Hello! We are the Beijing agricultural science and technology service hotline. There are very few rice plants in Beijing. For the water onion control you mentioned, you need to choose the right pesticide. Relevant reports should prove that the mixture of bentazone and 2-methyl-4-chloride has a special effect on water onions during the peak period of water onions. Use 150 ml (3 taels) of 480 g/L bentazone per acre, mix 15 to 18 g of 562 methyl 4 chlorine, mix with 15 kg of water and spray evenly. One week after applying the medicine, the water onions died completely. You can try it on a small area first.