Selection of Chemical Herbicides and Its Application Technique in Maize Field

5 different chemical herbicides were tested before the germination of maize seeds and at maize seedling period to investigate the weeding effect in maize field.The results indicated that 96% Metolachlor EC,50% Acetochlor EC and 50% Butachlor EC all had the better effect of controlling grassy weeds and bad effect of controlling hardwood weeds when these herbicides were applied before the germination of maize seeds,and the optimum application amount of 96% Metolachlor EC,50% Acetochlor EC and 50% Butachlor EC was 72 g(a.i.)/667m2,50 g(a.i.)/667m2 and 70 g(a.i.)/667m2 respectively.25% Rimsulfuron DF and 4% Nicosulfuron RS could effectively control grassy and hardwood weeds in maize field when the chemical herbicides was sprayed at maize seedling period,and the optimum application amount of 25% Rimsulfuron DF and 4% Nicosulfuron RS was 1.125 g(a.i.)/667m2 and 2.6 g(a.i.)/667m2 separately.