On October 2, 2005, at 0900 Pacific daylight time, a Bell 206B, N201SC, impacted a wire and terrain during an aerial application flight near Pixley, California. The pilot, the sole occupant, sustained serious injuries, and the helicopter was substantially damaged. The helicopter was registered to, and operated by, Slykerman Ag Aviation, Inc., Bakersfield, California, under the provisions of 14 CFR Part 137 as an aerial application flight. Day visual meteorological conditions prevailed, and a flight plan had not been filed for the local flight that originated from the spray field about 40 minutes prior to the accident. According to the pilot's written statement, he finished spraying the field and was respraying the boarders on the west side of the field. He checked the wires on the southwest corner of the field for clearance, and elected to fly under the power lines to avoid drift onto the grapes to the south of the sprayed field. He flew to the south, checked the wires again, and came back around to start the spray run. Just as the helicopter neared the wires, the pilot noticed a guy-wire running from pole-to-pole under the power lines. The pilot lowered the collective in an attempt to miss the wire, but struck it with the topside of the vertical stabilizer. The helicopter then impacted the edge of a canal bank and rolled into the canal. The pilot was wearing a helmet. He reported no anomalies with the helicopter or engine.