2,4-D is a hormonal selective herbicide

2,4-D is a hormone selective herbicide. It has a strong selective effect on plants. Plant roots, stems and leaves can absorb the drug and transmit it to the action site through the transport tissue. It can kill dicotyledonous weeds at common doses and is harmless to gramineous crops. Therefore, it can only be used to control annual and perennial dicotyledonous weeds in rice, wheat, corn and other gramineous crop fields (it can be used for killing weeds in non-agricultural areas). The efficacy is greatly affected by temperature. The effect is good at high temperature. If it is lower than 15 ℃, the effect is very poor. It has large mobility in soil, and the residual effect period (summer) can reach about 20 days.

Weed control types: in agricultural areas, it can only be used to control annual and perennial dicotyledonous weeds on rice, wheat, corn and other crops, such as wild amaranth, gray cabbage, Carex, duckweed, Portulaca oleracea, cangrong, dwarf Sagittaria, Sparganium, sedge, hyssop, etc. However, it can not control barnyardgrass, Kentucky bluegrass, kanmai Niang, Dogtail and other gramineous weeds. Sometimes it is also used for soil treatment after maize sowing and before seedling to prevent and eliminate a variety of monocotyledon and dicotyledon weeds. The herbicidal effect can be increased by mixing with herbicides such as atrazine and prometryne, or acid fertilizers such as ammonium sulfate. When the temperature is 20 ~ 28 ℃, the efficacy increases with the increase of temperature, and decreases below 20 ℃. 2,4-D  volatilizes greatly at high temperature and is easy to diffuse and drift, damaging adjacent dicotyledonous crops and trees, so it must be used with caution. 2,4-D has strong adsorbability, and the used sprayer must be fully washed to prevent sensitive crops such as cotton and vegetables from being damaged by residual trace agents. But it is safe for people and animals.

2,4-drop herbicides can only be used on rice, wheat and other gramineous crops to control non gramineous weeds. Therefore, the concentration of liquid medicine, the dosage per unit area, the appropriate period of application and the technical requirements of application must be strictly mastered.