Pest Management

Documenting the Extent of Resistance to Group 15 Herbicides in Illinois Waterhemp Populations

To better understand the frequency of resistance to Group 15 herbicides, this project will collect and screen waterhemp populations from Illinois soybean fields. Results will be used to provide farmers with recommendations on how best to incorporate these herbicides into integrated weed management programs. Resistant populations will be used in subsequent research to identify the gene(s) conferring the metabolism-based resistance.

Project Information

  • How widespread is Group 15 herbicide resistance in waterhemp populations across Illinois?
  • What level of resistance is present in Group 15-resistant waterhemp populations?

  • Waterhemp seeds will be collected from at least 100 locations across the state

  • Waterhemp populations in Illinois have evolved resistance to herbicides from more site-of-action-groups than any other weed species.
  • The confirmation of resistance to Group 15 herbicides in 2019 makes managing this weed one of the most daunting challenges Illinois soybean farmers face. Noticing potential resistance to this group of chemistry is more difficult because they are residual herbicides, and resistance could exhibit as shorter length of control rather than lack of control common with other classes of chemistry.
  • In addition, fields can contain waterhemp populations resistant to herbicides from multiple herbicide groups, with individual plants carrying genes for resistance to multiple herbicides.

  • Understanding the frequency of Group 15-resistant waterhemp will give farmers, their advisors and Extension the ability to refine integrated weed management recommendations to help slow resistance development in more waterhemp populations.
  • After gaining a better understanding of how extensive Group 15 resistance is in Illinois waterhemp populations, researchers intend to conduct a genome-wide association study to identify the gene(s) responsible for Group 15 resistance. This data could lead to rapid molecular assays for future resistance diagnosis.

  • Dr. Patrick Tranel, Professor, UIUC
  • Travis Wilke, Master’s Student, UIUC

About the Lead Researcher

Dr. Aaron Hager
Professor & Weed Science Extension Specialist
University of Illinois Urbana-Champaign (UIUC)
217-333-9646
hager@illinois.edu

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