On June 10, 2004, at 0700 central daylight time, a Grumman-Schweizer G-164B, N48517, piloted by a commercial pilot, was substantially damaged during an in-flight collision with tree branches while performing aerial application near Hope, North Dakota. Visual meteorological conditions prevailed at the time of the accident. The aerial application flight was operating under the provisions of 14 CFR Part 137 without a flight plan. The pilot was not injured. The local flight departed the Hashbarger Farm Airstrip (8NA9), Hope, North Dakota. According to the pilot's written statement, the accident transpired during the first spray-run of the day. The pilot reported the left wing tip impacted tree branches during the spray-run, resulting in substantial damage to the wing. The pilot stated that an uneventful landing was made after dispensing the remainder of his chemical load.