Work

Changing landscape of waterhemp herbicide resistance in Wisconsin: a comparative analysis over time

Year: 2026

Type: article

Abstract: A comprehensive assessment of herbicide resistance in waterhemp accessions to herbicides commonly used on corn and soybean over time is crucially necessary for documenting shifts in herbicide resistance patterns and identifying effective management options. Therefore, a greenhouse study was conducted to evaluate the response of statewide waterhemp accessions collected in 2023 to commonly used preemergence and postemergence herbicides and to assess changes in resistance over a 5-yr period by comparing these results with previous statewide data from 2018. One hundred percent, After a postemergence application of atrazine, 2,4-D, dicamba, fomesafen, and mesotrione at 1× rates, 100%, 88%, 83%, 41%, and 24%, respectively, of 2023 accessions exhibited ≥50% survival. Glufosinate provided complete control, with 0% survival and ≥97% biomass reduction among all accessions. The 1× rate of mesotrione, metribuzin, and S -metolachlor applied preemergence resulted in >95% density reduction in all accessions. The 1× rate of atrazine and fomesafen resulted in <90% density reduction in 50% and 82% of accessions, respectively. The 2023 accessions exhibited a significant increase in survival when several postemergence herbicides were applied at the 1× rate, including 2,4-D (from 11% to 52%), dicamba (from 8% to 49%), atrazine (from 11% to 81%), fomesafen (from 3% to 21%), and mesotrione (from 2% to 11%), compared with the 2018 accessions. Similarly, a change in waterhemp density reduction was observed between the 2018 and 2023 accessions when preemergence herbicides were applied, including atrazine (from 84% to 91%), fomesafen (from 97% to 81%), and S -metolachlor (from 98% to 95%). No changes were observed in the density reduction of the 2018 and 2023 accessions in response to mesotrione and metribuzin at the 1× and 3× rates. The rapid adaptation herbicide resistance within 5 yr by waterhemp highlights the urgent need to incorporate effective integrated weed management strategies in Wisconsin cropping systems.

Source: Weed Technology

DOI: 10.1017/wet.2026.10132

Authors: Luma Lorena Loureiro S. Rodrigues, Ahmadreza Mobli, Felipe de Andrade Faleco, Rodrigo Werle

Institutions: University of Wisconsin–Madison, Universidade Federal Rural do Semi-Árido

Language: English

Topic: Weed Control and Herbicide Applications

Subfield: Plant Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Zero hunger

Open Access status: gold

Estimated APC paid: $3,550