On June 18, 2011, about 0730 mountain daylight time, a Piper PA-25-235, N7018Z, was substantially damage during an in-flight collision with terrain near Faith, South Dakota. The pilot sustained minor injuries. The aircraft was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 137 as an agricultural application flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight departed Faith Municipal Airport (D07) about 0700. The pilot reported that after completing an agricultural spray run he thought he could turn around without extending out over an adjacent river bank. As he climbed to initiate the turn, the airplane began to stall. There was not enough altitude to recover and the airplane subsequently impacted the ground. He commented that the river bank was about 250 feet above the height of the field, and that the wind may have changed due to the terrain. He stated that there were no problems with the airplane prior to the accident. He added that making a wider turn, outside of the river bank, might have prevented the accident. The wind at D07, located about 15 miles northwest of the accident site, at 0656, was from 190 degrees at 13 knots. At 0756, the wind was from 160 degrees at 11 knots, with gusts to 17 knots. The pilot reported a south wind at 13 knots and no wind gusts.