Interaction of 2,4-D with Glyphosate or Graminicides on Grass Weed Control in Enlist E3 Soybeans

The introduction of Enlist E3 soybean allows growers to use postemergence (POST) applications low-volatile formulations 2,4-D choline (Enlist One) for in-season control glyphosate-resistant weeds. POST One and glyphosate (Roundup PowerMax) mixture can be tank-mixed with clethodim (Select Max) or quizalofop (Assure II) both grass broadleaf weed control. However, reduced species has previously been reported when graminicides Max Assure are auxinic herbicides (2,4-D dicamba). main objective this research was determine the effectiveness One, Roundup PowerMax, Select Max, and/or II alone in various combinations on soybean. Field experiments were conducted during 2020 growing season at Kansas State University Agricultural Research Center (KSU-ARC) near Hays, KS, Nebraska Lincoln, NE (UNL). dominant KSU-ARC site southwest cupgrass green foxtail. predominant UNL giant foxtail, hairy fall panicum. Herbicide treatments, including II, PowerMax applied V3-V4 stage combination One; sequential treatments followed by (separated 5 days) vice-versa investigated. Results from indicated that treatment days prior application provided highest (87% 90%) foxtail 28 after (DAT). In contrast, did not exceed 78% rest treatments. Soybean grain yields ranged 7 16 bu/a majority showed addition these (69% 79%), (70% panicum 79%) DAT compared (93 97%). Furthermore, an tank-mixtures improved all three species. 21 55 conclusion, results support hypothesis compromise efficacy II; however, help optimize