Fan Sprayer Research Articles

Spray Angle and Uniformity of the Flat Fan Nozzle of Deep Loosener Fertilizer for Intra-Soil Application of Fertilizers

This paper deals with the problem of predetermining the spray angle and uniformity of the flat fan sprayer with a semicircular impact surface for the intra-soil application of liquid mineral fertilizers. The jet impact on a round splash plate and radial atomization properties are investigated theoretically, the formation features of the spray with an obtuse angle are studied in a geometrical way, and the design search of the nozzle shape and optimization calculations are performed using computational fluid dynamics (CFD) simulations and then verified experimentally. It was revealed that the spray rate and spray angle can be adjusted by changing the parameter s, and when the spray angle is within s = 0–0.2 mm, it forms spray angles with range of 140°–175°. The spraying angle, in turn, shows the potential length of the tillage knife in accordance with the undersoil cavity dimensions. A spray uniformity of up to 74% was achieved, which is sufficient for applied studies and for intra-soil application operations. According to the investigations and field experiments, it can be concluded that the designed nozzle is applicable for the intra-soil application of liquid mineral fertilizers. The use of flat fan nozzles that form a spraying band under the soil cavity and along the entire length of the tillage knife ensures a highly efficient mixing process, the liquid mineral fertilizers with treated soil (particles) positively contributing to plant maturation.

Improvement of the technological scheme fan cotton sprayer OВХ-600 for biologically effective plant protection

The article presents the developed technological scheme of the ОВХ-600 fan cotton sprayer, to switch to a low-volume spraying method with flow rate of working fluid in the range of 50-100 liters per hectare. Conducted studies of the technological scheme sprayer show that to ensure agrotechnical requirements of the low-volume process spraying needs improvement system for supplying working fluid to the sprayer. That is, the supplied working fluid must be the most homogeneous and given volume. Solving these problems for installation on the sprayer flow diagram led installation of a self-cleaning filter and dispenser tap. For facilitating installation and dismantling of the sprayer, as well it is proposed to reduce non-operating costs completely mounted version of the fan sprayer, without special constructive changes.

EFFICIENCY OF PESTICIDE APPLICATION BY MECHANIZED AND ROBOTIC SPRAYER

By differentiated application of pesticides in the precision gardening system, mobile robotic sprayers and sprayers with intelligent control, it is possible to ensure a high level of protective measures in gardening, greater efficiency of their implementation, minimize environmental pollution with pesticides. At the development stage, it is necessary to compare traditional and innovative technical means according to various criteria in relation to real production conditions in order to assess the effectiveness of the upgraded technical solution and calculate the economic effect of its use. (Research purpose) The research purpose is conducting a comparative analysis of the economic efficiency of using a fan sprayer for a differentiated method of applying pesticides mounted on a mobile robotic chassis and a similar device of classical layout for continuous spraying aggregated with a tractor. (Materials and methods) The article presents the main indicators for standardized methods, the content of which is described by industry regulatory and technical documents. (Results and discussion) The article presents a list of initial technical and operational indicators of the compared units. To assess the economic efficiency of the use of two variants of technical means, their comparative assessment was made: indicators of operating costs, their savings, annual economic effect, the size and payback period of additional capital investments. (Conclusions) When using a fan sprayer for differentiated application mounted on a robotic mobile power facility, operating costs are reduced by 25.03 percent, but its shift performance is more than 8 times lower than that of a similar solution using MTZ-80. The payback of additional capital investments spent on the innovative technical solution will be 2.19 years.

Comparative hygienic assessment of working conditions and potential risks for workers' health when applying pesticides in different technics

In the structure of regional and planetary pollutants, pesticides are in the top ten, and among food contaminants along with heavy metals – they occupy first place in the world. It is known that pesticides and agrochemicals, which belong to the group of biologically active compounds, are one of the important factors affecting the human body.
 The aim: comparative hygienic assessment of working conditions and occupational risk when using pesticides by different methods of application (knapsack, rod, ventilator, unmanned and aviation) on the example of the fungicide Amistar Extra 280 SC.
 Materials and methods. Field studies were conducted in 2018–2021. When applying the formulation knapsack sprayer SOLO-10, trailed boom sprayer AMAZON 1201 UF combined with a tractor MTZ 82.1 Belarus, unmanned aerial vehicle (UAV) for spraying fields Agras T16, AN-2 aircraft combined with OZh-2 were used.
 Results. As a result of field researches of working conditions of employees during the performance of production operations on the pesticides application, it was found that in the air treatment areas and in areas of possible drift the levels of studied active ingredients were below the limit of quantification of the method. The difference between azoxystrobin (0,04±0,003) and cyproconazole (12,4±0,5) for the tank refueler and the UAV external pilot in the field studies is significant according to Student's criterion (p >0,05). For the operator who applied the pesticide with a knapsack sprayer, the values of inhalation risks were significantly higher than for the tankers of the sprayer tank at p >0,05. The values of the combined risk when using a fan sprayer (0,46±0,02) significantly exceeded the data obtained when using a rod sprayer (0,14±0,006)
 Conclusions. Analysis of the obtained results showed that the values of the combined risk are significantly higher for the operator / tractor driver, signalman than for their refuelers (at p <0,05). The values of the combined risk of the external pilot were significantly lower than those of the tanker when using a pesticide using a UAV.

Development of a combined unit for chemical and electric radiation treatment of cotton plants

The study is devoted to a combined unit that has been developed for cotton harvesting tractors. This unit combines technologies of chemical and electric radiation treatment of cotton plants. Thus, the authors solve the task of reduction of the negative impact of pesticides on the environment during chemical treatment of plants, including defoliation of cotton, by reducing consumption rates of chemicals. The paper discusses the basic sprayer to form a combined unit selected on the basis of preliminary field tests of boom and fan sprayers with movable and fixed working bodies. The work has established that a fan sprayer with two fixed nozzles has the main positive characteristics of boom and fan sprayers in chemical treatment of cotton, taken as the basis for formation of a combined unit. The authors concluded that field trials of a combined unit have shown that chemical treatment (defoliation) with simultaneous electrical irradiation accelerates the opening of cotton bolls 1.2-1.25 times. This makes it possible to start early harvesting of cotton in risky agriculture to reduce consumption rates of pesticides.

Advanced Disc Spray Tip Universal Fan Sprayer

Fan sprayers such as OVH-600 and VP-1 are of indisputable importance in the fight against agricultural pests and diseases, but they have significant disadvantages associated with uneven application of pesticides due to the oscillating movement of their working bodies. To eliminate this drawback, the Agrikhim joint venture developed a universal fan sprayer VP-1IB, which processes field crops, orchards and vineyards based on controlled airborne droplets with simultaneous continuous girth of the entire implement width within ± 900 of the sprayer symmetry axis (in a total of 1800), i.e. around the perimeter of the treatment area. The main working element of the universal fan sprayer is the spraying tips quality performance indicators, which largely depends on the correct choice of parameters of its parts, including the radius of the input channels to the swirl chamber on the swirl disk, to justify the rational value of which this article is aimed.

Justification the Number of Spray Tips of the Universal Fan Sprayer

The authors noted the disadvantages of fan sprayers such as OVH-600 and VP-1, associated with uneven application of pesticides due to the oscillatory motion of the working parts, especially in the junction of adjacent passages. (Research purpose) To increase the uniformity of the pesticide solution application over the entire width of the fan sprayer. (Materials and methods) The JV «Agriхim» developed a universal fan sprayer designed for the treatment of field crops, orchards and vineyards controlled by air-droplet flow. It was shown that the number of nozzles depends on the technological scheme of operation and the width of the sprayer. (Results and discussion) The authors determined the optimal number of injectors – 25 pieces. Depending on the flow rate of the working solution, three groups of tips were distinguished. (Conclusions) The authors revealed that the new design eliminates oscillatory movements of the working parts of the sprayer, a significant width (24 meters vs. 16 meters in production models) allows to increase dramatically the productivity of work, and the number of changeovers is minimized. They simplified and cheapened the design of the sprayer due to the rejection of a number of kinematic pairs and drives. They increased reliability of the unit, eliminating rubbing and moving parts and components. They presented the layout of 25 nozzles for high-quality pesticide treatment: 5 rear central nozzles were installed on the air ducts at an angle relative to the soil surface, and on the opposite direction of the air ducts placed 3 and 7 nozzles in each side of the axis of symmetry of the sprayer. It was calculated that the rate of flow of the working fluid in the range of 100-500 liters per hectare can be adjusted by changing the pressure in the system from 2 to 8 bar and the working speed from 3 to 7 kilometers per hour.

Dynamic evaluation of airflow stream generated by a reverse system of an axial fan sprayer using 3D-ultrasonic anemometers. Effect of canopy structure

Air assisted sprayers are currently used for the applications of plant protection products in fruit trees and vineyards. However, the use of these equipment carries a high environmental risk, mainly owing to the generation of airborne spray drift in the lower boundary layer above crop canopy. Hence, many tests are currently focused on investigating several factors that affect the efficiency of the spray process, in which air assistance and air behaviour are two of the most difficult parameters to evaluate. This present work proposes a first approach on the characterization of the airflow generated by an orchard sprayer equipped with an axial fan and an air reverse system in the outlet plane of the air, while circulated through two artificial rows of canopy representing vineyard trellis, using 3D-ultrasonic anemometers to measure the experimental data. A first series of static field tests measured the air velocity at different heights on both sides of the sprayer and at both sides of every row of artificial canopy and evaluated the effect of the canopy on the sprayer airflow passing through. A second set of experiments were carried out with the sprayer moving at 4.1 km h−1 between canopy rows to simulate the normal spray process. Finally, velocity vectors and turbulent intensities were calculated. The resistance of the vegetation was also characterized by using a drag coefficient, both when the sprayer was stationary and moving. The results between the static and dynamic tests were compared. Although there were similarities between the two tests, the results indicated that when the equipment moves along the canopy rows, the axial fan asymmetry on air velocities is more noticeable and turbulence intensity increased. In addition, the vegetation received direct airflow at different times. This could affect the trajectory of the droplets. On the other hand, the resistance of the vegetation on each side was similar. The air reverse system could be affecting the airflow direction to the driving direction. Ultrasonic anemometers were successful in characterizing sprayer fan airflows but it is necessary to continue working on the descriptive analysis of the airflow in other planes different from the air outlet only and with other vineyard systems.

Захист хмелю біологічними препаратами

The purpose. To study an opportunity of application of biological fungicide Avatar-1, r. Zashchita against the basic illnesses in technique of cultivation of hop. Methods. Field experiment was spent using S.A. Tribel’s technique (2001). After studying biofungicide Avatar-1, r. Zashchita within 3 years they have chosen the most efficient concentrations of working solution — 10 and 20 ml/10 l of water. They soaked (3 hours) cuttings of hop in the given water solutions before planting in soil. Fructifying plants they sprayed against pseudoperonosporosis with the help of tractor fan sprayer OPV-2000. In reference variant they used fungicide of systemic action Ridomil Gold MZ, inc. In control variant they used pure water. Presence of acids in hop cones was determined according to «GOST 4099:2009 Hop. Rules of sampling and test methods». Results. It is established that soaking of cuttings of hop in water solution of biofungicide Avatar-1, r. Zashchita before planting in field provides their survival up to 70% (on 6,5% more than in the control), and positively influences process of formation and exit of standard seedlings, enables twice to lower amount of ear shoots on sprouts of hop. Efficiency of protection of fructifying plants of hop against false mealy dew in the way of land spraying makes 74,2–74,4%; productivity of cones, in comparison with control, increases on 1,9–2,2 c/hectare, and contents of 2-acids — on 1,1%. Conclusions. Application of biofungicide Avatar-1, r. Zashchita in the system of protection of hop enables effectively to constrain development and distribution of the most dangerous illness of hop (pseudoperonosporosis) in the beginning of vegetation and to receive standard planting material or the planned productivity of hop cones of appropriate quality.

Vertical volumetric distribution of an axial fan sprayer on the Brevipalpus phoenicis control

ABSTRACT Spray distribution generated by axial fan sprayer, among other factors, should be critically analyzed, in order to prevent unnecessary costs and environmental contamination. This study aimed at evaluating the effect of the vertical volumetric distribution of an axial fan sprayer on the Brevipalpus phoenicis control efficiency. First, an assay was performed to evaluate the vertical volume distribution uniformity of the sprayer, assessing different spray nozzles configurations on the spray arcs, sides of the sprayer and spray heights. Afterwards, another experiment was carried out to analyze the relationship between the distribution of the Fenpyroximate acaricide on Coffea arabica L. and the B. phoenicis control efficiency. The treatments were arranged in a 4 x 2 factorial + 1 additional control, consisting of four spray volumes (200 L ha-1, 400 L ha-1, 600 L ha-1 and 800 L ha-1) and two spray nozzles configurations (1: 100 % of MAG1.5 nozzles; 2: upper extension with 5 MAG3.0 nozzles, middle extension with 9 MAG1.5 nozzles and lower extension with 4 MAG3.0 nozzles). Configuration 2 provided the smallest coefficient of variation (28 %). Nozzle configurations had no effect on the incidence of B. phoenicis. The use of nozzles with different flow rates on the spraying arc improves the vertical volumetric distribution uniformity of axial fan sprayers, but does not affect the B. phoenicis control efficiency.

Impact of technical spraying factors on vertical liquid distribution with Agromehanika AGP 440 axial fan sprayer

Impact of technical spraying factors on vertical liquid distribution with Agromehanika AGP 440 axial fan sprayer

Spray deposition assessment using different application techniques in artificial orchard trees

Seven orchard spray application techniques were compared in terms of within-tree deposition quality and off-target losses to the ground and behind the target trees. The studied spray techniques included different sprayer types, fan speeds and air deflector settings. An artificial pear canopy was realized for this purpose. Filter papers and a multiple tracer methodology were used to evaluate deposition. All measurements were conducted indoor and will be used as an input and to validate a CFD orchard spray model.Results showed that spray application technique has an effect on spray deposition. Sprayer design caused major differences in spray distribution and off-target losses. A sprayer with individual spouts gave the highest deposits on the tree (0.15 L), followed by an axial sprayer (0.10–0.12 L). Changing settings on the axial sprayer only caused minor differences, although the high fan gear performed significantly better than the low gear. Lowest tree depositions were found for a cross-flow sprayer (0.08–0.09 L). A significant portion of the spray liquid was lost to the ground and directly behind the trees with all spray techniques. The axial fan sprayer and the sprayer with individual spouts caused higher ground deposits than the cross-flow sprayer. The cross-flow sprayer on the other hand gave higher losses behind the trees, especially when a high fan speed was applied.

Comparative performance of recycling tunnel and conventional sprayers using standard and drift-mitigating nozzles in dwarf apple orchards

The use of tunnel sprayers should be encouraged because they can potentially reduce pesticide input and drift in orchards. They could also allow smaller plot size in multifactorial trials in which fully randomized or randomized block designs are recommended. However, the effectiveness of plant protection products applied with tunnel sprayers cannot be reliably assessed without a thorough investigation into spray distribution in tree canopies. A set of three experiments was undertaken in an apple orchard to compare a new type of recycling tunnel sprayer with a standard axial fan sprayer, both of them fitted with either conventional hydraulic hollow cone nozzles (ATR) or drift-mitigating air induction cone nozzles (TVI). Its performance was assessed in terms of 1) spray deposit and coverage in the canopy, 2) sedimentation drift (spray drift to the ground) and 3) collection and recycling rate of the liquid sprayed in the tunnel. Artificial targets composed of cellulose papers and water-sensitive papers were used to evaluate the spray deposit and coverage at similar target positions for each treatment. A fluorescent dye was used as the spray tracer. The study showed that, when using the ATR nozzles, the spray deposit, at each sampling point in the tree canopy, produced by the tunnel sprayer was not significantly different from that produced by the standard sprayer. The spray deposited on the top of the trees when using the TVI nozzles, however, was significantly less than with the standard sprayer. At the same spray deposit level, the spray cover on the canopy, estimated by image analysis, was relatively better with the standard sprayer than with the tunnel sprayer. At the same spray deposit level, the TVI nozzles resulted in significantly poorer spray cover of the canopy than the ATR nozzles. At low wind speeds, the sedimentation drift varied on average from 5.8 to 9.1% of the total sprayer output, irrespective of the type of sprayer or nozzle. The overall mean of the sedimentation drift was not significantly different for the two types of sprayers. The recovery system, which included a continuous recycling process in the tunnel sprayer, led to average savings of 28 and 32% of the applied spray mixtures for the ATR and TVI nozzles, respectively. The tunnel sprayer might therefore be suitable for small-scale apple orchards when fitted with traditional ATR nozzles rather than with air-induced TVI nozzles.

1-Naphthaleneacetic acid and 6-benzyladenine thinning of a common slender spindle ‘Jonagold’/M.9 apple orchard. II: Partial tree spraying

SummaryMature slender spindle ‘Jonagold’/M.9 apple (Malus × domestica Borkh.) trees were thinned using 10 mg l–1 1-naphthaleneacetic acid (NAA) or 100 mg l−1 6-benzyladenine (BA) and an axial fan sprayer at a spray volume of 1,500 l ha−1 applied to the whole canopy, or with smaller volumes, where only the upper half of each canopy was sprayed. Partial spray applications of NAA or BA (at 1,000 l ha−1, 750 l ha−1, or 500 l ha−1) to the upper half of the trees did not cause any reduction in final fruit numbers on the upper half, or on the lower half of each tree. When the whole tree was sprayed to run-off with the same thinning agent, or at 1,500 l ha−1, successful thinning on both the upper and lower parts of the canopy occurred. Good spray coverage (from 51% to 77%) was also observed on leaves at all canopy positions measured, when whole trees were sprayed at 1,500 l ha−1.The development of an innovative crop load regulation strategy was an objective of the ISAFRUIT Smartfruit Project.

Comparative Performance of Air-induction and Conventional Nozzles on an Axial Fan Sprayer in Medium Density Apple Orchards

A series of experiments was undertaken to compare the performance of an axial fan air blast sprayer equipped with air induction (AI) or conventional (C) nozzles in medium density apple (Malus ×domestica) orchards. Performance was compared by assessing 1) spray coverage within the canopy at four levels of across-row wind speeds, 2) ground deposits from airborne drift under still conditions, and 3) biological efficacy of a postbloom thinning spray and a seasonal “high-risk” fungicide program where thiophanate methyl was not included. Spray coverage was reduced by up to 50% with increasing across-row wind speeds, the most dramatic reductions occurring between 0 and 4 mph and at heights greater than 8 ft in the canopy. AI nozzles resulted in a 2-fold increase in spray coverage in the canopy of trees in the row immediately adjacent to the sprayer compared with C nozzles regardless of across-row wind speed. AI nozzles resulted in significantly less airborne drift compared with C nozzles under still conditions in an open field and within a mature ‘Cripps Pink’/ ‘M.7’ orchard planted in rows 20 ft apart. Sprayer efficiency, measured as the proportion of total spray volume that was intercepted by the tree canopy, was higher for an airblast sprayer fitted with AI nozzles (38%) than for C nozzles (26%). The efficacy of a postbloom thinning spray (100 ppm benzyladenine plus carbaryl at 1 lb/100 gal) applied to ‘Morgan Spur Red Delicious’/‘M.111’ trees planted at a between-row spacing of 15 ft was slightly greater when applied with AI nozzles compared with C nozzles. However, application of a “high-risk” fungicide program with AI nozzles resulted in a higher incidence of fruit with flyspeck (Zygophiala jamaicensis) at harvest compared with C nozzles. These inconsistencies were related to the combined effects of nozzle type, orchard row spacing, and canopy density on spray deposition on trees in the second row from the sprayer or to possible effects of nozzle type on droplet density on the target. AI nozzles should provide equivalent or possibly improved coverage and biological efficacy compared with C nozzles in well-managed orchards planted at distances of 18 ft or less between rows. However, when orchard rows are spaced greater than 18 ft apart, AI nozzles will result in reduced spray coverage and chemical efficacy compared with C nozzles because of a reduction in spray carry-over to adjacent rows as a result of reduced airborne drift.

Effect of Application Variables on Spray Deposition, Coverage, and Ground Losses in Nursery Tree Applications

Abstract An experimental cross-flow (CF) fan sprayer and a conventional, axial-fan (AF), orchard sprayer were used to treat multiple rows consisting of four year old, multi-stem, red maple trees, Acer rubrum L. and Turkish filbert trees, Corylus colurna L. The effects of sprayer type, fan orientation, application volume, and ground speed on canopy and ground spray deposits and canopy spray coverage across multiple target rows were evaluated. Variations in deposits and coverage across the canopies were generally smaller for the CF sprayer than the AF sprayer. The AF sprayer produced the highest overall deposits in the first row nearest the sprayer. Reducing fan speed kept more material in the tree row adjacent to the sprayer while decreasing spray volume did not affect the spray deposits in that row. Tower sprayer fan orientation did not affect canopy deposits but could be used to minimize spray drift. These results indicate that the most uniform spray distribution in a tree canopy is obtained by treating the canopy from each side. These findings also suggest growers should experiment with different spray volume and speed settings that can provide efficacious applications more efficiently.

CFD MODELLING TO TRACK THE PATH OF PESTICIDE DROPLETS FROM AN AIR-ASSISTED ORCHARD SPRAYER

To predict the fate of pesticide droplets generated by an air-assisted orchard sprayer, a CFD model was developed. The modelling was based on a Lagrangian multiphase flow model. The effects of fan rotational and sprayer ground speeds on the droplet distribution were studied. The simulation was done for fan speeds of 1360 and 1836 rev/min, and tractor speeds of 1.67 and 2.58 m/s. To consider the speed of the tractor a moving coordinate system was implemented. At the exit of the fan, the vertical velocity profile of the air jet was measured and used as an inlet boundary condition for the model. The droplets were injected from eight 80° hollow cone nozzles with a 5 bar pressure. The distribution of the sprayed droplets was highly influenced by fan rotational and sprayer ground speeds. With an increase in sprayer ground speed, there was an increase in the deflection of droplets opposite to the driving direction. The distance the droplets travelled to the direction of the jet was increasing with an increase in fan speed, but it was decreased with an increase in tractor ground speed. There was a good agreement between the predicted and measured vertical droplet distributions. Canopy interaction was not considered at this stage.

Comparison of spray deposits and efficacy against powdery mildew of aerial and ground-based spraying equipment in viticulture

Poor control of fungal diseases can be related with the application of fungicide which is difficult in steep vineyards . Spray distribution using a tracer obtained with a standard axial fan sprayer was compared to that of a large volume air blast sprayer, a helicopter, an over-row sprayer, a tunnel sprayer (recycling, not air assisted) and a motorized knapsack mistblower. Field experiments were conducted over two years in a flat area as well as in a steep vineyard on large experimental plots. A whole season spraying program with each equipment was applied on separated plots with powdery mildew assessed regularly and compared to unsprayed controls in order to correlate leaf deposits with the biological efficacy. The highest deposits on leaves were obtained using the tunnel sprayer, the knapsack mistblower, the axial fan sprayer and the over-row sprayer. The lowest losses to the ground and airborne drift were with the recycling sprayer and knapsack mistblower, in contrast to the helicopter and the large volume air blast sprayer. With all tested sprayers, except for the helicopter, losses to the ground were lower under a fully developed canopy than at the four-leaf stage. The tunnel sprayer gave the best prevention of drift and the best deposit on the upper leaf surface . Control of powdery mildew with fungicides applied at the same spray intervals was good with all sprayers, except for the helicopter and the large volume air blast sprayer. Powdery mildew control was better when the deposit was more even on both leaf sides. Economical losses can occur when inadequate spraying equipment is used and there is high disease pressure.

IT—Information Technology and the Human Interface: Comparison of Different Spray Volume Deposition Models Using LIDAR Measurements of Apple Orchards

This paper reviews the models of spray volume deposition that have been developed to enable the adjustment of pesticide output from an axial fan sprayer to suit different apple orchards. The review has been limited to the empirical models of leaf deposit D formulated as D= Q/ UL, where L is a length-scale that describes the scaling effect of crop structure and Q/ U is the ratio of the spray volumetric flow rate to sprayer speed which defines the volume application rate on a per unit row length basis. The comparative performance of different models was evaluated using field measurements of leaf deposit on Cox apple trees with different combinations of rootstock, plantation density, age and growth stage. A tractor-mounted light detection and ranging (LIDAR) system was used to record orchard structural detail. Different methods for calculating the length-scale L from this information have been developed based on a range of different orchard crop structural parameters. Linear regression analysis of the measurements showed that the standard method of adjusting pesticide output, based on a linear scaling of the spray volume application rate per unit ground area, accounted for only 9% of the variation in the measurements. The use of other models, based on different geometric scaling parameters of orchard structure were demonstrated to give improved correlation with measurements. Of these models, the best correlation was obtained by using a length-scale proportional to the ratio of the tree volume to total ground area and this accounted for 43% of the variation in the measurements. The use of orchard structure parameters, based on crop area estimates derived from a local Poisson distribution of light transmission, gave further improvements. Of these models, the best correlation was obtained with a length-scale proportional to the tree area density and this accounted for 78% of the variation in the measurements. The tree area density is thus the best single crop structure parameter to use as the basis for pesticide dose expression for the practices of apple orchard spraying represented by these measurements. The calculation of this parameter relies on the availability of LIDAR measurements. Alternatively, a simple method for estimating this parameter might easily be constructed as a pictograph showing the relative tree area density associated with orchard tree images that can be reconstructed from these measurements. This research further identifies the need for this type of crop structural information to improve standardization of the dose recommendations on pesticide labels.

FORCES ON APPLE TREES SPRAYED WITH A CROSS–FLOW FAN AIR JET

To provide necessary plant protection in orchards, spray drops are transported to and into the canopy with an air jet from a fan sprayer. The interaction between the spray air jet and the tree canopy is central to effective droplet transport, spray coverage, and pest control in orchard spraying. A new method was developed to study this interaction by measuring forces applied to the tree by the sprayer jet during spray passes. A dwarf apple tree, sawed off at the trunk, was attached to the top of a multi–component force transducer, which in turn had its base secured to the ground. Forces in three directions, as well as the moment about the axis parallel to the fruit tree row, were measured. A two–unit cross–flow fan orchard sprayer was moved past the sensor–equipped tree. A plane jet, with both fan units vertical, and a converging air jet, with the top fan unit inclined 19³ towards the sprayed tree, were used. Two output power levels (fan rpm) were used with both fan conditions. Results presented are: maximum x–forces and moments, and the integral over time for forces and moments created by the moving air jet. There were significant differences between all treatments. Highest values were obtained with the converged air jets and high fan output, followed by the plane jet and high fan output. Next was the converged jet with low fan output, while the lowest force and moment values were measured for the plane jet with low fan output. Greater force and moment values resulted in more output power being transferred to the tree through jet air velocity acting on the canopy. Measured forces provide an integration of many individual actions between the air jet and the separate elements of the tree canopy and thus balance out short–time fluctuations. Repeatability in the measurements was very high, both for single values of force and moment and in the shape of pulses for each treatment replication.