Comparison of Non-Chemical Control Methods as Part of an Integrated Weed Management Strategy in Soybean (2022)
Sustainable Production
AgricultureCrop protectionHerbicide
Lead Principal Investigator:
Kevin Bradley, University of Missouri
Co-Principal Investigators:
Prashant Jha, Iowa State University
Sarah Lancaster, Kansas State University
Bill Johnson, Purdue University
Bryan Young, Purdue University
Karla Gage, Southern Illinois University
Mandy Bish, University of Missouri
Amit Jhala, University of Nebraska at Lincoln
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Project Code:
Contributing Organization (Checkoff):
Leveraged Funding (Non-Checkoff):
The Missouri Soybean Merchandising Council (MSMC) provided funding for the purchase of the Weed Zapper and for the initial Missouri-specific research. The United Soybean Board funds research related to cover crops and HWSD. Results from MSMC- and USB-funded research will complement this proposed research by advancing our understanding of the most effective and economical non-chemical options in soybean.
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Institution Funded:
Brief Project Summary:
Weeds with multiple herbicide resistances and a lack of new chemistries have resulted in the need to assess and integrate non-chemical weed control methods with herbicides for more effective weed management programs. The project evaluates weed electrocution in six states with the Annihilator 6R30 weed zapper as a method of preventing weed seed production for common Midwest weeds. A second non-chemical treatment is included at each location as a comparison to electrocution, such as in-row cultivation, hand weeding, windrow burning, weed seed grinding mills, and others.
Key Beneficiaries:
#applicators, #Extension specialists, #farmers, #weed management specialists
Unique Keywords:
#electrocution, #herbicide, #weed control, #weed management, #weeds
Information And Results
Project Summary

The project will be a comparison of weed electrocution as part of an integrated weed management program compared to a second, non-chemical treatment. The work will address questions pertaining to overall effectiveness of weed electrocution on common weed species; effects of weed density; and effects of tractor speed. For weed electrocution treatments, the Annihilator 6R30 Weed Zapper will be utilized. The University of Missouri weed science program recently purchased this machine with funding provided by the Missouri Soybean Merchandising Council. The group is willing to transport the machine to multiple sites within the North Central region for a more comprehensive analysis if funding can be secured. A second non-chemical treatment will be included at each location as a comparison to better evaluate the feasibility and efficacy of the Weed Zapper. The comparative treatment will be selected by the investigator at each location and options include in-row cultivation, hand weeding, windrow burning, weed seed grinding mills, among others. Additional locations for this research include Illinois, Indiana, Iowa, Kansas, Missouri, and Nebraska. The size of the research project and weed species targeted will vary by location based on available equipment and predominant weeds at each site. Proposed species include Palmer amaranth, waterhemp, giant ragweed, Marestail, common lambsquarters, and velvetleaf. The target stage for electrocution treatment will be once the majority of the weed species of interest has emerged through the soybean canopy and prior to weed seed set.

Project Objectives

To evaluate weed electrocution as a method of preventing weed seed production for some of the most common weeds encountered in Midwest soybean production systems.

Project Deliverables

Data collection will address questions pertaining to:
• efficacy of weed electrocution on common weed species
• effects of weed density on electrocution efficacy
• effects of tractor speed on electrocution efficacy
• effects of electrocution on reducing the soil weed seed bank

Preliminary research from the 2021 growing season will be summarized and shared through
extension outlets and with technical audiences. Research will be completed following the 2022
growing season. The two years of data will be summarized and shared with the appropriate
extension outlets, at technical meetings, and in a technical research manuscript, which is planned
following conclusion of the study.

Research will be completed following the 2022 growing season. Data will be summarized and shared with appropriate extension outlets as listed in FY21. Additionally, data will be shared at technical meetings, and a technical research paper is planned following conclusion of the study.

Progress Of Work

Updated March 23, 2022:
All data from 2021 trials has been collected and summarized for presentations at farmer meetings and regional scientific societies. Plans for conducting the second field season of research in 2022 are ongoing. All participating cooperators have been sent an updated protocol and are determining the most suitable location to place the 2022 field trial. The Weed Zapper implement is currently having routine maintenance conducted in preparation for use this season. We will still plan on hiring a towing service to transport the implement to all participating states.

Final Project Results

Updated November 30, 2022:
Experiments were conducted in Illinois, Indiana, Iowa, Kansas, Nebraska, and Missouri as planned during the 2022 season. We are currently collecting all final data from cooperating universities pertaining to the weed control evaluations, but not all universities have completed soybean harvest yet. All final data will be summarized and compared to results from the 2021 trials and presented at local, regional and national meetings.

View uploaded report PDF file

The increasing prevalence of herbicide-resistant weeds in U.S. agriculture has led to increased interest in non-conventional methods of weed control, including weed electrocution. The Weed Zapper is a commercially available weed electrocution implement that has become popular among organic and specialty crop producers. In 2021 and 2022, the effectiveness of the Weed Zapper as a rescue treatment for waterhemp, Palmer amaranth, common lambsquarters, velvetleaf, giant ragweed and giant foxtail was evaluated in soybean. The experiment was conducted in Illinois, Indiana, Iowa, Kansas, Nebraska, and Missouri in 2021 and 2022. Due to regional differences and the time in between treatment at each location, soybean height ranged from 12 to 40 ihches at the time of electrocution, and soybean growth stage ranged from R1 to R6. Weeds were electrocuted at speeds of 3 or 5 mph, and an additional non-conventional rescue treatment was evaluated at each location for comparison. The comparison rescue treatments were selected based on the resources available at each location and included inter-row cultivation, inter-row mowing, and rope-wick herbicide application. In certain locations, a standard pre-emergence followed by post-emergence herbicide program was also included for comparison.

Visual control ratings after application indicated that speed of electrocution had no effect on weed control. However, there was an effect of weed electrocution on the control of different weed species. When averaged across all sites and years, electrocution of weed escapes provided highest control of giant ragweed (mean control of 76%) and waterhemp (69%), followed by Palmer amaranth and giant foxtail (37% and 23%, respectively), and velvetleaf (13%). However, one of the primary findings from this research project is that there can be high variability in the level of weed control achieved with electrocution across different sites and years. For example, control of waterhemp escapes was less than 10% at the Illinois location in 2021 but approximately 60% in 2022. In other locations, waterhemp control was closer to 80% with electrocution alone, but when electrocution occurred following an earlier weed management tactic like inter-row cultivation, overall waterhemp control was greater than 90%.

Other non-conventional rescue treatments like rope-wick herbicide applications or inter-row cultivation or mowing also performed similarly or in some cases better than electrocution on certain weed escapes in this research.

Soil surface sweep samples collected after harvest in 2021 revealed a greater reduction in viable seeds for waterhemp and Palmer amaranth (30% reduction over non-treated control for each) than for common lambsquarters (7%), and giant ragweed (2%). Soil surface sweep samples collected after harvest in 2022 are still undergoing separation and analysis.

Overall, the results from this research indicate that weed electrocution can be a viable option to eliminate certain weed escapes like waterhemp and shows promise as a component of an integrated weed management program in soybean. However, this research but has also generated more questions pertaining to the reasons for the variability in the weed control observed. The effects of plant and soil moisture, electrocution boom placement, and plant density on electrocution efficacy will continue to be explored with the data generated from this research.

Benefit To Soybean Farmers

Weeds with multiple herbicide resistances and a lack of new chemistries have resulted in the necessity to integrate non-chemical methods with herbicides for the most effective weed management programs. Yet there remain many questions about the efficacy and efficiency of non-chemical methods as viable weed management options for U.S. soybean producers. Research is lacking on whether weed electrocution is a feasible and effective option for conventional soybean producers in the North Central region.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.