EVALUATION OF AN AIR-ASSISTED GROUND SPRAYER FOR CONTROL OF BOLL-WEEVIL (COLEOPTERA, CURCULIONIDAE) AND BEET ARMYWORM (LEPIDOPTERA, NOCTUIDAE)

Control of bell weevils, Anthonomus grandis grandis Boheman, and beet armyworms, Spodoptera exigua (Hubner), in cotton using air-assisted gr ound application of insecticides was studied in field and laboratory b ioassays, and by insecticide residue analysis with gas chromatography. A Hardi Twin air-assisted ground sprayer was used to apply malathion( 1.12 kg [AI]/ha) and Spod-X LC (247 ml/ha). Laboratory bioassays of in dividual leaves and squares using bell weevils were used to compare ap plications with and without air-assistance. A field bioassay also was conducted by caging boil weevils on individual plants. Bioassays of co tton treated with Spod-X LC were conducted by caging beet armyworm lar vae on the undersides of leaves at mid-canopy. In these tests, the eff ectiveness of angling the air curtain was compared to application with the air oriented straight down. Air-assistance did not significantly increase bell weevil mortality in the bioassays of individual leaves, nor were there differences in malathion residues on leaves al top and mid-canopy. Bioassays of squares, caged plant bioassays, and residue a nalysis of squares showed enhanced efficacy when air-assistance was us ed. Application with air-assistance enhanced beet armyworm mortality A ngling the air curtain forward 30 degrees increased beet armyworm mort ality above that of the other treatments in one test and produced nume rically higher, though not significant, mortality in another test. Air -assistance shows potential for enhancing the control of the bell weev il and beet armyworm.