By Michelle Quast,

Bohemian knotweed really likes it out here in the Pacific Northwest and happens to wreak havoc on our precious salmon habitat. It’s listed as a Class B Noxious Weed in Washington State—meaning the goal is to prevent the spread of the weed. Unfortunately, knotweed is a common sight for many residents living along Bear Creek, though many may not realize that they have it in their own backyards!

Landowners can quickly identify the plant by answering the following questions:
• Does the plant grow incredibly fast throughout the spring and summer, reaching up to 15 ft at its peak height?
• Does the plant have large, lush, green leaves that are flat at the base?
• Does the plant have bamboo like stalks that are hollow?
• Does the plant look like it dies each winter, leaving a dead cane?

If you answered yes to all of these and your plant looks similar to those pictured, then you likely have knotweed.

So why are we worried about knotweed? After all, it is very pretty! The problem is that invasive knotweed grows extremely well along rivers and streams. Its shallow root system leads to increased erosion, making streambanks unstable and water quality poor. Native trees and shrubs can’t compete with the fast growing weed, resulting in a lack of trees growing beside the river. This reduces the shade cover and leads to higher water temperatures: a fatal condition for salmon. While native trees and shrubs would drop their leaves into the water each fall providing food for bugs, our regional insects don’t want to eat knotweed! And without more bugs to eat, our salmon are left hungry and unable to grow fast enough to survive.

Knotweed spreads quickly and easily, making it one of the most difficult invasive plants to control around the world. A single segment of knotweed or a small piece of its root can break off and grow to become another full-sized plant. This is how knotweed spreads along rivers—going for a swim during floods and landing somewhere new. It can also travel when people unknowingly move it around, sometimes by taking contaminated soil to a new location, or by mowing down the weed and breaking each cane into hundreds of little chunks. If you think you have knotweed on your property, please don’t mow it!

Does this sound all too familiar? You can participate in our knotweed control program to receive free help. Since 2010, Forterra has been working with partners and landowners on the Cedar River to control knotweed and restore the riverbanks, and the results are incredible. Up to 95% of the knotweed is gone! Now we are excited to bring our successful program to Bear Creek. In 2016, our adventure begins as we work with landowners to identify knotweed infestations on the main-stem of Bear Creek. Our first step is completing a comprehensive survey from the top to the bottom, looking for knotweed all the way down. In 2017 we are coming back to offer free knotweed control assistance to participating landowners. If you or anyone you know lives on the creek, please contact us to learn more about how you can support our work. With our proven method and your participation, we can really make a difference.

In addition to knotweed control, we are working with landowners to improve water quality and habitat conditions for wildlife by planting beautiful native trees and shrubs along the creek. Knotweed and other invasive weeds grow exceedingly well in ground that has been recently cleared and has nothing else growing on it. Replanting your riverbank with native plants is one great way to protect your land from additional weed infestations. This assistance is provided at no cost, and it is fun! Our team designs lovely native plant gardens with landowners and works with a Washington Conservation Corps crew to do the installation. Let us know if you’re interested and we’ll gladly come out to meet you and your land.

For more information contact Michelle Quast at: (206) 905-6907 or mquast@forterra.org
Forterra is a non-profit organization working in Washington State to bring people together to protect our beautiful region. Funding for this work is provided by the King County Wastewater Treatment Division.