Two pass weed control programs in conventional corn

Earlier this year we met with the O’Brien brothers, Dan and Mark, to discuss our waterhemp research plans at their farm for the 2021 growing season. During our meeting, Dan and Mark asked if we could conduct a study looking at herbicide programs in conventional corn given they produce seed corn in an atrazine prohibition area in Wisconsin and were having a difficult time controlling waterhemp and annual grasses.

With the assistance of our lab, Ryan DeWerff (Weed Science Research Specialist) developed and conducted a study evaluating multiple two pass herbicide programs for weed control in corn without glyphosate and atrazine. The 2021 studies were conducted at the UW Arlington Agricultural Research Station near Arlington, WI and at the O’Brien Family Farms near Brooklyn, WI. Weed control data were collected at and following POST application. Corn yield data were collected only at Arlington; the study at Brooklyn was destroyed before the crop tasseled to avoid cross pollination with the O’Brien’s seed corn production.

With the ongoing glyphosate shortage, the data from this study is also very relevant to growers who may opt not to use glyphosate in glyphosate-resistant corn and save it for their soybeans.

Click HERE to download the complete PDF report with data and plot pictures compiled by Ryan DeWerff: 2021 WiscWeeds Comparison of Herbicide Programs for Conventional Corn

This study will be replicated in 2022! Stay tuned and Happy Holidays!


  • Ryan DeWerff, Weed Science Research Specialist, Department of Agronomy, University of Wisconsin-Madison
  • Nick Arneson, Weed Science Program Outreach Manager, Department of Agronomy, University of Wisconsin-Madison
  • Rodrigo Werle, Assistant Professor and Extension Cropping Systems Weed Scientist, Department of Agronomy, University of Wisconsin-Madison