Dimethyl carbon tetrachloride is a selective systemic conduction hormone herbicide of phenoxyacetic acid, which can destroy the conduction tissue of dicotyledonous plants, interfere with the growth and development, distort the stems and leaves, and enlarge and thicken the stem base or cracks. The volatility and action speed are lower and slower than that of 2,4-D. Dimethyl carbon tetrachloride is very sensitive to Gramineae plants at seedling stage, and the resistance gradually increases after 3-4 leaf stage, and it is the strongest at the end of tillering stage, and the sensitivity increases again at the young panicle differentiation stage. When the temperature is lower than 18℃, the effect is obviously worse, and the effect on unearthed weeds is not good. Usually the dosage is 30 ~ 60g (active ingredient) per mu. Dicotyledonous crops are prohibited.

Cyperus rotundus (scientific name: Cyperus sedge), alias Cyperus sedge, Tuxiang (Taiwan Province Province and Minnan), Shuixiangling and Dixiang, is a perennial herb of Cyperaceae, with erect triangular stems and a height of 40 cm. Leaves near base, slender, linear, slightly shorter than stem, about 20 cm. The veins are parallel, the midvein is obvious, and it blooms and heads in spring and summer. Cyperus sedge is mostly born in hillside grassland or waterside wetland, which is widely distributed in China.