Evaluation of Aerial Delivery Systems for Spray Deposition and Efficacy against Sweet Potato Whitefly on Cotton
2008
Latheef, M.A. | Kirk, I.W. | Bouse, L.F. | Carlton, J.B. | Hoffmann, W.C.
Sweet potato whiteflies (SWF), Bemisia argentifolii , live on the bottom surface of cotton leaves. Except crawlers, nymphal stages of the insect will not move about to contact insecticides. Aerial sprays to suppress SWF require improved application techniques designed to increase spray deposition and penetration to the lower layers of cotton canopy. Using Rotary atomizers, Winglets, and Trumpet nozzles with combination of air speed and boom heights, fenpropathrin 2.4E + acephate 90S at 0.22 + 0.56 kg active ingredient/ha, respectively, were applied at 46.7 L/ha on furrow-irrigated cotton near Maricopa, Arizona. Deposition of active ingredients and season long efficacy against SWF were determined and compared with conventional CP-03 nozzle. Neither spray deposit nor percentage coverage of active ingredients significantly varied consistently between aerial delivery systems. Rotary nozzles produced significantly smaller droplet size and higher droplet density compared to Winglets, Trumpet, and CP-03 nozzles. There was no consistent trend favoring one aerial delivery system over the other treatments against suppression of B. argentifolii on cotton. Further improvements in aerial delivery systems are needed to achieve increased control of insects that live and feed on the bottom surface of cotton leaves.
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