Apple is fine, as long as it hasn't been sprayed with insecticides, if not sure you can always give the branches a wash before putting them in. With apple they say its the pips that are not good for our birds, but they would have to eat a lot of them before they did them any real harm.
I'll have to find the other list up that I have it gives most of the ones that we can readily find in the UK, I'll get it up and posted as soon as I find it.