Cotton bollworm (Helicoverpa armigera) is a common pest on cotton, frequently active on the undersides of leaves and tender shoots. When population densities are high, leaves are damaged by feeding and plant vigor is reduced. Timely intervention and precise targeting of the affected plant parts are key to effective control of cotton bollworm—Ruifu 50% Cypermethrin + Chlorpyrifos EC is registered for use against cotton bollworm on cotton.
Helicoverpa armigera is most susceptible and easiest to control during the early instar larval stages; once the population surges and leaf rolling occurs, subsequent insecticide applications become both costly and difficult to manage. Before spraying, determine whether the larvae are located on the adaxial or abaxial leaf surface, and whether they are in the whorl or the ear, so as to thoroughly cover the critical target sites.
Rui Fu 50% Cypermethrin + Chlorpyrifos EC, Registration No. PD20083727 (subject to the actual label). Applied to cotton for bollworm control at 30–50 mL/mu, diluted with water for foliar spray. Apply during early larval stages; repeat application at intervals of 7–10 days depending on pest pressure. Observe the pre-harvest safety interval.
Ensure thorough spray coverage of all primary infestation sites, including the undersides of leaves and tender shoots. For cypermethrin–chlorpyrifos EC, rotate with products of different modes of action to delay resistance development. Adhere to the pre-harvest interval and avoid application during bee foraging periods. Always follow the label instructions.
