On August 2, 1997, at 2010 central daylight time, a Cessna A188A, N9902G, operated by Dale's Flying Service, collided with the terrain during a 14 CFR Part 137 aerial application flight in Norfolk, Nebraska. Visual meteorological conditions prevailed and no flight plan was filed. The airplane was substantially damaged and the pilot was not injured. The flight originated from Norfolk, Nebraska, at approximately 2000 cdt. The pilot reported that he was unfamiliar with the area so he was following another heavily loaded Cessna 188 to the field. The lead airplane was to fly over the field and apply his smoke to indicate to the accident pilot which field was to be sprayed. The pilot reported that once over the field the lead airplane descended to about 20 feet above ground level (agl) and bisected the field from south to north. The accident pilot reported he circled around to line up for his first spray run which was along the eastern edge of the field from south to north. The pilot reported he then pulled up over trees and made a right 270 degree turn to line up for the second pass which was from east to west over the north edge of the field. He reported, "I entered the field over trees, rounded out at 4 feet above the crop and a split second later encountered bad air from what I can only figure to be the lead a/c's wake/vortices that still persisted form his flight through that exact area (thought I wasn't aware of it) approx 60- 80 seconds prior." The pilot continued to report that his airplane "instantly fell" and he tried to arrest the descent with elevator back pressure to no avail. The airplane impacted the bean field in a level attitude. The pilot reported that he later found out that the lead airplane's flight path was perpendicular to his during the second swath run. He also reported that he encountered the lead airplanes wake twice while flying to the field.