Axial Fan Sprayer Research Articles

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.

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.

CANOPY STRUCTURE AND DEPOSITION EFFICIENCY OF VINEYARD SPRAYERS

A field study was performed to analyse how deposition efficiency from an axial-fan sprayer was affected by the canopy structure of vines trained to the High Cordon, Low Cordon and Casarsa systems, at beginning of flowering and beginning of berry touch growth stages. An empirical calibration method, providing a dose rate adjustment roughly proportional to canopy height, was used. The canopy structure was assessed using the Point Quadrat method, and determining the leaf area index (LAI) and the leaf layer index (LLI). Spray deposits were measured by colorimetry, using a water soluble dye (Tartrazine) as a tracer. Correlation between deposits and canopy parameters were analysed and discussed. Foliar deposits per unit leaf area were relatively constant, suggesting that empirical calibration can reduce deposit variability associated with different training systems and growth stages. Total foliar deposition ranged from 33.6% and 82.3% of total spray volume, and increased proportionally with the LLI up to LLI<4. Deposits on bunches significantly decreased with the LLI in the grape zone. The results suggest that sprayer efficiency is improved by a regular, symmetrical canopy, with few leaf layers in the grape zone as in Low Cordon. However, a LLI<3 over the whole canopy and >40% gaps in the foliage both reduced total deposition, and may increase the risk for larger drift losses.

Field evaluation of a calibration method for air-assisted sprayers involving the use of a vertical patternator

Vertical spray patternators are used in Europe for the inspection and calibration of orchard and vineyard sprayers. However, little information is available about their reliability, particularly when used for crop-specific calibration, involving the adjustment of nozzle position and orientation according to canopy size and geometry. A method, based on the use of a lamellate patternator, was evaluated for adjusting the nozzle orientation of a conventional, axial-fan sprayer. The treatments included: (a) keeping the nozzle orientation as determined by the manufacturer (no calibration); (b) adjusting the nozzle orientation in the field, following visual observation (in-field calibration); and (c) adjusting the nozzles in order to obtain, on the lamellate patternator, a vertical spray pattern reflecting the canopy outline of the vineyard (patternator calibration). The above treatments were applied in a hedgerow vineyard, at beginning of flowering and at fruit set, and spray deposits on the canopy determined by colorimetry, using a water-soluble dye (Tartrazine) as a tracer. No calibration gave the most uniform deposit distribution in the first experiment, whereas in-field calibration was best in the second experiment. In both experiments, Patternator calibration gave the largest differences between deposits at different heights on the canopy, related to low collecting efficiency of the patternator, particularly at the middle and top canopy locations.

DETECTION AND QUANTIFICATION OF NURSERY SPRAY PENETRATION AND OFF-TARGET LOSS WITH ELECTRON BEAM AND CONDUCTIVITY ANALYSIS

Spray penetration and off-target loss from a conventional, air-assist, axial-fan sprayer and a high-clearance, boom-type sprayer were investigated in Honey Locust (Gleditsia triacanthos) and Canadian Hemlock (Tsuga canadensis) trees located in two different production nurseries. Aqueous tracer solutions of either Ca(NO3)2 foliar fertilizer or Cu(OH)2 fungicide were used in the experiments. Spray deposition distributions within canopies and off-target loss to drift and the ground were assessed via residues collected on foliage, electron microscope stubs, artificial plates, vertical and ground-level profile plastic tapes, and high-volume air samplers. Electron beam analysis (EBA) was used to assay residues on stubs, leaves, and needles placed and collected at several locations and heights in the canopy. Plastic tape samples were evaluated with a laboratory spray deposit analyzer using a conductivity detector. Both assessment methods used in the present study were useful for detection and quantification of Ca or Cu spray penetration within nursery canopies. The average spray deposit on upper surfaces of leaves was three times that deposited on lower surfaces within the Honey Locust trees. Spray deposit at the top of Canadian Hemlock tree canopies was 14 times higher than that at the middle and bottom of canopies. Spray deposit on ground targets greatly decreased as the distance from the spray path increased in both nurseries; however, airborne spray deposits did not decrease as much with increasing downwind distance as ground deposits.

Field evaluation of a calibration method for air-assisted sprayers involving the use of a vertical patternator

Vertical spray patternators are used in Europe for the inspection and calibration of orchard and vineyard sprayers. However, little information is available about their reliability, particularly when used for crop-specific calibration, involving the adjustment of nozzle position and orientation according to canopy size and geometry. A method, based on the use of a lamellate patternator, was evaluated for adjusting the nozzle orientation of a conventional, axial-fan sprayer. The treatments included: (a) keeping the nozzle orientation as determined by the manufacturer (no calibration); (b) adjusting the nozzle orientation in the field, following visual observation (in-field calibration); and (c) adjusting the nozzles in order to obtain, on the lamellate patternator, a vertical spray pattern reflecting the canopy outline of the vineyard (patternator calibration). The above treatments were applied in a hedgerow vineyard, at beginning of flowering and at fruit set, and spray deposits on the canopy determined by colorimetry, using a water-soluble dye (Tartrazine) as a tracer. No calibration gave the most uniform deposit distribution in the first experiment, whereas in-field calibration was best in the second experiment. In both experiments, Patternator calibration gave the largest differences between deposits at different heights on the canopy, related to low collecting efficiency of the patternator, particularly at the middle and top canopy locations.

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.

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

Two field experiments compared spray deposits and losses from very fine (volume median diameter (VMD)=156 μm), fine (VMD=198 μm) and medium (VMD = 237 μm) quality spray applications to young dwarf, dwarf and semi-dwarf apple trees from an axial fan orchard sprayer fitted with hydraulic hollow cone nozzles. All other spray application variables were kept constant. In one experiment, the very fine quality treatment deposited slightly but significantly less spray on leaves than the other treatments but there were no significant differences in the other. The very fine spray quality treatment deposited significantly less on fruitlets in both experiments, but differences were small. The leaf-to-leaf and tree zone-to-tree zone distributions of deposits were not affected significantly by the spray quality. The percentage spray cover, estimated by image analyses, on water-sensitive papers fixed horizontally in the middle of the trees was not markedly affected by spray quality though values were variable. The very fine and fine spray qualities gave significantly greater grand mean percentages of spray drift than the medium spray quality treatment in one experiment, though differences were either not or only just statistically significant in the other. Drift was greatest in the small trees and least in the large trees, consistent with an inverse relationship with tree area density (TAD). The medium spray quality gave significantly smaller deposits on the ground sampling lines than the very fine and fine treatments. In conclusion, variation in spray quality over the range investigated did not greatly affect the amount or macro-distribution of spray deposits on apple trees from the axial fan sprayer. The coarser sprays gave slightly greater mean deposits and smaller spray losses and are preferable from these points of view. Further work is required to establish the effects of spray quality on the micro-distribution of deposits on the target. A coarser pattern of spray deposition on the plant surface could be less efficacious biologically for some pesticides. Therefore, evaluation of the effects of spray quality adjustment on biological efficacy is required.

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

Spray deposit and off-target contamination distribution measurements were made in apple trees of different sizes and row spacings for an axial fan sprayer with different spray liquid flow rates ( c 3.8, 11, 29 l min −1) but otherwise constant conditions (air flow=11.3 m 3 s −1; speed=5.8–5.9 km h −1, VMD=156–159 μm). Leaf deposits (normalised by the applied dose) were not affected by the spray liquid flow rate except on young dwarf trees at the high flow rate due to saturation. The volume retained on the crop increased with tree size. Deposits on individual leaves were approximately log normally distributed. Variability was usually marginally greater for the low flow treatment than for the medium or high flow treatments and usually greater in the larger than in the smaller trees. Mean deposits on the undersides of leaves were about double those on upper surfaces. The mean percentage of the surface area of water sensitive papers in the centre of the tree covered with spray varied in direct proportion to the spray liquid flow rate. Spray cover was least in the larger trees. Deposits on fruitlets were affected significantly by spray liquid flow rate. The high flow rate treatment gave the smallest deposits on fruitlets due to the deposit exceeding local saturation conditions. The deposits on fruitlets tended to be greater in the smaller than in the larger trees. Normalised spray drift deposits on vertical, 10 m tall polythene sampling lines positioned 5 m downwind of the sprayer were somewhat greater for the low flow rate than the medium and high flow rate treatments but differences were at least partly due to differences in wind direction. High values occurred where the wind direction was perpendicular to the tree rows, low values where the wind direction was parallel to the tree rows. Drift generally decreased with increasing tree size. There were no consistent differences in normalised ground deposits due to spray liquid flow rate, though ground deposits were greater in the smaller trees than in the larger trees. As a whole, these results showed that wide variation in spray liquid flow rate had only small effects on normalised spray deposits on the tree, on spray drift and on losses to the ground but greatly affected spray cover which varied in proportion to the spray liquid flow rate. This implies that the spray liquid flow rate for foliar application of an agrochemical should be determined by the degree of spray cover that is needed for adequate efficacy. Furthermore, the pesticide dose rate may be conveniently adjusted in direct proportion to the spray liquid flow rate at constant concentration for deposits lower than the target saturation level.

Foliar deposition and pesticide losses from three air-assisted sprayers in a hedgerow vineyard

Three commercial air-assisted sprayers were tested in a hedgerow vineyard, at full vegetative development (end of July; leaf area index = 1.94), using a water-soluble food dye as a tracer. The spraying equipment used was (1) a high-volume (1355 l ha −1) axial-fan sprayer; (2) a low-volume (246 1 ha −1) compressed-air sprayer (3) a sprayer fitted with deflectable air outlets, allowing an adjustment of the output angle, relative to the row direction, from 90 ° to 118 °. All application techniques appeared to be capable of delivering more than 64% of the sprayed material onto the leaves and grapes. The high-volume sprayer provided the most uniform distribution over the foliage. The change of the output angle from 90 ° to 118 ° did not significantly affect total leaf deposition, but increased the overall variability of the deposits.

Field evaluation of a tunnel sprayer and effects of spray volume at constant drop size on spray deposits and efficacy of disease control on apple

SummaryAn air assisted tunnel sprayer (the Noric Joco EX2) incorporating CDA rotary atomisers (Volume Median Diameter (VMD) =c. 140 μm, volume rate = 50 litre ha‐1 forward speed = 3.9 km h‐1) gave at best equal but in some cases significantly poorer control of apple powdery mildew and scab than the standard commercial practice of spraying with an axial fan sprayer with Micron XI rotary atomisers (VMD =c. 90 μm, volume rate = 50 litre ha‐1, forward speed = 7.2 km h‐1). Approximately 30% of the spray volume applied was collected for recycling with the tunnel sprayer. Increasing spray volumes at approximately constant drop size (c. 140 μm) from 50 to 100 to 200 litre ha‐1 with the tunnel sprayer consistently improved efficiency of mildew and scab control. Bulk spray deposits on leaves, and their gross distribution in the tree, was similar with the different spraying methods and volumes. The mean percentage leaf area covered with spray deposit increased with spray volume as did the number of spray deposits per unit area. The tunnel sprayer at 50 litre ha‐1 gave a similar though less variable mean level of cover than the axial fan sprayer at the same volume rate. It gave 2–3 times more cover on upper than on lower leaf surfaces. The axial fan sprayer gave approximately equal cover on upper and lower leaf surfaces.The main limitations of the tunnel sprayer were its slow maximum forward speed and the restricted tree size and shape on which it can be used.

The Effect of Spray Application Rate and Airflow Rate on Foliar Deposition in a Hedgerow Vineyard

Two experiments were performed in a hedgerow vineyard, in June (after end of blossom) and July (full vegetation development) to assess the influence of spray application rate and air output on the spray distribution from an axial-fan sprayer. Measurements were performed by fluorometry, using Brilliant Sulpha Flavine as a tracer. Increasing spray application rate and air output both led to higher losses to the ground and lower deposition on the foliage. However, differences were statistically significant only in the July experiment. Losses to the soil ranged from 34·5 to 36·8% for the lower spray rates (313-391 l/ha), and from 41·3 to 48·9% for the medium spray rate (648-782 l/ha) treatments. Losses due to drift outside the experimental plots and deposition on branches, shoots and poles ranged from 6·5 to 10·5% for the lower air output (7·0 m 3/s), and from 7·8 to 19·8% for the higher air output (8·6m 3/s). The highest deposition on the foliage was recorded for the combination of a low spray rate and a low airflow rate (54·2 to 56·7%). Deposits per unit leaf surface were invariably lower in the middle (1·2 to 1·6m high), denser part of the canopy. However, differences between heights were lower than in a previous experiment.