THE AIRPLANE IMPACTED THE GROUND AS IT COMPLETED A TURN TO REVERSE DIRECTION AFTER AN AERIAL APPLICATION SWATH RUN. WITNESSES DESCRIBED SEVERAL STEEP, 'AGGRESSIVE' TURNS, AND EXTREME NOSE HIGH PITCH ATTITUDES DURING THE FLIGHT PRIOR TO THE ACCIDENT. THEY REPORTED THE PILOT WAS 'DOING HAMMERHEADS WHILE SPRAYING...' AND 'FLYING LIKE A STUNT PILOT.' GROUND FLAGMEN ASSISTING WITH THE AERIAL APPLICATION WERE IN RADIO COMMUNICATION WITH THE PILOT. THE PILOT TOLD THEM THE AIRPLANE STALLED DURING THE PREVIOUS TURN.