Can't tell from the photo. Even when I blew it up.
If the green stuff is a) hard, and b) on top of the dark brown surface, then no it is probably only malachite encrustations and harmless.
If the green stuff is a) soft (try to poke it with a
sharp steel pin), and b) in a hole or depression in the dark brown surface, then it is BD. In fact if it is soft but
still appears to be on the surface then it is also likely BD and may simply be covering a hole.
If it is BD and your coin is covered in any form of wax - its colour and glossy sheen look a
bit like old waxed coins - then you may have a real problem with the BD possibly spread under much of the surface.
I sincerely
hope that it is not BD.........
Shawn
