Database Research Summaries
2018 Control of Pigweed with an Integrated Systems Approach in Soybean

calendar_today Year of Research: 2018
update Posted On: 12/04/2019
group Anita Dille (Principal Investigator, Kansas State University)
bookmark Kansas Soybean Commission

Research Focus

The focus of this project is to develop an integrated approach to effectively manage pigweed in soybean.


  • Evaluate the effect of an integrated systems approach including herbicide, cover crop, row-crop cultivation, and row spacing in managing pigweed in soybean.
  • Educate soybean producers and agronomy professionals of the outcomes of this experiment to optimize soybean yields and increase grower profitability in terms of pigweed control.


  1. All treatments containing the herbicide program component resulted in excellent (> 97%) pigweed control, which demonstrates the importance of using overlapping residual herbicides with multiple effective sites of action.
  2. Treatments containing row-crop cultivation (RC) tended to reduce pigweed density and biomass at 3 and 8 weeks after planting (WAP) in all locations compared to the 30-inch row width no cover crop treatment. Mixed results were observed when the effect of winter wheat cover crop (CC) was considered: in about half of the site-years, CC provided approximately 50% reductions in pigweed density and biomass whereas in the remainder CC provided no change to an increase in pigweed density.
  3. Decreased row widths achieved the most consistent results by reducing pigweed biomass at 8 WAP when data were pooled across location: decreasing row widths from 30-inches to 15-inches resulted in a 23% reduction whereas decreasing from 15-inches to 7.5-inches achieved a 15% reduction.
  4. In conclusion, RC should be incorporated where possible as a mechanical option to manage pigweed, and decreased row widths should be used when economically feasible to suppress late season pigweed growth. CC achieved inconsistent pigweed control in this research and should be given special consideration prior to implementation.


This system will be critical to the sustainability of soybean production in Kansas through the adoption of a zero-tolerance policy for pigweed presence in fields.

For more information about this research project, please visit the National Soybean Checkoff Research Database.

Funded in part by the soybean checkoff.