Multiple herbicide resistance in waterhemp (<i>Amaranthus tuberculatus</i>) accessions from Wisconsin

Abstract A comprehensive, Wisconsin state-wide assessment of waterhemp response to a diverse group herbicide sites action has not been conducted. Our objective was characterize the collection accessions postemergence (POST) and preemergence (PRE) herbicides commonly used in corn soybean Wisconsin. Greenhouse experiments were conducted with more than 80 from 27 counties. POST treatments included 2,4-D, atrazine, dicamba, fomesafen, glufosinate, glyphosate, imazethapyr, mesotrione at 1× 3× label rates. PRE mesotrione, metribuzin, S-metolachlor 0.5×, 1×, Ninety-eight percent 88% exhibited ≥50% plant survival after exposure imazethapyr glyphosate rate, respectively. Seventeen percent, 16%, 3% respectively, applied rate. Survival all ≤25% 2,4-D or dicamba either rate evaluated. No any accession survived glufosinate Forty-five &lt;90% density reduction atrazine fomesafen Plant ≥96% S-metolachlor, results suggest that resistance is widespread Wisconsin, whereas present lower extent. One (A75, Fond du Lac County) multiple when POST. Overall, ineffective for control Proactive management use effective are fundamental