Spray application variables affect air velocity and deposition characteristics of a tower sprayer

Masoud Salyani, Young M. Koo, Roy D. Sweeb


An airblast tower sprayer was operated in open area at two discharge rates and two ground speeds. Spray deposition was quantified by copper colorimetry and air velocity profiles were obtained by hot-film anemometry. Air and spray samples were taken at several spatial locations on both sides of the sprayer. Spray deposition and its variability increased as spray volume rate decreased from 4,115 to 623 L/ha. Increasing the sprayer ground speed from 2.4 to 4.8 km/hr increased the mean deposition by 71.6% and 41.8%, in high and low-volume applications, respectively. However, higher speed gave more variable deposition. The targets nearer to the sprayer showed a lot of runoff and maximum deposition was achieved at about 2.8 m from centerline of the sprayer. Air velocity decreased sharply as the distance from the sprayer increased. In all sample locations, air velocity decreased as sprayer ground speed increased. Overall, it appears that lower air velocities could increase spray deposition at nearer sample locations. This means that both air and liquid flow outputs need to be optimized in order to increase spray deposition on most canopy locations.


colorimetry; anemometry; deposition; ground speed; volume rate

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283