Effect of emitter type and mounting configuration on spray coverage for solid set canopy delivery system

doi:10.1016/j.compag.2014.07.012

Computers and Electronics in Agriculture

Volume 112, March 2015, Pages 184-192

https://doi.org/10.1016/j.compag.2014.07.012 Get rights and content

Highlights

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Significantly greater spray coverage on upper-side of leaves than on under-side of leaves when using SSCD system.
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Emitters with 80° spray cone angle provided greater coverage and penetration compared to other emitters.
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Configuration-4 provided uniform canopy coverage but in upper third 0.8 m high canopy region.
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Uniform canopy coverage could be achieved by installing additional emitters in configuration-4.

Abstract

Timely and precise application of chemicals is critically important for improved pest control and reduced off-target movement of chemicals. A fixed or solid set canopy delivery (SSCD) system with emitters within a tree canopy has potential to reduce chemical loss and cost by applying right amount of spray at right time and location under favorable ambient conditions. The study was conducted to quantify spray coverage using various emitters mounted at different configurations within tree canopy using a SSCD system. Six different emitter (E) types with varying characteristics were selected for a field study. Each emitter was installed in four different mounting configurations. Water sensitive cards (WSCs) were mounted on upper- and under-side of leaves at 22–25 locations on each tree. After spray application, the WSCs were scanned and analyzed for percent coverage. The configuration with 80° hollow cone emitters (E6) attached to a Y-connector and mounted at height of 2.0 m from the ground exhibited greater mean coverage on the WSCs placed on upper-side (58%) and under-side (21%) of leaves as compared to other emitter and configurations. It was found that coverage with this arrangement was nearly equal in upper (57.5%) and under-side (51.3%) of leaves in the high canopy region, which was the area where emitters were spraying directly. Therefore, configuration using E6 on Y-connector provided the desired uniform canopy coverage, however emitters at more locations would have to be installed to achieve similar coverage in the medium and low canopy regions.

Introduction

Airblast sprayers have traditionally been used for orchard spray application. These sprayers are set to operate at application pressure as high as 1400 kPa to provide canopy coverage from 23% (Cross et al., 2003) to 75% (Landers, 2008) depending on canopy density and training system. The application pressure and dosage are seldom set to match the tree geometry (Cross, 1991, Giles et al., 1989, Wiedenhoff, 1991). As a result much of the pesticide is lost and deposited on the ground or lost as volatile compounds. Cross et al., 2001a, Cross et al., 2001b, investigated the effects of spray droplet size and application volumes on spray deposit in an apple orchard and reported that 43–61% of the applied spray was lost to ground deposit within 4.6 m of the row being sprayed. The study also concluded that application volume with orchard sprayers varied so much that differences in selected emitter type have very little effect on deposition. The reason for the lack of effect of emitter type on deposition was because volume of spray used saturated the trees completely and excess spray simply trickled down the tree resulting in loss. In the state of Washington, there is a growing concern of harmful effects of pesticide runoff from orchards into aquatic systems, like the Columbia River and its tributaries. Therefore, there is a need to devise an alternate system to deliver pesticides, and nutrients which has a potential to provide uniform canopy coverage, and reduce spray loss and environmental pollution.

A solid set canopy delivery (SSCD) system has potential as an alternative method of precision and timely delivery of pesticides while providing equivalent spray coverage compared to orchard airblast sprayers in tree fruit orchards. A SSCD system is a fixed spray application system consisting of hoses and emitters through which a spray solution is delivered. Since emitters in a SSCD system are installed within tree rows, spray droplet could deposit quickly on tree canopy. An automated fixed or portable mixing and injection system including a pump connected to the SSCD system would be as an integral part of the spray application technology for precision control of application rate. A SSCD system provides producers an opportunity to schedule a pesticide application when environmental conditions favor the least amount of drift and off-target movement. Additionally, pesticide applications can be conducted even when ground conditions are not favorable for driving through the orchard. This concept was initially tested by Lombard et al. (1966) using high flow impact sprinklers. Carpenter et al., 1985 presented design consideration for setting up a permanent spray application system. The authors concluded that a single sprinkler permanently mounted in the top center of each tree appeared to be an effective method of pesticide application. However the study provided little insight into pesticide coverage using different nozzles and indicated the need for further research. This approach of mounting sprinklers and/or nozzles in the top center of trees would potentially result in spray material loss to the ground.

Recent studies have reported potential for equivalent pest control efficacy with a SSCD system compared to a tractor-pulled air blast sprayer (Agnello and Landers, 2006). The study utilized one emitter type and mounting configuration and authors stressed further studies be conducted to understand spray distribution within tree canopy. Pesticide coverage throughout the tree canopy has been the concern in the fixed delivery systems tested by Lang and Wise (2010). However, spray coverage, among other factors, depends on the selection of appropriate emitter type and mounting configuration to achieve uniform tree canopy coverage. Therefore, knowledge of emitters, mounting configuration and its impact on coverage in different canopy regions would be critical for improving system design, commercial implementation and adoption of SSCD system. No study was found characterizing canopy spray coverage due to emitter types and mounting configurations for a SSCD system. Therefore this study was designed to study the spray coverage with various emitters and mounting configurations, which will provide the fundamental knowledge for designing an effective SSCD system. The two specific objectives of this research were to:

(1)
Quantify spray coverage in upper-side and under-side of leaves in tree canopy using different emitter types and mounting configurations in a SSCD system, and
(2)
Evaluate spray penetration within different regions of the canopy with those configurations.

Section snippets

Test site and spray system

The test site involved a four year old commercial apple orchard (pacific rose variety) located near Prosser, WA. The orchard was trained in super spindle architecture. The tree rows were spaced at 2.4 m with an intra-tree distance of 0.8 m resulting in a density of 5425 trees per ha. The tree height varied from 2.8 m to 3.0 m. A set of five trees were randomly selected for this study. The trees (Fig. 1) were morphologically different in regards to foliage and branches. Three middle trees were used

Coverage on upper- and under-side of leaves

It was observed that emitters mounted in configuration-1 (Fig. 2) could not develop good spray pattern because of the close proximity of emitter to tree canopy. Visual observations showed that the spray droplets after hitting leaves in the upper canopy region dripped downward along the central leader of tree and did not provide good coverage in any canopy regions of the tree. Therefore, after initial tests, configuration-1 was not considered to be a viable location for mounting emitters and was

Conclusions

Four emitter mounting configurations were used to evaluate spray coverage with six different types of emitters. Spray application was conducted at a application rate of 937 L/ha and an application pressure of 275 kPa. Coverage data was collected using water sensitive cards (WSCs) mounted on upper- and under-side of randomly selected leaves. Water sensitive papers were analyzed to quantify coverage in various canopy regions and following conclusions were drawn:

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All emitters in configuration-4

Acknowledgements

This research was in part supported by Michigan State University, Project No. MICL05050 as a subcontract to Washington State University and by Washington State University Agricultural Research Center federal formula funds, Project Nos. WNP0748 and WNP0728 received from the U.S. Department of Agriculture National Institutes for Food and Agriculture (NIFA) and by Washington State University Center for Precision & Automated Agricultural Systems. Any opinions, findings, conclusions, or

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Fixed spray systems, an alternative to conventional pesticide application equipment, are under investigation in perennial fruit crops for improving spray applications. A prototype of a hydraulic fixed delivery spray system (31 m length) was evaluated for its suitability to be adopted as crop protection technology. In this research, two emitter densities selected from previous studies were used. Field trials were conducted to evaluate the performances of the system for spray mixture delivery, and to this extent, homogeneity distribution and cleaning performances were tested. Results showed that the emitter nearest to the injection point will deliver, the spray mixture first and water second, sooner than those further down the line. This delivery delay balanced the amount of spray mixture delivered by the fixed spray system along the line. Thus, the system delivered a similar amount (CV = 6.91%) of mixture from every sampled location in both emitter densities tested. Cleaning the line with water reduced the residue concentration by a factor greater than 300 in both emitter densities. In addition, the optimal time for cleaning that also reduced the water volume was identified as 2:30 and 4:30 min for high and low emitter densities, respectively. Linear regression models were built to estimate water volume consumption and cleaning step timing according to the fixed spray system's flow rate. In conclusion, emitter flow rate, emitter number, and spray mixture volume injected resulted the three key factors affecting dose applied, homogeneity of distribution among emitters, and cleaning performance.
Comparison of within canopy deposition for a solid set canopy delivery system (SSCDS) and an axial–fan airblast sprayer in a vineyard
2020, Crop Protection
Solid set canopy delivery systems (SSCDS) are novel ways of pesticide spray applications in modern high–density orchards and vineyards. Through our prior efforts, SSCDS variants have been tested and adjusted to provide optimal system configurations for spray application in high–density apple orchards and vineyards. This present study compared two prior optimized variants of an SSCDS comprising treatments with 1–tier and 2–tier of emitters/nozzles and an axial–fan airblast sprayer for spray performance in a modified vertical shoot position (VSP) vineyard. Such vineyards have the vine canes constricted under trellis wires, with the top of canes being loose and more sprawling. SSCDS 1–tier had a pair of full–circle emitters installed per vine at 76 cm above the cordon. For SSCDS 2–tier, two hollow–cone nozzles were installed per vine near the drip line at 45 cm above ground level in combination with additional emitters as in 1–tier. The sprayate was a fluorescent tracer dissolved in water at 500 ppm. Spray deposition and coverage were quantified in different canopy zones and on either side of leaf surfaces using mylar cards and water sensitive papers (WSPs) as samplers, respectively. The samplers were respectively analyzed using fluorometry and image processing techniques. Analysis of deposition data indicated statistically similar mean deposition for different treatments, however, uniformity of distribution was higher for the airblast sprayer treatment. Similar and uniform deposition on the mylar cards on the adaxial and abaxial leaf surfaces was observed in all the treatments, indicating that emitters/nozzles placed within a canopy can deposit similar amounts of active ingredient as an airblast sprayer. Contrary to the deposition data, spray coverage was highest for the airblast sprayer (33.5 ± 2.8%) followed by SSCDS 1–tier (21.5 ± 2.9%) and 2–tier (19.9 ± 3.0%). Such differences could be because of the use of air-assist which was absent in SSCDS based application. In summary, SSCDS provided higher canopy deposition, however, the airblast sprayer provided higher spray coverage and better spray application uniformity. Prior biological efficacy studies in apple orchards have reported equivalent insect-pest control for SSCDS and airblast sprayer, notwithstanding the uniformity and heterogenous spray coverage. Therefore, future studies are warranted to collect season long pest management data in economically viable plot sizes in a vineyard.
Drift potential from a solid set canopy delivery system and an axial–fan air–assisted sprayer during applications in grapevines
2019, Biosystems Engineering
Citation Excerpt :
Typical SSCDS rely on hydraulic or pneumatic pressure to deliver agrochemicals through a network of micro–emitters (or nozzles) positioned directly within the plant canopy. Several of such SSCDS prototypes have been evaluated in apples and grapes (Agnello & Landers, 2006; Carpenter, Reichard, & Wilson, 1985; Grieshop et al., 2015; Grieshop & Owen–Smith, 2015; Ranjan et al., 2019; Sharda et al., 2015; Sinha, Khot, Hoheisel, Grieshop, & Bahlol, 2019; Verpont, Favareille, & Zavagli, 2015). They have shown to provide season–long pest control in apple orchards (Agnello & Landers, 2006; Grieshop et al., 2015; Verpont et al., 2015, pp. 53–54).
Solid set canopy delivery system (SSCDS), consisting of fixed spray micro–emitters distributed throughout the tree or vine crop canopy, has the potential to reduce off–target spray drift and deposition because they do not use air–assistance for spray delivery. This study evaluated two different SSCDS configurations and a conventional axial–fan air–assisted sprayer for drift potential in a modified vertical shoot position trained vineyard. The application systems were evaluated using 500 ppm solution of Pyranine 10G® as a fluorescent tracer. Spray was captured on mylar cards and water sensitive paper (WSP) samplers downwind the spray row. Samplers were placed above the canopy and on the floor between the vine rows. Spray material collected on mylar cards was quantified by fluorometry, and coverage was estimated by processing pertinent WSP images. Overall, the air–assisted sprayer had significantly higher losses to the ground and airborne spray drift compared to the two SSCDS configurations. The SSCDS had minimal amounts of spray losses to air (<1 ng cm⁻²). Similarly, off–target spray movement was confined within 4.5 m downwind of the sprayed row. However, no significant difference in ground runoff was observed among the studied spray systems.
A model to estimate the spray deposit by simulated water sensitive papers
2019, Crop Protection
Citation Excerpt :
However, when used rationally and carefully, the undoubtable benefits of pesticides, including increased crop and livestock yields, improved food safety, quality of life and longevity, energy use and environmental degradation, must not be forgotten (Cooper and Dobson, 2007). A continuous evolution has affected spraying techniques in the last decades towards precision agriculture: monitoring of spray drift, using sensors to characterise canopies, mapping of crop parameters, and developing variable rate sprayers, are all aspects analysed by researchers and sprayer manufacturers to make pesticide application more sustainable (Zhang et al., 2002; Gil et al., 2013, 2014; Escolà et al., 2013; Sharda et al., 2015; Jiao et al., 2016; Grella et al., 2017; Pascuzzi et al., 2018). Spray characteristics affect both the biological efficacy and the environmental impact of every spraying application.
Spray deposit and superficial coverage play key roles in phytosanitary treatments. Their measurement is a quite complex task that requires adding suitable tracers to the mixture (deposit) and using some artificial targets (superficial coverage). With these laboratory tests, unit deposit values, measured in Petri dishes containing silicon oil, were correlated with percentage of covered surface, measured with water sensitive papers (WSPs) after spraying a water solution with red Ponceau at 2% concentration. An Albuz ATR 80 hollow cone nozzle was used at the spraying pressures of 0.3, 0.5, 1.0 and 1.5 MPa. The results showed a significant correlation between unit deposit $d_{u}$ (μL cm⁻²) and the fraction of covered surface $x_{S}$ ( $d_{u} = 2.2095 \cdot x_{S} - 0.3473$ , R² = 0.761, p-level < 0.001), that could allow estimating spray deposition from WSP analysis only, even with high values of percentage of superficial coverage (30%–80%). Moreover, measured data were used to simulate the WSP behaviour. The results of simulation showed that in a practical spray application with a high fraction of superficial coverage, spread factors higher than those reported in WSP datasheets should be considered.
Feasibility of a Solid set canopy delivery system for efficient agrochemical delivery in vertical shoot position trained vineyards
2019, Biosystems Engineering
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The E2 emitters had a hollow–cone spray pattern and were recommended by the emitter manufacturer for applications that needed effective spray penetration. Both emitters are readily available in the market and have shown adequate spray performance in apples (Agnello & Landers, 2006; Sharda et al., 2015). In configuration 1 (C1), the two E1 emitters were installed using a quick–connect tee (Jain® Irrigation Inc., Fresno, CA, USA) having two mirrored outlets with 180° orientation, at a height of 760 mm above the cordon (Fig. 3a).
Solid set canopy delivery systems (SSCDS) offer advantages such as reduced off–target drift and human exposure to chemicals compared to conventional axial–fan airblast sprayers. In this study, six different SSCDS configurations (C1–C6) with two different emitter types (E1 and E2) were installed in a vertical shoot position (VSP) trained grapevine and evaluated for spray deposition and coverage during early, mid, and late growth stages. Emitters E1 and E2 had full–circle and hollow–cone spray pattern, respectively. Configuration C1 had a pair of E1 emitters installed per vine at 760 mm above the cordon. Configurations C2 and C3 had 2 pairs of emitters (E2 and E1, respectively) installed per vine near the cordon and C4 was a combination of C1 and a pair of E2 emitters at the cordon. Configurations C5 and C6 had two E2 emitters per vine installed near the drip line, and C5 also had E1 emitters 760 mm above the cordon. Overall, configurations with emitters installed close to both the top and bottom canopy zones (i.e., C1, C4 and C5) provided the best coverage and deposition in a VSP trained vineyard. Deposition for C1, C4 and C5 was 588 ± 159 ng cm⁻² (mean ± std. error), 653 ± 123 ng cm⁻² and 607 ± 114 ng cm⁻², respectively. Coverage for respective configurations was 19 ± 4%, 23 ± 4% and 25 ± 4%. Overall, deposition did not differ significantly between upper–and under–sides of leaves whereas deposition and coverage in the top and bottom zones differed significantly among different configurations.
Characterization of irrigator emitter to be used as solid set canopy delivery system: which is best for which role in the vineyard?
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View full text

Effect of emitter type and mounting configuration on spray coverage for solid set canopy delivery system

Highlights

Abstract

Introduction

Section snippets

Test site and spray system

Coverage on upper- and under-side of leaves

Conclusions

Acknowledgements

Current progress in development of a fixed spray pesticide application system for high-density apple plantings

NY Fruit Quart.

Design and feasibility of a permanent pesticide application system for orchards

Trans. ASAE

Patternation of spray mass flux from axial fan airblast sprayers in the orchard

BCPC Monogr Air-assisted Spraying Crop Prot.

Spray deposits and losses in different sized apple trees from axial fan orchard sprayers: 1. Effects of liquid flow rate

Crop Prot.

Spray deposits and losses in different sized apple trees from axial fan orchard sprayers: 2. Effects of spray quality

Crop Prot.

Spray deposits and losses in different sized apple trees from an axial fan orchard sprayer: 3. Effects of air volumetric flow rate

Crop Prot.

A history of air-blast sprayer development and future prospects

Trans. ASAE