THE PILOT COMPLETED HIS SECOND SWATH RUN AND ROLLED INTO A 90-270 DEGREE TURN AT ABOUT 100-FEET AGL. AFTER ROLLING FROM THE LEFT BACK TO THE RIGHT, HE FELT THE AIRCRAFT ENCOUNTER AN AREA OF TURBULENT AIR. BELIEVING THAT HE HAD INADVERTENTLY FLOWN ACROSS THE VORTEX TURBULENCE GENERATED BY ANOTHER AIRCRAFT IN THE AREA, HE SAID THE TURBULENCE CAUSED HIS AIRCRAFT TO DESCEND AND THE RIGHT WING CONTACTED THE GROUND BEFORE HE COULD REACT AND RECOVER. THE PILOT STATED, THAT AT THE TIME OF ACCIDENT, THE AIRCRAFT'S GROSS WEIGHT WAS APPROXIMATELY 3,700 POUNDS.