The pilot reported that during the landing roll, with all three landing gear on the runway he perceived that a strong gust of wind started to veer the airplane to the right. The pilot’s efforts to correct the veer were unsuccessful, directional control was lost, and the airplane exited the right side of the runway. The airplane impacted a ditch which collapsed the nose gear and the right wing impacted terrain. The airplane’s lower fuselage, empennage, and right wing were substantially damaged during the accident. Wind conditions at the time of the accident were 190 degrees at 19 knots gust 22 knots. There were no preaccident anomalies with the airplane.