L’uso dei banchi prova per la regolazione delle irroratrici nei trattamenti in vigneto

Some spraying tests have been carried out in a Sicilian vineyard in order to investigate sprayer adjustments alternative to the visual one in field, able to increase the leaf deposit and improve the uniformity of distribution and the penetration of the spray jet inside the canopy. The vineyard, spur-cordon pruned, was with 2.0 m x 1.2 m spacing; the sprayer, mounted, was with mechanical pulverisation, arc-shaped bar and nozzles with ceramic disks. A vertical patternator with square 0.2 m x 0.2 m metallic trays was used for sprayer calibration. The tests have been carried out in two phenological stages: berries lead-shot (29 Eichhorn & Lorenz code, June 2001), and beginning of ripening (35 Eichhorn & Lorenz code, July 2001). For each phenological stage three sprayer set-up have been tested: visual calibration in field (T1, with 714 L/ha), calibration with vertical spray pattern similar to the thickness (T2, with 667 L/ha) and LAI of the trees (T3, with 667 L/ha). All the tests have been carried out with ground speed of 1.4 m/s and pressure of 1 MPa. The experimental plan was based on a randomised block design with 4 replicates. Spray deposits were measured by colorimetry, using water-soluble food dye (Poinceau Red, 10 g/L) as a tracer. Sampling was effected on three bands of height and on the two sides of the row, picking 8 leaves in each position. The tests have shown, above all, the difficulty in realising, with this type of sprayer, the reference profiles, as the spray jets are heavily influenced by the fan air flows. Several attempts need, changing position, number and inclination of the open nozzles, before to achieve an acceptable profile. Then, in both stages, the mean normalised leaf deposit was statistically equal for the three treatments, but, considering recovery, vertical uniformity and penetration of the spray jet across the canopy, sprayer set up T2 and T3 furnish a little better results than T1. Finally, the good uniformity obtained encourages the prosecution of the studies on using patternators as tools for preventive calibration of sprayers.