On July 10, 2024 ICCON was pleased to kick off the 2024 summer series “Weeds & Disease & Pests, Oh My!” by welcoming Emily Unglesby and John Wallace of the Getting Rid of Weeds (GROW) network to share information about what the GROW network is and an overview of the research GROW is conducting regarding the use and management of cover crops as a tool for weed management in conservation cropping systems.
To kick things off, Emily Unglesby, director of outreach and extension for GROW, provided the group with a comprehensive overview of the network. In a nutshell, GROW is a publicly led network of scientists working to help farmers and the agricultural industry test and adopt non-chemical alternatives to weed control, to help slow and overcome the industry-wide problem of herbicide-resistant weeds. Collaborators are conducting research projects and working to develop integrated weed management strategies all over the US. GROW focuses efforts into three main areas for their grant funded research – cover crops, harvest weed seed control, and precision Integrated Weed Management (IWM) and sustainable agriculture. Apart from research the GROW network engages in, Unglesby gave us a glimpse of the comprehensive nature of the outreach efforts GROW takes to provide farmers and ag professionals with the tools they need to effectively implement integrated weed management strategies.

GROW has various resources and opportunities for you to get involved! GROW offers weed management tools, a weed ID library, farmer case studies, a weekly newsletter, and more.
Following Unglesby’s overview, Dr. John Wallace, assistant professor of weed science and extension specialist for field and forage crops at Penn State gave an overview of some of his research into the use of cover crops as part of an integrated weed management (IWM) system. Dr. Wallace explained that much of the research being done today is looking at fields where the cover crop is “planted green.” Planting green allows farmers to get their cash crop (often soybeans in IL) planted early while still allowing the cover crop to grow and accumulate additional biomass. The increased quantity of biomass is the key to the cover crop’s ability to function as a weed suppression tool.
Given the need to be adaptable in cover crop systems and the ever changing spring weather conditions farmers experience, Dr. Wallace indicates that while achieving weed suppression with cover crop biomass is possible and effective, it should not always be the primary objective for cover cropping farmers looking to use covers for that purpose. Optimal planting conditions and soil moisture are greater considerations when planting green and making cover crop termination timing decisions. In other words, farmers do not want to sacrifice stand establishment or their ability to get a crop planted for the sake of accumulating more cover crop biomass for weed suppression.
Dr. Wallace also gave an overview of a current 9-state experiment that is under way in its second year. Researchers are looking to help provide some context and answers around weed management as well as water management questions. Finding the proper balance between these different areas can be a challenge and is often a moving target each year.
Lastly, Dr. Wallace touched on additional research that is wrapping up regarding the interactions of residual herbicides and cover crop residue. There are still many unknowns about the efficacy of certain residual chemistries. In a higher biomass scenario, the residues may interfere with the herbicide droplets getting to the soil during application. This subsequently causes greater wash off potential of the herbicide from rain after application. From these summaries of the models, the GROW network encourages folks to check back to their website where they will publish a fact sheet that summarizes their research.
The GROW network is committed to helping develop strategies for long-term success as they understand the ways effective weed management systems are critical to having a successful and sustainable farming operations. GROW houses a wonderful one stop shop of resources ranging from weed identification to farmer case studies. They also send out weekly newsletters to help subscribers stay in the loop about projects within the GROW network as well as weed management work and research from outside the network.
GROW network’s full presentation can be viewed on ISAP’s YouTube channel. The ICCON Summer series will continue in August with disease management in cover crop systems. Register for upcoming ICCON call here. If you are interested in joining the Illinois Cover Crop On-Farm Network to learn about new research and hear from cover crop specialists across the Midwest, please join our google group by sending an email to hvanbeck@farmland.org.