Cirsium arvense management with electrical weed control and clopyralid

Canada thistle [Cirsium arvense (L.) Scop.] is a perennial weed that is difficult to control due to its extensive root system and prolific seed production. Although herbicides such as clopyralid provide effective control, they are not suitable for all production systems. Electrical weed control (EWC) is a nonchemical method that applies high voltage to plant tissues, causing irreversible cellular damage through loss of cellular integrity. This study evaluated the efficacy of EWC using a commercial tractor-mounted unit (EH30; Zasso), clopyralid, and integrated EWC-clopyralid programs for managing C. arvense, including single and sequential applications of each approach.

In Corvallis, EWC provided 39% and 53% control with one and two applications, respectively, whereas in Canby, control increased from 38% with a single application to 94% with two applications. Clopyralid provided 96% control with a single application and 95% with two applications in Corvallis, compared with 43% and 78% in Canby. Two EWC applications reduced shoot biomass by 95% in Canby. Combined treatments were highly effective: EWC followed by clopyralid achieved 89% control in Corvallis and 87% in Canby, and the reverse sequence achieved 98% control.

EWC provided transient control of C. arvense, and integration with clopyralid improved control, supporting its role in integrated weed management. Because C. arvense is a perennial species, multiyear studies are needed to determine the long-term effectiveness of EWC. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.