Tank mixture of glyphosate with 2,4-D accentuates 2,4-D injury in glyphosate-resistant corn

Abstract

Six field trials were conducted at Ridgetown, ON, over a 2-yr period (2015 and 2016) to determine the tolerance of two corn hybrids to 2,4-D (560 and 1120 g a.i. ha−1) and glyphosate (1800 g a.e. ha−1) applied alone or in combination at stage V1, V3, or V5. In DeKalb DKC52-61 corn, 2,4-D caused as much as 24%, 16%, 11%, and 11% visible injury at 1 wk after each postemergence herbicide application (WAT), 2 WAT, 4 wk after the last postemergence herbicide application (WA-C), and 8 WA-C, respectively. Plant stand was not affected, but plant height decreased by 5 cm at 560 g a.i. ha−1 and 7% at 1120 g a.i. ha−1. As the application timing was delayed from stage V1 to V5, there was a trend to increased injury at both 2,4-D rates. Corn yield decreased 8% with 2,4-D applied at 560 g a.i. ha−1 and 12% at 1120 g a.i. ha−1. In Pioneer P0094AM corn, 2,4-D caused as much as 16%, 9%, 7%, and 7% visible injury at 1 WAT, 2 WAT, 4 WA-C, and 8 WA-C, respectively. Plant height was not affected, but goosenecking and brace root malformation were increased as the rate of 2,4-D was increased. There was generally no difference between glyphosate rates (1800 vs 0 g a.e. ha−1) at the V1 corn stage but visible injury, goosenecking, and brace root malformation at other application timings was as much as 15%, 3%, and 19% greater when 2,4-D was applied in a tank mixture with glyphosate, respectively. Yield was reduced by 12% when 2,4-D (1120 g a.i. ha−1) was applied with glyphosate in the tank mixture.

Influence of Adjuvants on the Control of Glyphosate-Resistant Canada Fleabane and Waterhemp in Corn with Tolpyralate

“…Metzger et al [47] found tolpyralate + atrazine + MSO + UAN to have a wide margin of crop safety on some commonly used corn hybrids in Ontario when used according to label recommendations, although environmental variables may affect corn injury levels. In contrast to research by Soltani et al [34] that reported increased crop injury when glyphosate was added to 2,4-D, the addition of glyphosate to tolpyralate + atrazine did not enhance crop injury. Any visible crop injury symptoms in these studies did not affect corn yield.…”

“…Armel et al [52] also reported improved control of common ragweed and giant foxtail with mesotrione (105 or 140 g•ai•ha −1 ) when in a tankmix with glyphosate compared to mesotrione alone. Soltani et al [34] reported an interaction between glyphosate and 2,4-D where corn injury is enhanced with the addition of glyphosate, speculated to be caused by the aggressive adjuvant system in a commercial glyphosate formulation. In contrast to results from Soltani et al [34], crop injury was not accentuated with the addition of glyphosate to tolpyralate + atrazine, however there was an influence on weed control.…”

“…Soltani et al [34] reported an interaction between glyphosate and 2,4-D where corn injury is enhanced with the addition of glyphosate, speculated to be caused by the aggressive adjuvant system in a commercial glyphosate formulation. In contrast to results from Soltani et al [34], crop injury was not accentuated with the addition of glyphosate to tolpyralate + atrazine, however there was an influence on weed control. Glyphosate tank mixtures are reported to be complementary for herbicides like saflufenacil, chlorimuron and imazethapyr, exhibiting an additive effect [35] [38].…”

“…For example, Roundup WeatherMAX® contains proprietary surfactants to improve the penetration of the herbicide into the plant tissue [33]. In a tankmix, glyphosate formulations have been found to influence crop injury [34], weed control [35] [36] or absorption and translocation of the tank mix partners. Adjuvants add an additional cost to the complete weed control program.…”

The Growth and Yield of Sweet Corn under Minimum Tillage Technology by Using Various Doses of Herbicide Mixtures of Glyphosate and 2,4-D

“…Glyphosat and 2,4 -D herbicides have a different mechanism but a mixture of both had been reported compatible and showed a synergistic effects on the target weeds (Wehtje and Gilliam, 2012). Mixures of these two herbicides may increase herbicide efficacy, reduce a dose of application either on glyphosate or 2,4-D, and also prevent the evolve of resistant weeds (Robinson et al, 2012;Soltani et al, 2018).…”