I have a Rowan tree in my garden - about 3-4 metres high that has always done well. When I moved home after renting the house out - the tree was leaning severely and I think they had tied their dog to it's trunk. I re-staked it it but it has grown only buds, no leaves or flowers. The tree is still alive but looking decidedly unwell. I also noticed that the base if the trunk is very wet and looking green and a bit rotten. Can I save the tree or should I just get rid and plant a new tree in it's spot?