Wow! That's a major case of scale.

With such a heavy infestation, it'd be easiest to discard the plant and start over.

Or you could begin by rubbing off what you see, then applying an appropriate spray.

Whoa - I'd recommend malathion for a quick knock-down (they'll be dead fast), then use a systemic (such as Bayer Advanced Tree & Shrub) for longer-lasting control. Best of luck.