The term "conjure" is used by three groups of people to refer to similar folk magic and medicinal practices. Those three groups of peoples are:
1.) African-Americans, "conjure" used as a synonym for hoodoo
2.) Scott-Irish, "conjure" used as a synonym for Appalachian Folk Magic or "Granny Magic"
3.) Native-American, "conjure" used to describe traditional folk magic and healing.
Because of such multi-use of the term conjure, it may have been difficult to pinpoint the identity of the peoples actually being referenced. It should also be noted that all three traditions did indeed blend and become the practice that is now commonly referred to as one of three names, hooodoo, rootwork, or conjure. I would take it farther and theorize that each practice to be non-distinct, but rather "pooled" in certain geographic zones in the Southern U.S. and having "blurry" boundaries. In the blurry boundaries the practice would be a good mixture of the practices of multiple cultures while further into a given geographical area one of the cultures would become more dominate. Unfortunately, I'm not even sure of how this "theory" could even be tested at this point in time.