After being refueled, the helicopter departed for an aerial application flight. As the helicopter lifted off, the pilot lost directional control of the helicopter and the nose of the helicopter turned right. The pilot confirmed that the throttle was open and after the helicopter turned 180 degrees, he reduced the engine's power to idle, maintained a level attitude, and touched down hard on uneven terrain. The tail rotor contacted a pile of debris resulting in substantial damage to the tail rotor. There were no reported malfunctions or failures which contributed to the accident. The helicopter was estimated to be about 66 pounds over the helicopter's maximum gross weight. In addition, the accident occurred in rugged terrain which likely resulted in an unexpected wind shift during the takeoff. The circumstances of the accident are consistent with the helicopter's loss of tail rotor effectiveness and directional control.