It is mentioned in Dune Messiah that Muad'Dib's jihad resulted in the "sterilization" of a number of planets.
“Very good, Stil.” Paul glanced at the reels in Korba’s hands. Korba stood with them as though he wished he could drop them and flee. “Statistics: at a conservative estimate, I’ve killed sixty-one billion, sterilized ninety planets, completely demoralized five hundred others. I’ve wiped out the followers of forty religions which had existed since—”
The question of why his followers felt the need to wage a Jihad is addressed here but I'd like to know how this particular feat (sterlising planets) was accomplished and what these poor souls did to deserve such treatment.