Due to great human awareness of environmental conservation and public health,pesticides must be applied in economically viable and environmentally sensitive ways,and it requires deep understanding on the distributions of pesticide application.The distribution is the process occurring immediately after application.When applied,the pesticide can distribute in the following way:loss by wind drift,deposition on leaves or other parts of the target plant and deposition on ground (soil).The sum of these three components (plant,soil and drift) should equal to the amount of spray emitted.However,there are concerns over the intended effect (deposition on plant) and unintended effect (deposition on ground and wind drift) of pesticide application on the effectiveness and risks associated with the use of pesticides.Oriented to distribution of pesticide application,droplet deposition on different parts was measured in the research.Spray deposition was tested by recovery of a fluorescent tracer (pyranine) in the 1.75 m wide,1.75 m high and 10 m long working section of the wind tunnel.A single nozzle was positioned in the centre of the wind tunnel at a height of 0.6 m above the wind tunnel floor and then sprayed moving along the length of the tunnel at a speed of 1 m/s.The nozzle moved over the top of the plant so that application amount was the same to a typical spray in agriculture and the pesticide distribution was measured.Mylar cards (plastic) were used to collect the deposition on ground,diameter polythene lines were horizontally mounted to provide an estimate of the wind drift of spray,and the sow thistle plant was put under the nozzle to test the deposition on the target.To evaluate the influence of different factors on spray distribution,the trial was carried out for three plant types (sow thistle,cotton and barnyard grass) at three growth stages (leaf area were 15 cm2,135 cm2 and 300 cm2,respectively).After spraying,fluorescent dyes were easily washed off the three different samples so good recoveries can be got.The amount of spray on the plant,ground and wind drift was calculated and expressed as a percent (or fraction) of the amount of spray that came out of the nozzle.Based on the frame straddling technique,velocity of droplet was investigated by particle image velocimetry (PIV),and the test system included laser imaging system,pulse generator and analysis software.The influences of droplet size (VMD),droplet velocity,spray angle,flow rate,height of nozzle,wind speed and growth stage of plant on deposition at various parts were investigated.Correlation between different factors and spray distribution (fraction of spray deposited on ground,plant and drift) was calculated to judge the impact.The results indicated that the distribution of the spray was influenced by droplet size,release height wind speed and growth stage.Meanwhile,spray angle,sheet velocity flow rate and plant type had no significant effect on the spray distribution.The ground deposition was the lowest with the fine sprays.It was found that ground deposition from application of pesticides was 57.7％ for finer droplet(VMD was 181 μm) which was increased to 82.7％ for coarser droplet (VMD was 445 μm).Deposition on plant surfaces was also found to be more than 13.4％ with release height at 40 cm to 60 cm and wind speed less than 4 m/s.For soil-active herbicide,a proportion of deposit on the ground was increased by bigger VMD,and this is a desirable result.For controlling flying pest,airborne deposit can increase chemical's spread on its body,so smaller VMD was more effective.It was also shown that the proportion of spray depositing on plant surfaces was increased as the plants got larger and the amount depositing on the ground was decreased.The result can be used to effectively aid spray decisions to maximize the effectiveness of pesticides and minimize risks to the environment from chemical spraying activities.Chemical application must be as precise as possible,so populations of unwanted organisms (insects or diseases) can be reduced and less environmental impacts created in the agricultural production.An understanding of the pesticide application process can be utilized to improve the estimate of the distribution on pesticide from a spray operation.

Retention of sprays on plants is a critical component influencing the effectiveness of agrichemical applications. Previous simulations of spray retention by plants gave poor agreement for hard-to-wet species when compared with actual measured retention. A new model is developed here that accounts for: species wettability, impaction angle, droplet bounce, partial retention on shatter, a variable time to shatter, and the number of daughter droplets produced. The aim of this study was to compare predictions from the new model with data obtained by spraying five mixtures via five nozzles onto easy-to-wet cotton (Gossypium hirsutum L.), and hard-to-wet wheat (Triticum aestivum L.) and fat hen (Chenopodium album L.). The new model correctly predicts retention to be highest on cotton and lowest on wheat. The trend in both measured data and the model predictions is for retention to decrease with increasing droplet size, on all three plant species. Formulation is correctly predicted to have little influence on retention by easy-to-wet cotton plants and to enhance retention by the harder-to-wet wheat and fat hen plants. The parameters that describe partial retention on shatter and variable time to shatter have a substantial influence on retention, as they affect primary or secondary droplet capture. A better understanding of the kinetic energy effects and the interactions between the formulation and the leaf surface are needed to refine their input values.

A University of Queensland research project titled A generic approach to improving spray coverage has been established to help Australian vineyards maximise spray coverage while reducing environmental risks associated with using agricultural plant-protection products. Much of the work is being carried out at Treasury Wine Estates’ vineyards at Lake Cullulleraine in North-western Victoria and Langhorne Creek in South Australia. A mass-balance approach has been adopted to quantify the amount of applied product that is retained as coverage on the canopy (upper/lower leaves and inner/outer canopy), the amount that is lost to the ground and the amount that is lost to drift, including the fraction that deposits on downwind flat surfaces and that which is carried away as airborne flux.

BACKGROUND:Previous research has sought to adopt the use of drift-reducing technologies (DRTs) for use in field trials to control diamondback moth (DBM) Plutella xylostella (L.) (Lepidoptera: Plutellidae) in canola (Brassica napus L.). Previous studies observed no difference in canopy penetration from fine to coarse sprays, but the coverage was higher for fine sprays. DBM has a strong propensity to avoid sprayed plant material, putting further pressure on selecting technologies that maximise coverage, but often this is at the expense of a greater drift potential. This study aims to examine the addition of a DRT oil that is labelled for control of DBM as well and its effect on the drift potential of the spray solution. The objectives of the study are to quantify the droplet size spectrum and spray drift potential of each nozzle type to select technologies that reduce spray drift, to examine the effect of the insecticide tank mix at both (50 and 100 L ha(-1) ) application rates on droplet size and spray drift potential across tested nozzle type and to compare the droplet size results of each nozzle by tank mix against the drift potential of each nozzle.RESULTS:The nozzle type affected the drift potential the most, but the spray solution also affected drift potential. The fine spray quality (TCP) resulted in the greatest drift potential (7.2%), whereas the coarse spray quality (AIXR) resulted in the lowest (1.3%), across all spray solutions. The spray solutions mixed at the 100 L ha(-1) application volume rate resulted in a higher drift potential than the same products mixed at the 50 L ha(-1) mix rate. The addition of the paraffinic DRT oil was significant in reducing the drift potential of Bacillus thuringiensis var. kurstkai (Bt)-only treatments across all tested nozzle types. The reduction in drift potential from the fine spray quality to the coarse spray quality was up to 85%.CONCLUSION:The addition of a DRT oil is an effective way to reduce the spray solution drift potential across all nozzle types and tank mixes evaluated in this study. The greatest reduction in drift potential can be achieved by changing nozzle type, which can reduce the losses of the spray to the surrounding environment. Venturi nozzles greatly reduce the drift potential compared with standard nozzles by as much as 85% across all three insecticide spray solutions. Results suggest that a significant reduction in drift potential can be achieved by changing the nozzle type, and can be achieved without a loss in control of DBM. © 2016 Society of Chemical Industry.

Polymers and surfactants are commonly used as adjuvants in agrochemical spray solutions. In this study, we probe the effects of changes in steady state polymer chain conformation (as a result of surfactant addition) on the physical properties of dilute polymer solutions and the resulting spray performance when such solutions are processed through a commercial spray nozzle. To create a panel of model adjuvant formulations for spraying, we added either an associative (sodium dodecyl sulfate (SDS)) or non-associative (Tween20 (polysorbate20)) surfactant, over a range of concentrations, to a base dilute Poly( ethylene oxide) (PEO) solution. The addition of the associative SDS to the PEO solution decreased the dynamic surface tension, slightly increased the zero shear viscosity and substantially increased the extensional properties of the solutions, with a strong dependency on SDS concentration. Under the high deformation processes experienced in a spray nozzle, the addition of SDS shifted the droplet size distribution to larger droplet sizes, and substantially reduced the spray drift. No such changes were seen for the non-associative PEO/Tween20 system. The changes in the dynamics of extension of the PEO chains induced through the association of a surfactant were found to be the dominant effector dictating spray performance. (C) 2016 Published by Elsevier B.V.

This paper combines experimental data with simple mathematical models to investigate the influence of spray formulation type and leaf character (wettability) on shatter, bounce and adhesion of droplets impacting with cotton, rice and wheat leaves. Impaction criteria that allow for different angles of the leaf surface and the droplet impact trajectory are presented; their predictions are based on whether combinations of droplet size and velocity lie above or below bounce and shatter boundaries. In the experimental component, real leaves are used, with all their inherent natural variability. Further, commercial agricultural spray nozzles are employed, resulting in a range of droplet characteristics. Given this natural variability, there is broad agreement between the data and predictions. As predicted, the shatter of droplets was found to increase as droplet size and velocity increased, and the surface became harder to wet. Bouncing of droplets occurred most frequently on hard-to-wet surfaces with high-surface-tension mixtures. On the other hand, a number of small droplets with low impact velocity were observed to bounce when predicted to lie well within the adhering regime. We believe this discrepancy between the predictions and experimental data could be due to air layer effects that were not taken into account in the current bounce equations. Other discrepancies between experiment and theory are thought to be due to the current assumption of a dry impact surface, whereas, in practice, the leaf surfaces became increasingly covered with fluid throughout the spray test runs.

Air-assisted spray equipment used for horticultural cropping systems depend on high air velocities to project the spray as well as to open the canopy for greater droplet penetration and deposition. However, these sprayer-types are also at a heightened risk for spray drift as they possess the potential to place drift prone droplets in the atmosphere where they can be carried to off-target locations. Unfortunately, quantifying these droplets can be difficult and expensive using samplers such as high-volume air samplers, rotating rods and strings. However, while these measuring techniques may give some idea of flux, no particle information can be gained which is imperative to predicting the mass which may be the most prone to drift. In wind-tunnels and field studies, polyester and nylon strings have proven to be an efficient collecting surface. Therefore, it was the objective of this study to assess the potential for the use of a novel, field grade Phase Doppler Interferometer (PDI) as a replacement for strings as a sampler for driftable mass for orchard type sprayers.

The aim of the present study was to investigate the influence of nozzle configurations on spray drift and explain the influences using several atomization characteristics (length of spray sheet, spray angle, velocity distribution of flow field, fluctuation of velocity, and droplet size). Nozzles manufactured by one company (Lechler GmbH, Germany) were tested by spraying local tap water in a wind tunnel at an operating pressure of 0.3 MPa and under room temperature. The nozzles tested were compact air-induction flat fan nozzles (IDK120-02, IDK120-03), standard flat fan nozzles (ST110-02, ST110-03), and hollow-cone swirl nozzles (TR80-02, TR80-03). The atomization process was recorded using a Particle Image Velocimetry (PIV) system, droplet size was measured by a Sympatec Helos laser-diffraction particle-size analyzer, and spray drift was evaluated in a wind tunnel with deposition measured using a calibrated fluorometer (Turner-Sequoia model 450). Results showed that spray drift was significantly different among nozzle types (P<0.0005) and that nozzle configurations influenced breakup length, spray angle, droplet size, and velocity. Nozzles producing larger droplet sizes had lower velocity. Smaller droplets were produced when longer and wider spray sheets were produced. Compared to ST and TR nozzles, IDK nozzles started to breakup in the center of the liquid sheet, producing droplets with larger diameter, lower velocity, and less velocity fluctuation. The IDK nozzle is a good choice for low spray drift at higher wind speeds.

To combat mosquitoes and the public health hazards they present, spraying chemical adulticides is an efficient and timely control method for immediate reduction of adult populations. With the growing consciousness of environmental and public health concerns, effective mosquito control means not only maximizing the effectiveness (in terms of mosquito mortality rates) of the pesticide application, but also minimizing the unintended effects (health hazard and environmental pollution). A series of experiments was carried out to assess the efficacy and deposition of ultra-low volume (ULV) sprays on adult mosquitoes which included the influence of chemical type, spray volume, spray concentration, droplet size, and deposit location (where the droplets land on the mosquito). A modified Potter Tower was used to apply an extremely fine spray (volume median diameter ∼20 μm) on caged adult mosquitoes (Culex quinquefasciatus). Reslin® (50 g/L bioresmethrin) was diluted in either water or D-C-Tron® plus spray oil (782 g/L paraffinic petroleum oil), Twilight® (89 g/L phenothrin) was diluted in D-C-Tron®, and the mosquito mortality was assessed 24 h after spraying. A fluorescent tracer was added to the spray mixture to determine the amount of spray on mosquitoes. A fluorescent microscope was also used to view the deposit of droplets on mosquitoes. It was found that droplet retention and mortality were reduced with the larger droplet sizes. Large water-based droplets tend to bounce off adult mosquitoes. There is a tendency for droplets approximately 20 μm in size to be retained on the fine hairs on the mosquito. The largest spray deposit was found on the adult mosquito wings and the lowest deposit on the head. Mortality was higher for formulations diluted with oil compared to those diluted with water. ULV applications with ultra-fine sprays (VMD 20 μm) and oil-based products resulted in maximum target efficacy under laboratory conditions, at minimum cost, and with the minimum amount of chemical adulticides.

With greater environmental awareness, the movement of pesticides within and off of a spray target area is a critical public concern. Ideally, all of the material applied should be deposited within the targeted swath on the intended pest or plant. But realistically, a portion of the spray remains airborne and is carried downwind to non-target areas. Airborne spray leaving the targeted area reduces the applied dosage, and could cause damage to neighboring plant and water source or other detrimental environmental impacts. To study the influences of nozzle type, spray mixture and wind speed on spray drift, experiments were conducted using a wind tunnel. Spray drift risk was assessed by adding a tracer to the spray mixture and measuring the quantities of spray deposited downwind from the nozzle on horizontal polythene lines with 2 mm diameter perpendicular to the wind direction in a vertical and a horizontal array. At a distance of 2 m downwind from the static nozzle, five collector lines (V1 toV5) were positioned one above the other at the spacing of 0.1 m to provide an estimate of the spray still airborne through this vertical profile. An additional five sampling collector strings (H1 toH5) were placed in a horizontal array with one-meter horizontal spacing at 0.1 m height to determine the fallout volumes and gradients of the spray from 2 to 6 m downwind. A water-soluble fluorescent tracer was dissolved into tap water as the spray liquid, and after the experiments, the collecting lines were washed with deionized water to measure deposit and drift. The results indicated that deposits on sampling collector decreased with increased vertical elevation and horizontal distance. Average fallout and airborne deposit resulting from the different spray applications were shown in the paper. These figures showed the expected fallout and airborne profiles for all tested nozzle types and sizes. The highest fallout deposits were measured at a position closest to the nozzle (H1) with a systematic decrease with the distance from the nozzle. The highest airborne deposits were found at the lowest sampling collector (V1) with a systematic decrease with increasing height above the wind tunnel floor. Airborne spray drift was affected by wind speed. At all sample positions, deposits on collectors were reduced at lower wind speed. Nozzle’s structure was also found to influence droplet’s size, so injector/pre-orifice nozzle produced coarser droplets and reduced spray drift. The amount of spray recovered is based on the amount of active ingredient of spray mixture within each droplet rather than the total droplet volume. On that basis, a multiple non-linear model for statistical drift prediction including four independent, non-correlated variables (target distance, wind speed, nozzle type and chemical type) was established. The regression model provided a drift evaluation approach, and it was important in the interpretation of wind tunnel data for different nozzle types, chemical types and sampling methodologies.

In order to investigate the function expression of droplet size distribution in the spray sheet for agricultural nozzles to improve the pesticide efficacy, some common nozzle types were tested in this study. At present many methods and equipment were used for measuring droplet size. Droplet size is a main parameter influencing the deposition rate and distribution uniformity of pesticide on the target. However, different test results may be caused by different methods or equipment. For selecting a suitable analyzer to test droplet size distribution, three common droplet size analyzers were applied to measure droplet sizes of ST110-03 and ST110-02 nozzles which were standard flat-fan nozzles manufactured by Lechler GmbH. The three analyzers were Particle/Droplet image analysis system, Sympatec HELOS Vario particle size analyzer and Spraytec laser diffraction system and were referred to as PDIA, Sympatec and Spraytec, respectively. Their respective locations were the Institute for Application Techniques in Plant Protection of JKI (Julius Kühn-Institut), Germany, the Centre for Pesticide Application and Safety of the University of Queensland, Australia, and the Centre for Chemicals Application Technology of China Agricultural University, China. For all the sprays in this study, tap water was sprayed at an operating pressure of 0.3 MPa, and each apparatus was operated complying with its corresponding experimental procedure. For each nozzle type, 3 nozzles were tested with three replications. Results showed that absolute results differed between different tests depending on measuring protocol and type of measuring apparatus, but the nozzle classifications were the same, comparing the results with limits of BCPC nozzle classification obtained by PDIA in JKI. Spraytec was more accessible to authors than other analyzers; therefore, it was selected to study the distribution of droplet size. The volume median diameters (VMDs) of air-induction compact nozzles (IDK), standard flat-fan nozzles (ST) and hollow-cone nozzles (TR), with the orifice sizes of 02 and 03 for each type, were measured at different positions in the spray sheet. The nozzles were all produced by Lechler GmbH in Germany. It was found that the VMD distributions were symmetric for all tested nozzles and the axis of symmetry was the centerline of spray sheet. The VMDs of IDK nozzles were significantly larger than other two types’. The coefficient of variation (CV) of droplet sizes, which were tested at different spray heights but the same horizontal position, indicated that the VMDs of IDK nozzles varied with spray height obviously. Meanwhile, at a fixed spray height, the VMD distribution of IDK along the horizontal direction appeared to be W-shaped; the distributions of ST and TR were parabolas. The parabola opening of ST was larger than that of TR. The tested VMD was then fitted with program code using Matlab software based on least square method. In the fitted VMD distribution equation, independent variables were spray height and horizontal position and dependent variable was VMD. The significant relationship between distribution position and VMD was found, the significance thresholdα was set at 0.05. Results also showed that theF-statistic calculated from the data of each nozzle was greater than the critical value of theF-distribution for the desired false-rejection probability of 0.05. The coefficient of determination was greater than 0.8 for all fitted equations. All of these pointed that the obtained equations could describe the droplet size distribution correctly and predicate the size at any position in the spray sheet with precision. The fitted function research involved in this paper will provide the valuable basis to study the VMD distribution of overlapped spray sheet for boom sprayer; the study will improve the uniformity of deposition rate and biological efficacy. Meanwhile, the fine droplet zone in the spray sheet is the target of drift control. Therefore, the VMD distribution is also conducive to the development of novel anti-drift sprayer to reduce the risk of pesticide.

Realistic virtual models of leaf surfaces are important for several applications in the plant sciences, such as modelling agrichemical spray droplet movement and spreading on the surface. In this context, the virtual surfaces are required to be smooth enough to facilitate the use of the mathematical equations that govern the motion of the droplet. Although an effective approach is to apply discrete smoothing D2-spline algorithms to reconstruct the leaf surfaces from three-dimensional scanned data, difficulties arise when dealing with wheat (Triticum aestivum L.) leaves, which tend to twist and bend. To overcome this topological difficulty, we develop a parameterisation technique that rotates and translates the original data, allowing the surface to be fitted using the discrete smoothing D2-spline methods in the new parameter space. Our algorithm uses finite element methods to represent the surface as a linear combination of compactly supported shape functions. Numerical results confirm that the parameterisation, along with the use of discrete smoothing D2-spline techniques, produces realistic virtual representations of wheat leaves.

The use of existing geospatial technologies such as GIS and global positioning systems (GPS) to precision forestry is booming. The objective of this study was to examine the applicability of GPS and radio beacon differential global positioning system (RBN DGPS) for forestry machinery positioning. This would be an important step toward the realization of site-specific chemical application in China. A Trimble AG132 GPS receiver was mounted on a moveable platform and real-time differential GPS signals were obtained from the Yangtze River Beacon Station. The experiments were conducted on campus of Nanjing Forestry University, China. GPS data were collected and downloaded into a laptop computer via a RS-232 serial port and customer-developed data-acquisition software. Two tests were conducted: (1) a stationary test (where the mobile platform was maintained at a fixed location) in an open sky and forest condition to examine the precision (repeatability) of GPS signals, and (2) a mobile test (where the platform was moving) to examine the dynamic conformity degree. Analysis of variance was used to clarify the effects of positioning mode and stand area on the precision of GPS. In the stationary test, the variability of X and Y coordinates is smaller in RBN DGPS mode than that in the non-differential mode; and the performance of GPS in terms of position dilution of precision, horizontal dilution of precision, vertical dilution of precision, time dilution of precision values, effective positioning rate and the number of visible satellites was superior when used in RBN DGPS mode. In the mobile test, the desired traces of the moveable platform (circles) were much better followed by the GPS locations recorded in the RBN DGPS mode. Compared with non-differential mode, RBN DGPS is more suitable for precision forestry positioning requirements. RBN DGPS improves accuracy both in open sky and forest condition, and the service is available to end users in China with no additional costs.

Pesticides are commonly applied by using hydraulic nozzles to generate droplets. The properties of these spray droplets can influence the effectiveness and risks associated with the use of pesticides. Initial spray characteristics (initial droplet size and velocity, fan angle and spray liquid density) were therefore measured for a range of hydraulic nozzles and spray mixtures. Particle Image Velocimetry (PIV) was used to measure the spray sheet velocity.There was a significant difference between a standard hydraulic nozzle, Turbo TeeJet (R) and air induction nozzle for all measured spray characteristics. The standard hydraulic nozzle generated the smallest droplet sizes, the highest velocity and the highest spray liquid density. The air induction nozzle generated the largest droplet size, the slowest velocity and the lowest spray liquid density. The type of air induction nozzle and spray formulation was also found to influence spray characteristics.This work has demonstrated that initial spray characteristics such as droplet size and velocity, liquid density, fan angle and included air can vary depending on nozzle design, operating parameters and spray formulations. Initial droplet velocity was found to be significantly correlated to droplet size (D-v0.5) and spray pressure. (C) 2013 Elsevier Ltd. All rights reserved.

Pesticides used in agricultural systems must be applied in economically viable and environmentally sensitive ways, and this often requires expensive field trials on spray deposition and retention by plant foliage. Computational models to describe whether a spray droplet sticks (adheres), bounces or shatters on impact, and if any rebounding parent or shatter daughter droplets are recaptured, would provide an estimate of spray retention and thereby act as a useful guide prior to any field trials.Parameter-driven interactive software has been implemented to enable the end-user to study and visualise droplet interception and impaction on a single, horizontal leaf. Living chenopodium, wheat and cotton leaves have been scanned to capture the surface topography and realistic virtual leaf surface models have been generated. Individual leaf models have then been subjected to virtual spray droplets and predictions made of droplet interception with the virtual plant leaf. Thereafter, the impaction behaviour of the droplets and the subsequent behaviour of any daughter droplets, up until re-capture, are simulated to give the predicted total spray retention by the leaf. A series of critical thresholds for the stick, bounce, and shatter elements in the impaction process have been developed for different combinations of formulation, droplet size and velocity, and leaf surface characteristics to provide this output.The results show that droplet properties, spray formulations and leaf surface characteristics all influence the predicted amount of spray retained on a horizontal leaf surface. Overall the predicted spray retention increases as formulation surface tension, static contact angle, droplet size and velocity decreases. Predicted retention on cotton is much higher than on chenopodium. The average predicted retention on a single horizontal leaf across all droplet size, velocity and formulations scenarios tested, is 18,30 and 85% for chenopodium, wheat and cotton, respectively. (C) 2013 Elsevier B.V. All rights reserved.

利用开路式风洞系统和Sympatec激光粒度仪测试了参考喷头的雾谱尺寸以此作为喷头雾谱等级的依据。对扇形雾喷头在不同压力、风速、喷头与激光粒度仪距离情况下的雾滴粒径、数量和范围进行了试验。试验结果表明,压力、风速、喷头与激光粒度仪之间距离的增大,都导致扇形雾喷头的雾滴体积中径变小,尺寸小于150μm的雾滴占全部雾滴体积的百分比变大,增加了农药脱靶飘移的可能性,同时压力和风速的增大都导致部分喷头的雾谱等级降低。为了保证激光粒度仪对雾滴粒径测试结果的可靠性,可以使用风洞试验和调整喷头与激光粒度仪的距离,来减小因细小雾滴通过激光束过程中速度迅速衰减而对测量结果带来的影响。