Comparison of Weed Management Systems in Narrow-Row, Glyphosate- and Glufosinate-Resistant Soybean (Glycine max)¹

Abstract

Field experiments were conducted near DeKalb and Urbana, IL, and Columbia, MO, in 1997 and 1998 to evaluate weed management systems in glyphosate- and glufosinate-resistant soybean planted in 18-cm rows. Overall weed control was improved to a greater extent when the rate of glufosinate was increased from 300 to 400 g ai/ha than when the rate of glyphosate increased from 630 to 840 g ae/ha. Sequential applications of glufosinate improved control over single applications, whereas sequential treatments of glyphosate generally provided no advantages over single applications. When averaged across all weed species in these trials, the systems that provided 95% or higher average control were sequential applications of glufosinate, sequential applications of glyphosate, and clomazone followed by (fb) glyphosate. Single applications of glufosinate provided somewhat variable control of giant foxtail, common lambsquarters, ragweed, and common cocklebur similar to that observed with pendimethalin fb imazethapyr. The addition of fomesafen to glufosinate did not improve control of any of the weeds in this study with the exception of velvetleaf at DeKalb. The addition of clomazone to glufosinate treatments resulted in slightly better giant foxtail and velvetleaf control. Single applications of glyphosate provided somewhat variable control of giant ragweed at DeKalb in 1997 and ivyleaf morningglory and common cocklebur control at Columbia. The addition of fomesafen to glyphosate provided an increase in ivyleaf morningglory and common cocklebur control at Columbia but did not improve control of any other species. The addition of clomazone to glyphosate-based programs resulted in slightly higher velvetleaf, common cocklebur, and ivyleaf morningglory control. In the glyphosate-based herbicide programs there were no substantial differences in relative yield, with all programs protecting over 95% of soybean yield. Glufosinate-based programs were effective in protecting 85 to 92% of soybean yield.

Flat fan and air induction nozzles affect soybean herbicide efficacy

“…A similar response was observed with the AI nozzles, where there was an increase in weed control of 1-24% when glyphosate was applied at the manufacturer's full recommended dose compared to the half dose. Wiesbrook et al (2001) also found that glyphosate applied at 840 g ha -1 provided excellent control of Setaria faberi (giant foxtail), A. theophrasti, and C. album. There was no effect of the water carrier volume with the FF nozzles, but the AI nozzles with the 100 L ha -1 rate improved the control of A. theophrasti (4%) and P. persicaria (8%).This is consistent with the results of Knoche (1994), who found that, with glyphosate, herbicidal performance increased as the carrier volume decreased.…”

Comparison of weed control strategies in glyphosateresistant soybean [Glycine max (L.) Merr.] in Atlantic Canada

“…Sequential glyphosate treatments provided 89 to 100% weed control in both years and were more effective than the single treatment in 1998, supporting findings of Wait et al (1999) and Payne and Oliver (2000) that sequential treatments result in greater and more consistent weed control. Wiesbrook et al (2001), however, found that sequential treatments of glyphosate gave no advantages over single applications in weed control or soybean yield. The best option for growers would be to apply glyphosate at the second to third trifoliate stage and then scout fields and decide on the need of a second glyphosate treatment based on weed density and potential for yield loss due to late season competition.…”

“…Research in the USA has shown that weed control with glyphosate is affected more by rate than time of application (Ateh and Harvey 1999;Mulugeta and Boerboom 2000;Vangessel et al 2000;Krausz and Young 2001). Sequential applications have provided greater and more consistent weed control than have single applications (Wait et al 1999;Payne and Oliver 2000;Wiesbrook et al 2001). However, level of weed control was dependant on time of application of single treatments and on crop row width, with Abbreviations: CHU, corn heat unit 1199 greater control at narrow-row spacings (Ateh and Harvey 1999;Young et al 2001).…”

Effect of Row Spacing, Seeding Rate, and Herbicide Program in Glufosinate-Resistant Soybean on Palmer Amaranth Management

“…The use of soil-residual herbicides not only can increase the number of MOAs used in a herbicide program, but can also offer extended weed control compared to POST herbicides (i.e., glyphosate or glufosinate) that lack residual activity (Taylor-Lovell et al 2002;Wiesbrook et al 2001). The efficacy of soil-residual herbicides is highly dependent on either rainfall or irrigation shortly after application, which places the herbicide molecules into soil solution where they can be taken up as weeds germinate and emerge (Krausz et al 2001;Stewart et al 2010).…”