AIRBLAST SPRAY PARTITIONING IN A MATURE PECAN ORCHARD

Abstract

Spray applications of Malathion were made with a radial airblast sprayer in an 11 m tall, mature pecan orchard,in the Middle Rio Grande valley of New Mexico. Measurements of drop size distributions from the sprayer were made withan imaging laser drop size measurement system. Sprayer effectiveness in penetration of the tree canopy was examined bysampling a vertical profile of droplet sizes on the opposite side of the row from the application. Spray volume samples werecollected with continuous string samples arranged on a cross-row rectangle frame encompassing two tree rows. The first treerow reduced the overall Dv0.5 by a factor of 7. The measurements indicated that, overall, 4.5% of the total mass sprayed wentout the top of the canopy; 22.2% was deposited on the ground between and beneath the adjacent tree rows; 12.2% passedthrough the left side tree row; and 4.0% passed through the right side tree row. The remainder, 57.1% of the material, wasassumed captured by the adjacent tree rows.