The nexus of formulation, application and digital technologies: very-low volume formulations as an enabler for future small, automated, precision application vehicles

Abstract Purpose Precision agriculture (PA) utilises data to enable more accurate application of agricultural inputs such as plant protection products (PPP) with precision and variable rate application (VRA) equipment. New evolving application technologies offer the ability to downsize this to small, automated vehicles with many advantages concerning cost, efficiency, sustainability, safety, and operator requirements. A new and important component of precision agriculture is the design of formulations: current generation PPP formulations were not designed for very-low volume application (VLV, 5–50 L/ha for 2D crops) and can lose performance at VLV. Formulations designed to perform at VLV have the potential to maintain or in some cases even increase performance at VLV and enable the application equipment to be downsized to small, automated vehicles such as unmanned ground vehicles (UGV) and unmanned aerial vehicles (UAV). This work investigates the performance of VLV optimised formulations from lab-scale to field-scale and how this may enable future VLV precision application of PPPs. Method VLV optimised suspension concentrate (SC) formulations were prepared with low dose-rates of high-spreading and uptake-enhancing formulants (adjuvants) and evaluated for leaf deposit spreading and coverage, leaf cuticle penetration and biological efficacy. Results At VLV, formulations containing high-spreading formulants maintained good coverage and formulations containing uptake-enhancing formulants showed enhanced uptake in cuticle penetration tests. In greenhouse tests on tomato plants, formulations without these formulants lost performance at VLV (15 L/ha) compared to higher spray volumes (200 L/ha) against disease infection while formulations containing these formulants demonstrated better performance nearer to that demonstrated at higher spray volumes. In field tests on rice, a formulation containing high-spreading formulants showed higher efficacy against disease infection at VLV when applied by UAV relative to a formulation without these formulants applied at the same spray volume. Conclusion Formulations designed for VLV spray application can achieve good efficacy not only at standard spray application volumes but also at VLV with UAV application and is a formulation design technology that can enable future VLV precision application.