On July 9, 1998, approximately 1000 Pacific daylight time, a Rockwell "Thrush" S-2R, N4996X, owned by Gerald Titus and being operated by Air-Trac, Inc., and being flown by a commercial pilot, sustained substantial damage when it nosed over during the landing roll following a near total loss of power on takeoff, seven nautical miles east-northeast of the Pasco airport, Pasco, Washington. The pilot was uninjured. Visual meteorological conditions existed and no flight plan had been filed. The flight, which was for the aerial dispensation of chemicals, was to have been operated under 14CFR137, and was departing from a private airstrip when it crashed. The pilot reported that while taking off to the west and climbing through about 40 feet above ground, the engine went to idle. He stated that he dropped his chemical load and immediately landed in an open potato field. The landing roll was reported to be crosswise to the furrows and the aircraft ultimately nosed over. FAA on-site inspection conducted by an inspector from the Spokane FSDO revealed a disconnect of the throttle linkage just forward of the firewall where it attaches to a 90 degree bell-crank designed to translate forward/aft motion into left/right lateral motion. The threads on the bell-crank attach end of the longitudinal throttle tube were found to be heavily worn.