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Thursday - September 06, 2012

From: San Antonio, TX
Region: Southwest
Topic: Diseases and Disorders, Trees
Title: Sap dripping from a lacey oaks in San Antonio
Answered by: Barbara Medford


I have a lacey oak tree, approximately 6 ft. tall that has been in the ground almost a year. The tree looks healthy but there is a small area on the trunk that looks and feels wet. The substance is sticky and appears to be sap oozing from the tree. The area is approx. 8 inches long on one side of the trunk starting under a nub where a small branch was removed a few months ago. The area is about 1 1/2 - 2 ft. off the ground. Is this something I should be concerned about?


Yes. If you follow this plant link Quercus laceyi (Lacey oak) to our webpage on this tree, you will learn that it is very popular in Central Texas because it is more oak wilt resistant than the red oak Quercus buckleyi (Texas red oak) or Quercus fusiformis (Escarpment live oak). The fact that the ooze is near a "nub" where a branch has been removed is another clue. Unfortunately, "oak wilt resistant" is not "oak wilt immune;" just as "deer resistant" is not "deer proof."

So, we need to ask a couple of rhetorical questions. Was that branch removed between November and January? And was the wound painted with pruning paint? There is this little beast called a nitidulid beetle who is very fond of oak sap. The only way he can get at the sap is if something (pruning, weedeater, lawnmower) breaks the bark and the sap begins to ooze out. He is not active in the coldest months of the year, so that is when we recommend any pruning to an oak be done. We also recommend that if any branch bigger around than your thumb is pruned the wound be covered immediately in pruning paint.

And why is this little beetle so scary? Because we have wide-spread infestations of Oak Wilt in Central Texas. When sap is draining from an infected tree, the beetle (who doesn't harm the tree at all) comes along and has a snack, he will probably take away some of the fungus from the Oak Wilt, and generously share it with the next tree he visits. In addition, infection can sometimes pass from one oak to another via roots, which means you need to act quickly to save other oaks around that tree from infection that way.

Please go to this website Texas Oak Wilt.org. and read all of it. It can give you the information you need much better than we can. On that Home Page, click on Get Help. Next, we would direct you to the page on Texas Agrilife Cooperative Extension. There you will see a map indicating that Bexar County does have Oak Wilt present and that there are experts to help you. Start with the Texas Agrilife Extension Service Office for Bexar County. Alternatively, you can go to the Texas Forest Service. Bexar County is in the Kerrville District, so scroll down the Forest Service page to the Kerrville District, where you will find the contact information you need.

We urge you not to delay in taking care of this problem. The tree is so young and small,  the experts may recommend taking it out and destroying it before the contagion can spread. Take their advice on when and how to take it out and when it will be safe to replace it. Remember: we recommend that all woody plants, trees and shrubs be planted in November to January, when they are dormant. This applies to any woody plants, not just those prone to Oak Wilt.



From the Image Gallery

Lacey oak
Quercus laceyi

Texas red oak
Quercus buckleyi

Escarpment live oak
Quercus fusiformis

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