On July 3, 1998, at 1430 mountain daylight time, a Grumman G164A, N36RA, was substantially damaged when it nosed over during a forced landing near Stratton, Colorado. The commercial pilot, the sole occupant onboard, was not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the aerial application flight being conducted under Title 14 CFR Part 137. The flight originated approximately 1345. According to the pilot, he was spraying a field and was circling for his last spray run when the engine lost power. He attempted to restart the engine, but was unsuccessful. He made a forced landing in a muddy corn field. When the wheels contacted the ground, the airplane nosed over, crushing the vertical stabilizer. The engine was later disassembled and examined. No evidence was found to indicate the reason for the power loss.