A modular system for weed control for a rail vehicle, wherein the modular system comprises - a support and control module comprising - a control unit configured - for generating a first set of control signals for controlling valves and mixers in a separate herbicide and mixing module for mixing a herbicide mixture; and - for generating a second set of control signals for controlling valves of a nozzle assembly; and - a control station for manually monitoring and checking the control unit, the herbicide and mixing module and the nozzle assembly, - the herbicide and mixing module comprising - a water fitting, which selectively has a selective fluidic connection to the valves and mixers, and - terminal elements, via which electrical signal connections can be established to terminal elements of the control unit, so that the first control signals generated in the support and control module can be conducted to the valves and mixers of the herbicide and mixing module, and - the nozzle assembly, which is spatially independent of each of both the support and control module and the herbicide and mixing module, comprising - a first set of nozzles for spraying herbicides, - a fluidic connection to selected ones of the valves and mixers of the herbicide and mixing module, characterized in that the herbicide and mixing module comprises a plurality of containers for accommodating different herbicides, which selectively have a selective fluidic connection to the valves and mixers, and the support and control module, the herbicide and mixing module and the nozzle assembly are each individually reversibly fixable on a carrier element, wherein the carrier element is a carrier car or multiple carrier cars coupled to one another for a rail usage. - a support and control module comprising - a control unit configured - for generating a first set of control signals for controlling valves and mixers in a separate herbicide and mixing module for mixing a herbicide mixture; and - for generating a second set of control signals for controlling valves of a nozzle assembly; and - a control station for manually monitoring and checking the control unit, the herbicide and mixing module and the nozzle assembly, - a control unit configured - for generating a first set of control signals for controlling valves and mixers in a separate herbicide and mixing module for mixing a herbicide mixture; and - for generating a second set of control signals for controlling valves of a nozzle assembly; and - for generating a first set of control signals for controlling valves and mixers in a separate herbicide and mixing module for mixing a herbicide mixture; and - for generating a second set of control signals for controlling valves of a nozzle assembly; and - a control station for manually monitoring and checking the control unit, the herbicide and mixing module and the nozzle assembly, - the herbicide and mixing module comprising - a water fitting, which selectively has a selective fluidic connection to the valves and mixers, and - terminal elements, via which electrical signal connections can be established to terminal elements of the control unit, so that the first control signals generated in the support and control module can be conducted to the valves and mixers of the herbicide and mixing module, and - a water fitting, which selectively has a selective fluidic connection to the valves and mixers, and - terminal elements, via which electrical signal connections can be established to terminal elements of the control unit, so that the first control signals generated in the support and control module can be conducted to the valves and mixers of the herbicide and mixing module, and - the nozzle assembly, which is spatially independent of each of both the support and control module and the herbicide and mixing module, comprising - a first set of nozzles for spraying herbicides, - a fluidic connection to selected ones of the valves and mixers of the herbicide and mixing module, - a first set of nozzles for spraying herbicides, - a fluidic connection to selected ones of the valves and mixers of the herbicide and mixing module,