On September 1, 1999, at 0845 eastern daylight time, an Aero Commander S2R, N8965Q, collided with the ground during an attempted forced landing in a field near Cairo-Grady Municipal Airport in Cairo, Georgia. The aerial application flight was operated under the provisions of Title 14 CFR Part 137 with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The airplane sustained substantial damage, and the commercial pilot was not injured. The flight departed Cairo, Georgia, at 0844. According to the pilot, shortly after liftoff from runway 12 at the Cairo-Grady Municipal Airport, the engine backfired and lost power. An eyewitness at the airport reported seeing black smoke coming from the airplane during the attempted takeoff. The pilot turned right and selected a field for the emergency landing. After clearing a nearby pond, the pilot dumped the load of chemicals, and landed in a field about 3000 yards beyond the pond. The pilot reported that during the emergency landing, the landing gear collapsed and the right forward wing spar sustained damage. The examination of the airplane failed to disclose a mechanical problem. During the examination of the engine, fuel was recovered from the fuel system. Examination of the carburetor also failed to disclose a mechanical malfunction or component failure. A review of the weather data disclosed that the temperature was 68 degrees, and the dew point was 66 degrees. According to the Icing Probability Curves, conditions were favorable for the formation of carburetor ice (see attached icing probability curves).