To provide a method which shows excellent effects in controlling pests in a field of soybean, corn or cotton.A method for controlling weeds in a field of soybean, corn or cotton, wherein the field of soybean, corn or cotton is treated with at least one PPO-inhibiting compound selected from the group consisting of flumioxazin, sulfentrazone, saflufenacil, oxyfluorfen, fomesafen-sodium, and the compound of the formula (I):before, at or after seeding with a seed of soybean, corn or cotton treated with one or more insecticidal compounds selected from the group consisting of fipronil, ethiprole, flupyradifurone, sulfoxaflor, beta-cyfluthrin, tefluthrin, and chlorpyrifos.
