For those who remember the futuristic cartoon series “The Jetsons,” George, the patriarch of the family, commuted to work in his flying saucer car. There was one episode where George and his boss, Mr. Spacely, enjoy a golf outing at Orbit City Golf Club. They used a flying golf cart, and therefore the golf course probably had a flying sprayer, too.
Recently in real life, researchers wanted to test an autonomous aerial sprayer for turf. They referred to this “flying sprayer” as a “remotely piloted aerial application system.” With this study, the objective was to evaluate the effects of nozzle type and water-carrier volume on the efficacy of quinclorac herbicide for postemergence control of large crabgrass (Digitaria sanguinalis). The study was conducted at two sites at Texas A&M University (College Station), specifically on common bermudagrass (Cynodon dactylon) mowed at 2-inch (5-centimeter) height, with mature crabgrass plants uniformly placed into each test plot.
The aerial sprayer (Model PV35X; Leading Edge Aerial Technologies, New Smyrna Beach, Fla.) was equipped with a single nozzle located on the underside of the drone body. The herbicide was applied in treatment combinations of three nozzle types (XR 80-015, conventional flat fan nozzle, fine droplet size; DG 80-015, drift guard nozzle, medium droplet size; and AI 80-015, air induction nozzle, ultra-coarse droplet size) and two water-carrier volumes (1 and 1.6 gallons per acre; 10 and 15 liters per hectare). For comparison, the herbicide was applied with a traditional CO2-pressured backpack sprayer with a water-carrier volume of 11 gallons per acre (102 liters per hectare) and an untreated control.
The aerial sprayer operated at 3.6 feet (1.1 meter) above the ground with flight speeds ranging from 6.7 to 10 mph (3 to 4.5 meters per second). The ground applications from the backpack sprayer contained a four-nozzle boom spaced 19.6 inches (50 centimeters) apart and held 19.6 inches above the turf canopy, with a walking speed of 3.5 mph (1.6 meters per second). With all treatments, the spray pressure was 30 psi (207 kPa).
The aerial sprayer delivered site-specific herbicide applications to the target weed, compared to the backpack sprayer that delivered the herbicide in the traditional blanket application. The crabgrass plants were evaluated for control and for spray solution coverage.
The herbicide quinclorac (Drive XLR8; BASF Corp., Research Triangle Park, N.C.) was applied once at the product label rate for postemergence crabgrass control. A modified vegetable seed oil adjuvant was added to all spray solutions. The target crabgrass plants were at the one-tiller stage and approximately 3 inches (8 centimeters) in height.
The backpack sprayer application resulted in the highest spray solution cover on large crabgrass plants compared to applications from the aerial sprayer. However, herbicide applications using the aerial sprayer with the DG nozzle (medium droplet size) and AI nozzle (ultra-coarse droplet size) at both water-carrier volumes provided similar weed control as the backpack sprayer. Weed control was not as good with the XR nozzle, because rotor downwash caused those fine spray droplets to drift off target. Overall, this study demonstrated that a site-specific postemergence herbicide application at low water-carrier volumes can be effective at controlling crabgrass.
The researchers concluded that comparable crabgrass control between the aerial sprayer and ground applications offers promise for further development of this technology for site-specific herbicide applications to turf. The aerial sprayer in this study has a 25-pound (11.3-kilogram) payload capacity, which translates to carrying only 3 gallons (11.4 liters) of spray solution. These aerial sprayers with low water-carrier volumes utilize site- or target-specific delivery instead of the traditional blanket application across large areas.
The potential benefits of using remotely piloted aerial application systems for site-specific or precision herbicide applications include: the ability to spray difficult-to-reach areas with a traditional vehicle sprayer with multiple nozzles aligned along a boom; reduced damage to turf that may occur from foot and vehicle traffic associated with ground applications; flexible operation scheduling (i.e., make applications at night when no golfers are on the course); reduced amount of product applied; and reduce any potential environmental impacts.
Source: Costam, A.G.F, D.E. Martin, U. Torres, et al. 2025. Nozzle type and spray volume effects on site-specific herbicide application in turfgrass using a remotely piloted aerial application system. Weed Technology 39:e43.
Mike Fidanza, Ph.D., is a professor of plant and soil science in the Division of Science, Berks Campus, at Pennsylvania State University in Reading, Pa. He is a 25-year member of GCSAA.