My poor apple tree!
 

Hi
I wonder if any kind person can help with this. I planted an apple tree last autum..it was doing fine but then we got a rescue dog who had a bit of a nibble of the trunk which now has a small split! This spring load sof leaves started coming on the branches and looked really healthy but they have now started to curl and turn yellow. Below the split from the lawn up new shoots are growing with many leaves. Do I leave it as it is in the hope it will recover..or chop of the top?

Any advise you can give would be much appreciated