THE ACFT CRASHED INTO TREES AND NOSED INTO THE WOODED TERRAIN AFTER A LOSS OF POWR. THE HELICOPTER HAD BEEN REFUELED THE DAY BEFORE THE ACC. NORMAL FUEL LOAD WAS 20 GALS. THE PLT HAD SPRAYED 20 ACRES & FLOWN 9 MILES TO ANOTHER FIELD TO SPRAY BUT ABORTED DUE TO WIND BEFORE A RETURN TO ARPT. THE DAY OF THE ACC THERE IS NO RECORD OF FUELING. THE PLT TOOK UP THE OPERATION WHERE HE HAD STOPPED BUT AFTER SPRAYING 10 ACRES HE STARTED BACK TO BASE. HE HAD FLOWN APRX 1/2 WAY BACK WHEN THE ENG QUIT. WITNESSES ON THE GROUND HEARD THE ENG POP & QUIT & SAW THE ACFT DESCENDING BUT COULD NOT SEE THE ACTUAL IMPACT DUE TO OBSTRUCTING TREES. THE FUEL TANKS OVER THE ENG HAD BUST DURING THE CRASH AND THERE WAS NO FIRE OR EVIDENCE OF FUEL SPILLAGE AT THE SCENE. NO MECHANICAL DISCREPANCIES OR HUMAN INPAIRMENT WAS REVEALED DURING THE INVESTIGATION EXCEPT EVIDENCE OF LACK OF FUEL.