Weed management strategies effect on glyphosate‐tolerant maize and soybean yields and quality

Abstract

Weed management (WM) is necessary to prevent crop losses through competition with weeds and maintain high yields. However, in the case of glyphosatetolerant (GT) crops, phytotoxic effects can occur after glyphosate-based herbicide (GBH) applications, which could impact yields and quality. In order to assess the agronomic performance of six WM strategies on GT soybean [Glycine max (L.

Glyphosate and aminomethylphosphonic acid contents in field crops soils under various weed management practices

“…It was neither realistic nor feasible to envisage control plots with no GBH applications. Indeed, without appropriate weed management treatment, the control plots would not have provided satisfying yields nor being representative of actual Canadian WMP in field crops (Oerke, 2006; Smedbol et al., 2020). Moreover, resulting weed infestation could also have posed a threat to the surrounding plots.…”

“…GBH1 corn = first glyphosate-based herbicide (GBH) application in all corn plots, GBH2 corn = second GBH application in corn plots weed management practices (WMP)2 and WMP4, GBH1 soybean = first GBH application in all soybean plots and GBH2 soybean = second GBH application in soybean plots WMP2 and WMP4. C1, C2, and C3 are sampling campaigns 1, 2, and 3, respectively provided satisfying yields nor being representative of actual Canadian WMP in field crops (Oerke, 2006;Smedbol et al, 2020). Moreover, resulting weed infestation could also have posed a threat to the surrounding plots.…”

“…To avoid band effect, only the center of each plot was harvested. Yields data were previously published by Smedbol et al (2020).…”

“…Glyphosate and AMPA persistence in soil could represent a threat for crops quality and yields since both compounds have the potential to be subject to root uptake (Alves et al., 2008; Gomes et al., 2014). It should be highlighted that AMPA is phytotoxic even for GR crops (Reddy et al., 2004; Saunders & Pezeshki, 2015; Smedbol et al., 2020). The effects of a single vs. sequential applications of GBH combined or not with other herbicides has been studied before in both corn and soybean fields but, to our knowledge, never in parallel with glyphosate/AMPA contents measurements in soils along the growing season.…”

Dissipation and effect of glyphosate during composting of organic wastes

“…Glyphosate dissipation mechanisms that occur during composting are similar to those in soils. The most important one is biological degradation, which is known to produce aminomethylphosphonic acid (AMPA), a noxious metabolite considered recalcitrant in soils (Büyüksönmez et al., 1999; Silva et al., 2018) and phytotoxic even for glyphosate‐resistant crops (Saunders & Pezeshki, 2015; Smedbol et al., 2020). Glyphosate can be readily degraded by two bacterial metabolic pathways: the AMPA and sarcosine pathways.…”