Study of a new model of sprayer for applications in "tendone" vineyards

The paper reports the results of some spray application tests carried out in awning vineyards to assess the performance of a new model of sprayer whose spray boom, made of seven adjustable spraying modules, partially meets the geometry of the vegetation. Two configurations were taken into consideration: spray boom closed (T2), to improve the in field manoeuvrability, and spray boom open (T3), to approach the target with the spray modules.The experimentation was carried out within a period of two years, comparing the two prototype configurations with a conventional sprayer (T1, first year) and the effects of airflow rate and forward speed of only the prototype T3 (after changing the fan) on the foliar deposition (second year).An experimental design with one (the sprayers setup, first year) or two (airflow rate and forward speed, both with two levels, second year) factors was adopted, arranged according to a randomised block design with three replicates.To take into account the development of the vegetation, the experimental plan was replicated in two phenological stages: “Berries pea sized” and “Berry touch” (first year), and “Berries pea sized” and “Beginning of ripening” (second year).After spray applications (just one spray pass for each replicate, delivering a water solution with a food dye as a tracer and a surfactant), a number of leaves were picked on each sample tree, so to consider transversal, longitudinal and in depth variations. Foliar deposition was measured by means of a spectrophotometer.The first year results showed no statistically significant differences in the mean foliar deposition among the three sprayer setup in the first stage and a better performance of the sprayer T2 in the second stage. The second year results showed an improvement in the performances of the prototype with respect the first year tests, suggesting that the fan changing was right. The differences in mean foliar deposits between low (1.81 m3/s) and high (2.14 m3/s) airflow rate in both phenological stages were not statistically significant. Forward speed gave opposing effects in the two phenological stages: higher deposits at lower speed (1.05 m/s) in the first stage and higher deposits at higher speed (1.58 m/s) in the second stage.