On March 26, 2004, at 0833 Pacific standard time, a Rockwell International S-2R "Thrush", N8420V, sustained substantial damage during the landing roll at a private airstrip near Mattawa, Washington. The airplane was operated by B & R Crop Care of Connell, Washington, as an aerial application flight under the provisions of Title 14, CFR Part 137, when the accident occurred. The commercial pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the local agricultural flight. In a written statement dated March 30, 2004, the pilot reported that shortly after landing, to the north, the airplane began to track to the left. The pilot reported that he applied brakes and corrective action, however, the airplane continued to track to the left, and exited the landing surface. After exiting the landing surface, the airplane collided with a pile of rocks and nosed over resulting in substantial damage. In the written statement, the pilot reported that local winds were from the south at 12 to 15 miles per hour, and added that a landing to the south was not recommended due to obstructions on the north end of the runway.