The Addition of Saflufenacil to Glyphosate plus Dicamba Improves Glyphosate-Resistant Canada Fleabane (Erigeron canadensis L.) Control in Soybean

Abstract

Glyphosate + dicamba has provided variable glyphosate-resistant Canada fleabane (GRCF) control in glyphosate/dicamba-resistant (GDR) soybean. Previous research has indicated improved GRCF control when a third herbicide was added to glyphosate + dicamba, though research is limited. The objective of this research was to ascertain if the level and consistency of GRCF control can be improved when adding tiafenacil, metribuzin, bromoxynil, pyraflufen-ethyl/2,4-D, 2,4-D ester, halauxifen-methyl or saflufenacil to glyphosate + dicamba applied preplant (PP) in GDR soybean. Four field trials were conducted in 2020 and 2021 in commercial fields in southwestern Ontario, Canada. Glyphosate + dicamba controlled GRCF 57, 93 and 94% at 2, 4 and 8 WAA, respectively. Adding bromoxynil to glyphosate + dicamba improved GRCF control from 57 to 77% at 2 WAA; adding saflufenacil to glyphosate + dicamba improved GRCF control from 57 to 92, 93 to 99, and 94 to 99% at 2, 4 and 8 WAA, respectively. All three-way tank-mixtures improved the consistency of GRCF control, except for glyphosate + dicamba + 2,4-D ester at 2 WAA, glyphosate + dicamba + 2,4-D ester, tiafenacil or metribuzin at 4 WAA, and glyphosate + dicamba + tiafenacil or bromoxynil at 8 WAA. This study concludes that the level and consistency of GRCF control was improved when saflufenacil was added to a PP application of glyphosate + dicamba in soybean.