A pneumatic spray delivery (PSD)-based solid set canopy delivery system (SSCDS) consists of in-line reservoirs and micro-emitter assemblies distributed throughout perennial crop canopies. The existing PSD-based SSCDS uses a large number of reservoirs, i.e., one unit per 3 m of linear spacing, which resulted in high installation and maintenance costs. These reservoirs also produces up to 25% post-spray chemical losses. Therefore, this study aimed to optimize the volumetric capacity and functionality of the existing reservoir for an efficient spray performance and the large-scale commercial adaptation of PSD-based SSCDS. Three reservoirs with volumetric capacities of 370 (1×), 740 (2×), and 1110 mL (3×) were developed to cover a spray span of 3.0, 6.1, and 9.1 m, respectively. Five system configurations with modified reservoirs and spray outlets were evaluated in the laboratory for pressure drop and spray uniformity. The three best system configurations were then field evaluated in a high-density apple orchard. These configurations had reservoirs with 1×, 2×, and 3× volumetric capacity and micro-emitters installed in a three-tier arrangement. Each replicate configuration was installed as a 77 m loop length encompassing 50 apple trees trained in a tall spindle architecture. A pair of water-sensitive paper (WSPs) samplers (25.4 × 25.4 mm) were placed on the abaxial and adaxial leaf surfaces in the bottom, middle, and top third of the canopy to evaluate the spray coverage (%). The PSD-based SSCDS showed no significant difference at the 5% level in terms of coverage among the three reservoir treatments. Coverage was more evenly distributed among the top, middle, and bottom zones for the 2× and 3× as compared to the 1× reservoir treatment. Overall, compared to the 1× reservoirs, the 2× and 3× reservoirs could potentially reduce the system costs by USD 20,000 and USD 23,410 ha−1, respectively, for tall spindle apple orchards and potentially reduce maintenance needs as well.

BACKGROUND Pneumatic spray delivery (PSD)‐based solid set canopy delivery systems (SSCDS) have demonstrated comparable spray deposition and reduced off‐target drift compared with axial‐fan airblast sprayers in high‐density apple orchards. An important next step is to quantify whether PSD‐based SSCDS can provide effective pest management. This study evaluated the biological efficacy of this fixed spray system variant and compared it with that of an axial‐fan airblast sprayer. Partial field trials were conducted in a commercial apple orchard (cv. Jazz) trained in tall spindle architecture. Insecticides were applied at a rate of 935 L ha−1 (100 gallons per acre) for both application systems. Twenty‐four hours after spraying, leaves and fruits were collected to prepare the laboratory bioassays enabling evaluation of efficacy against obliquebanded leafroller (OBLR) and codling moth (CM). RESULTS OBLR mortality for SSCDS, airblast sprayer and untreated control treatments after 24 h of larval exposure was 91%, 98% and 4%, respectively and increased to 98%, 100% and 19% after 48 h. First‐instar CM leaf bioassay mortality was 100% for SSCDS and airblast sprayer treatment, and 13% for the untreated control at 24 h post exposure. Larval CM mortality on fruit was 100% for SSCDS and airblast sprayer treatments, and 33% on the untreated control. CONCLUSIONS Insecticides applied using SSCDS and an airblast sprayer had comparable larval mortality in all three assays, significantly higher than the untreated controls. These results suggest that PSD‐based SSCDS may provide a viable alternative to axial‐fan airblast sprayers in high‐density apple orchards. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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