This canker or wound has grown considerably in last year. Is there any legal treatment?
Picture below.
Thanks
Hogthis

I don't think there is any possible treatment, but you should get rid of the tree before other plants become infected. That is really nasty. Can you see the birch is losing bark anyway. Once the bark goes, the tree dies.

Tick

Thanks. This tree,type, sheds it's bark all the time. Is it a bug or disease?

Yes, I know the type of tree. It looks like a fungus. Disease, maybe, if you want to call a fungus a disease. Get rid of it.

Tick

OMG:

Why didn't you stop it last year. Just under the bark is where the neutrients are carried to the leaves.

Almost looks like a borer to me. I've had to deal with things this bad and had to loose the branch.

You have to either kill the pest. I'd probably use insecticide used for carpenter bees and delta dust.

I'll bet if you spray any insectiside, the bugs will come running.

I do patch large holes successfully with an expansion cement called "Rockite" and "tree wound dressing".

Make sure that there is no rotten wood before patching.

Rubberized spray car undercoating works too.

I did try but to no avail. I'll try your method. It's a nice tree and I'll give it another round.
Thanks

Some links:

Guide to Birch Trees (http://gardenline.usask.ca/trees/birch2.html)

http://www.onlinegardener.com/trees/White%20barked%20birch.pdf