Damson tree dying.
I planted a small damson tree last year which blossomed well in first year and earlier this year. However the leaves started to shrivel and turn in soon after the blossom had ended. I found aphids and treated the tree with a chemical spray. Some new healthier leaves have appeared and some early small fruit but the tree looks dead. Is there anything I can do to save it. Should I remove all the shrivelled leaves?Thanks.Anna.
The Aphids look to be still active.
These links have more information.
I'm also concerned about the green algae growing on the bark; you tree may not be getting enough sunlight and air circulation around the tree.