Spray Capture Efficiencies of Ribbon and String Targets Used in Orchard Applications

Abstract

The main objective of the study was to establish the relationship between spray depositionon ribbon and string samplers in filed applications. The experiment involved five commonly usedcitrus air-carrier sprayers, which included both conventional and tower configurations, equipped withaxial- or cross-flow fans and hydraulic nozzles or rotary atomizers. A sampling structure, consistingof vertical and horizontal lines of polyester string and cotton ribbon, was constructed in a citrusgrove. Spray mixtures, containing a fluorescent tracer, were applied at different volume rates andground speeds (nine treatments) on a 30-m course between two tree rows. Shortly after sprayingeach replication, the lines were collected in pieces. In the laboratory, the amount of deposit wasdetermined by fluorometry. Weather data recorded during the applications were used as covariablesin the analysis of variance. Each treatment was replicated 3-5 times.<br><br>The results showed a significant difference between capture efficiencies of the two target types. In allsample locations, the amount of spray deposit on the string was higher than that captured on cottonribbon. Overall, the mean and standard deviation of the string/ribbon deposit ratios were 2.30.7.