The pilot reported that during his landing approach, about 15 feet above the ground, a gust of wind caused the airplane's nose to rise and turn to the left. He stated that he corrected and returned the airplane to a level attitude, but the it was then pointed about 20 degrees off of the runway heading. The pilot attempted to return to the runway heading, but the wingtip struck the ground. The airplane then entered a ditch adjacent to the runway. The pilot reported no mechanical failures or malfunctions of the airplane. A weather report from a station located about 8 miles away from the accident airport recorded the wind speed as 6 knots. No wind gusts were recorded. Postaccident examination revealed substantial damage to the left wing.