Posted: 10/02/2017 at 16:51
I imagine DOS1 wishes to get rid of the ivy because he prefers his mixed hedge with plants of his own choice, so who are we to tell him he must have an ivy hedge?
Firstly, contact your local council to find out how to safely dispose of the sodium chlorate.
Then, set about cutting all the ivy down to ground level and stripping it out of the hedge. It will look a bit messy for a while until the other shrubs have regained some shape, but in my experience it doesn't take long to subdue ivy to the point where it stops trying to come back.