Novel efficient comprehensive chemical prevention and treatment method for rice field weed sagittaria trifolia

The invention discloses a novel efficient comprehensive chemical prevention and treatment method for a rice field weed sagittaria trifolia. The method comprises the following steps: 1) 5-10 days before rice transplanting, applying 30% anilofos and 15% ethoxysulfuron, or 10% pyrazosulfuron-ethyl to a rice field, keeping water for 7-10 days, discharging out the water with the pesticides, changing water, and transplanting rice, wherein a water layer is 3-5cm when the chemicals are applied, and the application amount of the 30% anilofos is 20-30 g/mu; 2) after rice transplanting, applying 48% bentazone to the rice field, discharging out a shallow water layer before chemical application till weeds are exposed on the water surface, returning the water into the rice field after chemical application, and keeping the water layer, wherein the amount of the bentazone is 160-200 ml/mu. Tests show that by adopting the chemical prevention and treatment method disclosed by the invention, growth of the rice field weed sagitt