We have a potted lemon tree that we bought from a nursery a year ago. It was doing pretty well, loads of flowers, and we even got a few lemons off it.
It had a few scales every now and then we dealt with, then after a little neglect through winter it seems to be overrun by them now.
I'm not sure how bad the problem needs to get before it's detrimental to the tree health but it's to a point now that it would take a lot of work to try to treat them all by hand, but mostly I'd be uncertain about getting to them all.
Instead, I was thinking we could give the tree a severe chop, getting rid of most of the top foliage and small branches, and most of the scale with them.
Then try to pick off the reamining scale when the tree is smaller and more manageable.
(then obviously keep up the work on prevention and maintenance from there while it grows back).
So a couple of questions:
Is this a bad idea?

Any general advice for treating and preventing scale?