Air-assisted System Research Articles

High-Speed Fluorescence Imaging Corroborates Biological Data on the Influence of Different Nozzle Types on Cell Spray Viability and Formation

Treating severe dermal disruptions often presents significant challenges. Recent advancements have explored biological cell sprays as a promising treatment, but their success hinges on efficient cell delivery and complete wound coverage. This requires a good spray distribution with a small droplet size, high particle number, and ample surface coverage. The type of nozzle used with the spray device can impact these parameters. To evaluate the influence of different nozzles on spray characteristics, we compared air-assisted and unassisted nozzles. The unassisted nozzle displayed small particle size, high particle number, good overall coverage, high cell viability, preserved cell metabolic activity, and low cytotoxicity. Air-assisted nozzles did not perform well regarding cell viability and metabolic activity. Flow visualization analysis comparing two different unassisted nozzles using high-speed imaging (100 kHz frame rate) revealed a tulip-shaped spray pattern, indicating optimal spray distribution. High-speed imaging showed differences between the unassisted nozzles. One unassisted nozzle displayed a bi-modal distribution of the droplet diameter while the other unassisted nozzle displayed a mono-modal distribution. These findings demonstrate the critical role of nozzle selection in successful cell delivery. A high-quality, certified nozzle manufactured for human application omits the need for an air-assisted nozzle and provides a simple system to use with similar or better performance characteristics than those of an air-assisted system.

Development of an Electric Variable Air Assist System for Apple Orchard Sprayers

Highlights Electric air assist system was developed with electric fans, pulse width modulation (PWM) controllers, a custom-designed air channel, and a battery. Adjusting PWM duty cycles from 0% to 100% achieved average exit air velocities from 0 to 11.3 m s-1. Spray applications with the system at 50% and 70% power achieved canopy pass through spray coverages from 4.1% to 19.9% and 14.2% to 24.2%, respectively. A multivariable regression model was developed to adjust air assist outputs based on tree canopy density and off-target loss. Abstract. Air assist for apple orchard spray applications is a necessity to deliver pesticides to target crops. However, conventional orchard sprayers use axial fans to provide air assists which are generally designed for tall crops. Thus, these systems have very limited capabilities to control airflows to match canopy densities. An electric air assist system (EAAS) was developed with an electric fans, pulse width modulation (PWM) controllers, a custom-design air channel, and a 400-Ah LiFePO4 battery to address such limitations. The system could ramp up its airflow to nearly 80% of its maximum in 2.5 s, while it took approximately 4 s to reach 100% airflow from no air assist. The EAAS provided airflow of 11.3 and 5.3 m s-1 at the fan outlet and 1 m away, respectively, with 100% duty cycles (DC) of PWM. It was capable of modulating its average air velocities from 0 to 11.3 ms-1 by changing DCs. Spray coverage samples of constant rate applications with different air assist levels were collected from the behind apple tree canopies throughout the 2023 growing season to characterize the potential for off-target spray drift. A multivariable regression model for controlling DCs was developed with the spray coverage data and leaf area index (LAI) to minimize the off-target drift. The EAAS was a promising approach to developing more advanced air assist spraying systems to enable the adjustment of both air and liquid flows based on canopy characteristics to maximize spray depositions on intended targets while minimizing spray drift. Keywords: Air assisted sprayer, Automation, Crop protection, Fan, Penetration, Pesticide, Pulse width modulation, Variable air assistance.

A Simulation and Experiment on the Optimization Design of an Air Outlet Structure for an Air-Assisted Sprayer

In response to the issues of low-velocity zones and non-uniform jet velocity distribution in the airflow field of traditional air-assisted orchard sprayers, an arc-shaped air outlet suitable for axial-flow air-assisted systems is designed. This article employs the method of CFD numerical simulation and experimental verification to compare and analyze the internal flow field of the air-assisted system and validates the reliability of the numerical simulation results through calculation error and chi-square test. The wind speed of the cross-section is measured at different distances from the outlet, and the distribution characteristics of the outflow field wind speed before and after the structural optimization of the air-assisted system are compared. The horizontal distribution of fog droplets is collected using a fog collection chamber. The experimental results show that the design of the arc-shaped outlet increases the average wind speed of the annular outlet from 14.95 m/s to 18.20 m/s and reduces the proportion of low-speed area from 20.83% to 0.71%. When the rounded corner radius of the air outlet is 50 mm, optimal parameters are attained. The maximum error between the simulated and experimental values is 9.52%. At a significance level of 0.05, the χ2 value is 0.252, indicating that the simulated values follow the distribution of the actual measurement values. On the cross-sections located at distances of 0.5, 0.75, 1, 1.25, and 1.5 m from the air outlet, the wind speed distribution with no arc-shaped air outlets exhibits a “low left and high right” type, tending to shift towards the right as a whole. Fog droplets also display a drift tendency towards the right side. The wind speed distribution with arc-shaped air outlets shows a symmetric “high in the middle and low on the sides” type. Fog droplets concentrate in the central position. The optimized air-assisted system can reduce the air field’s low-flow area, increase the airflow distribution uniformity, improve the average wind speed at the outlet, and decrease fog droplet drift. This provides a reference for the structural design of air-assisted systems in current orchard sprayers of the same type.

Research on tunable bandgap characteristics of the phononic crystal duct with piezoelectric thin plates for the broad noise reduction

To achieve adjustable mid-low frequency noise reduction characteristics in pipeline systems, one hybrid phononic crystal duct with piezoelectric thin plates is proposed. Firstly, phononic crystal duct model with Helmholtz mufflers and built-in piezoelectric thin plates is established to reduce low-to-mid frequency noise in the duct. The theoretical transmission loss is verified using simulation methods, revealing the sound attenuation law and bandgap mechanism. Under the shunting effect of the RLC circuit, three locally resonant bandgaps are generated: the mechanical locally resonant band gap introduced by the thin plate, acoustic locally resonant band gaps caused by the Helmholtz muffler cavity structure, and the electromechanical locally resonant band gaps dominated by the shunting circuit. By adjusting the shunting circuit, the acoustic impedance of the piezoelectric thin plate can be controlled, and then the acoustic characteristics of low and medium frequencies will change. For the shunting circuit composed of inductance, capacitance and resistance in series, the inductance and capacitance can adjust the position of the three band gaps; the negative capacitance can effectively enhance the tunability of the electromechanical locally resonant band gap, which is helpful to obtain the low-frequency band gap; while resistance primarily affects the magnitude of acoustic attenuation within the bandgap. Subsequently, based on the analysis of the noise characteristics of the air-assisted system of one fuel cell vehicle, one hybrid phononic crystal duct with compact structures is designed to achieve a broadband duct noise reduction of 330 Hz–4000 Hz.

Design and test of powerful air-assisted sprayer for high stalk crops.

The canopies of high stalk crops, such as maize, intersect the rows at the later stages of growth, making conventional sprayers unable to enter the field for spraying. Air-assisted sprayers are often used to improve the deposition of droplets inside the canopy. In this study, the sprayer structure, the air-assisted system, and the spraying system were designed. The air-assisted conveyor system characteristics were numerically analyzed, and the wind-field distribution was tested. The wind-field distribution results showed that the near-ground wind speed exceeded 5 m s-1 in the sampling interval from 10 to 35 metres. The wind field covered a concentrated spatial area with a downward pressure trend, resulting in better drift resistance and penetration. Field tests for droplet distribution were conducted at three maize heights to verify the powerful air-assisted sprayer's technical performance and working quality. The test results showed that the droplet deposition and coverage decreased gradually along the range direction, and the top layer had the highest deposition and coverage across the canopy. The upper canopy of 0 to 12 metres range demonstrated a greater extent of coverage and deposition. The peak deposition area expanded from 9 to 33 metres in the lower canopy, with an average value of 3.77 μg cm-2. The droplet coverage within the 30 to 60 metres range only amounted to 15% to 18% of the total coverage.

Visualization of Lidar-Based 3D Droplet Distribution Detection for Air-Assisted Spraying

Air-assisted spraying is a commonly used spraying method for orchard plant protection operations. However, its spraying parameters have complex effects on droplet distribution. The lack of large-scale 3D droplet density distribution measurement methods of equipment has limited the optimization of spraying parameters. Therefore, there is a need to develop a method that can quickly obtain 3D droplet distribution. In this study, a 2D LiDAR was used to quickly scan moving droplets in the air, and a test method that can obtain the visualization of 3D droplet distribution was constructed by using the traveling mode of the machine perpendicular to the scanning plane. The 3D droplet distribution at different positions of the nozzle installed in the air-assisted system was tested at different fan rotation speeds, and the methods for signal processing, point cloud noise reduction, and point cloud division for 2D LiDAR were developed. The results showed that the LiDAR-based method for detecting 3D droplet distribution is feasible, fast, and environmentally friendly.

Design and test of a novel crawler-type multi-channel air-assisted orchard sprayer

In order to solve the problem of poor traveling stability and excessive pesticide application during plant protection operations in hilly orchards, a novel crawler-type multi-channel air-assisted sprayer that is particularly appropriate for hilly orchards was designed in this study. Considering anti-rolling requirements and the orchard environment in hilly areas, this study selected limits for uphill and downhill rolling angles as well as the transverse rolling angle as the evaluation indexes for determining both the layout and parameter settings of the sprayer. According to freely submerged jets and the requirements in plant protection operation, a multi-channel air-assisted system was developed. The test results showed that the anti-rolling performance and the designed air-assisted system were adequate. At 2 m from the longitudinal center plane of the sprayer, the airflow exhibited wavy distribution patterns under different parameter combinations since the four streams of the airflow were not thoroughly intersected and mixed. At 3 m from the longitudinal center plane of the sprayer, the jet was ejected at great velocity but underwent rapid attenuation; the airflow velocity in most areas barely satisfied the requirements for plant protection operation. In addition, different air outlet layout schemes led to significant differences in the spatial distribution of the airflow field. Compared with a traditional air-assisted sprayer, using the developed multi-channel air-assisted sprayer enhanced the droplet coverage uniformity by 19.4%, and the mean droplet deposition in the front, middle, and rear of the canopy was enhanced by 32.9%, 50.3%, and 78.1%, respectively, while reducing ground deposition and air drift by 26.8%. Keywords: fan, dual-flow-channel, plant protection, air-assisted, test DOI: 10.25165/j.ijabe.20201306.5362 Citation: Qiu W, Li X L, Li C C, Ding W M, Lv X L, Liu Y D. Design and test of a novel crawler-type multi-channel air-assisted orchard sprayer. Int J Agric & Biol Eng, 2020; 13(6): 60–67.

Atomization characteristics of a fan air-assisted nozzle used for coal mine dust removal: an experimental study

ABSTRACT This article focuses on the atomization characteristics of fan air-assisted nozzles, which is important in the emerging process of dust removal via air-assisted nozzles in underground coal mines. An experimental study on atomization characteristics of a fan air-assisted nozzle was conducted using a custom-built air-assisted spray system. The results reveal that the volume flow rate of the medium, i.e., either water or air, showed a negative exponentially increasing trend as itself pressure increasing and showed a linearly decreasing trend as the other pressure increasing. The drop size distribution met the Rosin-Rammler function. When the air pressure was 0.5 MPa, the drop distribution moved right, and the uniformity coefficient of the distribution fell as the water pressure increased from 0.1 MPa to 0.9 MPa; the drop distribution moved left and the uniformity coefficient raised as the water pressure increased from 0.9 MPa to 1.0 MPa. When water pressure was 0.5 MPa, the drop distribution moved left, and the uniformity coefficient fell as the air pressure increased. The drop size grew downstream; the growth speed was proportional to droplet density and water volume fraction and inversely proportional to drop size. The drop size first tended to increase then showed a decreasing trend as the water pressure increased; the value of the cutoff point increased as the water pressure increased. The drop size decreased as the air pressure increased.

Design and test of a novel crawler-type multi-channel air-assisted orchard sprayer

In order to solve the problem of poor traveling stability and excessive pesticide application during plant protection operations in hilly orchards, a novel crawler-type multi-channel air-assisted sprayer that is particularly appropriate for hilly orchards was designed in this study. Considering anti-rolling requirements and the orchard environment in hilly areas, this study selected limits for uphill and downhill rolling angles as well as the transverse rolling angle as the evaluation indexes for determining both the layout and parameter settings of the sprayer. According to freely submerged jets and the requirements in plant protection operation, a multi-channel air-assisted system was developed. The test results showed that the anti-rolling performance and the designed air-assisted system were adequate. At 2 m from the longitudinal center plane of the sprayer, the airflow exhibited wavy distribution patterns under different parameter combinations since the four streams of the airflow were not thoroughly intersected and mixed. At 3 m from the longitudinal center plane of the sprayer, the jet was ejected at great velocity but underwent rapid attenuation; the airflow velocity in most areas barely satisfied the requirements for plant protection operation. In addition, different air outlet layout schemes led to significant differences in the spatial distribution of the airflow field. Compared with a traditional air-assisted sprayer, using the developed multi-channel air-assisted sprayer enhanced the droplet coverage uniformity by 19.4%, and the mean droplet deposition in the front, middle, and rear of the canopy was enhanced by 32.9%, 50.3%, and 78.1%, respectively, while reducing ground deposition and air drift by 26.8%. Keywords: fan, dual-flow-channel, plant protection, air-assisted, test DOI: 10.25165/j.ijabe.20201306.5362 Citation: Qiu W, Li X L, Li C C, Ding W M, Lv X L, Liu Y D. Design and test of a novel crawler-type multi-channel air-assisted orchard sprayer. Int J Agric & Biol Eng, 2020; 13(6): 60–67.

Spray performance of air-assisted kerosene injection in a constant volume chamber under various in-cylinder GDI engine conditions

The performance of kerosene spray from an air-assisted system was investigated in a constant volume chamber by backlit imaging and shadowgraph technologies over various chamber pressures, temperatures, and fuel amount. The results show that the penetration decreases with the increase in the chamber pressures from 0.5 bar to 3.5 bar due to the reduction in the differential pressure between the air/fuel interface and ambience and the rise in the resistance to penetration as well. Liquid-phase penetration increases with an increase in temperature from 400 K to 500 K both at 1.0 bar and 3.0 bar for decreasing density of ambient gas. When ambient temperature was increased at 1.0 bar, there was no significant change in the vapor penetration. Therefore, increasing ambient temperature by internal EGR cannot reduce wall impingement when GDI engines fueled with kerosene. Furthermore, liquid-phase penetration decreases with the increase in fuel amount, while at the front end of spray the cross-sectional area increases since the spray is increasingly disturbed by the ambient gas.

NUMERICAL AND EXPERIMENTAL STUDY OF SPRAY COATING USING AIR-ASSISTED HIGH-PRESSURE ATOMIZERS

Airless and Air-assisted Airless spray guns are widely used in the spray painting industry. The present contribution summarizes ongoing investigations on the spray painting processes of these two atomizers using real paint material. Atomization processes under airless and air-assisted conditions were experimentally studied by measuring droplet size distributions and droplet velocities using a Spraytec Fraunhofer type particle sizer and Laser-Doppler Anemometry. A computational fluid dynamics code was applied to calculate the flow field and the droplet trajectories. The measured and calculated film thickness distributions on the substrate were compared. The experimental and simulation results provided the necessary information for understanding the painting process using airless and air-assisted systems and for improving the performance of these atomizers.

Techbits: Efficiency Improvements for Facilities Focus of Workshop

Techbits Innovations aimed at improving efficiencies in surface facilities were the focus of an SPE Applied Technology Workshop (ATW) titled "Surface Facilities: Improving Efficiencies in Production, Energy Conservation, CO2 Reduction, and Waste Management" held in Dubai. More than 50 attendees from 25 companies and 16 countries reviewed the challenges of oil/water/gas separation, conservation, emission, and waste management in the backdrop of increasingly stringent regulatory requirements. Abbas Ahmed Yousef, field manager for Adco's Bab field, opened the ATW with a keynote address focusing on the means to improve surface-facility efficiency, emphasizing the need for operators to adopt more enhanced oil recovery (EOR) techniques to improve production efficiencies. He also touched on the importance of energy conservation and emissions and waste management, particularly as producing fields mature. Oil/Water/Gas Separation and Handling In the ATW's first session, Ahmed Abdulmajeed of Saudi Aramco discussed process enhancements in gas/oil separation plants within his company. He reviewed how a new mixing valve for wash water going to desalters was able to reduce wash water consumption from 50 to 30 gallons per minute, resulting in more than 10 million gallons of water savings over one year. He also discussed how the implementation of a smokeless, high-pressure air-assisted flare system, which employs a new flare-tip design and additional flare-tip shield, provides for better gas combustion. Saudi Aramco is also testing an in-line water separator that promises to remove approximately 70–80% of water without the need to treat in a gas/oil separation plant and with quality in the range of 22–35 ppm of oil in water. Alexander de Kruijf of Petroleum Development Oman (PDO) discussed the pitfalls of improper oil and gas sampling and made predictions on future process-equipment design. Inaccurate measurement of H2S in one PDO application led to deteriorating sales gas quality, with H2S concentrations reaching 5 ppm. The result was 4 months of deferment equivalent to approximately 100,000 BOPD. To prevent acid corrosion in equipment, de Kruijf stressed the importance of routinely measuring for organic acid, using corrosion-resistant alloys with increased corrosion allowances, and implementing organic pH neutralizers. In general, he advised that production chemistry programs should be an integral part of a project's process. Oliver Garnier of Total reviewed a strategy to maintain production from his company's mature Abu Al-Bukhoosh field. The field has been producing since 1974, and present production is 15,000 BOPD with an average basic sediment and water (BS&W) of 86%. By implementing improvements, including increasing the impeller size in the gas recovery compressor, closing wells with too high a BS&W, optimizing well productivity by using multiphase flowmeters, and implementing de-emulsifier injection with gas lift, Total has managed to level the oil production potential to above 16,000 BOPD since 2007.

Evaluation of foliar fungicide application methods on soybean

A field trial was conducted at Fargo, North Dakota, in 2005 and 2006 to evaluate different fungicide application methods on soybean (Glycine max). Kromekote® paper cards were placed in the upper and lower canopy of soybean plants, and tebuconazole fungicide mixed with a blue dye was sprayed with different application methods at the R5 developmental stage. The applications were made with a conventional sprayer with Turbo TeeJet® 110015 flat-fan nozzles at 276 kPa liquid pressure, a conventional sprayer with XR TeeJet® 80015 flat-fan nozzles at 276 kPa liquid pressure, an AirJet® bifluid nozzle spray system with liquid pressure at 276 kPa and air pressure at both 76 and 48 kPa, or an air-assisted spray system with liquid pressure at both 221 and 83 kPa. An untreated control was also included to evaluate the effect of tebuconazole on soybean yield. Dye-sensitive Kromekote paper cards were analyzed to determine the percent coverage and the volume median diameter (VMD) of the droplets. Significant (P ≤ 0.05) interactions between year and application method were detected, most likely resulting from differences in plant height and development between the years. Droplet coverage in the upper canopy did not differ in either year among the application methods. Most application methods provided similar droplet coverage in the lower canopy in 2005, but the conventional sprayer with XR TeeJet 80015 flat-fan nozzles provided the greatest coverage in the lower canopy in 2006. Correlation analysis indicated that droplet coverage in the lower canopy increased with increased VMD of the droplets in 2005 (R = 0.91), and that yield increased with increased fungicide coverage in 2006 (R = 0.85). Visible symptoms of foliar fungal diseases were not present in either year, and tebuconazole had no effect on soybean yield, compared with the untreated control in either year.

An air-assisted spinning disc nozzle and its performance on spray deposition and reduction of drift potential

An air-assisted system was used with a Micromax III speed spinning disc nozzle and assess its effects on spray penetration, deposition and reduction of drift in an artificial canopy representing cotton plants. The effects of air-assist velocities (10, 15, 25 m s −1) to carry droplets and application volumes (20 and 40 l ha −1) and two droplet sizes obtained by changing disc speed on spray deposition and drift potential were investigated with different cross-wind velocities (1.5, 2.5, 3.5 m s −1) in a wind tunnel. Deposition data produced by the spinning disc nozzle with and without air assistance were compared using a fluorometric method. Spray pattern displacement (SPD) was also determined using a spray patternator in the wind tunnel. Wind velocity, air assistance, application volume, droplet diameter and their interactions significantly affected deposition on plants. The highest deposit on plants was obtained with the combination of no cross-wind, spray volume of 20 l ha −1, an air-assist velocity of 25 m s −1 and droplet diameter of 210 μm. Downwind drift was partly controlled at an air-assist velocity of 25 m s −1 when drift potential could be reduced up to 39%.

Efficacy of Pyrithiobac and Bromoxynil Applied with Low-Volume Spray Systems

Field experiments were conducted in 1994 and 1995 to determine if the sodium salt of pyrithiobac or bromoxynil applied in a low-volume, air-assist spray system controlled entireleaf morningglory, pitted morningglory, and smallflower morningglory as well as treatments applied with a conventional hydraulic fan spraying system, and to determine if herbicide rates could be reduced when using the low-volume spraying system. Pyrithiobac at 0.035 and 0.071 kg ai/ha and bromoxynil at 0.56 and 1.12 kg ai/ha were applied alone and in combination with DSMA at 1.7 kg ai/ha or MSMA at 1.7 kg ai/ha. Spraying systems were calibrated to deliver 26 L/ha and 140 L/ha for the low-volume and conventional systems, respectively. No significant differences in control were noted between low-volume and conventional spray systems when herbicides were applied at the suggested use rates of 0.071 and 1.12 kg ai/ha for pyrithiobac and bromoxynil, respectively. Morningglory control was reduced when pyrithiobac and bromoxynil were applied at one-half the suggested use rate regardless of the spraying systems. Bromoxynil alone generally controlled pitted and entireleaf morningglory better than pyrithiobac alone regardless of rate and application method. However, pyrithiobac generally provided better control of smallflower morningglory than bromoxynil. Adding MSMA or DSMA to bromoxynil and pyrithiobac increased control of both weed species.

Effect of Drift Retardant Adjuvants on Spray Droplet Size of Water and Paraffinic Oil Applied at Ultralow Volume

Adjuvants were evaluated to determine the effect on increasing spray droplet size and reducing the amount of spray dispensed in small driftable size particles when applying water and paraffinic oil at ultralow volume. Spray solutions were applied with an air-assist system at liquid flow rates of 28 and 56 ml/min and atomized with 14, 28, 42, 56, and 84 kPa of air pressure. Water and paraffinic oil were applied alone and with two drift retardant adjuvants mixed individually in each. The two water soluble adjuvants were mixed at concentrations of 0.25, 0.50, 0.75, 1.0, and 2.0%; oil soluble adjuvants were applied at 0.125, 0.25, and 0.50%. Adjuvants used in water and oil were effective at increasing droplet size and reducing the amount of liquid dispensed in small driftable size particles. Effectiveness of the adjuvants decreased as air pressures increased, with water soluble adjuvants being more susceptible to air pressure. Volume median diameters > 200 μm with water could be achieved without adjuvants; whereas with oil, an adjuvant was required.

Invert Emulsion Droplet Size and Mycoherbicidal Activity ofColletotrichum truncatum

When formulated and sprayed in an invert emulsion (IE), conidia of the mycoherbicide,Colletotrichum truncatum, controlled hemp sesbania in the absence of dew. To optimize hemp sesbania control, formulation droplet size influence upon the pathogen's germination and pathogenicity was investigated. Conidia germination in manually produced IE droplets decreased from 46% to 5% as droplet diameter decreased from 2700 to 900μm. Droplet size did not affect appressoria formation. On a per conidium basis, 900-μm droplets were more pathogenic to detached hemp sesbania leaves than were 2100-μm droplets. An air-assist spray system produced droplet spectra with volume median diameters of 421 and 104μm, respectively. The spectrum of smaller droplets covered the target better than did that of larger droplets. When applied to whole hemp sesbania plants in greenhouse trials, conidia in the smaller and larger droplet spectra gave 90 and 94% control, respectively. Sufficient conidia germinated in IE droplets of a variety of sizes to control hemp sesbania excellently.

Variables Affecting the Use of Positive Displacement Pumps to Apply Herbicides in Ultralow Volume

Water and paraffinic oils were used to determine variables that affect positive displacement pumps used to meter liquid flow in an air-assist spray system. Components needed to construct an air-assist spray system were described for use in spray chambers and on a tractor for field application of herbicides in ultralow volume (ULV). The flow rate of the pump varied less than 2% for the water and oil as the pump setting was varied from 0 to 100% of the pump's capacity. Linear relationships were shown for both liquids as the voltage input varied from 4 to 13 volts. Air pressures to 100 kPa and liquid temperatures to 35 C did not affect flow rate of the pump. Volume median diameter of the spray droplets decreased from 295 μm to 77 μm and 159 μm to 85 μm for water and paraffinic oil, respectively, as the air pressure was adjusted from 14 to 110 kPa.

Air-assisted spraying of arable crops, in relation to deposition, drift and pesticide performance

Field experiments comparing spray deposition, spray drift and the biological efficacy of one herbicide and a number of fungicides in several crops treated by hydraulic nozzle sprayers and a novel air-assisted sprayer (Degania) are reported. Air-assisted sprays using fine-spray hollow-cone nozzles spaced at 25 cm were compared with coarser sprays applied at similar or greater volumes from standard hydraulic pressure nozzles. The quantity of spray deposited on different crop types was generally similar from both methods of application, but the uniformity of droplet distribution from the air-assisted system was usually superior. The air-assisted sprayer generally produced more drift than the standard sprayer. All spray methods generally produced similar biological results at full and half pesticide dose rates. A Brussels sprouts crop normally considered as being difficult to spray showed some biological benefits from air-assisted spraying.

Measurement of spray deposition and efficiency of pesticide application in citrus orchards

Pesticide treatments on citrus, in Spain, are performed manually and with application rates varying from 3000 to 9000 l/ha. This work was carried out to find methods of mechanizing these operations as an alternative to the conventional methods, with the purpose of achieving equal efficiency, but at a lower cost. Spray penetration, droplet size, run-off, and pest control were determined for four types of equipment (hand lances, oscillating nozzles, air-assisted, and low pressure air-assisted sprayers). The experiment was conducted in a Salustiana orange orchard on a randomized block with three replications. With all the machines, pentration varied between the outside and the inside parts of the tree, especially for the two air-assisted systems. The oscillating nozzles method provided a very similar performance to that of the hand lances, and therefore, it could be used as a replacement or alternative method, with a considerable saving of production costs. Good pest control was achieved for aphids with all the equipment tested, and in this case, any of the two air-assisted methods could be used. For Lepidosaphes sp. there appeared to be better control of the pests in the outer zones than in the inner parts of the tree, and none of the methods used solved this problem completely.