Effective Preemergence and Postemergence Herbicide Programs for Kochia Control

Abstract

Field experiments were conducted in 2011 through 2013 at the MSU Southern Agricultural Research Center near Huntley, MT, to evaluate the effectiveness of various PRE and POST herbicide programs for kochia control in the absence of a crop. PRE herbicides labeled for corn, grain sorghum, soybean, wheat/barley, and/or in chemical fallow were applied at recommended field-use rates. Acetochlor + atrazine,S-metolachlor + atrazine + mesotrione, and sulfentrazone applied PRE provided ≥91% control of kochia at 12 wk after treatment (WAT). Metribuzin, metribuzin + linuron, and pyroxasulfone + atrazine PRE provided 82% control at 12 WAT. PRE control with acetochlor + flumetsulam + clopyralid, pyroxasulfone alone, and saflufenacil + 2,4-D was ≤23% at 12 WAT. Paraquat + atrazine, paraquat + linuron, and paraquat + metribuzin controlled kochia ≥98% at 5 WAT. POST control with bromoxynil + fluroxypyr, paraquat, tembotrione + atrazine, and topramezone + atrazine treatments averaged 84% at 5 WAT, and did not differ from glyphosate. Control with POST-applied bromoxynil + pyrasulfotole, dicamba, diflufenzopyr + dicamba + 2,4-D, saflufenacil, saflufenacil + 2,4-D, saflufenacil + linuron was 67 to 78% at 5 WAT. Because of the presence of kochia resistant to acetolactate synthase-inhibiting herbicides at the test site, cloransulam-methyl was not a viable option for kochia control. In a separate greenhouse study, kochia accessions showed differential response to the POST herbicides (labeled for corn or soybean) tested. Tembotrione + atrazine, topramezone + atrazine, lactofen, or fomesafen effectively controlled the glyphosate-resistant kochia accession tested. Growers should utilize these effective PRE- or POST-applied herbicide premixes or tank mixtures (multiple modes of action) to control herbicide-resistant kochia accessions in the field. PRE herbicides with 8 wk of soil-residual activity on kochia would be acceptable if crop competition were present; however, a follow-up herbicide application may be needed to obtain season-long kochia control in the absence of crop competition.