Repairing damage like this is pretty nigh impossible - sorry :-( The best you can do is to remove the branch on the right side as cleanly as possible and hope the tree survives and begins to fill in with additional branching from what's left on the left side.

There is no "repair gel" or wrap that will improve this situation. Unless repairs are made almost immediately after damage has occurred, the tree will begin its own process of compartmentalization to heal the wound and once that has started, the wood will never rejoin and seal together. Even if you caught the damage immediately, it is highly unlikely you would be able to successfully repair this type of damage and that joint would be extremely vulnerable to any kind of damage going forward -- next year's snowstorm would result in the same issue in the same place.

btw, using the term "jap" is considered a pejorative or cultural slur and can be offensive to some. Better to spell out "japanese" or just use the initial 'J'.

Gardengal are you in the right forum section? Or am i in the wrong section?
I am glad i did not read your bad advice before seeing this video. This is the way to do it.
http://www.youtube.com/watch?v=WD9tsau_UI0

Bad advice?? You think?? LOL!! First, the damage to your tree is far more extensive than that shown on the video. Second, waiting two days before effecting any type of repair seriously reduces the chances of success and sometimes survival. Trees start to compartmentalize and repair wounds almost immediately. If the right side branch has already begun this process - and in two days it would have - the ability of the tree to transport water and nutrients to that branch are seriously affected. It is pretty much just attached by bark with only a very thin section of wood remaining. There is a very good chance that branch will die regardless of whatever repair attempts you make.

Yeah, I'm in the right place - I grow and sell Japanese maples for a living, plus consult professionally on issues just like this. The problem with videos like this is that they are very generalized and cannot address the specifics of each individual case, which unfortunately sucker in novices like you that don't know any better. Try posting this same question in the Maples forum and see what kind of responses you get. Or just check other similar posts.

But no......you watch a video and now you're the expert. Good luck!!

We need a "like" button (like Facebook) for good responses. Thanks for standing your ground. I have given up on answering certain questions because there is always someone who thinks my 30 years in the hort industry is meaningless.

Pull it back up and about 1' up put a 1/2 " threaded rod threw and nuts and washers. I had a northern spy do that 12 years ago from the weight of the apples. I thin it better now and it is still one of my best producers.

oh, man, the ego's in this room!

Experience is worth alot, but what's the harm in attempting a repair like the one in the vid? Maybe he'll save a bit of the plant, maybe not, but such negativity in the name of years of experience and the implication of being an "expert"...I would steer clear of these responders based on that simple fact.
This space is for help, not one-upmanship of experience and "authority". In my experience at a nursery for many years and adoptive parent ot many "unsellable" plants, plants have a remarkable ability to heal and recover, in spite of the odds and human intention. Some don't. But, what is the harm in trying? I have succesfully repaired small shrubs and trees with the bolt/screw method, and they've gone on to live long lives...some didn't.

Humility goes a long way...

Amazing how someone brand new to these forums decides to come in and attempt to regulate what can or can't be said here!

First, this is not intended to be a "help" forum but rather one for discussion of professional topics of interest to green industry professionals. So someone - a nonprofessional - came in to ask advice of a professional and that advice was generously given. What is objectionable is the way that advice was summarily dismissed by the OP as "bad" - and rather rudely so - based on other information they subsequently discovered.

Neither advice is bad. Sure the OP could bolt together the torn branch if they wanted to.......it was only pointed out that this was unlikely to be as easy or as successful - based on the extensive amount of damage and the time delay - as the video alluded.

It has nothing to with egos but everything to do with common courtesy and politeness. I feel no need to exercise any 'humility' with regards to offering advice I have spent dozens of years accumulating working as a horticultural professional. If the OP didn't like the advice, he didn't have to follow it - his choice. But to come back and rudely and incorrectly state the advice was "bad" and pretty much imply that I didn't know what I was talking about based on his a viewing a single video, then claim - based on this extremely limited knowledge - that the video was the only "right" way was offensive.

Gardengal I am not a maple expert and you are. I just suggested the repair based on my fruit orchard. If it were summer I would remove the limb. when dormant I would repair. I should have taken it a little further. when I repair I treat it like a graft and prune the weaker branch hard. Yes when I am top grafting Only about 75% take.

Cut the branch off and grow on the remaining tree. J maples grow quickly. The scar will heal over. Buds will emerge from the bark down low on the trunk this year and a few years down the road no one will know you lost a branch.

Looks like surface of wood is now too dry to expect a full re-joining anytime soon, if ever. And won't it still be a bad fork, which was the problem in the first place?

I'd buy a new one.

this issue of bad forks on japanese maples has me completely flummoxed! i have been told avoid them like the plague-or-that because jpm are small trees it is not usually problem-or-that some like this linearlobum (that a reputable nursery, greer, sent me) naturally grow with extremely small, like fork

The issue arises primarily when there may be snow loads to consider. Many J. maples are quite shrubby in form and close forks/tight crotch angles are very common. Most will grow happily and without worry with these conditions present. If snow loads are an issue, spreading the angles with spacers can relieve some of the pressure or if appropriate, pruning to remove too close a forking condition. But if I lived where heavy snows or ice was a problem and given the choice - and this is hard to do with mail order - I'd select trees that don't have this issue to begin with.

Multi-stemmed JM's, or those that produce two or more major limbs from low on the trunk are also a very common growth habit. I'd be inclined to leave them be -- J maples are not considered to be single leader trees.

Lots of trees produce narrow branch angles, what matters is how the branches meet. Splits occur at forks where two branches are not fused inside, what's called "included bark" signals this condition.

We are probably looking at a double graft which is a very structurally weak situation anyway. Zoom your browser to 300% and you can clearly see the raised graft scar along the break.