Effective Strategies for Landscape-Scale Weed Control: a Case Study of the Skagit Knotweed Working Group, Washington

Numerous studies describe the biology of invasive plants and control techniques for addressing site-specific infestations. However, few describe the practical steps and components needed to control invasives at larger, more ecologically-meaningful scales. The Skagit Knotweed Working Group was formed in 2000 to control Japanese knotweed (Polygonum cuspidatum Sieb. & Zucc.) and related congeners (knotweed) throughout the upper Skagit River system. Based on our experience, we present several elements that we consider necessary for a successful landscape-scale weed control program: (1) delineation of a clearly defined project area; (2) setting realistic and attainable program goals; (3) the ability to quantify and report measures of control success; (4) engaged partnerships of major public and private landowners; (5) coordination of partner effort to encompass the entire project area; (6) participation of small private landowners; (7) biologically-based, adaptive, and prioritized control strategy; and (8) conducting continuous and rigorous status surveys. We suggest these elements as a framework to overcome challenges to controlling weeds at the landscape scale, using the knotweed control project in the upper Skagit as a case study.