Effective Herbicide Options for Controlling Glyphosate-Resistant Palmer Amaranth in Roundup Ready 2 Xtend Soybean

Authors

V. Kumar, Kansas State UniversityFollow
R. Liu, Kansas State UniversityFollow
T. Lambert, Kansas State UniversityFollow
D. E. Peterson, Kansas State UniversityFollow
C. L. Minihan, Kansas State UniversityFollow
P. W. Stahlman, Kansas State Univ. Agric. Research Center–HaysFollow

Keywords

dicamba-tolerant soybean, herbicide programs, glyphosate-resistant Palmer amaranth

Abstract

Glyphosate-resistant (GR) Palmer amaranth has become a serious challenge for soybean producers in the mid-south and central United States, including Kansas. Field experi­ments were conducted at the Kansas State University Agricultural Research Center (KSU-ARC) near Hays, KS, and Kansas State University Ashland Bottoms (KSU-AB) research farm near Manhattan, KS, to determine the effectiveness of preemergence (PRE) and PRE followed by (fb) postemergence (POST) herbicide programs on GR Palmer amaranth control in Roundup Ready 2 Xtend soybean. The study site at Hays was infested with GR Palmer amaranth population prior to soybean planting; whereas, the Manhattan site had natural infestation of GR Palmer amaranth. Eleven treat­ments, including PRE alone and PREfbPOST-applied herbicides were investigated. All PRE treatments included Roundup PowerMax for control of other weed species, while POST treatments were mixtures of Roundup PowerMax and Engenia herbi­cides. A single PRE application of Fierce XLT and Panther PRO had ≥ 90% control of GR Palmer amaranth; whereas, control with Authority Elite and Zidua PRO did not exceed 83% at 6 weeks after POST (WAPOST). Combined over two locations, all PREfbPOST treatments had excellent control (≥ 96%) of GR Palmer amaranth at 6 WAPOST. No significant differences for soybean grain yield were observed among herbicide treatments at the Hays site; whereas, an approximate 10% increase in grain yield was observed with PREfbPOST vs. PRE alone programs at the Manhattan site. Based on these results, the two-pass programs (PREfbPOST) investigated in this research can be effectively used for season-long control of GR Palmer amaranth in Roundup Ready 2 Xtend soybean.

Recommended Citation

Kumar, V.; Liu, R.; Lambert, T.; Peterson, D. E.; Minihan, C. L.; and Stahlman, P. W. (2019) "Effective Herbicide Options for Controlling Glyphosate-Resistant Palmer Amaranth in Roundup Ready 2 Xtend Soybean," Kansas Agricultural Experiment Station Research Reports: Vol. 5: Iss. 6. https://doi.org/10.4148/2378-5977.7792