Abstract: A weed killing system utilizes hot water or steam, alone, or in combination with an herbicide to kill weeds. Cart, backpack, and vehicle mounted versions are disclosed in propane and electrically powered embodiments. A cart mounted version includes a detachable wheel assembly to allow selective conversion into a manually manipulable wand, and may be provided with an angularly adjustable bifurcated distribution nozzle. In electrically heated embodiments, Salt may be added to the heated water in order to increase the boiling point to enable higher effective application temperatures. A gas powered version includes a microprocessor control system for regulating water level in a tank portion of a heater, gas supply to a burner assembly, electric spark ignition of the burner assembly, and hot water or steam outlet dependent upon temperature and pressure levels in the tank portion.