The University of Kentucky Research and Education Center aims to optimize drone-based spray systems to improve access to effective management of foliar diseases in Kentucky cornfields.
This multi-departmental effort of Plant Pathology and Biosystems and Agricultural Engineering at the UK Martin-Gatton College of Agriculture. Food and Environment has completed year two of its study, supported by the Kentucky Corn Growers Association, and plans to share the results with farmers through a workshop in late February.
According to plant pathology specialist and principal investigator Kiersten Wise, their previous research found that drones are a viable fungicide application option for farmers, especially in smaller fields that cannot be accessed by manned aircraft due to trees or other obstacles. If left untreated, corn foliar diseases can cost Kentucky corn growers nearly $15 per acre.
"Our 2019 on-farm research conducted with Cooperative Extension agents in several counties indicated that foliar fungicides applied by a drone at tasseling and early silking can effectively manage gray leaf spot in corn when using recommended spray carrier volumes," Wise said. "Once we learned that drone fungicide applications can be effective at managing foliar diseases, we had even more questions about how to optimize these applications."
Improved technology and an increase in demand for commercial drone fungicide applications prompted Wise and precision agriculture specialist Tim Stombaugh to determine how drones compare to traditional high-clearance ground-driven spray equipment and how factors like flight speed and height influence spray coverage and deposition.
"Just in the last couple of years, the amount of corn acres that are sprayed by drones has exploded," Wise said. "Farmers who may have contracted high-clearance equipment or helicopters and airplanes to apply fungicides are now using drones. And this is not just in Kentucky. It's a national trend."
Measuring spray width and pattern accuracy
Wise said they want to ensure that farmers and commercial drone applicators get the best return on investment for these types of applications.
Stombaugh explained that maximum sprayer swath widths are provided for each type of drone, but there is limited replicated research data on the reliability of these recommendations.
"Our research has shown that the actual swath width, or how much corn the drone covers in each pass, might be different than what the manufacturer says," Stombaugh said. "Swath width is also going to be based on factors such as application speed and height, and environmental factors such as wind speed, and that's really important information to convey to farmers and applicators."
Stombaugh said that while drone applicators may be trying to maximize the swath width of their drone application, they might not be getting spray deposition and coverage across the entire swath. They also found that the spray pattern can shift at wind speeds of 5 miles per hour or below.
"Even at low wind speeds, we sometimes see the spray deposition on the corn ear leaves can shift, which can also affect efficacy," Stombaugh said. "Those are some of the things that we've looked at and are trying to relay to farmers. Swath width and the pattern accuracy can be affected by a lot of different factors."
"Preliminary research from our program comparing drone versus ground-applied fungicide applications did indicate that both application methods provided similar levels of disease control and yield response, although disease pressure was low in these trials," Wise said. "Understanding how drone fungicide application parameters affect disease development will aid farmers in setting up their own drones and improve commercial applicator efficacy by providing optimized settings for application."
Research trials were established at the UK Research and Education Center in Princeton in 2024 and 2025. To compare the effect of spray application method on treating disease, fungicide was applied to corn plots via drone or ground application methods, and the spray solution deposited on corn ear leaves was measured.
Wise said that although the ground sprayer application of fungicide resulted in greater spray coverage compared to drone application, a greater amount of the spray solution was deposited onto the corn leaves with the drone application. Both application methods reduced disease where it was present.
Video of the research trial at the UK Research and Education Center in Princeton.
Sharing the results with farmers and commercial applicators
Wise and Stombaugh conclude that fungicide applications by drones are a viable way to apply fungicide in corn, but more research is needed to ensure farmers and applicators are optimizing the applications for disease control and yield benefits.
"We need to continue to research how flight speeds and wind affect pattern distribution and swath width and determine what impact those factors have on fungicide coverage and efficacy," Wise said.
To bring the initial recommendations for on-farm drone fungicide applications to corn farmers and commercial applicators, Wise and Stombaugh are working with the Kentucky Agricultural Training School (KATS), a program of the Cooperative Extension Service. A hands-on workshop focused on spray pattern testing is scheduled for Thursday, Feb. 26, 2026, in Princeton. Registration information can be found at https://KATSDronePatternTesting2026.eventbrite.com.
Wise expressed appreciation to the Kentucky Corn Growers Association for sponsoring the research that gives grain farmers more accessible options for disease control.
"Our partnership with the Kentucky Corn Growers Association has allowed us to research the factors that influence the efficacy of drone-applied fungicides," Wise said. "Sharing replicated, field-tested results with farmers and applicators is key to helping them better manage important foliar diseases in corn."
The full research report for "Ground-truthing Drone Fungicide Efficacy" can be found at https://graincrops.mgcafe.uky.edu/corn.
