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

Abstract

Optimally configured solid set canopy delivery systems (SSCDS) can provide adequate spray performance in high-density apple orchards with a minimized risk of off-target pesticide drift. SSCDS configured in a shower-down emitter arrangement have been reported to be the simplest and most economical system. However, existing off-the-shelf emitters used in shower-down configurations have resulted in minimal deposition in lower canopy zones. Therefore, this study was focused on the modifications of off-the-shelf emitters to obtain a desirable spray pattern for adequate spray deposition in all the canopy zones. The modifications include redesigning the impact plate of two existing micro-emitters. Field tests were conducted to evaluate the spray performance of SSCDS with the non-modified emitters (treatment: SD1 and SD3) and contrast the results with modified emitters (treatment: SD2 and SD4). While the treatments SD1 and SD3 had off-the-shelf emitters with swivel plate and static spreader, respectively, the treatment SD2 and SD4 had similar emitters with modified impactor plates. In each treatment block, the apple canopy was divided into six zones and sprayed with a 500 ppm fluorescent tracer solution. Mylar cards and water-sensitive paper samplers were placed on the adaxial and abaxial leaf surfaces in each canopy zone to quantify spray deposition and coverage, respectively. The SSCDS treatments retrofitted with modified emitters, i.e., SD2 and SD4, were observed to have uniform and numerically higher deposition and coverage compared to SD1 and SD3. The SSCDS treatment with modified static spreader (i.e., SD4) resulted in the highest overall spray deposition (1405.7 ± 156.4 ng cm−2 [mean ± standard error]) with improved mid (1121.6 ± 186.9 ng cm−2) and bottom (895.6 ± 149.3 ng cm−2) canopy deposition. Overall, the proposed emitter modification assisted in improved SSCDS spray performances and may be a way forward toward large-scale emplacements of such systems.

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.…”

“…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. A small orchard-scale study was conducted in Prigonrieux (France), targeting apple scab 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.…”

“…Drift results in environmental and natural ecosystem contamination and increases the risk of community exposure to harmful chemicals 21–24 . As an alternative, researchers have been exploring fixed spray systems most recently called solid set canopy delivery systems (SSCDS) 19,25–42 …”