Bark damage on Japanese Maple (girdling?)

[Sci_Guy83]

I have a Japanese Maple with a decent bit of bark damage. But first some history... I planted this tree about five years ago. The tree is now about 9 feet tall, and the trunk has a circumference of about 9 inches. A couple years ago there was a small quarter sized flake of loose bark that I simply remover and it seemed fine.

Last year we had a late freeze that killed up a lot of the new leaf buds, but luckily most of them grew new leaves and only a couple branches stayed bare. I pruned the dead wood off a couple branches that the freeze got and it rebounded nicely. This year growth has been robust, and the tree seems very happy.

However yesterday I noticed some bark laying at the base of the trunk, and another large strip half hanging on the tree. I removed this bark (same area of that old quarter size damage) to find the larger damage that was concealed behind that loose bark. So it would seem that the old damage was worse than I had thought, and it looks like it has already been as work at trying to heal. The loose bark did extend a little below the mulch line.

This tree is one of the centerpieces of my garden, so the damage concerned me and a search lead me to this site. The two likely culprits sounded like mechanical damage or girdling roots, so I excavated today and took some pictures. Does this look like it could have been caused by mechanical damage, or girdling roots?

If we say that the damage is at 6 o'clock, there is a medium sized root at 6 o'clock there that fuses into and around the trunk, but is below where the trunk begins to flare out. At 3 o'clock there is a thicker root, but since it is on the wrong side, would it have anything to do with this damage if a girdling root is the cause?

So my questions are these... If the root is that low and fuses with the trunk, is it still a girdling root? If so, do these look like they could be a problem? If so, should the be cut off at the fuse or elsewhere? I know that some threads I read suggesting removing the tree if it is a bad girdling issue, but removal and replacement is not an option with my present finances.

Also, if the roots are not a problem (or even if they are), is there anything I can do to promote faster healing of the trunk? Should a pull the mulch back? Should I thin it? Every year the weather washes some mulch away and every Spring I add some new on top of whatever is left. Is this a practice I should change and instead remove the old and put in all new?

Thanks in advance, and sorry about the 1,000 questions.

 

[ATH]

Both of those roots are going to cause problems. Not sure they are the source of the current problem...but they need to come off. And that is a lot of root to be taking off. I may take off the 6 oclock root now then the other in a year or two.

 

[Sci_Guy83]

Thanks for the quick reply. Since this is all new to me, where is the best place to remove the root? Just cut it where it fuses to the trunk, or track it back around and chisel the longer patch around the trunk off too? Then do you just bury it and forget it, or should the new root wound be 'dressed' in any way?

Also, the 3 o'clock root is bigger, but also seems to go deeper. I couldn't track it back to it's origin due to the time I had available. Hopefully I can save this tree from future problems, because it's doing great right now, and my wife and I love it.

 

[Jed1124]

That root is not fused to the trunk. You could certainly prune it. I would say though that your damage to the trunk is more likely mice damage from chewing after heavy snows after the last couple winters. I have seen a lot if it up here on jap maples.

 

[ATH]

I said the 6 oclock root first, because that looks like it is putting more pressure on the trunk. Cut it where it is away from the tree. Then, I'd also do the best to get it cut where it starts. Often that does involve chisels. Do not "dress it". Make it a clean cut and leave it exposed (not buried).

 

[Sci_Guy83]

That root is not fused to the trunk. You could certainly prune it. I would say though that your damage to the trunk is more likely mice damage from chewing after heavy snows after the last couple winters. I have seen a lot if it up here on jap maples.

It certainly looked like it became one piece with the trunk when I brushed the dirt off with a toothbrush, but admittedly, this is all new to me. As for chewing damage from the snows... I think you're on to something there. We did have snow on the ground for long periods, and with decent accumulations. Whenever it would melt, the grass did show signs of someone making tunnels beneath the snow. And I did find a mouse nest in the compost bin that is only 15 feet away from this tree.

I said the 6 oclock root first, because that looks like it is putting more pressure on the trunk. Cut it where it is away from the tree. Then, I'd also do the best to get it cut where it starts. Often that does involve chisels. Do not "dress it". Make it a clean cut and leave it exposed (not buried).

Sounds like a plan. As for not burring it... is that just until it dries out or heals over. Or will I need to keep the cut area uncovered long-term?

 

[BC WetCoast]

The scar on the trunk looks a few years old. Could be chewing but could also be mechanical damage done in spring with the sap is flowing and bark is easily knocked off. Landscapers with no control of their weed wackers or lawnmowers in the spring are often guilty of this.

 

[Sci_Guy83]

Okay guys, I've acquired a chisel and will likely be removing the one root this weekend. As for leaving the root exposed after I'm done... Is that temporary, or will that need be permanently uncovered? Just want to know so I can regrade the dirt/mulch ring it is in while I'm at it (if I need to).

 

[ATH]

You want the original (primary) root collar (also called root flare) to be at ground level, not buried. If your tree is like 89% of the others out there, it came too deep from the nursery. In other words, you will probably be pulling soil away from the trunk to find that and leaving the cut root exposed.

 

[Sci_Guy83]

Perfect! I'll do just that, and would like to thank everyone very much for their help.