S-metolachlor, a widely used herbicide, soon to be banned

Each spring, the fields of corn, wheat and dozens of other crops are watered with the same product, S-metolachlor. This little-known herbicide is one of the most widely used, with 2,000 tons applied each year. A molecule that the National Health Security Agency (Anses) nevertheless wishes to ban, because the product is found in the drinking water of many municipalities, such as in Ploërmel (Morbihan).

Some farmers can’t live without it

During spreading, the molecule remains on the surface, then penetrates the soil. With the rains, three of its persistent residues reach the water table. Franck Pelerin, cattle breeder and farmer, cultivates 200 hectares to feed his cattle. On his fields, one liter of herbicide is used for each hectare. For him, it is impossible to do without it. “Without this herbicide for vegetable crops, we don’t know what to do. Except to find robots, which will uproot the grass plants one by one, but that does not yet exist in the open field”, explains the farmer. However, according to some researchers, by accepting a drop in yield, other methods exist, such as “diversify their rotations”explains Xavier Reboud, research director in agroecology at INRAE ​​Dijon (Côte-d’Or).