Silver birch problems

[E Milner]

Hi - I have problem with one of 3 silver birches planted 4 years ago. 
bark has holes in side, small dots and also larger holes that go through to inside of tree and look like they’ve been pecked with woodpecker ?? 
leaves are smaller than the other 2 trees and yellowing with brown dots 

Any ideas of what’s causing and any remedies ?? 

[slack ma girdle]

14 minutes ago, E Milner said:

Hi - I have problem with one of 3 silver birches planted 4 years ago. 
bark has holes in side, small dots and also larger holes that go through to inside of tree and look like they’ve been pecked with woodpecker ?? 
leaves are smaller than the other 2 trees and yellowing with brown dots 

Any ideas of what’s causing and any remedies ?? 

There is nothing that will remedy that level of canker, other than a chainsaw.