Purchase fumigants from specific channels to avoid counterfeit products. Select appropriate dosage based on greenhouse area; do not arbitrarily increase dosage to avoid crop damage. Smoke particles have thermal migration: they are repelled by hot objects and deposit on cold surfaces. Therefore, apply fumigants in evening or early morning when leaf temperature is lower. Smoke flows easily: once holes appear, particles flow out with air current, affecting efficacy. After use, ventilate for 8-12 hours to remove harmful gases. Fumigant method saves labor and does not increase indoor humidity.