You cut too close and mauled it - look up "branch collar" so you can get a better outcome next time.

I honestly can't tell exactly what I am looking at here, but it doesn't look good! Here's a link that will show you how to properly prune just outside of the branch-bark-ridge/branch-collar: UF Horticulture on Pruning Cuts

I should've left more of a collar, the branch was at an awkward angle and was tough how to gauge how to cut it properly. Now that I've opened up the wound in a bad angle, should I get some black paint and cover it up so it doesn't rot?

No, paint and other sealant goop would INCREASE the chance or rot. Leave it as-is and let the tree cover the wound over.

jeez guys .... your motivational skills are lacking.. i will be surprise if they dont commit suicide tonight ...

first.. did you use a lumber saw.. rather than a pruning saw ... just a guess??

second.. no paint.. ever. ...

third.. the tree isnt going to die... the above noted guilt is really useless in helping you.. rather than chiding you ...

"D" ... lol ... i lose track of my numbering systems ... ... its too flat on top ...

V .... as in roman numeral ... do you or can you get your hands on a sawsall with a pruning blade ... last year such a blade cost me about 9 bucks ... the sawzall $120 ....

next ... double the declining angle of the lower ledge ... so it sheds water.. rather than maybe collects it ...

and then walk away ...

another thought.. did you cut off about 90% of the branch first.. thereby making the final cut easier .... ??

after that.. so what.. an otherwise healthy tree will heal ... encapsulate ... they have been doing it for millions of years ... it will take a few years ... that is tree time for fast ...

trust me.. out of every hundred cuts i have made.. 10 or so end up looking like this.. lol... NO TREE HAD EVER DIED ... period ... and anyone who claims they are perfect at such.. is lying to you.. because everyone of the experts.. made the same cuts.. before becoming said master of the universe ...

could it have been a better cut ... sure.. live and learn.. practice make perfect.. hindsight is 20/20 ...

dont lose a minutes thought.. beating yourself up about it ...

but NEVER paint it ...

ken

ps: by removing the vast majority ... you could have made a better cut.. from the bottom up .. pushing the limb into the tree to facilitate a gap to saw .... i will GUESS ... what baffled you.. was trying to do it from the top ...from the bottom.. and knowing that branch collar stuff.. you could have 'used' the saw in a way to protect the collar .. and make a better cut ... only took me a couple hundred mistakes before i figured that out..

pps: let me put it another way.. that was a horrible crotch angle.. already having included bark .. it was a failure waiting to happen.. there is no downside to removal ... even the way you did it... becasue in the future.. maybe when the branch was catastrophically large.. it would have failed.. no doubt about it ... so.. good work ... unfortunately.. the one behind it.. isnt much better ...

==>>>> wait a minute... is this one of those free range carp Siberian elms [i think i recognize the bark and crotch angles] .. that i hate with a passion of a million burning hot suns? ... crikey ..... if is is.. plant a new .. BETTER tree ... and practice cutting this thing up.. until you provide the ultimate basal cut... at ground level .. with malice and aforethought and a little stump killer ... murder it ... we had a county wide ice storm a few years back.. thousands of this tree were severely damaged ... every neighbor surrounding my 5 acres has a couple.. and i kill thousands of seedlings per year.. when i am not picking up branches broken off in minor winds storms ... i hate this tree ...but i digress ...

NO PAINT!!!

With the exception of the mulling on on the main trunk you made a decent cut based on where I see the heartwood.

There is no branch collar, just included bark.

It was likely a co-dom what was outpaced and compressed to create that included bark.

Jeff, Whaas's post made me look at your pictures again, including the larger versions at the links. I still can't be sure what I am seeing. Is the vertical/upper exposed area cut into the remaining trunk or is it left over wood from the removed branch? Another way of asking this is...is there included bark still behind this area?

Either your cut is way too deep (if it's part of the remaining trunk) or you need to cut just a little further (if it's left over from the removed branch and there's still included bark behind the exposed wood).

I'll disagree politely with the no sealer statements just to keep group think from setting in.

How large is that cut? Six inches across?

If this wound is going to be open for a decade at that angle I would wait until a dry period and seal the darned thing with SOMETHING. My neighbor has used frakkin UNDERCOATING on several of his trees. Not a one is dead somehow and no conks are sprouting from where he treated so I quit second guessing him.

Now its a guess as to what is best to use but I know what happens to them Fraxinus logs outside that are untreated vs the one I poly'd over to keep as a seat by the fire pit. Problem is on a live tree you gotta be careful about poisoning its living layers.

Despite my hundreds of millions of years of evolution we use Neosporin 'round here on our larger wounds.

Not perfect, but good enough the experts are arguing over it. ;-)

Ken, I also cut about a firewood length out from the final cut on difficult cuts. It sure makes it easier not having to deal with the weight of the limb on the final cut. I don't even bother with an undercut on the first cut unless the limb is very large. With a large limb it can split and 'barber chair' you right in the face.
Mike

Looks fine.

"If this wound is going to be open for a decade at that angle I would wait until a dry period and seal the darned thing with SOMETHING."

Nothing personal Toronado, but with all the info and science presented on the topic, I honestly find it hard to imagine that someone would have that opinion. I understand playing Devil's advocate, but I just don't see how anyone could possibly make a reasonable argument for such treatment.

"Problem is on a live tree you gotta be careful about poisoning its living layers."

The even bigger problems, detailed ad nauseum here in this forum before, is that sealing the wound seals moisture and decaying organisms in. If we were in a horror movie, recommending wound sealer is equivalent to recommending locking yourself inside after the villain and a bunch of monsters were known to be in the house!

"Despite my hundreds of millions of years of evolution we use Neosporin 'round here on our larger wounds."

Isn't this like comparing the space shuttle to marmalade?
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"Not perfect, but good enough the experts are arguing over it."

I think any differences in opinion or even most questions about the job already done arise from the inability to effectively judge the photographs (at least that's the case for me). The photos are really good quality photos, but are just hard to decipher (maybe it's a 2D versus 3D thing?).

I think it was Spruceman who used to recommend using copper fungicide to treat cuts/wounds. I have done it a few times myself with no ill effects.

I think a simple fungicide (that does NOT seal) is OK to use, just to try and stave off rot.

First off, thanks Ken, I'm breathing a little easier right now. To answer all of your questions. The tree is an American Elm, a Princeton Elm to be exact that's supposed to be resistant to Dutch Elm disease. It is about 20 feet tall, so still fairly young. I planted it 7 years ago and it has been growing great since then.

The branch I cut was about two inches thick, it was a deep V like in the picture I posted, but even tighter than the V in the picture. I probably should've left more of a collar, but it was a tough angle. The bare spot with no bark next to my cut on the main trunk is not from me. I wasn't there in the fall the last time I was up there, and I noticed it before I trimmed the branch off the tree. It does have me a little concerned though because it is a bare spot, although the tree was flowering fine above that bare spot so hopefully it'll be ok. I also did cut the branch off a foot above, so that it wouldn't split down the trunk when it let go.

"I think it was Spruceman who used to recommend using copper fungicide to treat cuts/wounds. I have done it a few times myself with no ill effects."

I actually haven't tried it yet, but I'm a big fan of the idea based on the theory. I think the chances of it being a very helpful technique are high. I have linked one of the related threads below. There are others. Some can be found with the appropriate Google search, because they appear to be too old for GardenWeb's search function (but they are still on here).

Here is a link that might be useful: One of Spruceman's Threads on the Topic

I have made much worse pruning cut in my life and the trees turned out fine :)

Just a reminder to careful what you do with any wood after cutting as dead wood will attract the insects that can still cary Dutch Elms Disease.

They say you should grind them up fine burn them, or keep them far from the living tree.