Analysis of and Experimental Measurements made on a Moving Air-Assisted Sprayer with Two-Dimensional Air-Jets Penetrating a Uniform Crop Canopy

Walklate, P. J.; Weiner, K.-L.; Parkin, C.S.

doi:10.1006/jaer.1996.0039

Cited by 34 publications

(21 citation statements)

References 1 publication

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“…In orchards, this is achieved using air assisted sprayers. Air assisted orchard sprayers use air jets generated by means of a fan to carry pesticide droplets, to displace the air in the crop canopy and to realize a homogeneous deposition on to the target canopy (Da Silva et al, 2006;Dekeyser et al, 2013;Delele et al, 2005;Escolà et al, 2013;Gupta et al, 2012;Khot et al, 2012;Sidahmed and Brown, 2001;Walklate et al, 1996). The pesticide deposition on the canopy can directly or indirectly be affected by the plant architecture, the physico-chemical properties of the pesticide, the meteorological conditions and the used spraying technique, among others (Catania et al, 2011;Celen et al, 2008;Cross et al, 2001;Dorr et al, 2013;Jaeken et al, 2001;Nuyttens et al, 2009;Pergher and Gubiani, 1995;Rosell and Sanz, 2012;Vallet and Tinet, 2013).…”

Section: Introductionmentioning

confidence: 99%

Spray deposition profiles in pome fruit trees: Effects of sprayer design, training system and tree canopy characteristics

Duga

Ruysen²,

Dekeyser³

et al. 2015

Crop Protection

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Air assisted orchard sprayers are characterized by a strong airflow that carries the pesticide droplets to the target canopy and assist in moving the plant parts to allow deposition throughout the whole tree. It has been shown before that different designs of orchard sprayers result in different airflow profiles, but it is still unclear whether these differences strongly affect on-target spray distribution, and what is the role of tree architecture. Here we present an in-field analysis of the on-target deposition profiles from three distinct sprayer types in trees of four different apple and pear training systems. 2The results obtained showed that there was a strong relationship between the vertical leaf deposition profile and the outlet air flow pattern from the sprayers. Stronger air assistance (higher air speed) was directly correlated to a higher on-target deposition. It was also observed that directing nozzles towards the target is always an advantage irrespective of tree architecture.Tree characteristics such as total leaf cover, leaf wall porosity and tree volume strongly affected the total on-target deposition, further confirming previous claims that ground surface area alone is an incorrect measure for dose calculation in fruit trees.

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Section: Introductionmentioning

confidence: 99%

Spray deposition profiles in pome fruit trees: Effects of sprayer design, training system and tree canopy characteristics

Duga

Ruysen²,

Dekeyser³

et al. 2015

Crop Protection

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“…β d has less physical meaning but is considered as the fraction of k dissipated by interactions with the vegetation or by short-circuiting of the cascade. Taking into account the suggestion of Walklate et al (1996) that β p is insignificant compared with β d in dense canopies and by taking β d = 1, a simplified model for S k is:…”

Section: Governing Equationsmentioning

confidence: 99%

“…Marucco et al (2008) reported that the best compromise to achieve a uniform coverage of pesticide on peach orchards was achieved when operating an axial flow fan sprayer at a forward speed of 1.97 m s −1 , air velocity magnitude of 14 m s −1 and spray volumes of 400 L ha −1 . However, practical difficulties arise during the operation of air-assisted sprayers due to the limited adjustment options and poor understanding of the airflow interactions with different canopy structures (Walklate et al 1996). For example, an uneven foliar distribution of pesticides in apple orchards and citrus trees was a result of the intricacy of controlling the direction of airflows and spray from air-assisted sprayers in order to match the plant geometry and target distribution (Hislop 1991;Pergher et al 1997).…”

Section: Introductionmentioning

confidence: 99%

“…On the one hand the air-jet helps to enhance the transport and deposition of pesticides in the crop, and on the other hand it can cause excessive environmental contamination and ineffective treatment if the flow characteristics are not properly matched to the target crop (Walklate et al 1996(Walklate et al , 2002. For these sprayers, adjustment of the airflow from the sprayers based on canopy conditions (type, growth stage and foliar condition) plays an essential role to achieve uniform deposition on different canopy parts.…”

Section: Introductionmentioning

confidence: 99%

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Modelling the Effect of Tree Foliage on Sprayer Airflow in Orchards

Endalew

Debaer²,

Rutten³

et al. 2010

Boundary-Layer Meteorol

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The effect of tree foliage on sprayer airflow through pear trees in a fruit orchard was studied and modelled in detail. A new three-dimensional (3-D) computational fluid dynamics model that integrates the 3-D canopy architecture with a local closure model to simulate the effect of the stem and branches and leaves of trees separately on airflow was developed. The model was validated with field observations made in an experimental orchard (pcfruit, Sint-Truiden, Belgium) in spring and summer 2008 and was used to investigate the airflow from three air-assisted orchard sprayers (Condor V, Duoprop and AirJet quatt). Velocity magnitudes were measured before and behind leafless and fully-leafed pear canopies across the row while the operating sprayers are passing along the row, and were compared with the simulations. The simulation results predicted the measured values well with all the local relative errors within 20%. The effect of foliar density on airflow from the three air assisted sprayers was manifested by changing the magnitude and direction of the sprayers' air velocity behind the canopy, especially at the denser regions of the canopy and by changing the pattern of velocity decay horizontally along the jet. The developed methodology will also allow a thorough investigation of atmospheric airflow in canopy structures.

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“…Vegetation dissipates the kinetic energy of the air, causing a reduction on its speed (Belcher et al, 2003;Yi, 2008;Yue et al, 2008). Studies of the turbulent nature of fan airflow as it passes through foliage have confirmed reductions in momentum and turbulent kinetic energy (Walklate et al, 1996). Vegetation absorbs part of the energy produced by the fan, which can help to reduce spray drift (Hofman & Solseng, 2001).…”

Section: Introductionmentioning

confidence: 99%

Description of the airflow produced by an air-assisted sprayer during pesticide applications to citrus

Salcedo¹,

Garcerá²,

Granell³

et al. 2015

Span. j. agric. res.

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Atmospheric drift of plant protection products is considered a major source of air pollution during pesticide applications. Citrus protection against pests and diseases usually requires application of these products using air-blast sprayers. Many authors have emphasized the influence of vegetation on the risk of spray drift. The aim of this work was to describe in detail how the airflow from an air-blast sprayer behaves when it reaches citrus trees and, in particular, the effect that the tree canopy has on this flow. Tests were conducted at a commercial citrus orchard with conventional machinery, placed parallel to a row of trees. Air velocity and direction was measured using a 3D ultrasonic anemometer in 225 points situated in three parallel planes perpendicular to the equipment. The stability of the airflow at each measuring point was studied and the mean velocities were graphically represented. Two vortexes, one behind the canopy, and another over the tree, have been deducted and never been reported before. Both may have an important influence on the trajectories of the sprayed droplets and, as a consequence, on the way in which plant protection products are diffused into the atmosphere. Observed turbulence intensities were higher than in similar experiments conducted in other tree crops, which may be attributable to the higher air volume generated by the machinery used for citrus protection and to the higher foliage density of citrus orchards.

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Analysis of and Experimental Measurements made on a Moving Air-Assisted Sprayer with Two-Dimensional Air-Jets Penetrating a Uniform Crop Canopy

Cited by 34 publications

References 1 publication

Spray deposition profiles in pome fruit trees: Effects of sprayer design, training system and tree canopy characteristics

Spray deposition profiles in pome fruit trees: Effects of sprayer design, training system and tree canopy characteristics

Modelling the Effect of Tree Foliage on Sprayer Airflow in Orchards

Description of the airflow produced by an air-assisted sprayer during pesticide applications to citrus

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