Refining Interseeding Winter Wheat Practices as a Sustainable Approach for Suppressing Common Waterhemp in Soybean

Project Overview

Project Type: Graduate Student
Funds awarded in 2020: $15,000.00
Projected End Date: 05/15/2022
Grant Recipients: Southern Illinois University; Southern Illinois University Carbondale
Region: North Central
State: Illinois
Graduate Student:
Faculty Advisor:
Dr. Karla Gage
Southern Illinois University Carbondale


  • Agronomic: soybeans


  • Education and Training: demonstration
  • Pest Management: chemical control, competition, mulches - living

    Proposal abstract:

    Refining Interseeded Winter Wheat Practices as a Sustainable Approach for Suppressing Common Waterhemp in Soybean

    The goal of this project is to collaborate with farmers to test the utilization of a novel integrated weed management (IWM) strategy which entails the sowing of winter wheat in the spring at the time of soybean planting. Preliminary research at Southern Illinois University (SIU), concluded that in most instances, intercropped winter wheat paired with a postemergence herbicide provided common waterhemp control that was greater than or equal to traditional preemergence followed by postemergence herbicide programs (Mueth et al. 2018; Decker et al. 2019). Previously, SIU has been drop spreading interseeded wheat at 3,706,500 seeds ha-1 and lightly incorporating the wheat seeds with a cultipacker. Once the winter wheat has been spread and incorporated, soybeans are planted. Postemergence herbicide applications are made when weed escapes have reached appropriate spray height (10-15 cm). In previous research, Roundup Ready® Xtend -soybean varieties were -utilized so that the mixture of glyphosate and dicamba could be sprayed to terminate the weeds and the wheat. The overall goals of this project are to refine the IWM practice of interseeding winter wheat and to share these results with farmers in a manner that will not only allow them to practice IWM but to also help them strategize the most efficient implementation. We would like to see this IWM tactic being utilized by farmers with the practices and equipment they have available. This means that we will ask the farmers to follow the guidelines for seeding rates and herbicide applications but will allow them to make decisions such as, tillage practices, drilled versus broadcasted winter wheat, and soybean row width. This research will be evaluated by visual weed control ratings paired with weed counts. At the end of the season, soybean yield will be measured. Additionally, subsamples of yielded soybeans will be collected to investigate the influence of interseeding on soybean grain quality, after preliminary SIU research has found alterations in seed protein and oil content. SIU has various outlets for grower outreach that would be suited for showcasing the results of this large scale study including field days, social media, and the SIU weed science online annual research report. Results of this research will directly benefit growers that are eager to adopt new cultural weed control tactics or are in need of alternative weed control practices to control herbicide-resistant populations.

    Project objectives from proposal:

    The initial outcome of this research is the testing demonstration and outreach of a novel IWM practice. Volunteer farmers will be consulted on study implementation prior to, during, and after the project completion to gather opinions, understanding, and future suggestions. Additionally, one or more volunteer farmers will be available to answer questions from other farmers during the proposed project demonstration at the SIU Belleville Field Day and the SIU Agronomy Research Field Day. Demonstration and presentations that highlight practices at SIU field days will help to introduce the practice to regional farmers and encourage adoption of integrated weed control strategies. Preliminary research at SIU was presented at the SIU Agronomy Research Field Day in 2019 resulting in positive remarks and articles in the Illinois Agrinews (SIU Studying Crop Based Strategy to Suppress Common Waterhemp) and Illinois Farmer Today (Under Cover: Interseeding Wheat May Help in Battle Against Resistant Weeds). We would like to continue targeted communication efforts with farmers to address misinterpretations and misconceptions about IWM practices. Targeted communication should highlight the cost effectiveness and approach methods of IWM to help increase its adoption thus increasing sustainability of the agro-ecosystem (Wilson et al. 2009). Additionally, working on a farm with growers will promote farmer-scientist interaction which is so incredibly important for keeping agronomic science grounded in tactics that are practical.


    Wilson, R.S. 2009. Targeting the farmer decision making process: a pathway to increased adoption of integrated weed management. Crop Protection 28(9): 756–764.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.