Updated November 8, 2024:
Update for the 2024 growing season conducted from April to October 2024.
Wisconsin
During the 2024 growing season, graduate research assistant Zaim Ugljic in Dr. Werle’s lab replicated the experiments also conducted in 2023.
Studies were conducted Seymour, IL and Janesville, WI evaluating the role of nozzle type, number, and boom height for targeted application technologies. The team also replicated experiments evaluating the impact of targeted application technologies at different growth stages with different spraying modalities with and without residual herbicides for control of Amaranthus species in soybeans. Herbicide savings were evaluated as a part of these experiments. Study objectives were to compare POST weed control across traditional broadcast application, spot spray application only of foliar herbicides or foliar and layered residual herbicide, and spot spray of foliar herbicides with broadcast application of a layered residual herbicide through the 2-boom 2-tank system at two different application times (early versus late). Application time “early” was triggered when soybeans were at V2 growth stage and “late” when soybeans were at V4 growth stage. The studies were arranged in a randomized complete block design with four replications. All treatments received a broadcast PRE herbicide application of saflufenacil 24 g ai ha-1 + dimethenamid-P 215 g ai ha-1 and were treated with glufosinate 655 g ai ha-1 + glyphosate 1,551 g ha-1 and + or - S-metolachlor 734 g ai ha-1 POST according to the respective treatment modality (i.e., broadcast, spot spray, 2-tank 2-boom system). Visual weed control and biomass data were collected 28 days after the late application timing. In 2023, results from Seymour, IL showed that the late application timing provided better weed control (>88%) but lower herbicide savings (26%). For the early POST application where higher savings of foliar herbicides was detected (76%), the addition of a layered residual herbicide was necessary to provided more effective control (89-92%). In 2024, with low weed pressure at Seymour, IL there was no difference in weed control (>95%) and herbicide savings (>67%) between application timings. However, under incredibly high weed pressure in Janesville 2024, the highest levels of weed control was 89%, regardless of modality, and savings were incredibly low (2%); an additional POST herbicide application would have been necessary for effective (>90%) end of season weed control. Our results suggest that the late applications provided more effective weed control, assuming effective foliar herbicides are available. Early applications with residual herbicides offered greater savings opportunities for foliar herbicides. Our results indicate that the benefits of targeted application technology are most visible in fields with low to intermediate weed pressure treated with an effective PRE herbicide program. In scenarios with high weed pressure, a broadcast application may be a more effective option.
Additional studies in collaboration with BASF Xarvio’s team were conducted in Wisconsin (Arlington and Janesville) and Seymour IL, where different weed detection thresholds in combination with different herbicide programs in corn and soybean cropping systems were evaluated. The objectives of this research were to investigate the role of nozzle type, number of nozzles triggered upon weed detection, and boom height on spray deposition and weed control. The weed control study was conducted in 2023 and 2024 at two Wisconsin locations, Arlington (ARL) and Janesville (ROK). A complementary study to investigate spray coverage was conducted at ARL over two years. The studies were conducted as 2x2x2 factorial experiment, including additional weedy checks for the weed control study. A three-nozzle boom (CO2 pressurized and calibrated to deliver 140 l/ha with nozzles positioned 38 cm apart) mounted on a bicycle wheel was built to conduct this research. Two different nozzle types with similar droplet size classification were selected: flat fan nozzle (TeeJet DG 80015) and even flat fan nozzle (TeeJet TP40015E). Nozzles were evaluated at two different boom heights: 53 cm from the target, which represents the ideal field scenario for the selected nozzle spacing, versus 76 cm from the target simulating boom sway. Lastly, the efficacy of one versus three nozzles activation was compared. Treatments received glufosinate POST (656 g ai ha-1 as the target rate) and application occurred when soybeans were at V4 growth stage and weeds were ~10 cm in height. Biomass samples were collected 14 days after treatment (DAT). Ambrosia artemisiifolia was the target weed at ARL and A. trifida at ROK. Three sub-samples were obtained from the middle row where simulated target weeds were present. According to our results, the activation of three nozzles, regardless of their type or height, provided better spray coverage (36-44%) and more effective weed control (>95%) across treatments within the target area. When only one flat fan nozzle was activated at the ideal target height (53 cm) it provided 89% control in the target area and 22% spray coverage whereas the higher boom treatment resulted in lower weed control (76%) and lower spray coverage (12%). Similarly, when a single even fan nozzle was activated at ideal target height (53 cm) it provided 92% control in the target area and 32% spray coverage, but the higher boom treatment resulted in lower weed control of 86% and 27% spray coverage. For single nozzle activation, the even fan nozzle provided better weed control and spray coverage than the flat fan nozzle. Activation of multiple nozzles upon weed detection may be necessary to achieve adequate spray coverage and effective weed control with smart sprayers, regardless of nozzle type or boom height.
In 2024, aerial images with DJI Phantom 3m drone were collected from all Wisconsin trials. All data are currently being processed and final results will be shared with soybean growers and academics during the winter conferences.
Kansas
In Kansas, during the April to October 2024 growing season, visiting scholar – Joaquin Enrria in Dr. Anita Dille’s weed ecology lab, conducted ONE SMART SPRAY (A joint venture of Bosch and BASF) sprayer studies for the third year on the soybean field located at the KSU Department of Agronomy Ashland Bottoms Research Farm. The overall goal has been to evaluate five different herbicide application programs placed on the same plots, now for the third year, in a no-till soybean-corn rotation field.
The application scenarios compared one- and two-pass programs, some including soil-residual herbicides in tandem with foliar-applied herbicides {either burndown green-on-brown (GOB); or postemergence green-on-green (GOG)}, and compared weed detection thresholds for targeted spraying as compared to broadcast treatments. We evaluated a one-pass residual-at-plant program that included a burndown (GOB), as well as a two-pass residual-at-plant program that had both GOB and GOG passes. Other application programs included a two-pass overlapping residual GOB and GOG program, a ‘spike’ program that included both a broadcast foliar-application as well as GOG when a weed was detected, and a targeted spray with GOB and GOG applications only.
The Research Farm received critical rainfall amounts starting in mid-April, which delayed soybean planting to early June. As the treatments were to be applied at-planting, many summer annual weed species had emerged and grown prior to burndown and residual herbicide applications. As a result, overall savings as measured by reduced herbicide amounts was not observed. Another challenge emerged in that the Palmer amaranth populations were resistant to some degree to several of the herbicide products used in the different passes. Follow-up GOG applications as part of the programs had greater savings with use of weed detection thresholds.
Overall, in northeast Kansas’ soybean production systems, it is still very critical for timely burndown and residual herbicide applications for suppressing Palmer amaranth and other summer annual grass populations to give soybean a successful start. Targeted spraying did reduce total herbicide used, thus savings, but selection of appropriate herbicide tools is also an important decision that needs to continually be updated.
We also conducted on-farm studies near Clay Center, KS, to explore impact of winter wheat stubble height and double-crop soybean situations on ability of the ONE SMART SPRAY sprayer to detect weeds and to compare a typical Farmer weed control program to a ‘premium’ program.
Nebraska
In Nebraska, research involved laboratory and greenhouse studies to investigate the coverage and coefficient of variation (CV) of even flat-fan spray nozzles under different spot-spray application scenarios, as well as the effect of weed size and application method on the control of various weed species using a pulse width modulation system to control herbicide rate. Adjusting the nozzle angle from 0° to 30° rearward resulted in a mean reduction of 7% in spray coverage for both AI6502E and TP6502E nozzles. This adjustmen t also led to a 6% decrease in CV for the AI6502E nozzle, while it had no impact on the TP6502E nozzle CV. Additionally, a 25% average increase in CV was observed when the boom height was reduced from 75 cm to 25 cm. Greenhouse research revealed that weeds exhibited high sensitivity to 2,4-D, dicamba, and clethodim, regardless of weed size and application method. In contrast, glyphosate and glufosinate provided superior control when applied at early growth stages, underscoring the importance of early postemergence herbicide management for these herbicides in variable-rate applications. The research findings from both studies enhance our understanding of how various application parameters can influence spot-spray operations and the sensitivity of weeds to different herbicides at different growth stages. This knowledge is crucial for establishing effective herbicide variable-rate strategies, optimizing weed control, and minimizing herbicide use.
2024 EXTENSION PRESENTATIONS
WiscWeeds Giant Ragweed Field Day – Janesville, WI – July 2024 (100 participants)
WiscWeeds Waterhemp Field Day – Brooklyn, WI – August 2024 (80 participants)
Wisconsin Extension Weed Science Workshop – Alington, WI – September 2024 (80 participants)
Ottawa County KS Conservation District - 3rd Annual field day – Joshua Lloyd’s farm – Joaquin Enrria, August 1, 2024
On-farm field day presentations, Joshua Lloyd’s farm – Joaquin Enrria and Anita Dille, - October 16, 2024
2024 PROFESSIONAL MEETING ABSTRACTS
Rodrigo Werle, Zaim Ugljic (2024) – Smart sprayer design and operation for improved weed management in corn-soybean production systems in the United States – XXXIII Congresso Brasileiro da Ciência das Plantas Daninhas – Brazilian Weed Science Society Meeting – Brazil (August 2024)
Zaim Ugljic, Rodrigo Werle (2024) Targeted sprayer design and operation: Translating spray quality to herbicide efficacy – American Chemical Society, Denver (August 2024)
Rodrigo Werle, Zaim Ugljic (2024) – Smart Sprayer Design and Operation for Improved Weed Management in Corn-Soybean Production Systems in the US – CPDA Meeting, Phoenix, AZ (April 2024)
Zaim Ugljic, Ryan DeWerff, Maxwel Oliveira, Kalvin Miller, Rodrigo Werle (2024) – Do postemergence herbicide application timing and strategy impact weed control and foliar herbicide savings when using targeted application technologies? – NCWSS Meeting, Kansas City, MO (December 2024)
Zaim Ugljic, Ryan DeWerff, Rodrigo Werle – The Impact of Spray Coverage on Weed Control When using Novel Targeted Herbicide Application Technologies – NCWSS Meeting, Kansas City, MO (December 2024)
Joaquin Enrria, Maxwel Oliveira, Alicia Montoya, Cheyanne Macagno, Anita Dille (2024) Evaluation of Weed Management Programs using the ONE SMART SPRY in corn and soybean in Kansas.
Publications:
Barnhart IH (2024) Use of artificial intelligence to locate and treat weds in Midwestern United States corn (Zea mays) and soybean (Glycine max) cropping systems. PhD Dissertation, Kansas State University. https://hdl.handle.net/2097/44344
Vitti, T (2024) Assessing even flat-fan nozzles for spot spray herbicide applications. MS Thesis, University of Nebraska Lincoln. https://digitalcommons.unl.edu/agronhortdiss/264/
2024 NCSRP Final Project Summary:
The project was conducted across several research sites in key soybean-growing areas, including Wisconsin, Illinois, Kansas, and Nebraska. These sites include large-scale trials with plots over 40 acres, as well as smaller, more controlled studies. Researchers tested different nozzle types, spray configurations, and herbicide application methods to optimize weed control and herbicide savings. The BASF-Bosch Smart Sprayer™ is a key tool in this project, as it allows for real-time, site-specific weed management, potentially reducing herbicide use while increasing control over challenging weed species like pigweed, ragweed, and horseweed.
This multi-year study also analyzed the long-term impact of targeted spraying on weed populations and soybean yield, particularly within a soybean-corn rotation. By exploring and demonstrating the potential of precision weed management tools, the research aim was to encourage broader adoption of sustainable practices that can reduce costs and environmental impact while improving weed management outcomes. Integrating this technology with other sustainable approaches, such as crop rotation and cover crops, could further increase the economic benefits for soybean farmers in the North Central US.
The work sponsored by NCSRP in 2023 and 2024 focused on ongoing university-led research on "smart sprayer" technology, which aims to make herbicide application more precise and efficient for farmers by using targeted spraying technology that only apply herbicides where weeds are detected. This research is led by teams at the University of Wisconsin-Madison, Kansas State University, and the University of Nebraska-Lincoln, with each focusing on specific aspects of smart spraying.
2023 Findings:
1. Kansas (Small Plot Sprayer):
o Combining herbicides that stay active in the soil (residual herbicides) with targeted foliar sprays provided weed control that was as effective as traditional broadcast spraying but at a lower cost.
2. Nebraska (Large Sprayer Studies):
o Study 1 (Combination of Broadcast and Spot Spray): In soybean fields, using a mix of high-rate broadcast spraying and low-rate spot spraying reduced weed density significantly after six weeks.
o Study 2 (Application Timing in Soybeans): Spraying during the V3 growth stage was most effective at controlling weeds, especially smaller weeds that may be hard to detect when crops reach later growth stages.
3. Wisconsin (Spot vs. Broadcast Spraying):
o Four experiments tested how spot spraying (targeting weeds directly) and broadcast spraying (covering the entire area) worked at different stages of soybean growth. Earlier applications resulted in higher savings of POST foliar herbicides but required a broadcast layered residual herbicide for season-long weed control. Later applications resulted in lower savings. The technology is most effective in fields with low to moderate weed pressure, but its advantages diminish in fields with high weed pressure.
o They also looked at how nozzle settings (like the number of nozzles activated upon weed detection, nozzle type, and nozzle height) affected the coverage and effectiveness of the spray. Activation of multiple nozzles resulted in more consistent spray coverage and weed control.
Outreach & Engagement:
• The findings were shared at various field days, webinars, and podcasts, reaching over a thousand people. This allowed farmers and industry professionals to learn about the benefits of these novel technologies.
Summary of 2023:
Studies showed that combining residual herbicides with precision spot spraying during the right crop growth stages is an effective way to manage weeds while saving on herbicides. This approach can also reduce environmental impacts by using less chemical input.
2024 Findings:
In 2024, the research continued in Wisconsin, Kansas, and Nebraska with a focus on improving herbicide application methods:
1. Wisconsin:
o Researchers repeated the 2023 experiments and tested how different spray nozzle types and settings affected weed control. They found that later spraying worked better in areas with high weed pressure, while early applications with residual herbicides were better for saving on herbicide use in areas with low weed pressure.
2. Kansas:
o In Kansas, research on the BOSCH-BASF ONE SMART SPRAY system continued. This system uses smart technology to target weeds specifically, reducing herbicide use. The study found that timely herbicide applications were crucial, and targeted sprays (when the system correctly detects weeds) reduced herbicide use. Research also looked at how factors like the height of winter wheat stubble affected weed detection.
3. Nebraska:
o In Nebraska, nozzle performance was tested in labs and greenhouses. Adjustments to the angle and height of nozzles showed that activating multiple nozzles improved spray coverage. Early herbicide application was also found to be most effective in controlling certain weed species.
Outreach & Engagement:
• Findings were shared again at field days and presented at international conferences to educate farmers about the benefits of targeted spraying technology.
Summary of 2024:
The research shows that precision spraying technologies work best in areas with low-to-moderate weed pressure, as they allow farmers to save herbicides and reduce costs. However, traditional spraying methods may still be better in areas with high weed pressure. These ongoing studies help refine the technology and ensure it supports sustainable, cost-effective farming practices.
Both years demonstrated that precision spraying technologies can significantly reduce herbicide use in low-to-moderate weed pressure areas, while traditional methods may still be more effective in fields with high-weed density. These findings may help farmers improve sustainability by using fewer chemicals, improving efficiency, and supporting eco-friendly farming practices.