The results showed that:①With applications preemergence, broadleaf weeds control effects were significant by using Sumisoya 150g/ha in spring-sown soybean fields and 75-150g/ha in summer-sown soybean fields.
The results of experiments showed that all treatments with Methyl Bromide were effective in controlling weeds, for flue - cured tobacco 99. 4 ~ 100%, for sun - cured tobacco 96. 4 ~97. 3 % during the appearance of seedlings, and for flue - cured tobacco 98. 7 ~ 100%, for suncured tobacco 97. 1 ~ 97. 7 % the appearance of seedlings after 21 days.
Methyl Bromide was injected and sealed with plastics for 24-48 hours. The results showed that all treatments were effective in Controlling weeds,for monocotyledon 100%,and for dicotyledon 94.7～97.4% duing the appearance ofseedlings. The effect of 40～80gm~(-2) no monocotyledon was 93.0%～96.8%,and on dicotyledon 91.3%～94.3%.
In general, under the safety aspects of wheat, improved yield and the effect of wheat field weed preventive and killing, the optimization scheme was: 2,4-D butylate (100～150ml/667m2)+ carbamide(22.5～30kg/667m2)and MCPA (100～150g/667m2)+ carbamide(22.5～30kg/667m2).
The results showed that the control efficiency of butachlor 1500ml/h m2 and bensulfuron 225g/h m2, mefenacet 900g/h m2 and pyrazosulfuron-ethyl 150g/h m2 , top-star 90g/h m2 and methyl 2 -benzoate 150g/h m2 was better in early stage of weed, the total control efficiency was up to 98. 8% , 99. 1 % and 98. 9% respectively .