Ovo-Larvicidal Activity of Curacron From Different Spray Droplet Attributes, 1990

Abstract

Abstract Curacron applied at 3 rates with 2 nozzle types was evaluated for % mortality of TBW eggs and neonate larvae and percent control of fruit damage by the neonate larvae. Cotton plants were grown in the greenhouse, 2 plants/pot, to average heights of 17-21 inches. TBW eggs (0-24 h old) were collected from a susceptible strain of laboratory reared moths and transferred to the cotton plants with a small water-moistened brush. Plants were sprayed in a laboratory spray chamber and then returned to the greenhouse for further treatment and evaluation. A factorial arrangement of treatments was used to determine the effect of droplet size and density and rate of Curacron on control of TBW eggs, neonate larvae, and fruit damage. Target droplet sizes, Dv0.3, of 285 and 180 μm with corresponding droplet densities of 25 and 70 drops/cm2 were obtained in preliminary screening of selected sections of the spray plume of Spraying Systems 8002E and 650033 nozzles, respectively. Rates were 0.057, 0.125, and 0.250 lb/acre in spray deposit rates of 1.12 and 2.28 gal/acre for the 650033 and 8002E nozzles, respectively. Nine eggs were placed on each of 3 fully expanded terminal leaves of each plant in each pot prior to spraying (54 eggs/pot). Eggs were similarly placed on other sprayed plants 1 and 2 DAT. This 2 × 3 × 3 (nozzle × rate × days posttreatment) experiment with 3 replications was conducted in triplicate. Six d after egg placement, the plants were examined for egg hatch, larval mortality, and fruit damage. The percentage eggs hatched, percentage larval recovery from hatched eggs, and percentage damaged fruit were converted to percent mortality and percent damage compared to an untreated check by Abbott's formula. Data were transformed by arcsine x prior to ANOVA and DMRT.