Evaluation of 2,4-D Amine, Glyphosate, 2,4-D Amine plus Glyphosate DMA and 2,4-D Choline/Glyphosate DMA for Their Efficacy on Glyphosate Susceptible and Resistant Canada Fleabane Populations

Abstract

The 2,4-D choline/glyphosate DMA formulation has reduced drift and volatility compared to the amine or ester formulation of 2,4-D and therefore is advantageous compared to a tank mix of 2,4-D amine or ester with glyphosate. The objective of this research was to compare the control of glyphosate susceptible and glyphosate resistant Canada fleabane with 2,4-D choline/glyphosate DMA with 2,4-D amine, glyphosate, and a tank mix of 2,4-D amine and glyphosate. Ten rates of 2,4-D amine (0-6708 g•ae•ha⁻¹), glyphosate (0-7052 g•ae•ha⁻¹), a tank mix of glyphosate plus 2,4-D amine (0-7052 g•ae•ha⁻¹ + 0-6708), and 2,4-D choline/glyphosate DMA (0-13760 g•ae•ha⁻¹) were examined in the greenhouse for the control of two susceptible (GS) and two resistant to glyphosate (GR) Canada fleabane biotypes. The tank mix of 2,4-D amine plus glyphosate and 2,4-D choline/glyphosate DMA provided equivalent control of the GR Canada fleabane biotypes at 35 days after the application (DAA). The 2,4-D choline/glyphosate DMA treatment was more efficacious than the tank mix on the GS biotypes. Glyphosate (880 g•ae•ha⁻¹) provided 50% and 100% control of the resistant and susceptible biotypes, respectively. The 2,4-D choline/glyphosate DMA formulation and the tankmix of 2,4-D amine and glyphosate provided similar control of GR Canada fleabane.

Postemergence herbicides for control of glyphosate-resistant Canada fleabane in corn

“…GR Canada fleabane population density and aboveground biomass for all of these glyphosate tank mixtures were greater than the weed-free control. These results are consistent with a report of decreased sensitivity of GR Canada fleabane to 2,4-D (Ford et al 2014) and with a study by Johnson et al (2004) indicating poor control of GR Canada fleabane with glufosinate. However, contrary to the results of the current study, Johnson et al (2004) found that atrazine, mesotrione + atrazine, and halosulfuron each provided greater than 90% control of GR Canada fleabane.…”

“…As a result, GR Canada fleabane must now be controlled in the major field crops of southern Ontario: corn (Zea mays L.), soybean [Glycine max (L.) Merr. ], and winter wheat (Triticum aestivum L.) (Byker et al 2013a;Ford et al 2014;Mahoney et al 2016).…”

“…Unfortunately for Ontario growers, there is limited published information on the control of GR Canada fleabane in corn (Brown et al 2016), especially with post-emergence (POST) herbicides. A recent study by Ford et al (2014) examined the control of GR Canada fleabane in corn with a new glyphosate and 2,4-D premix applied POST. While this is valuable information for Ontario corn growers, the resistance technology trait used in that study is still not widely available.…”

Herbicide tank mixtures to control co-existing glyphosate-resistant Canada fleabane and giant ragweed in soybean

“…For example, Byker et al (2013b) reported control 4 WAT as low as 62% with glyphosate + 2,4-D (900 + 560 g ai ha −1 ); but in a related study, Byker et al (2013a) found that control with glyphosate + 2,4-D (900 + 500 g ai ha −1 ) ranged from 78% to 92% at 4 WAT. Ford et al (2014), recently reported that Canada fleabane demonstrated varying levels of 2,4-D tolerance, which could explain this range in control. For two-way tank mixture of glyphosate + amitrole, Byker et al (2013a) found that control with 900 + 2000 g ai ha −1 at 4 WAT was similar to the current study.…”

“…However, due to the presence of multiple resistant biotypes in both species (Byker et al 2013c;Follings et al 2013b) and to observations of varying levels of 2,4-D tolerance in Canada fleabane (Ford et al 2014), we were interested in identifying three-way tank mixtures that could potentially delay further resistance development (Beckie 2011). Therefore, for Ontario soybean growers that may need to (Tables 2 and 3).…”