Switzerland is characterized by steep and sloped landscapes. Viticulture in mountainous regions is particularly demanding and requires substantial manpower. Consequently, the use of unmanned aerial vehicles (UAVs) for plant protection sprays has long attracted interest in Switzerland [1]. To address the specific operational and safety challenges associated with aerial spraying in complex topography, a dedicated regulatory framework was established and entered into force in 2019 [1]. Between 2018 and 2024, several Swiss public agencies conducted research projects aimed at characterizing both the potential and the risks associated with UAV-based pesticide application. Spray drift experiments conducted in accordance with ISO 22866:2005 were performed in grapevine [2], apple orchards [3], and arable crops [2,4]. In grapevine trials, preliminary data on direct bystander exposure to spray drift were obtained using a simplified experimental setup [2]. In most other experiments, human-shaped mannequins were deployed to represent bystanders positioned adjacent to the treated area [3,4]. The resulting exposure and drift levels were compared with reference values for conventional application techniques used in the European risk assessment of plant protection products [3,4]. Overall, spray drift from UAV sprayers was generally lower than the reference values for air-assisted sprayers in vineyards and orchards, but higher than those of tractor-mounted boom sprayers. As a result, UAV-based herbicide applications and treatments of low-growing crops are subject to additional buffer distances. A further project focused on spray deposition and biological efficacy of UAV-applied fungicides in grapevine [5], which represents the most relevant use case for UAV sprayers in Switzerland [1]. Deposition was found to be satisfactory in the upper canopy, but limited on leaves in the bunch zone and on the grape clusters themselves, indicating a potential risk of insufficient protection under high disease pressure. However, when UAV applications were combined with one or two supplementary ground-based treatments, disease control efficacy was comparable to that achieved with ground applications alone. Overall, UAV sprayers have become an established application technique in Switzerland, addressing a clear operational need in in agriculture and specifically in viticulture. [1] Anken et al. (2025), Pest Manag. Sci. 81:3419, doi: 10.1002/ps.8721 [2] Anken and Dubuis (2020), unpublished report [3] Dubuis et al. (2023), Sci. Total. Environ. 881:163371, doi: 10.1016/j.scitotenv.2023.163371 [4] Dubuis et al., submitted for publication [5] Dubuis and Jacquerod (2022), BIO Web Conf. 50:01006, doi: 10.1051/bioconf/20225001006