Studies on Herbicide Application by Stage to Control Barnyard Grass in Paddy Field of Cold Region

In order to solve the problems existing in conventional herbicide application once to control barnyard grass at the early stage of transplanting in the cold region,such as low herbicide effect and less security,the herbicides were applied twice,that is,five to seven days before transplanting and 15 to 20 days after transplanting.The results showed that the barnyard grass control effect was good and the security to rice was increased.