On August 12, 1995, at 2030 central daylight time (cdt), a Grumman G-164, N48611, piloted by a commercial pilot, was substantially damaged during a collision with the ground while maneuvering for a swath run. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 137 flight was not operating on a flight plan. The pilot reported minor injuries. The flight departed Wadena, Minnesota, at 2000 cdt. According to the pilot's written statement on NTSB Form 6120.1/2, "...the aircraft stalled without warning..." during a turn back maneuver. The pilot continued, "I started a recovery but ran out of altitude... ." He said he had just flown over the field he intended to spray and was about two-thirds the way through the turn when the event took place. During an interview the pilot said he was totally caught off guard by the stall event. He said the control feel did not tell him of the impending stall. An FAA Principal Maintenance Inspector (PMI) represented the NTSB on-scene. According to the PMI, the pilot told him he had not added enough power to the airplane's engine until it was mushing and shaking during the turn around maneuver. He said the pilot indicated the airplane was behind the power curve during the turning maneuver.