The invention relates to a modular system for weed control for a rail vehicle. The modular system has a control module including a control unit and a control module. The control unit is configured to generate a first set of control signals for controlling valves and mixers in an herbicide and mixing module configured to mix an herbicide mixture and to generate a second set of control signals for controlling valves of a nozzle assembly. The herbicide and mixing module has a plurality of containers for receiving different herbicides. The nozzle assembly has a first set of nozzles for spraying herbicides, and the control module, the herbicide and mixing module, and the nozzle assembly can each be individually fixed to a carrier element in a reversible manner.