At the end of each spray run to the east, the aircraft was flown under a power line before the turn to change direction was commenced. Several runs had been completed when the pilot climbed the aircraft to commence the turn and the aircraft collided with the power line. The pilot dumped the remainder of the load and the aircraft continued to fly, trailing the power line. After travelling a short distance the aircraft apparently stalled and struck the ground in a nose down attitude. A fire broke out and completely engulfed the wreckage. The pilot subsequently advised that he had temporarily overlooked the presence of the power line. It was probable that on this particular spray run a pole supporting the wire was no longer in the pilot's field of vision. The severed wire became entangled around the right wing and lift strut, resulting in bending of the strut and probably inducing stalling of the wing.