of open field. I couldn't stop safely, so continued on to finish my shopping, and on the way back, I parked a little ways away and made a patrol on foot. I was horrified at what I found. Although the quarter acre was the most densely covered by this invasive, I could see mounds of it throughout an acre or more of county/private property. I suspect it has been there for years, and I never noticed it because I never caught it in the flowering stage. I took coordinates and filed a report with the Invasive Plant Council, although with the Knapweeds listed as "Class B" weeds, the landowners are not required to control the infestation. It is precisely that short-sighted thinking which makes the campaign against invasive species so frustrating. Education is currently the most important tool we have to stop the spread of Class B invasives. More information and free pamphlets can be obtained through the Washington State Noxious Weed Control Board. Click the "Resources" tab.

Spotted Knapweed (Centaurea stoebe) is the second species of Knapweed I have found in Pierce County in 2016. Earlier this year, I was conducting a training for the IPC on the Bud Blancher Trail and discovered Meadow Knapweed, a related species. To date, the Town of Eatonville has not seen fit to control it, and when I checked on it two weeks ago, it was beginning to go to seed. The two species can be differentiated by looking at the tips of the bracts under a magnifying glass if you're curious (the fringes are "fringier" on C. jacea x nigra), but in any case, any Knapweed you happen to find should be regarded as the enemy.