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Traditional sprayers are limited to applying spray mixture solely to the upper surfaces of crops. To overcome this limitation, a variable angle spraying machine (VASM) was designed using a linkage system. This machine enables the adjustment of both the spray position and angle through a single input signal, facilitating multi-directional spraying from the top to the bottom of crops. By utilizing ADAMS simulation, the relationship between input signal and output angle of spraying connecting rod was analyzed. The study employs a control variable experimental methodology alongside multiple comparison analysis to investigate various experimental factors, specifically nozzle sweep time (t), spray pump pressure (p), and distance from measurement position to surface (l). The average coverage rate observed in the top, side, and bottom orientations during actual operational conditions serves as the primary evaluation index for experimental analysis. The experimental results indicate that the VASM can achieve comprehensive spraying of crops, effectively covering both the leaf surface and the leaf underside. As the l value increases, the downward spray coverage rate (DSC) gradually rises, while the sideways spray coverage rate (SSC) gradually declines. The upward spray coverage rate (USC) initially decreases before increasing. It was observed that the DSC is lower than both the USC and the SSC due to the influence of gravity, particularly in the surface and middle layers of crops. The VASM can significantly enhance coverage of the underside and inner layers of crop leaves, thereby achieving the objectives of reducing pesticide waste and minimizing environmental pollution. [ABSTRACT FROM AUTHOR]

BACKGROUND: The hydraulic spray delivery (HSD)‐based solid set canopy delivery system (SSCDS) emitter configuration has been optimized for agrochemical applications in vertical shoot position (VSP) vineyards. It uses cost‐prohibitive emitters, and their placement restricts the mechanical pruning activities. Therefore, this study focused on optimizing the spray performance of a pneumatic spray delivery (PSD)‐based SSCDS variant that addresses the earlier issues. Three PSD‐SSCDS emitter configurations (C1–C3) were designed using modified low‐cost emitters (E1: modified flat fan, E2: 90° modular flat fan) for agrochemical applications in VSP vineyards. C1 had an E1 installed on trellis posts at 1.67 m above ground level. C2 had a pair of E2 installed per vine at 0.3 m below the cordon, while C3 combined the emitter placement of C1 and C2. The spray deposition (ng cm−2) and coverage (%) were quantified (mean ± standard error) using mylar cards and water‐sensitive paper samplers placed within the canopy, respectively. RESULTS: Spray deposition for C1, C2, and C3 was 301.12 ± 63.30, 347.9 ± 66.29, and 837.6 ± 92.53 ng cm−2, respectively. Whereas spray coverage for corresponding configurations was 18.02 ± 2.63, 8.98 ± 1.84, and 28.84 ± 2.46%, respectively. CONCLUSIONS: Overall, configuration C3 provided significantly higher spray deposition and coverage than C1 and C2. Substantially reduced system installation cost and emitter density per hectare with improved spray performance were achieved by C3 compared to earlier optimized HSD‐SSCDS configuration in the VSP vineyards. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

A pneumatic spray delivery-based solid set canopy delivery system (PSD-SSCDS) has been successfully configured for efficient spray applications in modern apple orchards typical of the state of Washington state. This study investigates the spray performance of optimized PSD-SSCDS against an axial-fan airblast sprayer in terms of spray deposition, coverage, and off-target drift in a tall spindle architecture of a commercial apple orchard. For field evaluation, mylar cards and water sensitive paper samplers were placed in different canopy zones on either side of the leaf surface, and 500 ppm of biodegradable fluorescent tracer solution was sprayed with PSD-SSCDS and an airblast sprayer. Additionally, aerial and downwind samplers were installed to evaluate ground runoff and drift, as well as aerial drift. The spray deposited on the mylar cards was analyzed using fluorometry, and spray coverage on WSPs was evaluated using image processing techniques. PSD-SSCDS (645.0 ± 94.7 ng cm-2, mean ± standard error) and an airblast sprayer treatment (661.6 ± 26.9 ng cm-2) had comparable mean spray deposition with no significant difference in different canopy zones for both treatments. However, the spray coverage was significantly higher for the airblast sprayer (32.7 ± 2.4%) compared to PSD-SSCDS (22.5 ± 3.1%). These differences are likely due to air-assist in airblast spraying, which is absent in PSD-SSCDS. Evidently, the airblast sprayer had significantly higher losses to the ground and aerial drift compared to PSD-SSCDS, as the ground drift for the latter was mostly confined within 4.1 m downwind of the sprayed row and spray losses to air were minimal. [ABSTRACT FROM AUTHOR]

This study was aimed to reduce the amount of the sprayed solution lost during trees spraying. At the same time, the concentration of the sprayed solution on the target (tree or bush) must be ensured and to find the best combination of treatments. Two factors controls the spraying process: (i) spraying speed (1.2 km/h, 2.4 km/h, 3.6 km/h), and (ii) the type of sensor. The test results showed a significant loss reduction percentage. It reached (6.05%, 5.39% and 2.05%) at the speed (1.2 km/h, 2.4 km/h, 3.6 km/h), respectively. It was noticed that when the speed becomes higher the loss becomes less accordingly. The interaction between the 3.6 km/h speed and the type of Ultrasonic sensor led to a decrease in the percentage of the spray losses reached to 1.69. For the coverage percentage, the increase in the spraying speed from 1.2 km/h to 2.4 km/h, and then to 3.6 km/h led to a significant decrease in the percentage of coverage (from 17.73% to 13.14%, and then to 11.12%), respectively. The interaction between the type of sensor and the speed has significantly affected the spray density. The speed was 3.6 km/h, and the type of Ultrasonic sensor was superior in obtaining the highest spray density of 83.2 drops/cm² [ABSTRACT FROM AUTHOR]

To ensure that a variable-rate spray (VRS) system can perform unmanned aerial spray in accordance with a prescription map at different flight speeds, we examine in this paper such significant factors as the response time of the VRS system and the pressure fluctuation of the nozzle during the variable-rate spraying process. The VRS system uses a lag compensation algorithm (LCA) to counteract the droplet deposition position lag caused by the system response delay. In addition, pulse width modulated solenoid valves are used for controlling the flowrates of the nozzles on the variablerate spray system, and a mathematical model was constructed for the spray rate (L min-1) and the relative proportion of time (duty cycle) each solenoid valve is open. The pressure drop and solenoid valve response time at different duty cycles (50~90%) were measured by indoor experiments. Meanwhile, the lag distance (LD), spray accuracy, and droplet deposition characteristics of the VRS system were tested by conducting outdoor experiments at different flight speeds (4m s-1, 5m s-1, 6m s-1). The results show that LCA can effectively reduce the LD. The LD values of the VRS system with LCA ranged from -0.27 to 0.78m with an average value of 0.32m, while without LCA, the LD values increased to 3.5~4.3m with an average value of 3.87m. The overall spray position accuracy was in the range of 91.56~97.32%. Furthermore, the spray coverage and deposition density, determined using water sensitive paper, were used to evaluate the spray application performance taking into account the spray volume applied. The VRS system can provide the most suitable spray volumes for insecticide and fungicide plant protection products. Based on a prescription map, the optimized VRS system can achieve accurate pesticide spraying as well as desirable spray coverage and deposition density. [ABSTRACT FROM AUTHOR]

Bioherbicides offer many potential benefits as part of an integrated weed management system or a totally biological or organic cropping system. A key factor for success is the selection of appropriate formulation and delivery systems for each target weed and cropping/climatic region. For dry inoculum products, we discuss direct implantation as an example for successful control of woody weeds, with benefits in control extending beyond the treated weeds to surrounding weeds. These applications do not require water and will become less labor‐intensive with future robotic application platforms. Indeed, all bioherbicide applications are likely to improve and become more cost‐effective with the advance of new application platforms with sensors and targeted control at lower application volume rates. Unmanned aerial vehicles, as new application platforms, are one of several such potential progressive application systems for liquid formulations, and we discuss product design to maintain optimum conditioning of the active ingredient(s) and storage stability. The delivery system must not adversely affect the products and the application volume rate must be appropriate for coverage on the target. Where applied with other products, compatibility must be ensured and appropriate mixing orders observed to assure performance and avoid precipitation or settling. Droplet size is important for allowing the active materials to be included in the spray, which may require droplets with diameter >150 μm for some larger particle biologically active agents. However, droplet size should not be too large to achieve target coverage. In some cases, that may be plant stems rather than leaves, or narrow grass weeds which tend to have highest spray collection efficiency for small droplets. Narrow droplet size spectrum nozzles may help optimize droplet size. We propose spray calculators to help optimize performance for coverage, retention and avoidance of drift losses, bounce, shatter and runoff. These include regulatory‐supported, validated models. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Plant protection drone spraying technology is widely used to prevent and control crop diseases and pests due to its advantages of being unaffected by crop growth patterns and terrain restrictions, high operational efficiency, and low labor requirements. The operational parameters of plant protection drones significantly impact the distribution of spray droplets, thereby affecting pesticide utilization. In this study, a field experiment was conducted to determine the working modes of two representative plant protection drones and an electric backpack sprayer as a control to explore the characteristics of droplet deposition with different spray volumes in the citrus canopy. The results showed that the spraying volume significantly affected the number of droplets and the spray coverage. The number of droplets and the spray coverage area on the leaf surface were significantly increased by increasing the spray volume from 60 L/ha to 120 L/ha in plant protection drones. Particularly for the DJI T30, the mid-lower canopy showed a spray coverage increase of 52.5%. The droplet density demonstrated the most significant variations in the lower inner canopy, ranging from 18.7 droplets/cm2 to 41.7 droplets/cm² by XAG V40. From the deposition distribution on fruit trees, the plant protection drones exhibit good penetration ability, as the droplets can achieve a relatively even distribution in different canopy layers of citrus trees. The droplet distribution uniformity inside the canopy is similar for XAG V40 and DJI T30, with a variation coefficient of approximately 50%-100%. Compared to the plant protection drones, the knapsack electric sprayer is suitable for pest and disease control in the midlower canopy, but they face challenges of insufficient deposition capability in the upper canopy and overall poor spray uniformity. The distribution of deposition determined in this study provides data support for the selection of spraying agents for fruit trees by plant protection drones and for the control of different pests and diseases. [ABSTRACT FROM AUTHOR]

Plant protection drone spraying technology is widely used to prevent and control crop diseases and pests due to its advantages of being unaffected by crop growth patterns and terrain restrictions, high operational efficiency, and low labor requirements. The operational parameters of plant protection drones significantly impact the distribution of spray droplets, thereby affecting pesticide utilization. In this study, a field experiment was conducted to determine the working modes of two representative plant protection drones and an electric backpack sprayer as a control to explore the characteristics of droplet deposition with different spray volumes in the citrus canopy. The results showed that the spraying volume significantly affected the number of droplets and the spray coverage. The number of droplets and the spray coverage area on the leaf surface were significantly increased by increasing the spray volume from 60 L/ha to 120 L/ha in plant protection drones. Particularly for the DJI T30, the mid-lower canopy showed a spray coverage increase of 52.5%. The droplet density demonstrated the most significant variations in the lower inner canopy, ranging from 18.7 droplets/cm2 to 41.7 droplets/cm2 by XAG V40. From the deposition distribution on fruit trees, the plant protection drones exhibit good penetration ability, as the droplets can achieve a relatively even distribution in different canopy layers of citrus trees. The droplet distribution uniformity inside the canopy is similar for XAG V40 and DJI T30, with a variation coefficient of approximately 50%-100%. Compared to the plant protection drones, the knapsack electric sprayer is suitable for pest and disease control in the mid lower canopy, but they face challenges of insufficient deposition capability in the upper canopy and overall poor spray uniformity. The distribution of deposition determined in this study provides data support for the selection of spraying agents for fruit trees by plant protection drones and for the control of different pests and diseases. [ABSTRACT FROM AUTHOR]

The objective of this study was to review representative publications for improved knowledge of spraying dense field crop canopies to augment the current understanding of the interaction between target foliage characteristics, spray practices, and the environment. Emphasis was placed on measured deep-canopy spray deposits made by full-scale sprayers and studies of airflow within and around crop canopies. Airflow could act as a spray droplet carrier and/or indicator of the internal canopy structure that restricts droplet penetration. High variation in natural airflows was noted in several studies. Crop canopy descriptions for spray studies were generally limited to overall canopy/row dimensions, descriptions of individual plant structures, leaf shapes, and leaf area index. Few studies evaluated the internal canopy "openness" with characteristic shape and size of internal volumes that would accommodate spray droplet trajectories. There have been significant increases in available spray tip designs with multiple orifices, discharge configurations, and droplet sizes that offered the applicator many choices. Advanced sprayer technologies ranging from nozzle control to sensor navigation are available, provided that suitable algorithms can be developed in a timely manner that pertain to a wide variety of spray and crop conditions. The air-assist technique provides a dynamic alternative to traditional over-the-top sprays for increasing spray penetration and deposit, advocating that the specifics of air discharge, spray droplet sizes, and canopy structure can be integrated. The complexity of the spraying process needs an extensive collaborative effort of many stakeholders to develop solutions for sprays to penetrate foliage that is subject to diseases and pests. [ABSTRACT FROM AUTHOR]

Ground speed variations are common and unavoidable during pesticide applications with agricultural sprayers. Field tests were conducted to evaluate the effect of varying ground speeds on spray deposition and quality with a commercial agricultural boom sprayer without a rate controller (CNS) in 2021 and equipped with a rate controller (SRC) in 2022. During each year, the sprayer boom was split evenly among three different nozzle types (XRC, AIXR, and TTI) to attain different droplet sizes (medium, very coarse, and ultra-coarse, respectively). Prior to testing, the sprayer was calibrated to deliver an application rate of 187 L ha−1 at a spray pressure of 207 kPa and ground speed of 9.7 km h−1. For spray deposition and quality assessment, pesticide applications were made at five different ground speeds of 9.7, 12.9, 16.1, 19.3, and 22.5 km h−1, and data were collected by placing water-sensitive paper at different locations across the sprayer boom and in the field. Results for CNS indicated that spray deposition reduced significantly (p < 0.05) with an increase in ground speed across all three nozzle types, primarily due to a decrease in the quantity of spray droplets applied per unit area. The quantity of spray droplets and spray deposition was more consistent among the ground speeds for SRC. Ground speed affected spray quality for both CNS and SRC; however, the spray quality variations were greater for SRC due to an increase in spray pressure with ground speed. Among nozzle types, the trends in spray deposition and quality were similar for the XRC and TTI nozzles as observed for CNS and SRC. However, the AIXR nozzle showed inconsistent spray deposition and quality as ground speed varied. The results of this study indicated agricultural sprayers equipped with a rate controller provide adequate and consistent spray deposition compared to conventional sprayers (no rate controller) when ground speed changes occur during pesticide applications. While spray quality is also affected when using a rate controller, best management practices including proper nozzle selection and application at nominal ground speeds should be followed to minimize these effects and ensure effective technology utilization.

In many EU countries, spray applications should comply with increasingly stringent requirements regarding the drift reduction class of spray nozzles. Many farmers fear that the use of drift-reducing nozzles producing coarse droplet spectra may compromise the performance of contact herbicides on small weed targets. This study examined the effects of various ISO 03 drift-reducing flat-fan nozzles (pre-orifice and single and dual flat-fan air induction nozzles) differing in spray drift reduction class and spray pressure (2.5 bar, 5.0 bar) on (1) spray coverage, (2) droplet characteristics and (3) efficiency of contact herbicides bentazon and phenmedipham against cotyledon and 2-leaf stage plants of Chenopodium album and Solanum nigrum. Performance was compared to that of an ISO 03 standard flat-fan nozzle producing a finer droplet size spectrum. All sprayings were performed at a spray volume of 200 L ha−1. In most dose–response experiments, several drift-reducing flat-fan nozzles performed equally well as standard flat-fan nozzles, regardless of herbicide, spray pressure, growth stage or weed species. However, droplet size spectra of air-induction nozzles were too coarse for an adequate spray coverage and efficient application of contact herbicides on cotyledon stage plants of S. nigrum. In addition, the performance of air-induction nozzles in controlling difficult-to-wet C. album weeds with phenmedipham was better at 5.0 bar than at 2.5 bar. In contrast with droplet size characteristics, spray coverage characteristics determined on water sensitive papers were not good proxies for estimating the biological efficiency of contact herbicides. Air induction nozzles at 5.0 bar allow efficient control of 2-leaf targets, but nozzles emitting finer droplet spectra, such as pre-orifice nozzles, should be preferred for controlling cotyledon stage weeds at low-herbicide doses. [ABSTRACT FROM AUTHOR]

Ground speed variations are common and unavoidable during pesticide applications with agricultural sprayers. Field tests were conducted to evaluate the effect of varying ground speeds on spray deposition and quality with a commercial agricultural boom sprayer without a rate controller (CNS) in 2021 and equipped with a rate controller (SRC) in 2022. During each year, the sprayer boom was split evenly among three different nozzle types (XRC, AIXR, and TTI) to attain different droplet sizes (medium, very coarse, and ultra-coarse, respectively). Prior to testing, the sprayer was calibrated to deliver an application rate of 187 L ha−1 at a spray pressure of 207 kPa and ground speed of 9.7 km h−1. For spray deposition and quality assessment, pesticide applications were made at five different ground speeds of 9.7, 12.9, 16.1, 19.3, and 22.5 km h−1, and data were collected by placing water-sensitive paper at different locations across the sprayer boom and in the field. Results for CNS indicated that spray deposition reduced significantly (p < 0.05) with an increase in ground speed across all three nozzle types, primarily due to a decrease in the quantity of spray droplets applied per unit area. The quantity of spray droplets and spray deposition was more consistent among the ground speeds for SRC. Ground speed affected spray quality for both CNS and SRC; however, the spray quality variations were greater for SRC due to an increase in spray pressure with ground speed. Among nozzle types, the trends in spray deposition and quality were similar for the XRC and TTI nozzles as observed for CNS and SRC. However, the AIXR nozzle showed inconsistent spray deposition and quality as ground speed varied. The results of this study indicated agricultural sprayers equipped with a rate controller provide adequate and consistent spray deposition compared to conventional sprayers (no rate controller) when ground speed changes occur during pesticide applications. While spray quality is also affected when using a rate controller, best management practices including proper nozzle selection and application at nominal ground speeds should be followed to minimize these effects and ensure effective technology utilization. [ABSTRACT FROM AUTHOR]

An efficient application of phytosanitary products depends, among other factors, on a good selection of nozzles and the application volume rate of the solution used. Thus, the objective of this work was to evaluate the efficiency of different models of hydraulic tips and application volume rates on spray coverage on targets positioned in the upper, middle and lower thirds of corn plants. The application volume rates evaluated were: 50 l · ha−1; 100 l · ha−1; 150 l · ha−1; 200 l · ha−1; 300 l · ha−1 and 400 l · ha−1. The following nozzles were used: TT 11001, TTJ60 11002, TXA 8003, 30HCX 12, GRD120 02 and GAT11002. Applications were carried out in phenological stages V6–V7 of corn plants. There was a directly proportional relationship between an increase in application volume rate and the levels of spray coverage and droplet density in the three thirds of corn plants. The application volume rate evaluated, except for 50 l · ha−1 in the lower third, provided a number of droplets compatible with the literature recommendations for the application of systemic fungicides. All tips evaluated provided a number of droplets compatible with the recommendations in the literature for the application of systemic fungicides, therefore, they can be recommended for use in spraying on corn crops.

Pesticide spray drift has been a worldwide concern in terms of potential environmental pollution and ecosystem damage. This study defined the main drift reduction agent (DRA) characteristics that help to understand the drift formation process in agricultural spraying. Seven various DRAs and water were evaluated. Three solutions were created based on the following materials: calcium dodecylbenzenesulfonate, benzenesulfonic acid, C10-13-alkyl derivatives, and calcium salt. Drift measurements were performed by means of the open circuit-type wind tunnel and in the field under conditionally controlled conditions. Air-injector flat spray nozzles and standard flat spray nozzles were used during trials. The spray pressure was 4.0 bar. Solutions were sprayed at different wind speeds (from 2 m s−1 to 10 m s−1, increasing every 2 m s−1). Studies have shown that wind speed and nozzle design have the greatest influence on spray drift. For all DRA solutions studied, the standard flat spray nozzles resulted in ground spray drift, both in the wind tunnel and in the field, which was about two times higher than that of air-injector flat spray nozzles. The spraying of water and all DRA solutions with the air-injector flat spray nozzle showed that all new solutions statistically significantly reduced the drift both in the tunnel and in the field. Ground-drift studies in the wind tunnel showed a trend towards a less intense drift reduction in DRA droplets with increasing wind speed. With DRA7e, the drift can be reduced by up to 56% (at a wind speed of 4 m s−1) and up to 30% (at 10 m s−1). The effect of the solutions on the reduction in spray drift is significantly lower when spraying with standard flat spray nozzles. Spray drift can then be reduced by up to 30% (at a wind speed of 4 m s−1) and up to 12% (at 10 m s−1) for DRA7e. [ABSTRACT FROM AUTHOR]

Precision and efficient pesticide spraying is an important part of precision agriculture, banana is a large broad-leaved plant, with pests and diseases, has a high demand for spraying and pest control. The purpose of this study was to clarify the wettability of different pesticides on the banana leaf surface, and the effects of nozzle type and working parameters on the deposition distribution performance under air-assisted spray conditions. The wettability test results of different pesticides on banana leaf surfaces showed that the wettability of the adaxial side was always stronger than that of the abaxial side, the smaller the surface tension of the droplets, the better the wettability on the surface. The spray experiment was carried out on the previously developed air-assisted sprayer with the latest developed intelligent variable spray control system. Three types of nozzles were used to spray with different combinations of working parameters. The deposition distribution performance on the banana leaf surface was obtained by image processing using a self-compiled program. The experimental results show that the nozzle type, wind speed, and spray pressure have significant effects on the deposition distribution performance. Through the study of the interaction and coupling effect of nozzle type and working parameters on the spray droplet deposition distribution on both sides of banana leaves, the results show that under the conditions of hollow cone nozzle, 0.5Mpa spray pressure and 3-5 m/s wind speed, the spray coverage and droplet density are in the optimal state. This is mainly due to the low spray pressure and/or wind speed is not enough to make the banana leaves vibrate and improve the performance of pesticide deposition. excessive spray pressure and/or wind speed will cause large deformation of banana leaves and make them airfoil stable, which reduces the surface deposition performance. It is of great significance for promoting sustainable and intelligent phytoprotection. [ABSTRACT FROM AUTHOR]

Plant protection spraying has been the main way to prevent crops from pests and diseases at present. However, the average utilization rate of pesticides is only 20% to 30% in manual sprayers and large-capacity rain spraying, particularly with water consumption of 600-1 200 L/hm2 . The current pesticide spraying cannot fully meet the requirement of intensive agriculture in recent years. Among them, a large number of droplets with small particle sizes are susceptible to drifting by ambient wind. In this study, the mesh atomization of droplets was applied to reduce the wind drift for the high utilization rate of pesticides in the process of plant protection spraying. A systematic optimization was also made to investigate the secondary atomization characteristics of the droplets and the deposition effect of the droplets after the spray hits the mesh. The experimental variables were set as the pore size and the distance between the nozzle and the mesh. Phase Doppler Anemometry (PDA) was used to measure the velocity and particle size distribution of droplets after secondary atomization. A high-speed camera was selected to capture the spray angle. A 0.5 g/L methyl orange aqueous solution was prepared as a spray solution. The water-sensitive and filter tests were carried out to determine the droplet coverage and deposition amount, in order to evaluate the droplet deposition characteristics of the mesh atomization. The test results showed that: 1) the mesh effectively reduced the speed of the droplets. The average velocities of the measurement points were 1.80, 2.02, and 1.67 m/s under the mesh with pore sizes of 461, 350, and 227 μm, respectively. There were 23.40%, 13.90%, and 29.00% lower than those without the mesh (2.35 m/s). 2) The mesh reduced the particle size of the droplets. The maximum average particle sizes of the measurement points were 155.0, 165.6, and 173.3μm under the mesh with the pore size of 461, 350, and 227 μm, respectively, which were 19.5%, 14%, and 10% lower than those without the mesh (192.5 μm). 3) The spray angle of the droplet was varied in the pore size of the mesh and the distance between the nozzle and the mesh. Specifically, the maximum spray angle was 84.179° for the secondary atomized droplets at the pore size of 461 μm and the 10cm distance between the nozzle and the mesh, which was 20.366° larger than that without the mesh. 4) There was a great influence of pore size on the uniformity and penetration of the droplet deposition. The coefficient of variation of the deposition rate was between 33.51% and 88.08% at the sampling point of the mesh with the pore size of 350 and 227 μm, respectively, indicating similar deposition uniformity. By contrast, the maximum coefficient of variation of the deposition rate was 162.98% at the sampling points in each mesh layer with a pore size of 461 μm, indicating relatively less deposition uniformity. The better penetration of droplets was achieved in the mesh with the pore size of 350 μm, where the coefficient of variation of deposition between layers was between 0.8 % and 10.08 %. The better deposition was obtained in the mesh with the pore size of 461 μm in this case, compared with the pore size of 461 and 227 μm. There was no significant effect of the distance between the nozzle and the grid on the droplet coverage and deposition volume. In terms of the grids and large spraying droplets, the average droplet drift in the non-target area was 7.58 % of the deposition in the target area, indicating better performance after optimization. This finding can provide a strong reference to select the spraying and mesh parameters for the combination of plant protection UAV spray and mesh atomization. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The objective of this study was to review representative publications for improved knowledge of spraying dense field crop canopies to augment the current understanding of the interaction between target foliage characteristics, spray practices, and the environment. Emphasis was placed on measured deep-canopy spray deposits made by full-scale sprayers and studies of airflow within and around crop canopies. Airflow could act as a spray droplet carrier and/or indicator of the internal canopy structure that restricts droplet penetration. High variation in natural airflows was noted in several studies. Crop canopy descriptions for spray studies were generally limited to overall canopy/row dimensions, descriptions of individual plant structures, leaf shapes, and leaf area index. Few studies evaluated the internal canopy "openness" with characteristic shape and size of internal volumes that would accommodate spray droplet trajectories. There have been significant increases in available spray tip designs with multiple orifices, discharge configurations, and droplet sizes that offered the applicator many choices. Advanced sprayer technologies ranging from nozzle control to sensor navigation are available, provided that suitable algorithms can be developed in a timely manner that pertain to a wide variety of spray and crop conditions. The air-assist technique provides a dynamic alternative to traditional over-the-top sprays for increasing spray penetration and deposit, advocating that the specifics of air discharge, spray droplet sizes, and canopy structure can be integrated. The complexity of the spraying process needs an extensive collaborative effort of many stakeholders to develop solutions for sprays to penetrate foliage that is subject to diseases and pests. [ABSTRACT FROM AUTHOR]

To realize the online evaluation of spray quality, an online measuring system for spray coverage and deposition quality is developed. The measuring theory of spray coverage and deposition quality on an LWS (leaf wetness sensor) surface is analyzed. When the spray conditions are constant, there is a linear correlation between the spray coverage on the sensor surface, the spray deposition quality and the LWS output voltage increment. The results of calibration experiments show that when the spray conditions are constant, the coefficient of determination R 2 of the regression curves between the sensor output voltage increment and the spray coverage on the sensor surface is more than 0.75, and the coefficient of determination R 2 of the regression curves between the sensor output voltage increment and the spray deposition quality on the sensor surface is more than 0.90. Based on ZigBee wireless sensor technology, this paper reports an online measuring system for spray coverage and deposition quality at multiple points in the field. The test results show that the online measuring system has good uniformity. Field test results show that the LWS voltage increment and the coverage rate of water-sensitive paper have a good correlation, and the measuring results of the spray deposition quality trend are in good agreement. The fit of the spray deposition quality curves measured by the two methods was 0.8924. The research results in this paper can provide a reference for using LWS sensors to measure spray coverage and deposition quality. [ABSTRACT FROM AUTHOR]

BACKGROUND: In the last decade, unmanned aerial vehicle (UAV) sprayers have been growing rapidly worldwide as a new method for pesticide application, especially in Asian countries. More and more manufacturers and service providers are currently aiming at UAV spraying operation for fruit trees with higher economic value. We evaluated the spray performance of an electric six‐rotor UAV sprayer using an orchard operation mode (different application volumes and flight patterns) in a hilly apple orchard with small and sparse trees (SS) and a plain orchard with tall‐spindle trees (TS). RESULTS: Application volume (APV) had a significant influence on the spray coverage parameters in both orchards, while flight pattern, intra‐row, inter‐row and verti‐row, had a relatively limited influence at 60 0 and 85 7 L/ha. The UAV's downwash airflow produced a good spray penetration in the isolated SS trees, but not for the conjoined TS trees. It is better to fly along and above rows at 63.5 L/ha or higher for SS trees. The excessively low underside coverage is the main drawback of UAV orchard pesticide application and the underside droplet size was generally less than 200 μm. CONCLUSION: Spray performance is closely related to tree shape, planting pattern, UAV payload, application volume, spray droplet size and downwash airflow field. The results provide data support for the best operational practice development and the decision model for the application volume of UAV sprayer orchard operations. The underside spray performance requires further improvement by several effective measures. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Autonomous sprayer UAVs are one of the most used aerial machines in modern agriculture. During flight missions, some common narrow obstacles appear in the flying zone. These are non-detectable from satellite images and one of the biggest challenges for autonomous sprayer UAVs in farmland. This work introduces an obstacle avoidance architecture specifically for sprayer UAVs. This architecture has generality in the spraying UAV problem, and it reduces the reliance on the global mapping of farmland. This approach computes the avoiding path based on the onboard sensor fusion system in real-time. Moreover, it autonomously determines the transition of several maneuver states using the current spraying liquid data and the UAV dynamics data obtained by offline system identification. This approach accurately tracks the avoidance path for the nonlinear time-variant spraying UAV systems. To verify the performance of the approach, we performed multiple simulations with different spraying missions, and the method demonstrated a high spraying coverage of more than 98% while successfully avoiding all vertical obstacles. We also demonstrated the adaptability of our control architecture; the safe distance between the UAV and obstacles can be changed by specifying the value of a high-level parameter on the controller. The proposed method adds value to precision agriculture, reduces mission time, and maximizes the spraying area coverage. [ABSTRACT FROM AUTHOR]

An efficient application of phytosanitary products depends, among other factors, on a good selection of nozzles and the application volume rate of the solution used. Thus, the objective of this work was to evaluate the efficiency of different models of hydraulic tips and application volume rates on spray coverage on targets positioned in the upper, middle and lower thirds of corn plants. The application volume rates evaluated were: 50 l·ha-1; 100 l·ha-1; 150 l·ha-1; 200 l·ha-1; 300 l·ha-1 and 400 l·ha-1. The following nozzles were used: TT 11001, TTJ60 11002, TXA 8003, 30HCX 12, GRD120 02 and GAT11002. Applications were carried out in phenological stages V6-V7 of corn plants. There was a directly proportional relationship between an increase in application volume rate and the levels of spray coverage and droplet density in the three thirds of corn plants. The application volume rate evaluated, except for 50 l·ha-1 in the lower third, provided a number of droplets compatible with the literature recommendations for the application of systemic fungicides. All tips evaluated provided a number of droplets compatible with the recommendations in the literature for the application of systemic fungicides, therefore, they can be recommended for use in spraying on corn crops. [ABSTRACT FROM AUTHOR]

The western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is a major insect pest of greenhouse-grown horticultural crops. Western flower thrips causes direct and indirect damage by feeding on plant leaves, flowers, and fruits, and by transmitting viruses that can result in greenhouse producers experiencing substantial economic losses. Consequently, insecticides are used to suppress western flower thrips populations. However, issues associated with applying insecticides may affect the suppression of western flower thrips populations. Therefore, experiments were conducted under greenhouse conditions to determine the effects of the spray volume applied and application frequency on insecticide efficacy against western flower thrips adults located in transvaal daisy, Gerbera jamesonii, cut flowers. Four spray volumes (5.0, 10.0, 12.5, and 25.0 mL), two application frequencies (one or two spray applications), and three insecticides [spinosad (Conserve), chlorfenapyr (Pylon), and flonicamid (Aria)], each with a different mode of action, were tested. The insecticide treatments had the greatest effects on the mean percent mortality of western flower thrips adults regardless of spray volume or application frequency. However, in Expt. 3, the 5.0- and 10.0-mL spray volumes resulted in a higher mean percent mortality of western flower thrips adults than the 2.5-mL spray volume. Spinosad and chlorfenapyr resulted in a mean percent mortality of more than 72% for western flower thrips adults, whereas flonicamid resulted in mean percent mortality between 40% and 91%. Our study demonstrates that certain insecticides are more effective against western flower thrips adults located in transvaal daisy flowers than others, which will help greenhouse producers effectively manage western flower thrips populations.

Improving application efficiency is crucial for both the economic and environmental aspects of plant protection. Mathematical models can help in understanding the relationships between spray application parameters and efficiency, and reducing the negative impact on the environment. The effect of nozzle type, spray pressure, driving speed and spray angle on spray coverage on an artificial plant was studied. Artificial intelligence techniques were used for modeling and the optimization of application process efficiency. The experiments showed a significant effect of droplet size on the percent area coverage of the sprayed surfaces. A high value of the vertical transverse approach surface coverage results from coarse droplets, high driving speed, and nozzles angled forward. Increasing the vertical transverse leaving surface coverage, as well as the coverage of the sum of all sprayed surfaces, requires fine droplets, low driving speed, and nozzles angled backwards. The maximum coverage of the upper level surface is obtained with coarse droplets, low driving speed, and a spray angle perpendicular to the direction of movement. The choice of appropriate nozzle type and spray pressure is an important aspect of chemical crop protection. Higher upper level surface coverage is obtained when single flat fan nozzles are used, while twin nozzles produce better coverage of vertical surfaces. Adequate neural models and evolutionary algorithms can be used for pesticide application process efficiency optimization.

Trimen's false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae), has developed pest status in vineyards in the Northern Cape and Groblersdal areas of South Africa, and an integrated pest management system is required. The objective of this study was to test the susceptibility of A. trimenii larvae to three commercial products (Delegate®WG, Steward®150 EC and three doses of DiPel® DF). Bioassay tests using all three products, and semi-field trials to test the potential of DiPel® DF against A. trimenii larvae, applied at different water volumes (50 g/1 000 L/ha and 50 g/1 430 L/ha) were performed. The residual activity of DiPel® DF, when applied at different water volumes, was investigated daily. Delegate® WG, Steward®150 EC and the recommended dose of DiPel® DF showed 100% larval mortality within seven days. Delegate® WG and the recommended dose of DiPel® DF proved to be the fastest acting products. The product label recommended dose of DiPel® DF (0.25 g/500 mL distilled water) proved the most effective dose (in comparison to halved and doubled dosages) and showed 100% mortality five days after application. Increasing the water volume per ha of a spray application of DiPel® DF for the same application area, showed no significant increase in larval mortality. A reduction in insecticidal activity for DiPel® DF applied at both water volumes was seen between leaves picked four days after spraying and leaves picked five days after spraying, and no mortality was observed after day 6. To help improve efficacy, attention should be given to increasing spray coverage and residual activity of DiPel® DF, as well as using all tested products within an integrated pest management system. [ABSTRACT FROM AUTHOR]

Pesticide spray drift has been a worldwide concern in terms of potential environmental pollution and ecosystem damage. This study defined the main drift reduction agent (DRA) characteristics that help to understand the drift formation process in agricultural spraying. Seven various DRAs and water were evaluated. Three solutions were created based on the following materials: calcium dodecylbenzenesulfonate, benzenesulfonic acid, C10-13-alkyl derivatives, and calcium salt. Drift measurements were performed by means of the open circuit-type wind tunnel and in the field under conditionally controlled conditions. Air-injector flat spray nozzles and standard flat spray nozzles were used during trials. The spray pressure was 4.0 bar. Solutions were sprayed at different wind speeds (from 2 m s−1 to 10 m s−1, increasing every 2 m s−1). Studies have shown that wind speed and nozzle design have the greatest influence on spray drift. For all DRA solutions studied, the standard flat spray nozzles resulted in ground spray drift, both in the wind tunnel and in the field, which was about two times higher than that of air-injector flat spray nozzles. The spraying of water and all DRA solutions with the air-injector flat spray nozzle showed that all new solutions statistically significantly reduced the drift both in the tunnel and in the field. Ground-drift studies in the wind tunnel showed a trend towards a less intense drift reduction in DRA droplets with increasing wind speed. With DRA7e, the drift can be reduced by up to 56% (at a wind speed of 4 m s−1) and up to 30% (at 10 m s−1). The effect of the solutions on the reduction in spray drift is significantly lower when spraying with standard flat spray nozzles. Spray drift can then be reduced by up to 30% (at a wind speed of 4 m s−1) and up to 12% (at 10 m s−1) for DRA7e.

Background: Unmanned Aerial Vehicles (UAVs) are increasingly being used commercially for crop protection in East Asia as a new type of equipment for pesticide applications, which is receiving more and more attention worldwide. A new model of pear cultivation called the ‘Double Primary Branches Along the Row Flat Type’ standard trellised pear orchards (FT orchard) is widely used in China, Japan, Korea, and other Asian countries because it saves manpower and is suitable for mechanization compared to traditional spindle and open-center cultivation. The disease and pest efficacy of the flat-type trellised canopy structure of this cultivation is a great challenge. Therefore, a UAV spraying trial was conducted in an FT orchard, and a four-factor (SV: Spray application volume rate, FS: Flight speed, FH: Flight height, FD: Flight direction) and 3-level orthogonal test were designed. Results: These data were used to analyze the effect, including spray coverage, deposit density, coefficient of variation, and penetration coefficient on the canopy, to determine the optimal operating parameters of the UAV for pest efficacy in FT orchards. The analysis of extremes of variance showed that factor FD had a significant effect on both spray coverage and deposition density. Followed by factor FS, which had a greater effect on spray coverage (p < 0.05), and factor SV, FH, which had a greater effect on deposition density (p < 0.05). The effects of different factors on spray coverage and deposit density were FD > FS > FH > SV, FD > FH > SV > FS, in that order. The SV3-FS1-FH1-FD3, which flight along the row with an application rate of 90 L/ha, a flight speed of 1.5 m/s, and a flight height of 4.5 m, was the optimal combination, which produced the highest deposit density and spray coverage. It was determined through univariate analysis of all experimental groups, using droplet density of 25/cm2 and spray coverage of 1%, and uniformity of 40% as the measurement index, that T4 and T8 performed the best and could meet the control requirements in different horizontal and vertical directions of the pear canopy. The parameters were as follows: flight along the tree rows, application rate not less than 75 L/ha, flight speed no more than 2 m/s, and flight height not higher than 5 m. Conclusion: This article provides ample data to promote innovation in the use of UAVs for crop protection programs in pergola/vertical trellis system orchards such as FT orchards. At the same time, this project provided a comprehensive analysis of canopy deposition methods and associated recommendations for UAV development and applications.

Optimally configured solid set canopy delivery system (SSCDS) based spraying has potential to improve treefruit crop pest and disease management by reducing application time and eliminating dependence on ground conditions. In such an effort, this study attempted to optimize SSCDS variants. Four different emitter types (E1 to E4) installed in different mounting configurations (C1 to C4) were evaluated for spray deposition and coverage in a high-density apple orchard trained in tall spindle architecture. Emitters E1, E2, and E4 had full circle spray patterns, and E3 had a hollow-cone pattern. Configuration C1 had a pair of E1 emitters spraying in a vertical plane and installed between two trees at 1.5 m above ground level (AGL). Another E1 emitter spraying in a horizontal plane was mounted atop each tree at 3.3 m AGL. Configurations C2 and C4 had emitters (E2 and E4, respectively) mounted atop each tree at 3.3 m AGL, and C3 had a pair of E3 emitters installed in a three-tier arrangement between two trees in the crop row. During field trials, a tree canopy about 3.0 m tall was divided into three zones (0 to 1.4 m, >1.4 to 2.2 m, and >2.2 to 3.0 m AGL) as bottom, middle, and top canopy zones, respectively. Mylar cards were used to quantify spray deposition using fluorometry, and water-sensitive papers (WSPs) were used to quantify coverage using image processing. Configuration C3 with 80° hollow-cone nozzles in a twinemitter, three-tier arrangement had the highest overall spray deposition (581.1 77.8 ng cm-2, mean  standard error) and coverage (18.4% 4.1%). Moreover, C3 also had a significantly higher coverage on the abaxial surfaces of leaves compared to the other configurations. Configurations C1 was non-optimal because it lacked abaxial surface coverage as the canopy grew in the middle and late growth stages. Moreover, significant spray runoff from leaf surfaces was observed visually in the middle zone for C1 during the middle and late stages. This may be attributed to canopy growth around the emitters. Configurations C2 and C4, with emitters in a shower-down arrangement, had the highest deposition and coverage in the top canopy zone compared to the middle and bottom zones. Configurations C2 and C4 also had significantly higher spray coverage on the adaxial surfaces of leaves compared to the abaxial surfaces. Overall, despite the complex design of configuration C3 with six emitters per tree, it may be the most ideal arrangement for agrochemical application in an apple orchard trained in tall spindle architecture. For commercial feasibility, we recommend exploring this three-tier SSCDS configuration with low-cost emitter alternatives. Pertinent continuing efforts have been published by our group in which we successfully modified low-cost irrigation emitters, and the resulting three-tier SSCDS configurations had improved spray performance over expensive hollow-cone nozzles. [ABSTRACT FROM AUTHOR]

Unmanned aerial application systems (UAAS) have recently gained momentum for the application of crop protection (CP) products. Due to their high operational efficiency, mobility, and low cost, UAAS may be perceived as a more viable option for spray application when compared to conventional application techniques, especially backpack/knapsack sprayers. However, being a relatively new technology and not a common practice in the USA, there are no best management practices or guidelines for testing UAAS spray performance. Therefore, this study was undertaken to assess the impact of different attributes pertinent to UAAS flight (e.g., altitude, speed, etc.), application (e.g., droplet size, tank additive, etc.), and UAAS design (e.g., nozzle placement relative to a the rotor) on spray performance. The spray performance was evaluated in terms of swath and spray drift (ground and airborne) using water-sensitive papers (WSP) and mylar card/string samplers, respectively. The samplers were respectively analyzed using image processing and fluorometry techniques. The different treatments under study were UAAS type (MG-1P and AG V6A+), flight altitude (1.5, 2.5, and 4.0 m) and speed (2 and 3 ms−1), and nozzle type (XR11001 and XR8002 flat fan nozzles) with different droplet volume median diameter (VMD) at ~207 kPa (very fine [140 µm] and fine [196 µm], respectively). The results indicated a highly variable swath for both platform types. While nozzles under each rotor may be a common design in commercial UAAS, the results indicated that placement of nozzles out on a boom might have a less variable swath and a lower drift potential. In addition, flying slower, using a relatively larger droplet VMD (i.e., 196 µm at ~207 kPa) may reduce both ground and airborne drift. This study may serve as a guideline for growers/operators to evaluate their UAAS platforms and optimize key attributes pertinent to UAAS operation for effective spraying.

Proper nozzles arrangement is significant to improve spray deposition of crop protection unmanned aerial system (UAS). Besides fuselage structure, the control strategy is another nozzle location changing method when there are multiple sets of nozzles. A four-rotor crop protection UAS equipped with four centrifugal nozzles was used to conduct a field experiment in the rupturing stage of rice. Two sets of nozzles in the front and rear of the fuselage were enabled independently to investigate spray deposition, including spray coverage and droplet density on the sampling cards. Various nozzle rotating speeds and flight speeds were employed in the experiment to study the influence of nozzle location on the deposition. With different nozzle rotating speeds, the droplet spectrum could be controlled. The results show that the average coverage and average cumulative droplet density are negatively correlated with flight speed. Average droplet density is also negatively correlated with the droplet size. Spray deposition of front nozzles is significantly reduced compared with that of the rear nozzles under the same spray parameters, especially when the droplet size is too large or the flight speed is too fast. The reduction is mainly concentrated in the center area of the spray swath. As a result, the average cumulative droplet density of the front nozzles decreases by 25.96% in total. The average droplet density decreases by 18.54% when the droplet size is smaller than 100 μm, decreases by 25.02% when between 100 μm and 200 μm, and decreases by more than half when larger than 200 μm. This research can provide guidance for the installation of UAS nozzles and spray control strategy design. [ABSTRACT FROM AUTHOR]

To realize the online evaluation of spray quality, an online measuring system for spray coverage and deposition quality is developed. The measuring theory of spray coverage and deposition quality on an LWS (leaf wetness sensor) surface is analyzed. When the spray conditions are constant, there is a linear correlation between the spray coverage on the sensor surface, the spray deposition quality and the LWS output voltage increment. The results of calibration experiments show that when the spray conditions are constant, the coefficient of determination R2 of the regression curves between the sensor output voltage increment and the spray coverage on the sensor surface is more than 0.75, and the coefficient of determination R2 of the regression curves between the sensor output voltage increment and the spray deposition quality on the sensor surface is more than 0.90. Based on ZigBee wireless sensor technology, this paper reports an online measuring system for spray coverage and deposition quality at multiple points in the field. The test results show that the online measuring system has good uniformity. Field test results show that the LWS voltage increment and the coverage rate of water-sensitive paper have a good correlation, and the measuring results of the spray deposition quality trend are in good agreement. The fit of the spray deposition quality curves measured by the two methods was 0.8924. The research results in this paper can provide a reference for using LWS sensors to measure spray coverage and deposition quality.

This study was conducted to determine the effects of different position angles in twin-jet spray applications on droplet penetration of different nozzle types. Seven different nozzle types (standard flat fan, ST; narrow flat fan, STN; multirange, LU; lowdrift potential, AD; air-induction, IDK; twin-jet air-induction, IDKT) were used and nozzles were positioned +15° along the forward direction, perpendicular to ground surface 0° and reverse direction of forward -15°. Spray experiments at 100 L/ha constant application volume were conducted under controlled conditions of a closed facility. Water sensitive paper (WSP) was used as sampling surface. WSP samples were placed vertically and horizontally over both the metal frames and root collar of artificial plants. The present findings revealed that transport potential of spray droplets was quite lower on vertical planes than on horizontal planes. The greatest coverage was achieved with ST, STN, LU, and SC-type nozzles producing fine droplets. Compared to open targets, the coverage ratios around the root collars were quite low and insufficient. In all spray treatments, coverage ratio on the vertical planes was 86.1% lower than the coverage ratio on the horizontal plane. In other words, coverage ratio on the horizontal plane was 7.2 times greater than the coverage ratio on the vertical plane. Transfer efficiency of medium and coarse droplet-producing nozzles to root collars was greater than the transfer efficiency of fine droplet-producing nozzles. Such a ratio for AD, IDKT, and IDK-type nozzles was determined as 37.06, 37.85, and 41.02% respectively. According to the present findings, effects of nozzle position angle on droplet penetration were not found to be significant. However, nozzle position angle along the forward direction increased coverage ratios on the vertical planes. [ABSTRACT FROM AUTHOR]

BACKGROUND Pesticide drift is a serious environmental and safety concern that affects all of US agriculture. A number of mitigation techniques to reduce pesticide drift have been recommended by industry, academic and government agencies. These techniques are very costly or reduce the efficacy of the pest control product and have not been implemented by US agriculture. RESULTS: When using a novel spray technique (Air‐in), pesticide drift was significantly reduced by between 53% and 99% at 7.6 m from the orchard drip line when compared to the grower standard. This technique not only reduced pesticide drift, but also maintained or improved the amount of pesticide residue deposited (by 0.7–2.6‐fold) and the percentage pesticide coverage (by 1.0–1.4‐fold) with different air‐blast speed sprayers on almond, walnut and pistachio. CONCLUSION: The Air‐in technique shows great promise in reducing pesticide drift while maintaining or improving pesticide coverage with minimal cost to the grower. [ABSTRACT FROM AUTHOR]

Agricultural nozzles are the main components that perform the spraying of agrochemicals, and their proper functionality is a key element for uniform spray application on crops. Because nozzles have small orifices, they can become clogged when there is debris from the agrochemical in the tank. Nozzle clogging during spray application results in poor pest and weed management and increased cost for re-spraying the affected crop row. Measures used to prevent nozzles from clogging include using screens or strainers to filter out debris before it reaches the nozzle tip, as well as performing regular checks on the nozzles. However, nozzle clogging still occurs during spraying despite the precautions taken. Thus, a device that can detect nozzle clogging during spraying is necessary to enable a quicker response that will ensure uniform application across each row of the crop. A novel, patented device for detecting clogged nozzles that is externally attachable to each nozzle on a sprayer boom was developed in the Precision Application Technology Lab at Arkansas State University. The main objective of this article is to present a general description of this prototype nozzle clog detection device and the nozzle clog detection system. Spray droplet size and pattern tests under controlled conditions and spray coverage tests under field conditions were conducted with and without the device to determine if there were significant differences in droplet size, spray pattern, or spray coverage between using and not using the device. The tests demonstrated that this new technology has potential for detecting clogged nozzles without significantly influencing spray quality for extended-range nozzles but not for ultra low-drift nozzles. To increase the reliability of the performance of this new technology, further improvements in the design need to be considered. [ABSTRACT FROM AUTHOR]

Improving application efficiency is crucial for both the economic and environmental aspects of plant protection. Mathematical models can help in understanding the relationships between spray application parameters and efficiency, and reducing the negative impact on the environment. The effect of nozzle type, spray pressure, driving speed and spray angle on spray coverage on an artificial plant was studied. Artificial intelligence techniques were used for modeling and the optimization of application process efficiency. The experiments showed a significant effect of droplet size on the percent area coverage of the sprayed surfaces. A high value of the vertical transverse approach surface coverage results from coarse droplets, high driving speed, and nozzles angled forward. Increasing the vertical transverse leaving surface coverage, as well as the coverage of the sum of all sprayed surfaces, requires fine droplets, low driving speed, and nozzles angled backwards. The maximum coverage of the upper level surface is obtained with coarse droplets, low driving speed, and a spray angle perpendicular to the direction of movement. The choice of appropriate nozzle type and spray pressure is an important aspect of chemical crop protection. Higher upper level surface coverage is obtained when single flat fan nozzles are used, while twin nozzles produce better coverage of vertical surfaces. Adequate neural models and evolutionary algorithms can be used for pesticide application process efficiency optimization. [ABSTRACT FROM AUTHOR]

It has been recognized for decades that low and inconsistent spray coverages of pesticide applications represent a major challenge to successful and sustainable crop protection. Deployment of water-sensitive spray cards combined with image analysis can provide valuable and quantitative insight into spray coverage. Herein we provide description of a novel and freely available smartphone app, “Smart Spray”, for both iOS and Android smart devices (iOS and Google app stores). More specifically, we provide a theoretical description of spray coverage, and we describe how Smart Spray and similar image-processing software packages can be used as decision support tools and quality control for pesticide spray applications. Performance assessment of the underlying pixel classification algorithm is presented, and we detail practical recommendations on how to use Smart Spray to maximize accuracy and consistency of spray coverage predictions. Smart Spray was developed as part of ongoing efforts to: (1) maximize the performance of pesticide sprays, (2) minimize pest-induced yield loss and to potentially reduce the amount of pesticide used, (2) reduce the risk of target pests developing pesticide resistance, (3) reduce the risk of spray drift, and (4) optimize spray application costs by introducing a quality control.

Solid set canopy delivery systems (SSCDS) are fixed spray systems that consist of a network of permanently plumbed emitters in high-density tree-fruit orchard canopies. Most of the previously configured SSCDS worked on the principle of hydraulic spray delivery (HSD), which may not be suitable for large-scale installation due to the drop in operating pressure caused by frictional losses in the spray lines. Therefore, a pneumatic spray delivery (PSD) based SSCDS was developed in this study for potentially achieving uniform spray application at all locations along the spray lines. A reservoir subsystem was developed to contain a precisely metered amount of spray liquid. Once filled, compressed air pushed through the spray lines can pressurize the reservoir to help deliver uniform spray into the canopy through emitters. In this study, HSD and PSD systems of 91 m set length were installed in a high-density apple orchard. Both systems were evaluated for variations in operating pressure, spray output, and spray performance. Spray performance was quantified during the middle (BBCH 75) and late (BBCH 85) apple (cv. WA-38 on tall spindle architecture) crop growth stages. Deposition and coverage in three canopy zones and on both sides of leaves were evaluated using Mylar cards and water-sensitive papers (WSP) as samplers, respectively. The Mylar cards and WSP were respectively analyzed using fluorometry and image processing. Statistically similar operating pressure (p > 0.05) was observed for the HSD and PSD systems at 3 m (286.1 and 284.1 kPa, respectively), 33 m (268.4 and 270.5 kPa), 60 m (260.6 and 268.9 kPa), and 87 m (255.3 and 257.9 kPa) from the row inlet. Despite the operating pressure drop, the PSD system had uniform spray output along the 91 m spray line. Compared to the HSD system, about 4%, 3%, 5%, and 20% higher spray output was delivered with the PSD system at 3, 33, 60, and 87 m, respectively, along the spray line. Overall, the PSD system had significantly higher mean spray deposition (p < 0.01) compared to the HSD system during the middle (521 and 382 ng cm-2, respectively) and late (631 and 409 ng cm-2, respectively) growth stages. The PSD system also had numerically higher spray deposition compared to the HSD system for all the canopy zones and on either side of leaf surfaces. Spray coverage trends were similar to deposition; however, the differences were not significant. Overall, the PSD-based SSCDS shows potential for large-scale installation, with additional refinements, for uniform spray applications in high-density apple orchards. [ABSTRACT FROM AUTHOR]

BACKGROUND Air blast sprayers are not optimized for spraying the short statured trees in modern apple orchards, resulting in off target drift and variable coverage. A solid set canopy delivery system (SSCDS) consisting of a microsprayer array distributed throughout the orchard was investigated as a replacement agrochemical application method in this study. SSCDS's have the potential to optimize coverage, rapidly spray applications, and remove the operator and tractor from the orchard. RESULTS: Air blast and SSCDS applications were compared using water sensitive paper, bioassays, and pest damage assessments. Pest management and coverage were compared using application volumes of 700 and 795 L ha−1, respectively. In 2013, adaxial coverage measurements showed no difference between the treatments, but air blast sprayers had higher coverage levels on the abaxial surfaces. There were no significant differences in coverage in 2014. Bioassays using Choristoneura rosaceana fed on leaf discs treated by the SSCDS displayed 95.8% mortality in 2013 and 94.2% mortality in 2014, and air blast treated larval mortality was 95% in 2013 and 100% in 2014. Damage evaluations in both years generally showed no significant differences between the air blast plots and the SSCDS plots, but significant differences between the treated plots and untreated control. CONCLUSIONS: The prototype SSCDS was an effective pest management tool in high density apples, and offered a number of advantages over an air blast. Further engineering and research into coverage optimization would offer producers a novel tool for foliar agrochemical applications. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

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Jet breakup and dispersion from impact sprinkler are mainly influenced by the configurations of nozzle and dispersion device. Based on the structure, different types of nozzles were designed and tested with a pointed tip dispersion device under low pressure conditions. Experiments were performed using High-Speed Photographic technique, and Matlab computation program was established and applied to determine the initial jet breakup length and angle of dispersion from the nozzles. The sprinkler range decreased with the increase in diameter of nozzle, and the largest range of 15.1 m was produced from sprinkler with 6 mm nozzle size under a pressure of 150 kPa. The angle of dispersion decreased with the increase of jet velocity, the spray coverage from sprinkler with 6 mm nozzle size was 1478 mm under 150 kPa, and was not statistically different when the pressure was increased. A new range formula was established for sprinkler with dispersion device through curve fitting of the parameters of initial jet breakup length, angle of dispersion, nozzle size and working pressure. The new formula was reliable for calculating range with a relative error less than 3%. Since the formula is based on the angle of dispersion, it could be useful to estimate uniformity of water distribution in sprinkler irrigated fields. [ABSTRACT FROM AUTHOR]

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. Highlights • Solid set canopy delivery system (SSCDS) was evaluated in a vineyard. • Spray deposition and coverage was quantified for SSCDS configurations. • Identified were the optimal SSCDS configurations. • Emitters had uniform spray when placed in canopy top and bottom sections. [ABSTRACT FROM AUTHOR]

Seven hydraulic nozzle types (standard-ST; hollow cone-KH; multirange-LU; standard with narrow angle-STD; antidrift-AD; air-induction-IDK; twinjet air-induction-IDKT) were compared in terms of spray transfer and drop penetration. Spray treatments were carried out at a constant application volume of 90 L ha-1 with a linear-motion simulator. WSP's were placed onto metal poles and into artificial plant at both horizontal and vertical planes. Two different operating pressures (250 and 500 kPa) and the nozzle position angles (0&@176; and 45°) were used in the experiments. Spray transfer levels at vertical plane were quite lower than the spray transfer levels at horizontal plane. The greatest spray coverage was achieved with LU and ST nozzles producing fine droplets. The greatest drop penetration at vertical plane was obtained from IDK nozzle. Only 25% of the drops transferred to the open target reached the stem and root collar region of the plant canopy. With increasing operating pressures, spray coverage increased by 1,17 times at horizontal plane and 1,50 times at vertical plane. With increasing nozzle position angles, spray coverage at vertical plane increased by 40%. The greatest coverage was achieved on front surface of the vertical target and drops reaching to side and rear surfaces were quite low. [ABSTRACT FROM AUTHOR]

Bleach sprays suffer from poor surface coverage, dry out before reaching proper contact time, and can be inadvertently over-diluted to ineffective concentrations. Highlight®, a novel color additive for bleach that fades to indicate elapsed contact time, maintained >99.9% surface coverage over full contact time and checked for correct chlorine concentration. [ABSTRACT FROM AUTHOR]

Increased use of biopesticides has spurred demand for efficient and effective delivery systems. To this goal, laboratory tests were conducted to investigate six different classes of biopesticides discharged from five different types of flat-fan nozzles, each with three flow capacities. The biopesticide classes were horticultural oil insecticide (HOI), bacterial biofungicide (BBF), botanical extract bio-insecticide (BEBI), liquid fungal bio-insecticide (FBI-ES), wettable powder fungal bio-insecticide (FBI-WP), and mineral salt biofungicide (MSBF). Droplet size distribution, spray pattern width, spray deposition, and coverage on plant leaves and water-sensitive paper (WSP) were the spray parameters tested. These parameters varied greatly with biopesticide class, nozzle type, and nozzle flow capacity. The DV0.5 of the biopesticides ranged from 75 to 519 μm for 0.76 L min-1 nozzles, from 86 to 509 μm for 1.51 L min-1 nozzles, and from 99 to 622 μm for 2.25 L min-1 nozzles. The use of different biopesticides with the same nozzle significantly altered the spray pattern width. Compared to a water-only solution, the largest change of spray pattern width was 14.7% for the air-induction nozzle (AI11004) discharging FBI-ES. The amount of spray deposited on plant leaves for all tested biopesticides (except HOI) did not vary significantly with different nozzle types. However, the air-induction nozzles produced the most uneven spray deposition patterns. Therefore, to achieve optimal spray application efficiency and effectiveness for discharging specific classes of biopesticide, the choice of the proper nozzle type and flow capacity is critical [ABSTRACT FROM AUTHOR]

Solid set canopy delivery systems (SSCDS) are a novel foliar agrochemical delivery system designed as an alternative for airblast sprayers in high density fruit production. This study tested the pest management potential, coverage, and chemical deposition of an SSCDS using commercially available microsprinkler components over the course of a growing season. Spray coverage and deposition for a representative airblast sprayer and SSCDS were evaluated using water sensitive paper and tartrazine dye, respectively. Foliar sprays for pest suppression were applied through both systems, and damage assessments were taken at the midpoint and end of the growing season. SSCDS sprays demonstrated similar levels of coverage on the adaxial leaf surface as airblast sprays, but significantly lower coverage on the abaxial surface. However, mean levels of foliar chemical deposition was generally higher in the SSCDS. Evaluations found minimal arthropod and fungal damage in both airblast and SSCDS treated plots compared to untreated trees. The SSCDS was shown to be a viable alternative to the airblast, with inherent advantages such as rapid application time and improved worker safety. Furthermore, higher deposition on SSCDS treated foliage supports the hypothesis that SSCDS provide a higher droplet capture rate in the canopy, with less off-target loss and drift than airblast sprayers.