According to the pilot, a gust of wind struck the airplane as he began the landing flare, and the airplane drifted to the left side of the runway. The airplane touched down, and during the landing roll the left main landing gear departed the left side of the runway. The pilot unsuccessfully attempted to control the airplane with rudder input, but the left wing struck a tree, the airplane veered to the left, and came to rest in mud off the side of the runway resulting in substantial damage. The wind, recorded at an airport 14 miles to the south about the time of the accident, was from 200 degrees at 12 knots gusting to 16 knots. The pilot reported there were no preexisting mechanical anomalies with the airplane.