On August 17, 2011, about 1400 mountain daylight time, an Air Tractor, Inc., AT-602, N8518Y, impacted power line wires while maneuvering to spray a potato field near Pine Bluffs, Wyoming. The impact with the wires directed the airplane toward the ground and resulted in an unplanned landing. Top Hat Aerial Applicators, Inc., operated the aerial application flight under the provisions of 14 Code of Federal Regulations Part 137. The pilot, the sole occupant, received minor injuries; the airplane was substantially damaged. Visual meteorological conditions prevailed for the local area flight, and no flight plan had been filed. The flight departed from Pine Bluffs Municipal Airport (82V), Pine Bluffs, Wyoming, about 1300, and was scheduled to terminate at 82V. According to the pilot's written statement, the airplane struck the top wire of a power line set just prior to commencing the spraying operation. The pilot stated that the airplane descended toward the field, and the right wing hit the ground followed by the engine. The airplane rolled to the left, with the left wing and tail sections contacting the ground; the airplane came to rest upright. The pilot reported no mechanical problems with the airplane, and the accident could have been prevented if he had paid more attention to the wire height and maintained additional clearance above the wires.