Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2008
Publication Date: 6/2/2008
Citation: Latheef, M.A., Kirk, I.W., Bouse, L.F., Carlton, J.B., Hoffmann, W.C. 2008. Evaluation of aerial delivery systems for spray deposition and efficacy against sweet potato whitefly on cotton. Applied Engineering in Agriculture. 24:415-422. Interpretive Summary: Sweet potato whiteflies (SWF) can be a serious pest in cotton affecting both yield and cotton quality. This study investigated the effects of SWF control products applied with different aerial application spray nozzles combined with several products for controlling SWF. While there were no significant differences in the level of control of SWF from the different spray nozzles, rotary nozzles produced significantly smaller droplet size and higher droplet density compared to the other nozzles tested. 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.
Technical Abstract: 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, AZ. Deposition of active ingredients and season long efficacy against SWF were determined and compared with conventional CP 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 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.