According to the pilot in command, the airplane began to yaw to the right as power was being advanced following a three-point landing. The airplane heading was toward a ditch that bordered the runway. The pilot indicated that he tried to correct the "movement but was to late." The airplane went through that ditch, over to the crossing runway, and came to rest in a wetland area. The airplane sustained substantial left wing tip and empennage damage. The pilot reported that there were no mechanical malfunctions with the airplane during the flight.