There are a few things that may be the source of your problem. A possibility is Mealy Bug. If it is Mealy Bug the “white powdery” stuff (which is the bugs) would be concentrated at the base of the leaves. Another possibility could be build up from minerals collected from moisture while the plant was in the nursery, this can be cleaned away with a light solution of dish soap & warm water. Another possibility could be powdery mildew, this would show up disbursed over the surface of the leaves, also clean away with dish soap & water solution, and check the environment of the plant. If it is in a high humidity space that allows moisture to build up in the surface of the leaves, the plant will need to be moved to a space that has optimum airflow and keeps the surface of the leaves dry.