Research Station for Fruit Growing Pcfruit

Sint-Truiden, Belgium

Research Station for Fruit Growing Pcfruit

Sint-Truiden, Belgium
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Duga A.T.,Catholic University of Leuven | Endalew A.M.,Catholic University of Leuven | Nicolai B.,Catholic University of Leuven | Verboven P.,Catholic University of Leuven | And 3 more authors.
Acta Horticulturae | Year: 2013

The relative balance between environmental contamination and biological efficacy determines the performance of agricultural sprayers. This balance is mainly affected by the design and operational parameters of the sprayers apart from the tree architecture and environmental conditions. The design and operational parameters of the sprayer have been analyzed in this study to address this issue. The performance of three orchard sprayers (BAB Duoprop, Hardi Condor V and Hardi Tango) were characterized to see the effect of machine design on on target and off target deposition. Fan speed and deflector setting were the two operational parameters considered for this study. This analysis was done using Computational Fluid Dynamics (CFD). The CFD models represent controlled indoor trials carried out using artificial pear trees. The three different sprayer designs gave different air and spray flow profiles. The CondorV and Tango sprayers gave a relatively higher velocity air passing the canopy near the ground and there is a higher spray coverage at higher heights for the Duoprop and Tango sprayers than for the Condor V sprayer. In terms of the two operational parameters, shifting from low to high gear setting increased both the on target (leaf and trunk) and off target deposition due to the increase in the penetration capacity of the spray. Shifting the deflector setting from optimal to extreme setting also increased both the on and off target depositions. But the increase in trunk and leaf deposition obtained by changing the deflector setting from optimal to extreme is minimal compared to the resulting drift problem.

Duga A.T.,Catholic University of Leuven | Ruysen K.,Research Station for Fruit Growing Pcfruit | Dekeyser D.,Belgium Institute for Agricultural and Fisheries Research | Nuyttens D.,Belgium Institute for Agricultural and Fisheries Research | And 3 more authors.
Chemical Engineering Transactions | Year: 2015

The high velocity air jet generated from air assisted orchard sprayers offsets the effect of wind on the spray flow pattern in front of the tree and within the vicinity of the tree height. This combined with the small wind magnitude at lower heights of the boundary layer results in insignificant wind effect within this zone. Once the spray droplets pass through the trees, the velocity of the air jet is significantly reduced by the resistance of the trees increasing the chance of deflection by wind. The projection of the spray droplets also affects the extent of the wind effect and strongly depends on the outlet design of the sprayer. The classical single axial fan sprayer used in this analysis projects part of the spray beyond the tree height resulting in a higher risk of deflection by wind. The CFD modeling approach used in this work allowed studying these wind effects of spray applications in a comprehensive way. It was observed that wind blowing opposite to the spraying direction significantly deflected the spray back to the sprayer. The effect is increased with wind velocity magnitude. Wind blowing in the direction of spraying increased the amount of spray passing through the trees (resulting in increased drift potential), but also increased on-target deposition for this type of sprayer that blows a significant amount of spray over the trees. In this case, wind helps to contain the air assistance of the axial sprayer within the canopy height to some extent. Copyright © 2015, AIDIC ServiziS.r.l.

Duga A.T.,Catholic University of Leuven | Dekeyser D.,Belgium Institute for Agricultural and Fisheries Research | Ruysen K.,Research Station for Fruit Growing pcfruit | Bylemans D.,Research Station for Fruit Growing pcfruit | And 3 more authors.
Boundary-Layer Meteorology | Year: 2015

A computational fluid dynamics (CFD) model of airflow and spray application in orchards was validated using field trials and used to assess the effect of wind and sprayer type on spray distribution in different orchard training systems. Three air-assisted orchard sprayer designs (a cross-flow sprayer, an axial sprayer and a sprayer with individual spouts) and four different training systems of apple and pear trees were used for this analysis. The CFD model integrates the tree architecture into the model geometry, rather than using a generalized canopy profile approach. Predicted vertical on-tree deposition profiles agreed well with measurements. The lower airflow rate generated by the sprayer with individual spouts resulted in a significantly larger deflection of the spray particles under the same wind conditions. A detailed assessment was made on the most common axial sprayer. An increase in the magnitude of the wind speed for flow across the tree row resulted in an increase in the amount of spray detected in the air around the trees and in the ground deposition in front of the tree row. Environmental airflow in the direction of spraying gave the largest deposition on the tree, constraining the spray in the canopy region. A wind direction opposite to the spraying direction, however, resulted in an increase of the ground deposition and the amount of spray remaining in air. The model can be used to analyze the effects of implementation of more sustainable spray application procedures taking into account wind conditions, tree and machine characteristics. © 2015 Springer Science+Business Media Dordrecht

Endalew A.M.,Catholic University of Leuven | Hendrickx N.,Research Station for Fruit Growing PCFruit | Goossens T.,Research Station for Fruit Growing PCFruit | Nuyttens D.,Belgium Institute for Agricultural and Fisheries Research | And 2 more authors.
American Society of Agricultural and Biological Engineers Annual International Meeting 2010, ASABE 2010 | Year: 2010

Drift is of more concern for air-assisted orchard sprayers than for field sprayers due to the high air jet velocity involved and the horizontal application direction. Orchard sprays are applied sideways to the trees, with a high risk for aerial drift by wind. Air-assistance has also been shown to be non-uniform, but the consequences for deposition uniformity in the canopy have yet to be demonstrated. Off-target deposition can be minimized and uniformity can be improved with the use of proper equipment and methods under favourable weather conditions depending on the nature of the target canopy and the level of infection. To this end knowledge of the canopy flow conditions of both the air and the spray are needed. It has been difficult to obtain such information experimentally. A Computational Fluid Dynamics (CFD) model that allows the simulation of spraying process for different machines including environmental and canopy conditions is presented. This comprehensive model considers the effects of wind velocity and turbulence, and the nature of the canopy on air assistance distribution. Orchard experiments were conducted on airflow profile from three air assisted orchard sprayers in leafless and fully leafed pear tree (Pyrus communis L.) orchards. The model results compared well to the measured profiles of airflow distribution, with average accuracies as high as 80%. The model is used to study effects of sprayer and nozzle design and operational parameters, weather conditions, and for different planting systems and development stages.

Wouters N.,Catholic University of Leuven | De Ketelaere B.,Catholic University of Leuven | Deckers T.,Research Station for Fruit Growing pcfruit | De Baerdemaeker J.,Catholic University of Leuven | Saeys W.,Catholic University of Leuven
Computers and Electronics in Agriculture | Year: 2015

Thinning of pome and stone fruit involves the reduction of tree crop load in order to regulate fruit set and quality. As it is typically carried out through manual labor, thinning comprises a large part of a grower's production costs. Mechanized thinning has been shown to be a cost-effective alternative but the performance of existing thinning devices needs to be further improved by taking the variation in bearing capacity of the individual trees into account.In this work, a multispectral camera system is developed to detect the floral buds of pear (cv. Conference) during the growth stages prior to bloom. During a two-year field trial, the multispectral system was used to measure orchard scenes in six distinct optical wavebands under controlled illumination. These wavebands are situated in the visible and near infrared region of the spectrum and were selected based on hyperspectral laboratory measurements described in previous work.The recorded multispectral images were converted to a database containing the spatial-spectral signatures of the objects present in the orchard. Subsequently, canonical correlation analysis was applied to create a spectral discriminant model that detects pixels originating from floral buds. This model was then applied to the recorded data after which an image analysis algorithm was designed and optimized to predict the number of floral buds. In total, approximately 87% of the visible floral buds were detected correctly with a low false discovery rate (<16%). Therefore, it is expected that the multispectral sensor can be used to improve the efficiency of existing thinning devices. Additionally, it could as well be used as a stand-alone sensor for early-season yield estimation. © 2015 Elsevier B.V.

Duga A.T.,Catholic University of Leuven | Ruysen K.,Research Station for Fruit Growing pcfruit | Dekeyser D.,Belgium Institute for Agricultural and Fisheries Research | Nuyttens D.,Belgium Institute for Agricultural and Fisheries Research | And 3 more authors.
Crop Protection | Year: 2015

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.The 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. © 2014 Elsevier Ltd.

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