Study On The Feasibility Of Tribenuron-methyl To Control Broad-leaved Weeds In Summer Cornfield

Studied the effect on tribenuron-methyl to control broad-leaved weeds in summer cornfield and the safety of tribenuron to corn and the effect on tribenuron-methyl to control weeds in summer cornfield with acetochlor, alachlor· acetochlor·atrazine and propisochlor.The result showed that 75% tribenuron-methyl had a good effect in controlling broad-leaved weeds in summer cornfield. On the 45th day after applying tribenuron-methyl, the death rate of the Chinese mallow, amaranth and copperleaf herb was 94.8%—100.0% and the reduction rate of green weight of the Chinese mallow, amaranth and copperleaf herb was 98.7% — 100.0%, the death rate of the purslane and convolvulus arvensis was 68.4% — 81.1% and the reduction rate of green weight of the purslane and convolvulus arvensis was 86.6.7% ~ 90.8%. The dosage of tribenuron-methyl from 0.8g/667 m~2 to 1.2g/667 m~2 were safe to 4 varieties of corn, and resulted in a reduction of output in Zhaoyu—six only. The injury was serious to majority of corn varieties when dosage of tribenuron-methyl was higher than 1.6g/667 m~2, and the injured corns showed that plant height was lower, the leaf color was more yellow , the nervure color was more purple and the output were lower than the normal, there were a few of corn-seedling died also. The majority of corn-seedling died when the dosage of tribenuron-methyl was higher than 2.0g/667 m~2. The washing powder with 0.2%dosage raised the effect on tribenuron-methyl controlling broad-leaved weeds-the death rate of broad-leaved weeds increased 2.5% and the reduction rate of green weight of broad-leaved weeds increased 3.1%,which had a same result as a high dosagel of tribenuron-methyl. The effect on tribenuron-methyl controlling broad-leaved weeds was better when broad-leaved weeds were younger, the effect was best when broad-leaved weeds had 2—3 leaves, but the effect was reduced when broad-leaved weeds was older because it could pullulate and resumegrowing after applying tribenuron-methyl. The effect on controlling all of weeds in summer cornfield was better when tribenuron-methyl was applied with alachloracetochlor-atrazine and propisochlor, the average death rate all of weeds was 94.7% and the average reduction rate of green weight all of weeds was 97.0%, it reduced the density and green weigh of wheat-seedling in summer cornfield also.The test proved that tribenuron-methyl was feasible to control the broad-leaved weeds in summer. The appropriate dosage of 75% tribenuron-methyl was 0.8—1.0g/667 m'.The varieties of corn having a higher ability to resist tribenuron-methyl should choose a higher dosage and the varieties having a lower ability to resist tribenuron-methyl should choose a lower dosage in the dosage range. As a difference resisting tribenuron-methyl there is among corn varieties, a safety test would be done before applying tribenuron-methyl. The proper time to apply tribenuron-methyl is when corns have 3—4 leaves. It was adviced that 75% tribenuron-methyl with a dosage of 0.8~1.0g/667 m1 should be applied with 42% alachloracetochlor-atrazine SE with a dosage of 240ml/667 m* or 41% propisochlor SE with a dosage of 240ml/667 iflJ when there are more gramineous weeds and broad-leaved weeds in summer cornfield. Alachlor-acetochlor-atrazine SE and propisochlor SE should be applied in the stage from sowing corn to emergence of corn-seedling.Tribenuron-methyl should be applied when corns have 3—4 leaves. Tribenuron-methyl should be applied with washing powder with a dosage of 0.2% when there are more weeds in summer cornfield to raise the effect on tribenuron-methyl controlling broad-leaved weeds.