On May 11, 1998, at 0730 central daylight time, a Piper PA-18- 150, N83679, operated by the State of South Dakota, collided with the terrain following a loss of control while maneuvering over Artesian, South Dakota. The pilot and passenger received minor injuries. The airplane was substantially damaged. The public use flight was being operated under 14 CFR Part 91. Visual meteorological conditions prevailed and no flight plan was filed. The local flight departed from Huron, South Dakota. Purpose of the flight was predator (coyote) control for the State of South Dakota Department of Game, Fish, and Parks. The pilot and a gunner were attempting to chase a coyote out of a "slew" into an alfalfa field when the accident occurred. The pilot reported they were in a left, slightly descending turn at an altitude of 150 feet above the ground when the stick went "limp." The pilot reported he added full power, leveled the wings, and applied forward stick pressure in an attempt to regain lift. According to the pilot the airplane continued to descend and it impacted the edge of the alfalfa field in a wings level attitude. Upon impact the main landing gear separated form the airplane and the airplane slid approximately 60 feet prior to nosing over. The pilot reported that he suspects "wind shear" caused the accident. Winds reported at Huron, South Dakota, (30 miles northwest of the accident site), at 0755 cdt, were from 140 degrees at 7 knots.