Database Research Summaries2018 Investigation of Herbicide Resistance in Waterhemp and Palmer amaranth in Kansas: Survey, Mechanism, and Management
The focus of this project is to better predict and manage 2,4-D resistance in putative waterhemp and Palmer amaranth populations by understanding the level and the mechanism of resistance.
- Determine the baseline sensitivity of waterhemp and Palmer amaranth populations from Kansas’s fields to glyphosate, 2,4-D, and dicamba.
- Investigate the mechanism of 2,4-D resistance in Palmer amaranth.
- Evaluation of integrated herbicide programs for managing herbicide-resistant (HR) waterhemp and Palmer amaranth in Roundup Ready 2 Xtend® soybeans.
- Develop and deliver education materials for management/containment of HR waterhemp and Palmer amaranth in Kansas soybean production.
- Results suggest that resistance to glyphosate is fairly common among Kansas Palmer amaranth populations and there are few populations that showed unacceptable control with 2,4-D herbicide.
- Results confirmed the first case of a Palmer amaranth population from Kansas with multiple resistances to RoundUp PowerMax, Glean, Aatrex, Callisto, and Defy herbicides.
- Dose-response analysis of visual injury data suggested that KCTR is 13.6-fold and 10.2-fold resistant compared to KSS and MSS respectively. The dry shoot biomass data indicated that KCTR is 14.6-fold and 9.3-fold resistant compared to KSS and MSS respectively.
- Preliminary data suggests there is no difference in maximum 14C 2,4-D absorption in these populations. However, MSS showed relatively higher time required achieving maximum absorption compared to KCTR and KSS. Experiments are in progress to assess the 2,4-D translocation and metabolism in KCTR in comparison with MSS and KSS Palmer amaranth. In summary, KCTR is ~ 10-14-fold resistant to 2,4-D compared to MSS and KSS.
- The use of two-pass herbicide programs, including PRE herbicides such as Fierce XLT, Panther PRO, Authority Elite, or Zidua PRO followed by a sequential POST application of Roundup PowerMax + Engeniaare recommended for effective and season-longcontrol of GR Palmer amaranth in Roundup Ready 2 Xtend soybean.
- Information generated through this research project was communicated to Kansas’s growers through various outlets. The results have also been published in annual field research reports and one refereed journal article.
- The results from the experiments will provide information for the first time about the potential evolution of 2,4-D resistance in Palmer amaranth in the US and common waterhemp in KS.
- Understanding the mechanisms of 2,4-D resistance will help to formulate and recommend viable weed management strategies that can delay the evolution of 2,4-D resistance.
- Also, this research will aid in further work and research efforts aimed at utilizing integrated herbicide programs (PRE and POST) for multiple herbicide-resistant (HR) Palmer amaranth and waterhemp management in Roundup Ready 2 Xtend soybean production systems.
For more information about this research project, please visit the National Soybean Checkoff Research Database.
Funded in part by the soybean checkoff.