Control of glyphosate resistant Canada fleabane with saflufenacil plus tankmix partners in soybean

Abstract

Six field trials were conducted over a two-year period (2014, 2015) to determine the level and consistency of glyphosate-resistant (GR) Canada fleabane control with glyphosate plus saflufenacil plus a third tankmix partner. GR Canada fleabane interference reduced soybean yield 73% compared with the weed free control. At 4 and 8 weeks after application (WAA), glyphosate plus saflufenacil provided 99% and 88% control of GR Canada fleabane respectively, and at 8 WAA, reduced GR Canada fleabane density by 96% and biomass by 89%. Glyphosate plus saflufenacil plus dicamba improved the control of GR Canada fleabane to 100% and 97% at 4 and 8 WAA, respectively. At 8 WAA, glyphosate plus saflufenacil plus amitrole reduced GR Canada fleabane density and biomass 99% and 97%, respectively. At 8 WAA, glyphosate plus saflufenacil plus dicamba at 300 or 600 g a.i. ha−1 reduced GR Canada fleabane biomass 97% and 98%, respectively. Tank-mixing dicamba with glyphosate plus saflufenacil applied pre-plant improved control of GR Canada fleabane; however, this caused 14% and 46% crop injury at 2 and 4 WAA, respectively. Soybean yield for saflufenacil alone and saflufenacil tankmix treatments were similar to the weed free control, with the exception of dicamba (600 g a.i. ha−1).