Examining the plant-back interval for glyphosate/glufosinate-resistant corn after the application of ACCase inhibitors

Abstract

Field experiments in 2013 and 2014 examined corn (Zea mays L.) tolerance to acetyl-coenzyme A carboxylase (ACCase) inhibiting herbicides in a scenario where they would have been used to terminate a failed corn stand prior to replanting. To simulate this, herbicides were applied 1 wk or 1 d preplant (PP) and several parameters were measured. Corn injury 1, 2, 4, or 8 wk after emergence (WAE) was similar to the untreated control, regardless of herbicide, rate, or PP application timing. Across herbicides and rates, PP timing did not affect plant stand and aboveground biomass 2 WAE, plant height 4 WAE, or yield. Across application timings, plant stand and aboveground biomass were similar to the untreated control, regardless of herbicide treatment or rate; however, some herbicides reduced height and (or) yield. For example, compared with the untreated control, fluazifop-p-butyl (75 and 150 g ha−1) and sethoxydim (300 g ha−1) each reduced height by about 3%, while clethodim (30 and 60 g ha−1), fluazifop-p-butyl (150 g ha−1), and quizalofop-p-ethyl (72 g ha−1) each reduced yield by about 2%. Therefore, in situations where a grower may need to terminate a failed corn stand, the selection of ACCase-inhibiting herbicides could be based on efficacy rather than plant-back restrictions.