AS THE PILOT WAS MAKING A SWATH RUN NEAR A MAJOR POWER LINE, THE ACFT'S RIGHT WING HIT A GUY WIRE THAT WAS ANCHORED ABOUT 95 FT TO THE SIDE OF THE POWER LINE. THE GUY WIRE SEVERED THE RIGHT WING & THE ACFT CRASHED. THE PLT RPRTD THAT IF THE UNMARKED GUY WIRE HAD BEEN MORE VISIBLE, THE ACDNT WOULD NOT HAVE OCCURRED.