THE COMMERCIAL PILOT SAID HE HAD USED THIS PVT STRIP ON THREE PREVIOUS OCCASIONS, AND THAT ON THE DAY OF THE ACCIDENT, HE HAD ALREADY DISPENSED ABOUT 14 LOADS. ALSO, HE SAID THAT THE WIND HAD BECOME CALM, WHEREAS ON PREVIOUS TAKEOFFS, THERE WAS AN EXISTING WIND. SHORTLY AFTER TAKEOFF, THE ACFT CONTACTED TALL GRASS AT THE DEPARTURE END OF THE STRIP. A SPRAY BOOM CAUGHT THE TALL GRASS, THEN THE ACFT SPUN AROUND AND WAS DAMAGED. THE PLT BELIEVED THAT IF THE GRASS AT THE END OF THE STRIP HAD BEEN MOWED, THE ACCIDENT WOULD NOT HAVE HAPPENED.