On October 27, 2016, about 1235 central daylight time, an Air Tractor AT-502B, single-engine airplane, N8525G, was substantially damaged after impacting terrain while maneuvering near Hereford, Texas. The pilot was seriously injured. The airplane was registered to and operated by Wilbur Ellis Air, LLC; Huron, South Dakota, as a Title 14 Code of Federal Regulations Part 137 aerial application flight. Visual meteorological conditions (VMC) prevailed and a visual flight rules (VFR) flight plan had not been filed. The pilot reported that that he was in a right turn, flying a circular swath to "trim-up" on the outside edges of a center-pivot irrigated cotton field, when the right wingtip "got too far into the cotton crop" causing him to lose control. The airplane impacted terrain and cartwheeled, but came to rest upright. The propeller and engine were impact separated and there was substantial damage to the fuselage, empennage, both wing spars, and all flight control surfaces. There was a fuel leak at the scene but there was no postimpact fire. At 1235 the KHRX Automated Surface Observation System at Hereford, Texas, about 5 miles northeast from the accident location, reported wind from 180 degrees at 7 knots, visibility 10 miles, sky clear of clouds, temperature 24 degrees Celsius (C), dew point 10 degrees C, with an altimeter setting of 30.33 inches of mercury.