En Español

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
    
 
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
Not Yet Rated

Saturday - May 08, 2010

From: Austin, TX
Region: Southwest
Topic: Trees
Title: Sap flowing from live oak trees in Austin
Answered by: Barbara Medford

QUESTION:

I have live oak trees in my backyard,17 to be exact. I live in Northwest Austin, in Williamson county. There are two live oaks growing about 4-5 feet apart in the center of my yard. One appears to have a wound where sap is seeping out. Butterflies or moths have been flocking to it to drink the sap. This happened a few years ago to the other tree. Are my trees sick? I have mostly natives planted in my yard with a flower bed around these two trees. What can I do?

ANSWER:

The first thing we want to ask is, what do you have growing in your flower beds under the oaks? This probably has nothing to do with the wound on the oaks, but ordinarily, it is difficult to impossible to grow much of anything under oaks because of allelopathy, or the ability to emit substances that will retard the growth of competing plants beneath the oak.

The second question: Is the first tree that showed the symptoms still healthy? Or alive? Read this article from Texas A&M Horticulture Things You Should Know About Live Oak Decline. We don't know what caused the wound, disease or a blow from some mechanical source, but we know the sap being available between February 15 and June 15, when the nitulidid beetle is active, is bad news. This beetle also feeds on the sap, but if the little beastie has been visiting an oak tree with Oak Wilt, he will carry the fungus for Oak Wilt on his body, and infect the wounded oak. 

So let's get back to the wounds and the insects visiting the wounds. From Eric Becker of the Texas Forest Service:

"After being stressed by the drought many of our oaks were further damaged by Hypoxylon and borers.  As soon as you hear someone say the bark has fallen off, you can bet that their drought stressed tree has hypoxylon cankers (first brown and powdery, and then a silvery crust) and the prognosis is not good."  

Go to the  TAMU AgriLife Extension Plant Pathology page to find three fact sheets about hypoxylon:  Hypoxylon Fact Sheet #1, Hypoxylon Fact Sheet #2, and Hypoxylon Fact Sheet #3. 

If you live in the areas north of a Wimberley to Kyle line then there is the chance that oak wilt could be at play as well.  Trees damaged by oak wilt can also display hypoxylon cankers, so then we look for the pattern of mortality, groups of oaks dying side by side, and the brown vein leaves.  Drought mortality accompanied by hypoxylon cankers usually occurs on one or two oaks over here and another two or three over there—the sick trees are scattered about with healthy ones in between."

However, you should visit the Texas Oak Wilt site to familiarize yourself with the symptoms, prevention and treatment of the disease."

Williamson County is in the Austin District of the Forest Service, and you will find Mr. Becker's office contact information at this page in the "Getting Help" section. You need to do this as soon as possible; there is no cure for Oak Wilt and if it has already invaded some of your trees, all of your others are at risk, also. 

 

 

 

 

More Trees Questions

Flaming sumacs in trouble in Wimberley TX
August 31, 2010 - I planted three flaming sumacs last fall and all leafed out this spring. Then, early this month all the leaves turned brown on one and it appears to have died. Today I noticed that a second one is d...
view the full question and answer

Keeping squirrels out of pecan tree from Garland TX
August 17, 2013 - My yard is covered in green pecans with one bite eaten by squirrels. How do I keep squirrels out of my pecan tree?
view the full question and answer

Replacing Drought-Stricken Cedars
January 16, 2012 - Hello, I live in Williamson County on a couple acres. We have several dead cedars as a result of drought; we're reluctant to cut them down because many of them provide a friendly barrier between us...
view the full question and answer

Fruiting times of native trees and shrubs in the Pacific Norhwest
December 30, 2013 - I am looking for information on fruiting/seeds/nuts times of native trees and shrubs in the Pacific Northwest. Obviously they fruit after they bloom but all I can find is very general information such...
view the full question and answer

Seedlings of elm trees in Illinois
June 09, 2008 - I have what I believe to be young elm trees sprouting throughout my front yard. I will pull them up and over night more sprout and will be 5+ inches tall. I would like to know how to get rid of them, ...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | JOBS | SITEMAP | STAFF INTRANET
© 2016 Lady Bird Johnson Wildflower Center