N51857

The pilot reported that he was paralleling a highway as he was applying chemical to a cornfield. He gained altitude to clear a homestead and then descended into the field to continue spraying once he cleared the homestead property. He reported that the helicopter impacted an unmarked wire that was strung diagonally between the road he was paralleling and the corner of the homestead property. The helicopter impacted the field and the main rotor blades separated from the airframe, causing the helicopter to cartwheel prior coming to a stop. The pilot reported that there was no mechanical malfunction or failure of the helicopter prior to the wire strike.