Develop integrated weed management strategies that combine cover crops, herbicides, and tillage to control herbicide-resistant waterhemp, protect soybean yields, and support long-term sustainability.

• Waterhemp is the top weed threat to Illinois soybean farmers, as identified in recent ISA surveys.
• Waterhemp has developed resistance to eight herbicide sites of action, including glufosinate (Liberty), signaling the loss of the last remaining POST herbicide option in soybeans.
• Resistance to 2,4-D + glufosinate has been identified in southern Illinois—an alarming, globally novel discovery.
• Conventional weed management strategies are becoming ineffective, creating an urgent need for integrated solutions.
• This project explores integrated weed management (IWM) strategies combining:
  • Cover crops (cereal rye, including scissor-cross planting)
  • Tillage (strip-till vs. no-till)
  • Herbicide approaches (banded vs. broadcast, with vs. without PRE)
• The project also supports Endangered Species Act (ESA) compliance, where cover crops and reduced tillage contribute runoff/erosion mitigation points for herbicide applications.

• Provides practical, side-by-side comparisons of cover crop, herbicide, and tillage systems for maximum waterhemp suppression.
• Helps farmers maintain profitability by identifying effective alternatives to conventional herbicide programs.
• Supports ESA compliance for herbicide applications by using cover crops and reduced tillage to achieve required mitigation points.
• Reduces herbicide use and input costs by testing banded applications, which can use up to 60% less herbicide while maintaining control.
• Improves long-term weed management by integrating cultural and chemical practices, reducing the risk of future herbicide resistance.
• Enhances sustainability by improving soil protection and water quality alongside weed suppression.

• Dr. Karla Gage, Associate Professor, Southern Illinois University
• Amir Sadeghpour, Associate Professor, Southern Illinois University
• Eric Brevik, Professor, Southern Illinois University

• SIU Agronomy Research Center, Carbondale, IL

Dr. Karla Gage
Associate Professor
Southern Illinois University
618-453-7679
kgage@siu.edu