Location: Columbia Plateau Conservation Research Center
Project Number: 2074-21600-001-011-A
Project Type: Cooperative Agreement
Start Date: Jul 1, 2025
End Date: Jun 30, 2026
Objective:
1)Evaluate the efficacy and efficiency of precision herbicide application using spot spraying for weed mapping
2) Continue enhancing the PNWHRI resistance mapping system by integrating new survey data that will ensure the most current and comprehensive representation of herbicide-resistant weed populations across the Pacific Northwest.
Approach:
Objective 1: This project will use a Generation 4 Weed-It spot sprayer integrated with a John Deere RTK 7000 series globe mounted on an AutoTrek-enabled Gator to map and manage weed populations in fallow and wheat production systems. The Weed-It system identifies individual weeds in real time based on chlorophyll detection and activates specific nozzles for targeted herbicide application. Activation points of each nozzle will be georeferenced using RTK positioning, which enables the system to generate maps of the precise spray areas representing treated regions. This data will be processed in processed in Geographic Information Systems (GIS) software (ArcGIS Pro) to calculate total area sprayed and quantify herbicide volume saved compared to conventional broadcast applications. To evaluate the accuracy and spatial relevance of the treatment zones, the spray maps will be overlaid with high-resolution aerial imagery, and comparisons will be made between the treated areas and the leaf area index (LAI) derived from the imagery. This integrated approach will validate the precision and efficiency of spatially targeted weed control while establishing a framework for repeat applications based on historical weed locations.
In addition to evaluating spatial spray mapping, the project will assess the performance of the updated Generation 4 Weed-It system equipped with “green-on-green” technology to determine its effectiveness in identifying downy brome within fall-planted wheat fields. This technology operates by detecting increases in chlorophyll levels—generated by the combined presence of crop and weed biomass—which trigger nozzle activation. The system’s ability to distinguish and target downy brome growing within the wheat canopy will be a primary focus, particularly during early growth stages. By using this chlorophyll-based detection approach, herbicide applications can be limited to zones where weeds are present, potentially reducing overall herbicide volumes. Additionally, data from these applications can be used to generate winter annual weed distribution maps, which can be incorporated into long-term management strategies for spatially targeted control and resistance mitigation.
Objective 2: A GIS database will be updated for dryland wheat production in Oregon, Idaho, and Washington of the Pacific Northwest, USA as part of the Pacific Northwest Herbicide Resistance Initiative (PNWHRI) team. Continued geomapping of dryland wheat regions will be achieved through multiple open-source databases. Herbicide resistant weed populations will be available as map layers based on surveys and as the survey and population data expands, the ability to assess resistance movement and analyze the spatial variation will increase. The collaboration across university and ARS scientists throughout the Pacific Northwest (PNW) will allow for greater understanding of the distribution of resistant weed species rather than a state-by-state approach. In addition, a grower focused web portal will be updated as a tool to identify which counties have resistance and the type of resistance.