Effects of 4 Kinds of Preemergence Herbicides on Control Efficiency of Winter-spring Herbs

Effects of four kinds of preemergence herbicides including trifluralin, dual gold, alachlor and acetochlor on controlling winter-spring herbs when applied in various concentration and timing were studied. The results showed that the control effectiveness of dual gold was the best, trifluralin and acetochlor were the second, and alachlor was the worst. The greater the concentration of herbicide was, the better the results were. The best timing of an application was on 20th Sept., with the next on 10th Sept., and the worst on 30th Sept.. The optimal scheme was high concentration of dual gold applied on 10th to 20th Sept., or high concentration of trifluralin on 20th Sept..