On August 4, 1998, at 0930 central daylight time (cdt), a Grumman-Schweizer G-164A, N8693H, operated by Robert's Aerial Service, of La Moure, North Dakota, was substantially damaged following what the pilot stated was a loss of engine power on takeoff from runway 34 at the Rott Municipal Airport, La Moure, North Dakota. The commercial pilot was not injured. The 14 CFR Part 137 aerial application flight was operating in visual meteorological conditions without a flight plan. The flight was originating at the time of the accident. The pilot reported the accident occurred during the first flight of the day. He reported the engine ran normally during start, taxi, and run-up. He reported the airplane lifted off approximately midway down the runway and by time he reached the end of the runway, the engine started to lose power and the airplane started to settle. The pilot reported that he dumped the load and veered to the right in order to avoid a power pole. The airplane contacted a grove of trees on the north side of Highway 13. The airplane owner/operated started the airplane engine on the day following the accident. He reported that the engine operated normally.