Efficacy of herbicides applied alone, tank mix and sequentially on weeds in soybean: their residual toxicity to wheat.

Field experiment was conducted during rainy seasons of 1994 and 1995 to test the efficay of three herbicides applied alone, tank mix and sequentially on weeds in soybean. Chlorimuron at 12 g/ha applied 20 days after sowing provided an average 89% carpetweed control. Similarly, fluazifop at 750 g/ha provided an average 95% barnyard grass control. Chlorimuron failed to provide any control of barnyard grass and fluazifop failed to control carpetweed. Sequential application of pre-plant trifluralin at 1000 g/ha: and post-emergence chlorimuron at 4 or 8 g/ha provided an average 94% carpetweed and 91% barnyard grass control in soybean. Chlorimuron antagonized barnyard grass control from fluazifop-p, when the two herbicides were applied in a tank mix combination. The tank mixture did not affect carpetweed control. Growth and yield of wheat seeded five months after soybean seeding were not influenced significantly by carryover of herbicides.