THE PILOT WAS PRACTICING AERIAL APPLICATION PROCEDURES WHEN HE MISJUDGED HIS CLEARANCE AND COLLIDED WITH TREES. EXAMINATION OF THE ACCIDENT SITE DISCLOSED THAT THE PILOT HAD TOUCHED DOWN ABOUT 45 FEET PRIOR TO COLLIDING WITH THE TREES. THE AIRPLANE FLIPPED INVERTED AND BURNED DURING THE CRASH SEQUENCE. EXAMINATION OF THE AIRPLANE FAILED TO REVEAL MECHANICAL OR SYSTEM MALFUNCTIONS.