Weed destroying apparatus carried on a vehicle has a generator; a step-up transformer having its secondary winding coupled to electrodes for contacting and killing weeds; a programmable semiconductor logic array; a first contactor coupled to an output of the logic array for connecting the generator to the transformer primary winding in the weed killing mode; a second contactor coupled to an output of the logic array for connecting the generator to electrical outlets for supplying electrical power to auxiliary farm equipment in a standby mode; a run/standby switch for providing binary signals to the logic array indicative as to whether the apparatus is to operate in the weed killing mode or the standby mode; a plurality of safety systems each of which has redundant interlock means for preventing an unsafe condition in which high voltage would be a hazard in the weed killing mode and sensing means for providing binary signals to the logic array indicative of whether each interlock means is in the safe condition or an unsafe condition; and a generator frequency interlock for detecting generator frequency in the standby mode and for applying binary signals to the logic array indicative of whether generator frequency is within a predetermined range.