On August 19, 1999, at 1500 hours Pacific daylight time, an Air Tractor AT-802A, N9190G, collided with a tree during a fire fighting aerial retardant application near Elko, Nevada. The aircraft was operated as a public-use aircraft under contract to the U.S. Department of the Interior, Bureau of Land Management (BLM), for wildfire suppression operations. Visual meteorological conditions prevailed for the local area aerial application operation conducted under 14 CFR Part 91. The aircraft sustained substantial damage. The commercial pilot, the sole occupant, was not injured. The flight originated about 1430 at the Elko airport on the day of the accident and was responding to a wildfire on BLM land. The pilot reported that he was following a larger aircraft on a fire application run. He successfully dropped half his retardant load on the fire and went around for another run. On the second pass, the aircraft encountered a strong downdraft as it neared the release point and the pilot recovered at a low altitude. During this process, the left outer wing collided with the top of a juniper tree. The pilot returned to Elko and landed. The most outboard 4 feet of the wing leading edge was crushed aft with rib damage.