Droplet size and spray volume effects on cotton canopy penetration and third instar Heliothis virescens (Lepidoptera: Noctuidae) mortality

摘要

Research was initiated to identify effects of droplet size and volumetric application rate on insect mortality and insecticide deposition when applied to cotton for control of Heliothis virescens (tobacco budworm). Karate (lambda cyhalothrin) 2.08 SC insecticide was applied to mature cotton in three distinct droplet sizes and three volumetric application rates. Third instar budworm mortality occurring in leaf-disk bioassays was highly correlated with insecticide deposits (#mu#g/leaf disk). Mortality occurring at the upper canopy level was negatively correlated with volumetric application rate. At the upper canopy level, droplet size was positively correlated with deposits, and small droplets deposited significantly less insecticide than the medium and large droplets. Droplet size did not significantly affect larval mortality. Results from this study do not support a recommendation to either increase the volumetric application rate or decrease droplet size in order to improve insect control within a cotton canopy.