Would you do anything about this rotting apex? (Blue oak)

[Mikecheck123]

The live part of this apex has thickened quite a bit this year. It's now noticably detaching itself from the dead core. In spring they were indistinguishable.

Does this look worrisome to anyone? If so should I just chop and seal it to prevent further rotting? I don't need it. It's just a sacrifice apex.

 

[Potawatomi13]

Personally love oaks and inclined to say no. Tree COULD be cut back to lower limb or could let grow with live part of tree making more interesting trunk as time goes by. Since trunk so straight might be inclined to combine both to keep at least some interesting scarring on trunk for future tree.

 

[Shibui]

The dead section is not going to affect the health of your tree.
I don't think the live section is detaching as such. The swelling line is called callus. That's the tree trying to heal the wound. If you scrape the old bark off the dead section you will probably see what's going on a bit better.
Dead sections are often carved out a bit to make it look like the trunk was damaged and rotted away leaving the new live apex. If it is done well that would add much needed taper to this trunk and add quite a lot of age and character.
If you don't like dead wood in your design do as above and chop just above the branch at the base of the dead.

 

[leatherback]

So you have some die-back. Besides the option @Shibui gave you, magic third: Only carve away the dead section which extends beyong the callus, and the next years focus on getting the bark to grow over the die-back. Not sure it will become pretty tbh.

 

[sorce]

Does this look worrisome to anyone? I

It sure does. Do you know what happened? Cuz if it wasn't a slipped machete it looks diseasish.

Sorce

 

[Mikecheck123]

It sure does. Do you know what happened? Cuz if it wasn't a slipped machete it looks diseasish.

Sorce

I was an 8 foot nursery stock tree. The top half died back. So I cut it off just above the highest living branch. As I mentioned, you couldn't tell the difference between the living trunk and the dead trunk until this summer. Now they're very different.

 

[Mikecheck123]

Here's a shot of the full tree. The troublesome section is in the back of the design. You wouldn't notice it if it was gone.

 

[Bonsai Nut]

Personally, I would reduce it to the next lower branch. The upper trunk looks completely dead except for a single live vein keeping the top branch alive. Given how the tree is trying to recover, I think you will be left with a strange trunk line with weird taper.

 

[sorce]

Sorry I see it now. That black is frightening!

Seems there will be this point where taking action will be most aesthetically pleasing, too early and it might be too thin, too late and it might bulge.

Seems to be giving you quite the clear line to shave.

Meh, if it's sac, let it sac! So long as that black ain't spreading.

Sorce

 

[TomB]

Personally, I would reduce it to the next lower branch. The upper trunk looks completely dead except for a single live vein keeping the top branch alive. Given how the tree is trying to recover, I think you will be left with a strange trunk line with weird taper.

Same here. I'd make a diagonal cut behind the second highest branch in picture 1, at the line where callus has developed. I'd expose some cambium at the edge of the callus, and seal over the whole thing with Kiyonal cut paste - an Oak I have has responded very well to that treatment.

 

[Mikecheck123]

That black is frightening!

Yes, it's a bit Stranger Things, isn't it? But it's not mine--it's is a shameless copy of Walter's aluminum foil technique.