The experiments are carried out in Makilala and Kidapawan, Cotabato to determine the effectiveness of fluazifop - butyl at various rates on the control of grass weeds in banana plantation. At rates of 0.15, 0.225 and 0.30 kg/ha applications of fluazifop - butyl, the grass weeds are effectively controlled for 40-50 days. The rate of 0.15 kg/ha is noted to be as effective as the higher rate of 0.225 and 0.30 kg/ha.