The pilot was landing at a strip aligned 070 degrees. He estimated the wind to have been gusting 20-25 knots from 090-120 degrees. Neither drift nor turbulence were excessive on finals. However, as the aircraft was flared, it suddenly rolled rapidly left to what the pilot judged was more than 60 degrees of bank. Despite the application of full power and opposite rudder, the pilot was unable to prevent the left wing contacting the upper branches of trees to the left of the strip. This resulted in the aircraft striking the ground nose first and coming to rest 80 metres left of the strip. The conditions existing at the time of the accident were such that strong wind gusts were possible. Other pilots who had used the strip reported experiencing wind gusts at a similar stage of the approach.