On June 12, 2005, about 1130 mountain daylight time, a Piper PA-25-260 Pawnee, N4768Y, sustained substantial damage following an off airport precautionary landing attempt near Geraldine, Montana. The airplane is owned by Scribner Ranch, Inc, and was being operated as an aerial application flight under the provisions of Title 14, CFR Part 137, when the accident occurred. The private pilot, the sole occupant of the airplane, sustained minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the flight that originated from the Geraldine Airport approximately 10 minutes prior to the accident. In a telephone interview, and subsequent written statement, the pilot reported that he was attempting to climb over a low ridge when the airplane encountered "bad air" and the airplane began to sink. The pilot stated he lowered the flaps and applied full power, however the airplane continued to sink and he elected to land the airplane in an effort to avoid approaching power lines. During the off airport precautionary landing attempt, the airplane collided with terrain in a left wing low attitude resulting in substantial damage to the wing assembly and fuselage.