Quinclorac is mainly absorbed through the roots of barnyard grass, and can also be absorbed by germinated seeds. A small amount is absorbed through the leaves and conducted in the barnyard grass. The symptoms of barnyard grass poisoning are similar to the symptoms of auxin substances, and they have the characteristics of hormonal herbicides. It has a long medication period and high safety for rice after the two-leaf stage. Solanaceae, Umbelliferae, Malvaceae, Leguminosae, Compositae, and Convolvulaceae are sensitive to Quinclorac, and contact should be avoided. Quinclorac has an accumulation effect in the soil.The fields where Quinclorac is applied cannot be planted in the next year, such as beets, eggplants, tobacco, tomatoes, carrots, etc., and can be planted after two years.