The pilot was conducting banner-tow operations in a 1978 Bellanca 7GCAA. During a banner pick-up, about 400 feet agl, the pilot heard a "snap." At that time, both control sticks lost elevator control, and the airplane initially pitched nose up. The airplane then pitched about 20 degrees nose down. The pilot attempted to correct the descent with elevator trim and engine power, but the airplane impacted a field. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the elevator cable had separated. Further examination revealed rust and corrosion on an approximate 2-foot section of the failed elevator cable. The rust and corrosion was consistent with exposure to moisture over a period of time. Review of aircraft maintenance records revealed that the last annual inspection was completed on November 13, 2005, about 10 months prior to the accident. The airplane had accumulated about 5,172 total hours of operation at the last annual inspection, and about 120 hours of operation since the inspection. The maintenance records noted that the cables were lubricated, but there was no record of rust and corrosion being detected.