Clopyralid is a synthetic plant growth hormone herbicide

Clopyralid is an organic substance and a synthetic plant growth hormone. Its chemical structure is similar to many natural plant growth hormones, but it has better persistence in plant tissues. Clopyralid is mainly absorbed by plant roots and leaves, and then conducted in plants, so its conductivity is strong. After the application of clopyralid to weeds, it is absorbed by the leaves or roots of plants, moves up and down in plants, and is rapidly transmitted to the whole plant. Low concentration of clopyralid can stimulate the synthesis of plant DNA, RNA and protein, resulting in uncontrolled and disordered growth of cell division, and finally lead to the destruction of tube bundles; High concentration of clopyralid can inhibit cell division and growth.

Clopyralid is a volatile substance, which can be volatilized into the air through plant leaves and soil after use, resulting in adverse effects on non target plants. However, according to EPA data, only 1% of clopyralid will volatilize to non target plants after application. Potato is a sensitive crop to clopyralid. This effect can be found in the year after application. After planting in the land where clopyralid has been used, its tubers will be obviously damaged.

Clopyralid may be harmful when used in areas with endangered plants. EPA found that 11 endangered plants will be endangered by clopyralid, of which 5 are extremely rare cacti. One of them will decline in biological activity 16 months after application, and the other will decline in quantity and activity six months later.

Clopyralid is used in plant communities to kill alien invasive organisms and promote the growth of native species. EPA experiments showed that the seeds of local plants were planted in the experimental field and treated with clopyralid for three times. After a period of time, it was found that the number of non-native broad-leaved plants decreased sharply, but the number of local plants increased slightly. The experimental results in the UK also showed that the number of broad-leaved plants would be reduced by 75% after application in the experimental field.

The activity of clopyralid in soil is general, and its adsorption by soil is not strong. Most of the adsorption behavior in soil is completed by plant roots. This herbicide can last for a long time in the soil without oxygen and a small amount of microorganisms. The half-life in the soil in general environment ranges from 4 days to 287 days. The main reason is that soil type, local climate and microorganisms in the soil will affect its degradation. The only degradation product identified in soil is carbon dioxide, and other degradation products have not been found.

Clopyralid is soluble in water and easy to move. Because soil particles do not adsorb it and its degradation in soil is unstable, it is very likely to penetrate into groundwater. The use of clopyralid in the soil with high permeability and shallow water layer may pollute the groundwater. In addition, the use of this pesticide around the sewage pool and in areas with obvious cracks on the surface may also pollute the groundwater, and the use around the wetland will seriously pollute the surface water.

Clopyralid is not easy to volatilize in the air, and plants treated with dichloropyridinic acid do not produce by-products after combustion.