Is this something I need to treat (sap from trunk of Idaho Locust)?

Affiliate Disclosure: We may receive a commision from some of the links and ads shown on this website (Learn More Here)

I have recently started seeing this stain on the trunk of my idaho locust, right at the top of the trunk.

It looks like someone has just poured water over it. The brown part is not sticky at all--nothing comes off when I run my fingers over the brown part.

We have not seen this on the tree before. It is maybe 5-6 years old. I posted a question about it in 2016 and said that I planted it 2-3 years prior.

Is this a sickness or infestation? The tree has no other signs that it is unhealthy--I just dug up a sprout from it about 20 feet away, so it has extensive roots, that's for sure. And the beautiful show of pinkish-purple blooms we got this year was every bit as spectacular as in previous years, so again its not acting like a sick tree.



Super Moderator
Staff member
Hi Paul!
It is sap leakage. Is the other side the same?
Cause: wind damage.....did you have any hurricane type winds over the past summer?
I'm looking at the V between the trunks. That is probably where the damage was done.
What can you do? Keep and eye on it the junction.
Remedial work: you can chip away the (looks like dead bark in the V) back to live careful not to damage the newer wood underneath..... it will show if there is any movement.
Long term: take a few photos and then we can go from there if there is any splitting!
Thanks. I'll post a pic of the other side tomorrow when I can take a photo, but this is the only part we have noticed it.

Now the idea of wind damage is interesting--we absolutely have not had any hurricane type wind damage this past summer--we did have some heavy winds--40 MPH but only for a very short while, and only for a week or two (and not every day at that). But I would think that strong winds would just move past the trunk/tree.

At any rate, the winds usually come from behind the house, so I would think that this tree would be protected from the strongest force of the winds.


Super Moderator
Staff member
Hi Paul!
Actually the winds would blow and bend the upper part of the tree, which would put a lot of stress on the lower trunk, specifically at the junction where the 2 trunks, on the right and left. There maybe a spit at the might need to do some pruning to reduce the weight of these 2 trunks by reducing the height of the tree. But do clean up the V so you can have a look at the condition hidden under the bark buildup.
I'm just worried that one of them will come crashing down if more stress occurs at the V!
You might like to have a tree expert come see your tree and do a proper assessment.
Ron, I went out to look at that V. The brown part really isn't wet at all, or even damp. It is fairly dry, and that V didn't have any mushy bits that I could easily scrape away.

Now if you are suggesting that I take a blade and cut into the base of that V, and then tell you what is just underneath, I can do that... I just didn't want to hurt the tree unnecessarily.


Super Moderator
Staff member
Here are a few more pics, of the same spot on the trunk, but from different angles.

View attachment 13578 View attachment 13579 View attachment 13580
Interesting that is is just one side of the tree and that is a good sign!
Are you willing to do some bark removal in the V?
You can use a small chisel, or sharp knife, to carefully chip away the dead bark down to new live wood.
Just remove a bit at a time, and take your time.
Take close-ups once you see live wood.
Exposing the live wood under the dead bark will not hurt the will help stimulate it....

More thoughts....since we are in Fall now, the tree will be going into slow mode preparing for the winter....
Also thinking wood borer damage...doing a bit of research! Will post later with more ideas.....
Anyway, removing the dead bark should expose any damage done by insect activity, the stained bark is one of the signs. is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to