Provided is a method which exerts an excellent effect in controlling a pest in a field of soybean, corn or cotton, using a SDHI compound and a PPO-inhibiting compound. A method of controlling a pest (a weed and/or a plant pathogen) in a field of soybean, corn or a cotton, including treating a field before, at or after seeding with a seed of soybean, corn or cotton treated with one or more compounds selected from the group consisting of SDHI compounds, with one or more PPO-inhibiting compounds selected from the group consisting of flumioxazin, sulfentrazone, saflufenacil, oxyfluorfen, fomesafen and a compound of the formula: