On April 8, 2003, about 1920 eastern daylight time, an Air Tractor 401, N4549N, registered to and operated by Indian River Flying Service, Inc., collided with a tree then the ground during an aerial application flight near Fellsmere, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 137 flight. The airplane was destroyed and the commercial-rated pilot, the sole occupant, sustained serious injuries. The flight originated about 15 minutes earlier from New Hibiscus Airpark, Vero Beach, Florida. The pilot stated that he doesn't remember the accident, but he did report that during a spray run, he overshot the end of the field due to sun in his eyes. He also reported there was no mechanical failure or malfunction. According to the president of the Indian River Flying Service, Inc., the pilot was just starting to pull-up after completing a spray pass when the airplane collided with a tree then the ground. According to an officer with the Indian River County Sheriff Department, the airplane collided with a tree located in an open area, then impacted the ground. A debris path was scattered over a 300 to 350 yard area. The wreckage comprised of two large pieces, and a chemical odor was noted at the accident site.