|Howard, Kevin - DELTA AND PINE LAND, CO.|
Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2000
Publication Date: June 1, 2000
Citation: MULROONEY, J.E., HOWARD, K.D. EFFECTS OF AIR DEFLECTORS ON INSECTICIDE DEPOSITION AND EFFICACY IN COTTON. SOUTHWESTERN ENTOMOLOGIST. 25(2):131-137. Interpretive Summary: Off-target movement and decreased deposition of insecticides applied by aircraft leads to increased application rates and cost of insect control. Methods to increase deposition of insecticides applied by aircraft are needed. Air deflectors mounted on the aircraft's spray boom were evaluated for effectiveness of insect control in cotton. Four years of testing showed that air deflectors significantly increased deposition of insecticides on the underside of cotton leaves. However, air deflectors did not significantly increase deposition on the leaf upperside, the mortality of boll weevils in bioassays of leaves treated with and without air deflectors, nor the amount of tarnished plant bug control in cotton. The lack of significant increases in insect control as determined by our evaluation methods and the increased energy required for use of air deflectors on aircraft make them impractical for the general application of finsecticides in cotton.
Technical Abstract: Experiments in 1992 and 1993 were conducted to measure the amount of bifenthrin deposited on cotton when applied by aircraft using a conventional spray boom or a boom with Chimavir air deflectors. Bifenthrin in residues from leaves, fruiting branches, and main stem sections in the upper part of the cotton plant were assayed. Residues were quantified by gas chromatography. There was no significant difference in deposition between the conventional boom and the boom with deflectors. In 1996 and 1997, aerial application experiments with either boom were designed to determine the effectiveness of these applications to control boll weevils and plant bugs. In these tests, malathion (1.12 kg[AI]/ha) and acephate (1.12 kg[AI]/ha) were applied to cotton. In 1996, malathion residues and boll weevil mortality were measured to evaluate the effectiveness of each boom. The air deflector boom significantly increased ddeposition on the underside of cotton leaves; however, deposition on the leaf upperside and boll weevil mortality did not differ between booms. In 1997, applications of acephate were targeted at plant bug populations in cotton. Reductions of adults and nymphs were not significantly different after application with the air deflector boom as compared to the conventional.