On April 4, 2015, about 1430 central daylight time, an Air Tractor AT-402A, N623LA, sustained minor damage during a forced landing to a field near Brickeys, Arkansas. The commercial pilot was not injured. The aerial application flight, owned and operated by Taylor Air Service, LLC., was being conducted under the provisions of 14 Code of Federal Regulations Part 137 without a flight plan. Visual meteorological conditions prevailed at the time of the incident. The local flight departed Dawson's Airport (15AR), Brickeys, Arkansas, about 1230. The pilot reported that during an aerial application pass the elevator control felt abnormal. As he completed the pass he pulled up and detected that the elevator was not responding. The pilot elected to return to the airport and the elevator control continued to be unresponsive. The pilot attempted to maintain pitch control through the use of the elevator trim but turbulence and power changes made this difficult. During an off field landing, the airplane nose pitched down. The pilot countered with nose up trim and the airplane stalled. There was minor damage to the propeller during the impact with the ground. A post incident examination established that the attachment hardware, including the bolt and nut, was missing from the forward end of the #2 elevator control pushrod. The bolt was located in the airplane in the lower fuselage; however, the nut was not located. About 20 hours prior to the incident flight, maintenance had been performed on the forward rod end bearing on the #2 pushrod. The bolt and nut would have been removed and reinstalled during this maintenance. It is not known if original hardware was used or if the hardware was replaced during this maintenance.