Researchers study herbicide spray applications using drones

To bring drone spray technology to farmers’ fields, Virginia Tech researchers are looking to standardize unmanned aerial systems (UAS) for herbicide spray applications.

The project, led by Vijay Singh, an assistant professor in the College of Agriculture and Life Sciences and Virginia Cooperative Extension specialist at the Eastern Shore Agricultural Research and Extension Center, stemmed from Singh’s previous research efforts on UAS spray research few years ago, which was a first for the mid-Atlantic region.

Producers spend between $6 billion to $8 billion annually in the U.S. on herbicide usage. Repeated use of the same herbicides over the years has resulted in the evolution of herbicide resistance.

Additional practices and strategies to deal with herbicide-resistant species have led to increased costs of $50 to $100 per acre. General crop production cost and use of labor in specialty crops, such as watermelon, have increased in recent years, which acts as a barrier to achieving higher returns. Researchers have observed that increasing spray efficiency, timely application, and site-specific operations can effectively control weeds and reduce herbicide-usage significantly.  

“Until recently, the use of UAS for weed management was limited to mapping and classification only,” Singh said. “However, UAS-based herbicide applications have opened new opportunities to control weeds in areas inaccessible by tractors, in wet fields, and to manage late-season weed escapes.”

The two grants totaling approximately $1 million from the National Institutes of Food and Agriculture will not only focus on research objectives but through these projects, UAS technologies will be demonstrated at producers’ fields, and they will be provided firsthand experience. The project team will evaluate different spray volumes, droplet sizes, altitude, spray speed, and large-scale spray operations.  

The Agriculture and Food Research Initiative grant will evaluate the efficiency of blanket applications of both preemergence and postemergence herbicides in row crops. The Crop Protection and Pest Management Program grant will focus on watermelon and other vine crops. Spot-spray operation process will be streamlined, and precision and efficiency will be evaluated and both projects involve economic assessment of the proposed technologies.

“The testing of UAS is the first step but the overall goal of these technologies is to automate the process and conduct real-time weed detection and spray applications, which we will achieve in the next few years,” Singh said.

Previously, the team has worked with LeadingEdge Aerial Technologies and Homeland Surveillance & Electronics LLC for conducting preliminary studies. With the project’s expanded scope, additional drones and UAS industry partners will be included. 

The other team members of the projects are Kevin Kochersberger, associate department head in the Department of Mechanical Engineering, John McGee, professor and geospatial Extension specialist in the College of Natural Resources and Environment, Shamar Stewart, assistant professor in the Department of Agricultural and Applied Economics, and Daniel Martin, research engineer with the U.S. Department of Agriculture's Agricultural Research Service.

These projects further strengthen Virginia Tech’s smart farming initiative by unlocking the potential of drone-spray technology to optimize herbicide application, reduce environmental impact, and assist with climate-smart agricultural practices.