A good companion plant to use to ward off White Fly is Marigolds. I once had a grow op in a shed and my plants got infested with White Flies. I planted several Marigold plants just outside the door, and never had White Flies again.
I found that a large Mulberry tree in my front yard was also infested with White Flies, and in research I discovered that an ingredient in worm castings was good at killing them, so I watered that area several times with worm castings tea, and that tree was cleared of White Flies, too.