Apparatus to electrically kill a plant or at least attenuate plant growth comprising an electrical energy processing unit and an electrical continuity system, the electrical energy processing unit to transmit processed electrical energy between an applicator electrode of an applicator unit and an earth electrode of an earth unit, the electrical continuity system comprising: a signal generator configured to generate a continuity signal and to transmit said signal around a continuity circuit including, or in operational proximity to, one or both of the said electrode(s); a signal processing arrangement configured to at least partially isolate the transmitted continuity signal from the processed electrical energy; a control circuit operable to: determine, using said isolated continuity signal or a property related thereto, an electrical continuity between the ground and one or both of the said electrodes; control, using said determined electrical continuity, the processed electrical energy.
