Foster Creek Conservation District
Foster Creek Conservation District

Weed Control in Riparian Restoration

The hot summer sun is out!  For our riparian enhancement and restoration projects that means one thing: weed control.  Controlling invasive weeds is an integral part of every restoration project.  If left uncontrolled, weeds will outcompete the newly planted native vegetation for resources such as sun, water, and nutrients.  A riparian ecosystem provides a complex set of processes and functions that provide numerous benefits to both landowners and wildlife including water storage, water filtration, and habitat.  When invasive weeds overrun natural riparian ecosystems these processes and functions are degraded or destroyed.


Foster Creek Conservation District prefers to take an integrated approach to weed management whenever possible. Integrated Pest Management (IPM) is a process consisting of the balanced use of mechanical, cultural, biological, and chemical procedures that are environmentally compatible, economically feasible, and socially acceptable to reduce pest populations to tolerable levels.


One of our current riparian restoration projects exemplifies the IPM strategy well.  Part of the project area has a dense infestation of Canada thistle (Cirsium arvense), reed canarygrass (Phalaris arundinacea), and creeping bentgrass (Agrostis stolonifera).  We placed weed mats around the newly planted shrubs to inhibit weed growth through shading (a combination of cultural and mechanical methods).  As can be seen in the pictures below, the weeds find a way around and through the mats, which is why FCCD staff make regular visits to the sites with a brush cutter to mow the weeds down (mechanical method).  Ideally, weeds will be mowed down at least three times a year.  Each time mowing occurs, the weed will have to use energy stored in the roots to regrow aboveground biomass, and over time, this will weaken the weeds.  After several years of mowing, up to 3-5 years for substantial infestations, herbicides can be applied (chemical method) to the weakened weeds with greater success and/or lower rates than if herbicides only were used at the site.  Over time, the native riparian species we have planted will be big enough to shade and outcompete the weed species for resources (cultural method) and the site will trend back to a fully functioning natural riparian ecosystem.


Invasive weed management takes a dedicated, persistent and integrated effort over time.  If you are interested in technical assistance or securing cost-share dollars to combat invasive weeds on your land, please contact Aaron Rosenblum at 509-423-5990 or

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Foster Creek Conservation District 203 S Rainier Waterville, WA 98858 509-888-6372 © Foster Creek CD