Modular system for weed control for a rail vehicle, the modular system comprising - a control and monitoring module which comprises: - a control unit designed - to generate a first set of control signals for controlling valves and mixers in a separate herbicide and mixing module for mixing an herbicide mixture, and - to generate a second set of control signals for controlling valves of a nozzle assembly; and - a control station for manually supervising and monitoring the control unit, the herbicide and mixing module and the nozzle assembly; - an aforementioned herbicide and mixing module which comprises: - a water connection which is in selective fluid connection selectively with the valves and mixers; and - connection elements via which electrical signal connections to connection elements of the control unit can be established such that the first control signals generated in the control and monitoring module can be transmitted to the valves and mixers of the herbicide and mixing module; and - a nozzle assembly, the nozzle assembly being spatially independent of both the control and monitoring module and the herbicide and mixing module, which comprises: - a first set of nozzles for spraying herbicides; - a fluid connection to selected valves and mixers of the herbicide and mixing module, the control and monitoring module, the herbicide and mixing module and the nozzle assembly each being individually and reversibly securable to a carrier element, characterized in that the herbicide and mixing module comprises a plurality of containers for receiving different herbicides which are in selective fluid communication selectively with the valves and mixers, and in that the control and monitoring module and the herbicide and mixing module are constructed as containers. - a control and monitoring module which comprises: - a control unit designed - to generate a first set of control signals for controlling valves and mixers in a separate herbicide and mixing module for mixing an herbicide mixture, and - to generate a second set of control signals for controlling valves of a nozzle assembly; and - a control station for manually supervising and monitoring the control unit, the herbicide and mixing module and the nozzle assembly; - a control unit designed - to generate a first set of control signals for controlling valves and mixers in a separate herbicide and mixing module for mixing an herbicide mixture, and - to generate a second set of control signals for controlling valves of a nozzle assembly; and - to generate a first set of control signals for controlling valves and mixers in a separate herbicide and mixing module for mixing an herbicide mixture, and - to generate a second set of control signals for controlling valves of a nozzle assembly; and - a control station for manually supervising and monitoring the control unit, the herbicide and mixing module and the nozzle assembly; - an aforementioned herbicide and mixing module which comprises: - a water connection which is in selective fluid connection selectively with the valves and mixers; and - connection elements via which electrical signal connections to connection elements of the control unit can be established such that the first control signals generated in the control and monitoring module can be transmitted to the valves and mixers of the herbicide and mixing module; and - a water connection which is in selective fluid connection selectively with the valves and mixers; and - connection elements via which electrical signal connections to connection elements of the control unit can be established such that the first control signals generated in the control and monitoring module can be transmitted to the valves and mixers of the herbicide and mixing module; and - a nozzle assembly, the nozzle assembly being spatially independent of both the control and monitoring module and the herbicide and mixing module, which comprises: - a first set of nozzles for spraying herbicides; - a fluid connection to selected valves and mixers of the herbicide and mixing module, the control and monitoring module, the herbicide and mixing module and the nozzle assembly each being individually and reversibly securable to a carrier element, characterized in that the herbicide and mixing module comprises a plurality of containers for receiving different herbicides which are in selective fluid communication selectively with the valves and mixers, and in that the control and monitoring module and the herbicide and mixing module are constructed as containers. - a first set of nozzles for spraying herbicides; - a fluid connection to selected valves and mixers of the herbicide and mixing module,