The kind of fire that kills Scotchbroom is also the kind of fire that's hard on the soil. Long residence times and good surface intensity enough to work on the seed bank also destabilizes that healthy layer of top soil. Like Nate said, it's several different methods in conjunction that produces results. What we did down here was mechanically pull it from roadsides in the affected corridors and piled that and burned it, sprayed the stuff further in, and ran fire through openings where it was getting a foothold. It's expensive, and time and labor consuming. The story here is that broom was brought over from Europe by the wife of a DOT supervisor who thought it would make good cover in the roadside landscaping and highway interchanges in the 40's.