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Saturday - September 15, 2012

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders, Trees
Title: Bark problems with Monterrey oak from Austin
Answered by: Barbara Medford

QUESTION:

I planted a 65 gallon Monterrey Oak (White Oak) in my front yard in February of this year. I water it once a week. All of the leaves and branches appear very healthy and there is no discoloration. About a month ago I noticed some dark areas (patches) on the bottom 5 feet of the trunk. They are not soggy or wounds, just discolored areas. They also don't appear to have a thick layer of bark. Well, about 2 weeks ago I also noticed a small hole with dark sap coming out of it. I have not observed any bugs on the tree or any bug trails. I also haven't pruned or injured the tree in any way. The discoloring and sap are on one side of the trunk ranging from 6 inches to 4 feet of the ground. I would like to know what you think it is?

ANSWER:

First, we would comment that is a heck of a big tree to transplant; luckily, you did it in February, so hopefully we can rule out transplant shock. Maybe.

We have recently answered a couple questions on white oaks (Quercus polymorpha (Mexican white oak, Monterrey Oak) and Quercus laceyi (Lacey oak), both considered resistant to Oak Wilt, but with some similar problems. First, we would ask that you read both of these previous questions, to see if they answer your question.

Austin, TX

San Antonio, TX actually, this is on a Lacey Oak, but it is also a white oak, considered resistant to oak wilt, but it is a very similar problem

Beyond that, the little hole could be caused by a woodpecker or sapsucker who are shopping for either bugs or the sap in the bark of the tree.

Holes in ash in Austin

Holes in pecan branch in Cooper, TX

In the final analysis, diagnosing a tree we cannot see is a near impossibility. If the situation appears alarming enough, you should contact some of the specialists that are mentioned in the various links.

From the Image Gallery

Mexican white oak
Quercus polymorpha

Lacey oak
Quercus laceyi