THE AG PILOT WAS ON HIS THIRD SPRAY PASS OF A SMALL FIELD. DURING THE CLIMBOUT, THE AIRCRAFT COLLIDED WITH TREES AT THE PERIMETER OF THE FIELD. THE PILOT REPORTED THAT THERE WAS A GUSTING TAIL WIND AT THE TIME, AND HE WAS CARRYING A 'SUBSTANTIAL' LOAD OF PESTICIDES. HE ALSO REPORTED THAT AIRSPEED WAS DIMINISHED DUE TO THE CONSECUTIVE PASSES OF THE SMALL FIELD. HE REPORTED NO MECHANICAL MALFUNCTION OR FAILURE WITH THE AIRCRAFT.