Comparison of the pesticide coverage achieved in a trellised vineyard by a prototype tunnel sprayer, a hydraulic sprayer, an air-assisted sprayer and a pneumatic sprayer

Abstract

Spraying is the main method used to apply pesticides to trellised vines in Castilla-La Mancha, Spain. If the efficiency of spray applications is to be improved, the amount of pesticide employed is to be reduced, and the performance of existing and new spray technology enhanced, the leaf coverage achieved must be known and a system developed that can rapidly determine it. With these aims in mind, the authors built and tested a prototype tunnel sprayer and compared its efficiency to the three types of sprayer most commonly used in the region: the hydraulic sprayer, the air-assisted sprayer and the pneumatic sprayer. To determine and compare the coverage produced by these four machines, a rapid analysis system that combines the use of water-sensitive paper strips and an artificial vision system was developed. All four machines were used to spray a commercial fungicide (dose 200 L ha -1 ) at working pressures of 0.1, 0.3 and 0.6 MPa onto vines in a trellised vineyard. With all four models, the quality of the application improved with the spraying pressure, although the best spraying coverage was obtained with tunnel sprayer. Even though the results obtained were not optimum (the formation of a uniform film of fungicide on the leaf surface), the mean coverage achieved by the tunnel sprayer (as recorded by the water-sensitive papers attached to the leaves) was 54%, and on occasion over 79%.Additional key words: drift, fungicide, trellised vines, water-sensitive paper. ResumenComparación del recubrimiento con productos fitosanitarios alcanzado en viña en espaldera por un prototipo de pulverizador tipo túnel, un pulverizador, un atomizador y un nebulizador La pulverización es el principal método usado en Castilla-La Mancha para aplicar productos fitosanitarios a la viña en espaldera. Si la eficiencia de las aplicaciones se incrementa, la cantidad de pesticida empleado se reduce y el rendimiento de las máquinas existentes y de las nuevas tecnologías aumenta. Para ello, debe conocerse el recubrimiento alcanzado en las hojas y desarrollarse un sistema que pueda determinarlo rápidamente. Con estos objetivos se construyó y ensayó un prototipo de pulverizador tipo túnel, y se comparó su eficiencia con los tres tipos de máquinas de aplicación de productos fitosanitarios más utilizados en esta región: pulverizadores, atomizadores y nebulizadores. Para determinar el porcentaje de recubrimiento logrado por las máquinas, se desarrolló un sistema rápido que combina el uso de cartulinas de papel hidrosensible con la visión artificial. Con todos los pulverizadores se usó el mismo fungicida comercial (200 L ha -1 ) y se ensayaron, a tres presiones diferentes (0,1 MPa, 0,3 MPa y 0,6 MPa), en un viñedo en espaldera. Se demostró que en los cuatro modelos la calidad de la aplicación mejora con la presión de la pulverización, y que el mejor recubrimiento se obtuvo con el prototipo de pulverizador tipo túnel. Aunque los resultados obtenidos no fueron óptimos (formación de una película uniforme de fungicida), el valor medio alcanzado...

Field assessment of a newly‐designed pneumatic spout to contain spray drift in vineyards: evaluation of canopy distribution and off‐target losses

“…14(a)). The magnitude of off‐field loss reduction achieved by the low‐drift pneumatic spout options (AP and XP) is comparable to values other researchers have reported using drift reducing hydraulic nozzles in vineyard field trials, 36,70,71 laboratory measurements, 38,72 or by indirect methods of assessment 67 …”

“…In rank order, the best surface coverage was at Out‐A (finger‐type nozzle closest to the vegetative strip), which was followed by In‐B (inner canopy) and then Out‐C. The wide variation in coverage at the various canopy sampling positions might relate to uneven sprayer fan airflow volumes and speeds that could lead to poor disease control 67,68 …”

“…Once a reduction in off‐field ground losses was detected, the area under the near‐field sedimentation curves (Fig. 14) was calculated using the mid‐ordinate rule method, 67 and the related cumulative deposition charts of off‐field ground losses were also determined (Fig. 14).…”

Assessing the influence of air speed and liquid flow rate on the droplet size and homogeneity in pneumatic spraying

“…The pneumatic diffusers generally mounted on vineyard sprayers and, in some cases, in orchard sprayers, consist of spouts in which spray droplets are generated by the action of a high‐speed, high‐pressure air stream on a liquid conveyed at low pressure (0.15 MPa maximum) inside the spout . The Venturi effect created at the internal part of the spouts generates very fine droplets.…”

Development of Drift-Reducing Spouts For Vineyard Pneumatic Sprayers: Measurement of Droplet Size Spectra Generated and Their Classification

“…Pneumatic spraying is a well-known technique for its fine droplet size generation. As aforementioned, small droplets are generally requested by the farmers to achieve a uniform target spray coverage that is essential for contact PPP; thus, this technique is very widespread, especially among large-farm vine growers in America and Europe [49,50]. In Italy there are large areas in which vineyard treatments are performed almost exclusively with pneumatic sprayers [51].…”