The pilot stated he thought he smelled smoke in the cockpit while en route to his destination. During a precautionary landing on a dirt road, the pilot stated he encountered a "dust devil" as the airplane touched down, and the airplane veered into a ditch. The aircraft sustained substantial damage to the left wing and fuselage. Winds in the area were reported light and variable. The pilot holds a repairman certificate for the airplane; he reported a post-accident examination of the airplane revealed no mechanical malfunctions or failures that would have resulted in abnormal operation of the airplane. He did not find anything related to the smell of the smoke.