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).

Control of glyphosate resistant Canada fleabane in soybean with preplant herbicides

“…ha -1 ) reduced GR Canada fleabane density 66%. In other studies Budd et al (2016) found that glyphosate plus saflufenacil plus metribuzin controlled Canada fleabane 96-99%, reduced density 98% and aboveground biomass 92% in soybean.…”

“…Saflufenacil alone has been documented to provide effective control (> 90%) of GR Canada fleabane (Byker et al 2013a). However, some studies have shown, and experience by Ontario soybean producers, that weed control with saflufenacil applied PP can be variable under Ontario environmental conditions (Budd et al 2016). Therefore, the objective of this research Eight field trials were conducted over a three-year period (2013, 2014 and 2015) in commercial soybean fields located near Blenheim, Harrow, Morpeth, Mull, Ridgetown and Windsor, Ontario with confirmed GR Canada fleabane.…”

“…Variable control of GR Canada fleabane with glyphosate plus saflufenacil, is consistent with results from Ikley (2012) which indicated only 37 and 57% control of GR Canada fleabane with glyphosate (900 g ae ha -1 ) plus saflufenacil (25 g ai ha -1 ) in soybean; but in contrast to Byker et al (2013a) who reported 90 to 100% and 88 to 100% at 2 and 4 WAT, respectively. Budd et al (2016) (Table 1). The tankmixes of glyphosate plus 2,4-D, cloransulam-methyl, chlorimuron plus metribuzin, smetolachlor/metribuzin or imazethapyr plus metribuzin controlled GR Canada fleabane 45 to 68%, reduced density 71 to 92% and reduced aboveground biomass 72 to 84% (Table 1).…”

Responses of Dry Bean to 2,4-D Ester Applied Preplant and Preemergence

“…There has been a rapid spread of glyphosate-resistant (GR) Canada fleabane [Conyza canadensis (L.) Cronq.] in Ontario in recent years [10]. GR Canada fleabane has been found in many dry bean growing areas of southwestern Ontario.…”

Distribution of glyphosate and cloransulam-methyl resistant Canada fleabane (Conyza Canadensis L. Cronq.) in Ontario

“…Control of GR Canada fleabane with POST herbicides in soybean are not effective, or have limited control (Loux et al 2006). Therefore it is desirable to use a PP herbicide with residual activity for GR Canada fleabane control in soybean (Loux et al 2006 (Budd et al 2016).…”