Abstract
Chemical plant protection treatments pose serious risks to operators, bystanders, and ecosystems. These risks are further exacerbated in bush and tree crops (orchards), where treatments involve spraying directly upwards, increasing the potential for off-target dispersion. Careful administration of these substances is therefore critical to reducing environmental dispersion while improving yields, economic viability, and produce quality. Adopting and evaluating appropriate technologies, tailored to specific contexts, is key to improving treatments; this awareness is rising among all stakeholders, from machine manufacturers to end users and consumers. Consequently, demand is growing for increasingly complex solutions, and their performance will need to be reliably and objectively compared. The main method to compare technologies is field testing, but its reliability is limited by the many uncontrollable variables involved (chiefly weather, plant training system and its vegetative stage). This work proposes a high-level conceptual framework to address the subject of sprayer performance measurements, emphasising the criticalities of current test methodologies. The issue is addressed through a systemic approach, separating the various aspects of machine performance, to enable more objective assessments. This approach breaks down the problem into several levels of detail: (a) the performance of single components, such as nozzles and air distribution systems; (b) the functional performance, concerning the interaction between components (e.g., the accuracy of distribution); and (c) the environmental performance, concerning the ability of machines of limiting off-target losses, especially drift. To limit and control the numerous uncontrollable variables influencing the measurements, the experimental work focuses on (semi )controlled laboratory conditions, introducing the concept of "semi-field" assessments to bridge the gap between laboratory and field testing. The work lays the foundations for evaluating field-ready sprayers in a wind tunnel. The experimental part of the work follows this conceptual framework, evaluating existing test methodologies, building upon them and applying them to evaluating sprayers and components. The concluding remarks propose steps to integrate the individual aspects of component and machine performance, with the perspective of modeling the performance of machines. The work paves the way for a wider discussion of standardised testing methodologies; its implications benefit users, sprayer manufacturers, research and development and decision-making in crop protection.