The pilot reported that, while maneuvering at low altitude during agricultural spraying, he noticed "some shuddering (stalling)" on multiple downwind low passes. He added that, on the fourth attempt to spray on a downwind line, he experienced "severe shuddering and loss of altitude," so he applied full power and dumped the entirety of the aerial application product. He further added that, after dumping the load, the airplane was about 10 to 15 ft above ground level and still would not climb. The pilot reported that he continued to "pull back on the stick," entered a right turn to avoid obstacles ahead, and the airplane "continued to [aerodynamically] stall until impact." The fuselage and both wings sustained substantial damage. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. An automated weather observation station 18 nautical miles south from the accident site reported, about the time of the accident, wind from 140° at 12 knots. The pilot reported that the wind had "picked up to 20-25 mph" and that the flightpath was "nearly directly downwind at the time of impact." The pilot reported that the airplane was not equipped with a stall warning device.