A spraying assembly is provided. The spraying assembly includes at least one nozzle for liquid that is to be sprayed, and at least one active substance injector which is situated directly upstream from the at least one nozzle and to which liquid to be sprayed is supplied by a pump or a pressurized reservoir, with interposition of an obturator on a conduit connecting the pump or the pressurized reservoir to the injector. The spraying assembly also includes an outlet valve for each injector designed to close each outlet orifice. The present invention avoids overdosing or underdosing of the product that is to be sprayed as active substance.
