Cork Oak lost cambium, healthy tree

[barely]

I have noticed that on some of my cork oak trees (25 to 35 years old), part of the trunk is missing and you can see the hard wood with the cambium still growing on the edges of the void. Tree looks totally healthy and growing nicely, so why does this happen? Pictures below.

 

[NOZZLE HEAD]

The most common reason in potted plants is some sort of physical damage. I would not expect cork oaks to be particularly susceptible to this.

Boring insects, sunburn on young trees, and rodents are also a possibility.

In field conditions herbicides can also cause damage that looks like that, but herbicide damage is pretty uncommon in the bonsai world. It is slightly more common in production nurseries, but also a rare occurrence.

 

[barely]

The most common reason in potted plants is some sort of physical damage. I would not expect cork oaks to be particularly susceptible to this.

Boring insects, sunburn on young trees, and rodents are also a possibility.

In field conditions herbicides can also cause damage that looks like that, but herbicide damage is pretty uncommon in the bonsai world. It is slightly more common in production nurseries, but also a rare occurrence.

Appreciate the feedback. These trees are all around 35 years old, grown from acorns and raised in nursery containers. The trees all look healthy with new growth and buds on all parts of the tree. I think that this condition did not occur over night. The rest of the bark on the tree appears very healthy. Don't think it is rodents. I read that possibly a part of the branch can die off if roots feeding that part were cut too severely. Last time roots were cut on this tree was over two years ago. Hope this info helps. Any info from you would be greatly welcomed.

 

[Leo in N E Illinois]

I simply do not know.

 

[Potawatomi13]

Where is home? Please add location to profile. Tree appears dead wood has break in the middle. If tree bent severely or suddenly could have killed bark above/below break generally outside of bend area. Also appears from weathering of dead wood to be several years old damage. Not a problem as adds valuable character to tree. Also small possibility bark was scraped off accidently.

 

[barely]

Where is home? Please add location to profile. Tree appears dead wood has break in the middle. If tree bent severely or suddenly could have killed bark above/below break generally outside of bend area. Also appears from weathering of dead wood to be several years old damage. Not a problem as adds valuable character to tree. Also small possibility bark was scraped off accidently.

Trees are in Southern California. The loss of the bark does not appear to have damaged the cambium but not sure how to check that out. The loss of the bark is only on a few branches. As I noted earlier, the trees are very healthy and are growing well. it could be a good shari feature on the tree.

 

[barely]

I was also reminded that commercially grown cork oaks in Portugal and Spain have their entire bark removed periodically and in a few years the bark grows back.

 

[Housguy]

I have seen this many times, maybe and pure speculation, that a bug or fungus kills the cambium underneath the bark and over time the bark breaks off and exposes the dead area.

 

[Shibui]

As noted earlier that damage is not new. The cambium in the open area is dead but is growing back from the edges. It takes many months for the callus around the edges to form like that.
Also as already pointed out the damage can often be hidden by the corky bark until the healing process pushes the old bark away to expose the dead parts. This also happens on other species which makes it difficult to pin down the cause because that happened months before the signs are visible.
If damaged roots were the cause the dead part would usually extend down into the ground to the dead root.

It will probably completely cover the damaged area in a year or 2.