Effects of Tillage and Growth Regulator Pretreatments on Reed Canarygrass (Phalaris arundinacea L.) Control with Sethoxydim

Abstract

Reed canarygrass (Phalaris arundinacea L.) is a dominant perennial grass species in many sedge meadows and wet prairies. Efforts to control this species with herbicides have had limited short-term success, partly because reed canarygrass resurges from its rhizomes whenever applications are suspended. A system of apical dominance may operate in reed canarygrass rhizomes, resulting in a persistent rhizome bud bank that must be depleted in order to achieve effective, long-lasting control of this species. Pretreatments that overcome apical dominance may predispose reed canarygrass to more effective herbicidal control. I tested whether coupling pretreatment tillage or pretreatment plant growth regulator (PGR) application to herbicide application would result in greater reed canarygrass control compared to herbicide application alone. Three treatments were tested: (1) Sethoxydim (Vantage®) application only (standard method control), (2) Tillage followed by Vantage® application, and (3) Plant Growth Regulator application (2:1 (a.i.) Cycocel®/Proxy®) followed by Vantage® application. Tillage-Vantage® treatments had a larger effect on reed canarygrass suppression and native species abundance than the other two treatments, and these effects persisted into the subsequent growing season after treatments were discontinued. Coupling PGR pretreatments with herbicide application reduced reed canarygrass stem density 26% greater than herbicide application only. Tillage and PGR pretreatments have potential for enhancing the effects of Vantage®herbicide on reed canarygrass.