Spatial Distribution of Spray from a Solid Set Canopy Delivery System in a High-Density Apple Orchard Retrofitted with Modified Emitters

Abstract

Solid Set Canopy Delivery Systems (SSCDS) are fixed agrochemical delivery systems composed of a network of micro-sprayers/nozzles distributed in perennial crop canopies. A previous SSCDS design composed of a 3-tier configuration using hollow cone sprayer nozzles has been shown to provide excellent coverage and deposition in high-density apple orchards. However, the hollow cone nozzles substantially increases the initial system installation costs. This study evaluated the effect of irrigation micro-emitters replacement on spray deposition, coverage and off-target drift. A micro-emitter used in greenhouse irrigation systems was duly modified to enhance its applicability with SSCDS. After laboratory assessment and optimization of the micro-emitters, a replicated field study was conducted to compare 3-tier SSCDS configured with either of modified irrigation micro-emitters or traditional hollow cone nozzles. Canopy deposition and off target drift were evaluated using a 500 ppm fluorescent tracer solution sprayed by the field installed systems and captured on mylar collectors. Spray coverage was evaluated using water sensitive papers. The overall canopy deposition and coverage for treatment configured with modified irrigation micro-emitters (955.5 ± 153.9 [mean ± standard error of mean] ng cm−2 and 22.7 ± 2.6%, respectively) were numerically higher than the hollow cone nozzles (746.2 ± 104.7 ng cm−2 and 19.0 ± 2.8%, respectively). Moreover, modified irrigation micro-emitter SSCDS had improved spray uniformity in the canopy foliage and on either side of leaf surfaces compared to a hollow cone nozzle. Ground and aerial spray losses, quantified as deposition, were numerically lower for the modified irrigation micro-emitter (121.8 ± 43.4 ng cm−2 and 0.7 ± 0.1 ng cm−2, respectively) compared to the traditional hollow cone nozzle (447.4 ± 190.9 ng cm−2 and 3.2 ± 0.4 ng cm−2, respectively). Overall, the modified irrigation micro-emitter provided similar or superior performance to the traditional hollow cone nozzle with an estimated 12 times reduction in system installation cost.

Pneumatic spray delivery‐based solid set canopy delivery system for oblique banded leaf roller and codling moth control in a high‐density modern apple orchard

“…[21][22][23][24] As an alternative, researchers have been exploring fixed spray systems most recently called solid set canopy delivery systems (SSCDS). 19,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] SSCDS have been extensively tested and optimized for performance in terms of spray deposition and coverage. 19,[31][32][33][34][37][38][39][40][41][42] However, limited information is available on the biological efficacy of such systems for insect and pest management.…”

“…Our group has extensively researched SSCDS configurations for tall spindle apple architectures typical in WA state. 38,[40][41][42][43][44] PSDbased SSCDS developed by Sinha et al provided improved spray deposition and uniform spray discharge along the spray line compared with hydraulic-based SSCDS 38 . Our latest optimal PSDbased SSCDS provided similar spray deposition, reduced ground drift and negligible aerial drift, but lower spray coverage compared with an airblast sprayer in tall spindle apple orchard.…”

“…SSCDS have been extensively tested and optimized for performance in terms of spray deposition and coverage 19,31–34,37–42 . However, limited information is available on the biological efficacy of such systems for insect and pest management.…”

“…Our group has extensively researched SSCDS configurations for tall spindle apple architectures typical in WA state 38,40–44 . PSD‐based SSCDS developed by Sinha et al .…”

Effect of Emitter Modifications on Spray Performance of a Solid Set Canopy Delivery System in a High-Density Apple Orchard

“…A three-tier configuration with hollow cone emitters placed in top, mid, and bottom canopy zones was reported to provide adequate spray deposition and coverage in high-density apple canopies [16]. Ranjan et al (2021) [24] conducted a study to customize the design of the in-canopy static emitters that further improved the spray performance of a three-tier configured SSCDS. However, with six emitters per tree, such configurations may find a tough path toward adoption in commercial orchards.…”