Abstract: To illustrate the control effect of the mixture of pyroxasulfone and cyanazine on weeds in wheat field，indoor activity determination and field plot experiment were set up.The results of indoor test showed that the inhibition medium dose（GR₅₀）of pyroxasulfone and cyanazine on Alopecurus myosuroides were 1.14 g/ha and 108.43 g/ha，respectively. As mixing with the ratio of 1∶2. 5，1∶5，1∶7. 5，1∶10，the values of cotoxicity coefficient（CTC）were 128.74，127.42，146.52，172.71，which showed that the combination of the two herbicides had synergistic effect at the ratio of 1∶2. 5，1∶5，1∶7. 5，1∶10. When pyroxasutfone was mixed with cyanazine at the ratio of 1∶5，1∶7. 5 and 1∶10，the selectivity indexes against wheat and A.myosuroides were 8. 38，1. 30 and 1. 53 respectively.The results of field plot experiment demonstrated that at 100 days after treatment，the combined use of pyroxasulfone and cyanazine with the ratio of 1∶5 at 540，720，900，1 440 g/ha in field showed above 94% of plant number and fresh weight controt effects to Capsella bursa‑ pastoris and Geranium carolinianum，and 87%—93% to Alopecurus myosuroides，and the wheat yield increased by 14%—21%.In conclusion，the mixture of pyroxasulfone and cycazine at the ratio of 1∶5 is an efficient，broad spectrum and safe herbicide in wheat field.

Key words: Weed control, Pyroxasulfone, Cyanazine, Synergism, Wheat

摘要： 为了解砜吡草唑与氰草津混合使用对麦田杂草的防治效果，设置了室内活性测定及田间小区试验。室内活性测定结果表明，砜吡草唑、氰草津对大穗看麦娘抑制中剂量（GR50）分别为1.14、108.43 g/hm²，砜吡草唑与氰草津以1∶2.5、1∶5、1∶7.5、1∶10配施混用时具有增效作用，共毒系数（CTC）分别为128.74、127.42、146.52、172.71。砜吡草唑与氰草津混用以1∶5、1∶7.5、1∶10配施时对小麦及大穗看麦娘的选择性指数分别为8.38、1.30、1.53。田间小区试验结果表明，药后100 d，砜吡草唑与氰草津以1∶5混配，用量为540、720、900、1 440 g/hm²时对荠菜、野老鹳株防效及鲜质量防效均达94%以上，对禾本科杂草日本看麦娘鲜质量防效为87%~93%，小麦增产达14%~21%。综上，砜吡草唑与氰草津1∶5混配是一种高效、广谱、安全的麦田除草剂组合物。

关键词: 杂草防治, 砜吡草唑, 氰草津, 增效作用, 小麦