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

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 haE-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%.