What is wrong with my amelanchier? And what do I need to do?

Hi my amelanchier has greyish markings on the trunk.
The leaves have rusty coloured dots on them and some have turned yellow or red. They are falling quite rapidly.
Can anyone help?

 

Pretty sure the grey on the trunk is just harmless lichen.
Leaf problem looks fungal.

 

Thanks
Do you have any suggestions of what I need to do?
It’s a big tree so picking off infected leaves isn’t really an option

 

Well it's not a tree I have ever grown.
Unless someone else comes along I can only suggest you Google leaf spot on amelanchier and have a read.

Don't think there are any fungicides available these days that are likely to work, but I'm only guessing.