The agricultural spray airplane sustained substantial damage when it impacted terrain after a loss of control during a forced landing. The pilot reported that he had about two hours of fuel on board the airplane when he departed to spray a field. He was returning to his private airstrip about 1.5 hours after departure when the engine quit. He attempted a forced landing to a gravel road, but a car was approaching so he changed directions to avoid any traffic on the ground. He reported that the stall warning light illuminated while he was in a left bank. He reported, "I started to flare about 50 ft. above the ground and the plane stalled dropping the left wing before impact." The inspection of the airplane revealed that the fuel tanks were empty. The pilot reported that he had made the same trip three times earlier with the same amount of fuel. He reported that the "fuel gauge was cloudy."