Glyphosate-resistant giant ragweed (Ambrosia trifida L.) control with preplant herbicides in soybean [Glycine max (L.) Merr.]

Abstract

Vink, J. P., Soltani, N., Robinson, D. E., Tardif, F. J., Lawton, M. B. and Sikkema, P. H. 2012. Glyphosate-resistant giant ragweed ( Ambrosia trifida L.) control with preplant herbicides in soybean [ Glycine max (L.) Merr.]. Can. J. Plant Sci. 92: 913–922. Giant ragweed populations in southwestern Ontario have evolved resistance to glyphosate. Glyphosate-resistant (GR) giant ragweed interference in field crops can lead to significant yield losses. Eleven field trials [five with preplant (PP) burndown only and six with PP burndown plus residual herbicides] were conducted in 2010 and 2011 on Ontario farms with GR giant ragweed to evaluate the efficacy of various PP herbicides applied prior to soybean planting. Glyphosate applied at the recommended field dose failed to adequately control GR giant ragweed. The PP herbicides 2,4-D ester, cloransulam-methyl and saflufenacil applied alone and with glyphosate provided 97–99, 68–100 and 71–94% control, respectively and resulted in soybean yields equivalent to the weed-free check. Combinations of glyphosate plus cloransulam-methyl or linuron controlled GR giant ragweed 8 wk after application (WAA), 75–95 and 95–98%, respectively. Residual control with glyphosate plus linuron resulted in soybean yield equivalent to the weed-free check. Based on these results, GR giant ragweed can be controlled prior to soybean planting in southwestern Ontario.

Glyphosate-Resistant Giant Ragweed (<i>Ambrosia trifida</i> L.): 2,4-D Dose Response and Control with Postemergence Herbicides in Soybean

“…ha -1 was needed to achieve 95% control, respectively. This is similar to the findings of Vink et al [14] who reported 97% to 98% control of glyphosate-resistant giant ragweed with glyphosate plus 2,4-D ester applied at 900 g a.e. ha -1 + 500 g a.e.…”

Preplant and Postemergence Control of Glyphosate-Resistant Giant Ragweed in Corn

“…In other studies, poor GR giant ragweed control with glyphosate plus flumetsulam, applied PP, has been reported ranging from 12% to 66% [13] and 26% to 61% [14], 8 WAA. Reference [17] similarly reported unacceptable giant ragweed control of 9 to 52% 8 WAA with atrazine applied PP in corn.…”

Linuron Biologically Effective Dose for Glyphosate-Resistant Giant Ragweed (<i>Ambrosia trifida</i> L.) Control in Soybean (<i>Glycine max</i> L.)

“…In other PP linuron studies, Reference [24] demonstrated greater than 95% control of GR giant ragweed, while Reference [25] reported good, yet variable, control ranging from 23% to 99% at 8 WAA, in southwestern Ontario. This discrepancy in control may be due to application timing as Reference [24] applied PP linuron from May 20 to June 3, and Reference [25] during May 1 to June 2. In this study, linuron was applied May 1 to 17 ( Table 2), therefore the comparative low GR giant ragweed control may be due, in part, to early application dates.…”

“…In southwestern Ontario, giant ragweed seedlings are among the first weeds to emerge. Recent studies on GR giant ragweed have concluded that control prior to soybean planting is an effective management tactic [24] [25]. The objective of this study was to therefore determine the biologically effective dose of linuron for the control GR giant ragweed when applied pre-plant (PP) in soybean.…”