The Grumman G-73 Mallard took off from a private duck hunting camp at Lower Mud Lake, LA at 16:35. The pilot was advised that of reported icing conditions at 4000 feet. There was light snow and fog at the Shreveport Airport. At 17:45 the pilot reported that he was at 2000 feet and that they had picked up “a load of ice”. The flight was cleared to 1500 feet but the pilot reported descending to 1200 feet which was all he could hold. The flight was then cleared for the approach. Last radio contact was at 17:49 when the pilot reported below the clouds. The airplane was seen banking from side to side until it crashed in a wooded area at the north shore of Wallace Lake. PROBABLE CAUSE: “The Board determines that the probable cause of this accident was the rapid accumulation of wing ice to such a degree that the aircraft could not maintain altitude. A contributing factor was the pilot’s failure to acquaint himself with the pertinent weather forecasts.”