Herbicides are the primary tool used for weed management in soybean (USDA – National Agricultural Statistics Service). Difficult to manage weeds (pigweed species, ragweed species, foxtail species, common lambsquarters, kochia, horseweeed, etc.) as well as herbicide-resistant populations for many of these weeds have been selected over time across North Central US soybean cropping systems. Increasing herbicide cost and environmental concerns have only added to management challenges. Current herbicide application practices focus on broadcast applications that deliver a constant herbicide rate across an entire field. However, weed populations have great spatial variability that is influenced by factors such as weed species biology, soil type, crop rotation, and tillage and harvest practices. Previous research has evaluated site-specific weed management (SSWM) using weed species distribution maps and site-specific herbicide applications resulting in herbicide savings ranging from 23 to 89% (Gerhards et al., 2022). Despite the potential economic and environmental benefits with SSWM, current technologies have not been able to achieve this at field scale. With recent improvements and integration of active sensors and sprayer technologies, the ability to detect and treat weeds on a real-time site-specific basis should soon become feasible. Several companies are developing smart sprayers with the ability to detect and spray weeds in real-time both in fallow (green on brown) and early-season in crop (green on green). This technology has potential to shift from broadcast herbicide applications that deliver a constant herbicide rate across an entire field to only treating parts of the field where weeds occur. This would improve herbicide efficacy as doses could be adjusted based on weed size and weed species (as detection technology improves for species identification) potentially reducing overall herbicide cost and use. This system has potential to reduce future weed infestation levels using technology driven SSWM.
The long-term goal of this research project is to optimize herbicide applications with a smart sprayer system in the US to stimulate the adoption of precision agriculture tools for more sustainable weed management programs.
Our research team has the skills and research equipment related to weed management and pesticide application technology to successfully complete this project. The research project is planned to be conducted at the University of Wisconsin-Madison (Werle), University of Nebraska-Lincoln (Proctor), Kansas State University (Dille), and the BASF Midwest Research Farm near Seymour, IL (Kruger/Werle). The project collaborators have a well-established partnership with BASF (Dr. Greg Kruger, Dr. Bruno Vieira, et al.) enabling access to a small plot (mobile 10-ft tractor mounted) and two large-scale sprayers (90-ft boom, one located in NE and one in IL) equipped with the BASF and Bosch Smart Spraying Technology. These four research sites are located in strategic soybean producing regions of the United States. Moreover, these research sites are infested with the most common and troublesome weeds that North Central US soybean growers are facing (pigweed species, ragweed species, foxtail species, common lambsquarters, kochia, horseweed, etc.). While the BASF and Bosch Smart Spraying technology will be used in this project, inferences can be drawn for other similar technologies. This project will evaluate different configurations of site-specific herbicide applications to control weed infestations in soybean using POST herbicides. Studies will test the BASF and Bosch Smart Spraying Technology with large-scale (studies with >40 acres) field projects in IL and NE and small plot projects in IL, KS and WI to evaluate weed detection, targeted spray deposition, weed control, end-of season weed seed production, reduction in herbicide usage for spot-spray compared to broadcast herbicide applications, and soybean yield.
Multiple years are planned to be able to follow weed community response to spot-spray applications under a soybean-corn rotation with each phase of the rotation planted and evaluated each year. Plots will be established, maintained and evaluated for multiple years with same treatments applied to each plot through time.
A range of treatments will be evaluated in small- and large-plot studies. The large-plot sprayer is a commercial sprayer with one tank - one boom setup. The small-plot sprayer is designed with two spray tanks and two separate booms. This provides an opportunity to evaluate different application approaches (treatment 1, 1 tank + 1 boom) with a broadcast application, or as a spot spray application (treatment 2, 1 tank + 2 boom). With the two-boom system, a broadcast rate would be applied for control of small or undetected weeds while the second boom, once a weed is detected, will spot-spray that weed with a spiked rate of the same spray solution increasing the dose to the full label rate only where weeds are detected. A 2 tank + 2 boom system will allow for two different mixtures (e.g., soil-applied residual herbicide in one tank and postemergence herbicide in other tank) where the first boom can apply a low- dose of a burndown herbicide and include a residual herbicide as a broadcast application and the second boom can spike the POST herbicide, up to the high label rate, for detected weeds. These different configurations will be evaluated and provide ultimate flexibility in weed control with latest chemistries and sprayer application technologies.

Main objective is to Evaluate and demonstrate the efficacy of postemergence spot-spray herbicide programs in soybean on weed populations over time using the BASF Digital Farming GmbH (BASF) and Robert Bosch GmbH (Bosch)Smart Sprayer

• Technical Extension bulletins will be generated for growers and decision influencers.
• Several young professionals that will soon join the workforce and influence decisions will be trained on this novel technology while supporting the research.
• Field day demonstrations for soybean growers – especially targeted for North Central soybean checkoff members
• Social media posts highlighting in-season equipment demonstrations
• Multiple refereed journal articles, conference presentations, and proceedings will be developed with the project findings.
• Conference papers will be presented at professional meetings (e.g., North Central Weed Science Society, Weed Science Society of America) to discuss the study methods and research findings.
• Manuscripts will be published in scientific journals (e.g., Pest Management Science, Weed Technology).

Updated August 10, 2023:
Planning for the 2023 growing season was conducted from October 2022 to April 2023. Each university cooperator is planning to conduct a unique trial related to spot spray technology. Based on preliminary findings from 2022 highlighted below, the University of Wisconsin - Madison will conduct small plot trials evaluating different nozzle configurations and boom heights to determine the effect on weed control based on these treatments. Kansas State University will conduct trials using a small-plot smart sprayer to evaluate the effectiveness of spot spray technology within preemergence and postemergence herbicide programs. Data will also be evaluated to determine the impact on the cost for each herbicide program. The University of Nebraska - Lincoln will conduct large field-scale trials using a commercial sized smart sprayer to evaluate the effect of application timing at different soybean growth stages and how broadcast and spot-spray applications perform when applied alone or in combination. The results from these trials will be summarized and reported at the end of the funding cycle. In addition, the three universitas are planning to host a webinar in fall 2023 inviting 3 smart sprayer technology developers to highlight the technology for an online audience. Discussion will be facilitated to help growers and applicators understand the technology and how it might fit within their operations. The webinar will also be recorded and made available for those not able to attend in person on-line.

For the 2022 growing season, field studies were conducted at the University of Wisconsin-Madison, University of Nebraska-Lincoln, and Kansas State University using the Bosch BASF smart sprayer technology.
- 3 graduate students (2 PhD, 1 MS) and 3 undergraduate research scholars work on field project during the 2022 season. The students have had several opportunities to interact with BASF employees related to the development and implementation of their smart sprayer technology.
EXTENSION PRESENTATIONS
• Werle, R. 2023. Building effective integrated weed management control programs for soybean. 2323 BASF Innovation Symposium. Wisconsin Dells, WI. February 23, 2023. (60 minutes, 200 participants).
• Werle, R. 2023. Reflecting on a half-decade of farmer-driven integrated weed management research in Wisconsin. Keynote address. 25th Wild World of Weeds Workshop. Fargo, ND. January 17, 2023. (45 minutes, 200 participants).
• Werle, R., and N. Arneson. 2022. Weed management in non-GMO soybean. SB&B Foods Research Update Meeting. Eau Claire, WI. November 29, 2022. (150 minutes, 60 participants).
• Barnhart IH, Dille A. 2022. The Bosch® BASF® Smart SprayerTM was demonstrated at a field day organized by the Kansas State University Extension Weeds team on July 13, 2022. The 10’ research sprayer was demonstrated in a fallow field at the Kansas State University Ashland Bottoms Research farm (2850 W 32nd Ave, Manhattan KS 66502). Attendance was approximately 50 farmers, crop consultants, and graduate students from across Kansas. Aaron Hunsinger (Bosch BASF Smart Farming) gave a brief overview of the machine and how it works. This was followed by a demonstration of detecting weeds and spraying them with a mixture of water and fluorescent dye so that those in attendance could view the sprayed weeds. Many people were interested in the technology and had questions as to how this technology could benefit their farming operations.
INVITED PRESENTATIONS (CLASSROOM & SYMPOSIUM)
• Werle, R., Proctor C., Dille, A. 2022. Smart Sprayer Research – key insights from University of Wisconsin-Madison. Xarvio BASF – US Academic Panel. September 30, 2022. Cologne, Germany.
• Werle, R. Weed management challenges and innovations across the Midwest United States. Brazilian Weed Science Congress. July 25-28, 2022. Rio Verde, GO, Brazil.
• Werle, R. 2022. Innovations in the management of troublesome weeds in the United States. 5th SIMAL (Latin America Symposium) Evolution: Management of Challenging Weeds. June 08 and 09, 2022. Iguazu Falls, Parana, Brazil.
• Werle, R., Proctor C., Dille, A. 2022. Smart Sprayer Research Update. BASF – University Weed Science Round Table. March 04, 2022. Seymour, IL.


PROFESSIONAL MEETING ABSTRACTS
• Barnhart IH, Vitti TH, Proctor C, Miller KA, Kruger G, Dille A (2022) Locating weeds and patches with precision sprayers. Poster presentation #44: 2022 North Central Weed Science Society (NCWSS) annual meeting. December 6, 2022. St. Louis, MO.
• Barnhart IH, Kruger G, Miller KA, Proctor C, Werle R, Dille A (2022) Comparison of weed control outcomes when using precision sprayers versus traditional approaches. Oral presentation: 2022 North Central Weed Science Society (NCWSS) annual meeting. December 6, 2022. St. Louis, MO.
• Barnhart IH, Kruger G, Miller KA, Proctor C, Werle R, Dille A (2023) Comparison of weed control outcomes when using precision application versus traditional approaches. Oral presentation: 2023 Weed Science Society of America (WSSA) annual meeting. February 1, 2023. Arlington, VA.
• Barnhart IH, Proctor C, Vitti TH, Miller KA, Kruger G, Dille A (2023) Weed control in soybeans (Glycine max) using precision sprayers. Oral presentation: 2023 Weed Science Society of America (WSSA) annual meeting. February 1, 2023. Arlington, VA.
• Ugljic, Z., M.C. Oliveira, A. Dille, Chris Proctor, and R. Werle. 2022. Survey of corn-soybean weed management during the 2021 growing season and current stakeholder perception on targeted spraying technologies. Proceedings of the North Central Weed Science Society Annual Meetings, St. Louis, MO.
• Ugljic, Z., N.J. Arneson, R.P. DeWerff, A. Dille, C. Proctor, G. Kruger, K. Miller, and R. Werle. 2022. Delivering POST herbicides on the spot: evaluating a novel smart sprayer technology. Proceedings of the North Central Weed Science Society Annual Meetings, St. Louis, MO.
• Vitti, T, C. Proctor, G. Kruger. 2022. Evaluating even flat-fan nozzle coverage for spot spraying applications with a one or two-boom system. Proceedings of the North Central Weed Science Society Annual Meetings, St. Louis, MO.


• Questions received during the 2022 NCWSS meetings: People usually have been interested in nozzle type, when it’s going to be available on the market, how much is going to cost, how much you can save per acre, who is going to do maintenance, how often you need to update the software, how often you need to clean cameras.

• Questions received during Extension meetings: positioning of layered residuals (folks are often more excited about the 2-tank vs spot spraying), cost of technology, efficacy and accuracy, coop profitability, what to do with data collected (weed maps), what herbicides to use, what nozzles/carrier rate to use, can non-selective (non-registered) herbicides be used in spot applications.

Updated November 8, 2023:
Site-specific weed management with precision application technology
Field Research projects were conducted in Kansas, Nebraska, and Wisconsin during the 2023 growing season. Highlighted results include:

Kansas -
Small Plot Sprayer
• Results showed that treatments with residuals provided the greatest weed control; with simultaneous BCST of residuals and SS of foliar herbicides, it was possible to obtain weed control not statistically different than the broadcast applications, at a fraction of the cost.
Nebraska
Large Sprayer Study 1 – Combination of Broadcast and Spot Spray Application
• Weed density in soybean: 6 weeks after treatment, High rate broadcast + Low Spot Spray had the lowest weed pressure throughout all thresholds.
• Weed-free area rating in soybean: 6 weeks after treatment, all detection thresholds in the High Rate Broadcast + Low Spot Spray were not statistically different.
Large Sprayer Study 2 – Application Timing in Soybean
• The V3 spike treatment resulted in the most effective weed control.
• The difference between spot spray and spike was greatest at V3 timing.
• Difference in treatments is most likely due to small undetected weeds in the spot spay only treatment that were treated with a broadcast application and a spot application for the spike treatment.


Wisconsin
• Four soybean small plot field experiments were conducted in Seymour, IL in 2023 comparing spot spray versus broadcast applications at different crop growth stages
• Small plot field experiments were conducted in Arlington and Janesville, WI in 2023 comparing weed control and spray coverage with different nozzles, boom height, and number of nozzles triggered upon weed detection.

Extension Activities for 2023 Include:

• Preliminary results were presenting during the 2023 Arlington Agronomy and Soils field day (August 30 2023; 200 participants)
• A webinar was recorded for the Crop Protection Network TV (episode will be released in the winter)
• Two podcast episodes were recoded (UNL FarmBits podcast)
• Results will be presented during the 2023 North Central Weed Science Society meeting (December 2023, Minneapolis, MN) and 2024 Weed Science Society of America (January 2024, San Antonio, TX)

NCSRP Grant Funds Supported Webinar:
• September 06, 2023 – Spot Spray Technologies Zoom Webinar (2-hour event, 2 CEUs in Pest Management were Offered)
• 530 participants registered from 16 different countries
• 278 participants attended the live webinar
• Webinar recording is available via YouTube https://www.youtube.com/watch?v=x6D3Q5hUjWA&t=5381s
• >1,300 views of the webinar recording as of 10/30/2023

View uploaded report

This project will:
-Evaluate new weed management smart sprayer technology that may improve control of hard to manage/resistant weeds, reduce herbicide use/cost
-Investigate smart sprayer technology to determine how it might most effectively be utilized for managing weeds in soybean
-Provide insight into the potential return on investment of new smart sprayer technology