Spray Deposition and Coverage in Potato and Brussels Sprouts Using Drift-Reducing Spray Configurations

Abstract

In dense or structurally complex canopies, spray applications often fail to adequately reach the specific plant sites where pest organisms reside, typically the lower canopy and abaxial leaf surfaces. An additional challenge is balancing drift mitigation while providing adequate spray coverage and deposition. This study investigates spray deposition and coverage in potato (Solanum tuberosum L.) and Brussels sprouts (Brassica oleracea var. gemmifera DC.) crops using drift-reducing spray configurations. Across two growing seasons (2023 and 2024), seven spray configurations (varying per crop) were evaluated during field trials at three growth stages (early, mid and late). The configurations combined different application techniques (standard boom, air support, air-injection system, Wingssprayer, reduced boom height, droplegs) with nozzle types (flat-fan nozzles with 0%, 75%, and 90% drift reduction, and an angled nozzle). Deposition and coverage were quantified using artificial collectors (filter paper collectors and water sensitive papers) and multiple mineral chelate tracer analysis using spectrometry. This method provides a comparative assessment under standardized measurement conditions rather than absolute deposition on leaf surfaces. Significant interactions between spray configuration and collector position were observed in both crops (p < 0.001), except for relative deposition in potato at the mid and late growth stage, indicating that spray performance depended highly on canopy location. However, no consistent trends across configurations were identified. No single configuration outperformed or, more importantly, underperformed the others across all collector positions. This suggests that drift-reducing configurations could potentially be adopted without substantially compromising spray deposition and coverage, at least as indicated by measurements obtained with artificial collectors.