Posted: 12/09/2014 at 16:34
It looks like it might be a beech hedge if that helps. I agree with pansyface that regular watering and feeding are necessary in that size container.
Edit: Ideally, you should use a John Innes No. 3 formula compost for permanent plantings like a hedge, so I would recommend that you remove the MP compost you have added and replace with JI #3, if you can. If not, don't worry as the MP will certainly help. Each year, sprinkle a couple of handfuls of fish, blood and bone fertiliser per trunk in early spring and gently tickle it in with a hand fork. Keep up with the watering and the hedge should regain its health and the pests and diseases should go away without needing to resort to pesticides and fungicides.