Agronomy and Horticulture Department


Date of this Version



Kumar, V., Aulakh, J. S., Liu, R., & Jhala, A. J. (2023). Late postemergence glufosinate-based programs for glyphosate-resistant Palmer amaranth control in dicamba/glufosinate/glyphosate-resistant soybean. Agrosystems, Geosciences & Environment, 6, e20378.


open access.


Glyphosate-resistant (GR) Palmer amaranth (Amaranthus palmeri S. Watson) is widespread in the Central Great Plains. Introduction of newly developed dicamba/glufosinate/glyphosate (DGG)-resistant soybean varieties allows postemergence (POST) applications of dicamba and glufosinate for in-season control of GR Palmer amaranth. Limited information exists on the effectiveness of glufosinate applied late-POST for tall (70–90 cm) GR Palmer amaranth control in DGG-resistant soybean. The objectives of this study were to (1) determine the effectiveness of late-POST glufosinate-based programs for GR Palmer amaranth control, and (2) determine the impact of those programs on soybeans grain yields. Ten glufosinatebased programs were tested in a field study at Kansas State University Agricultural Research Center near Hays, Kansas. Results indicated that single (655 or 737 g ha−1) and all sequential (594 followed by [fb] 594, 655 fb 594, and 737 fb 594 g ha−1) applications (7-days apart) of glufosinate provided 87%–93% control of GR Palmer amaranth 28 days after last POST (DALPOST). Palmer amaranth control with single late-POST application of glufosinate (594 g ha−1) or glufosinate plus S-metolachlor did not exceed 84% at 28 DALPOST. Majority of the evaluated programs reduced shoot dry weights of GR Palmer amaranth by 83%–91%. The least control (11%) and shoot dry weight reduction (33%) of GR Palmer amaranth were observed with glyphosate fb glyphosate. Glufosinate-based programs resulted in soybean grain yield of 626–701 kg ha−1. These results conclude that glufosinate applied late-POST may provide effective control of tall GR Palmer amaranth in DGG-resistant soybeans.