North American Prairie Conference


Date of this Version



Published in Dave Egan & John A. Harrington, editors, Proceedings of the 19th North American Prairie Conference: The Conservation Legacy Lives On..., University of Wisconsin-Madison, August 8-12, 2004 (Proceedings of the North American Prairie Conference, 19), Madison, WI: University of Wisconsin-Madison, 2004.


Reed canarygrass (Phalaris arundinacea L.) is a dominant perennial grass species in many sedge meadows and wet prairies. Efforts to control and eradicate this species with herbicides have had limited short-term success. A system of correlative inhibition (apical dominance) may operate in reed canarygrass rhizomes, resulting in a persistent rhizome bud bank that must be depleted in order to restore function and diversity to reed canarygrass stands. Pretreatments that overcome correlative inhibition may predispose reed canarygrass rhizomes to more effective herbicidal control. I conducted a feasibility study to test the efficacy of pretreatment tillage and plant growth regulator (PGR) application for enhancing herbicidal effects of sethoxydim (Vantage) on reed canarygrass. Three treatments were tested: 1) Vantage application only (control), 2) tillage followed by Vantage application, and 3) PGR application followed by Vantage application. Species density, diversity, and non-reed canarygrass stem density were higher in tilled plots than PGR plots or Vantage only plots, although this outcome may have been an indirect effect of tillage removing litter. Plant growth regulator pretreatments led to higher species diversity than plots treated with Vantage alone, possibly due to increased lateral growth of desired species. All treatments suppressed reed canarygrass stem density to the same degree in the year they were administered. Treatment lags may exist while reed canarygrass bud banks become depleted, and the effects of pretreatments may not be immediately evident. This is an ongoing study, and collecting additional response data in upcoming growing seasons will clarify reed canarygrass responses to tillage and PGR application.