A field experiment was conducted to evaluate new herbicide viz., Ametryn 50FW (Gesapax SOFW) against the weed flora grown in the sugarcane field under flow irrigated area of Trichirappalli district of Tamil Nadu. This herbicide is in the formulation of flowable (crystals) and compared with standard, preemergence herbicide Atrazinc @1.25 kg/ha at Sugarcane Research Station, Sirugamani. The test variety of sugarcane was Co Si 95071 planted during late season of 2001–02. Results revealed that there was no phytotoxic symptom noticed on the cane crop by the herbicides Gesapax 2.0 kg/ha on 3 DAP has recorded 100 per cent WCE for grasses, 81.3 per cent sedges and 63.0 per cent of broad leaved weeds (BLW). The same treatment has given the highest cane yield of 147.2 t/ha and 17.0 t/ha of sugar yield.