Assessing spray efficacy of unmanned aerial vehicles compared to traditional ground-based applications, 2025

The utilization of Unmanned Aerial Vehicle (UAV) sprayer technologies has rapidly increased over the last 5 yr, with little data showing that they provide comparable control of insect pests to those made by traditional ground-based applications. A field study was conducted in a commercial cotton field to compare the efficacy of insecticide application made by UAV technology and ground-based sprayers targeting thrips in Hill County, Texas, United States. Treatments included Orthene 97S applied at 4 oz acre−1 by either a UAV (XAG P-150) or self-propelled sprayer (John Deere r4038). Applications were made at 3 gpa and 11 gpa for the UAV and self-propelled ground sprayer, respectively. Treatments were replicated 3 times in a RCB design, using plots that were 18.3 m (24 rows) wide by 335.3 m long. Thrips populations were estimated by destructively sampling 15 plants per plot and placing them in jars partially filled with 80% alcohol at 0, 3, and 7 days after treatment (DAT). Jars were strained through coffee filters, and the number of immature and adult thrips was counted under a stero-microscope. Percent control was calculated for 3 and 7 DAT sampling dates compared to the pre-treatment counts (0 DAT), using the percent reduction formula. Thrips populations were not normally distributed and were subjected to a Log(X + 1) transformation before analysis; however, results are reported as untransformed means. Thrips populations were subjected to analysis of variance procedures with a 95% confidence interval, and means were separated using Fisher’s protected least significant difference (P ≤ 0.05). To determine any significant treatment effects percent control by either application method was statistically analyzed in the absence of the untreated check using a Student’s t-test with a 95% confidence interval (P ≤ 0.05). The cotton growth rate at the start of this study was slow due to excessive moisture and cooler temperatures, which are conducive to thrips infestations. At the start of the trial, total thrips populations ranged between 52.7 and 70.3 thrips per 15 plants for the UAV and untreated check, respectively (Table 1). At 3 DAT, there were no observed statistical differences among treatments for total thrips or immature thrips. However, the UAV and ground sprayer application of acephate did have numerically less thrips than the untreated check. A total of 7 DAT statistical differences were observed among the treatments, with the untreated check having significantly more immature and total thrips per 15 plants than both the UAV and ground sprayer applications. No statistical differences were observed for the percent control provided by either application method at 3 or 7 DAT. However, the UAV application had numerically less control than the ground sprayer, indicating there is potential for control issues. The data in this study suggest that the utilization of UAV technologies could provide similar levels of control to that of traditional ground-based applications. Means within columns followed by the same letter are not statistically different based on a Fisher’s protected LSD (P ≤ 0.05). Data were Log(X + 1) transformed for statistical analysis, but the untransformed means are presented. Percent control was not calculated for the untreated check at 3 or 7 DAT. This research was supported in part by industry gifts of pesticides. This work was partially funded by Cotton Incorporated Texas State Support Committee (Proj.: 25-416TX), and the USDA-NIFA Extension Implementation Program (Proj. award: 2024-70006-43508, from the U.S. Department of Agriculture’s National Institute of Food and Agriculture. None declared.