Host an Event Volunteer Join Tickets

Support the plant database you love!

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
4 ratings

Wednesday - July 13, 2016

From: Boerne, TX
Region: Southwest
Topic: Diseases and Disorders, Trees
Title: Young Mexican White Oak Losing Leaves in Texas
Answered by: Anne Van Nest

QUESTION:

I have a 5 yr old Mexican white oak, 20 ft tall losing its leaves mostly at the top. They turn brown & fall off. It does not lose its leaves in the winter, right?. About 3 ft from the top down is bare, The root flanges are not showing at the base. Could the dirt be piled too high around the trunk? I am letting my hose slowly drip in case it is just too dry. What do you think? Do I have a problem?

ANSWER:

Mexican White Oak (Quercus polymorpha), according to the Texas A&M Forest Service says that this tree is only recently discovered in the U.S. (1992) as a native tree species, but widely available in commercial nurseries. Naturally occurring only in one known U.S. population, near the Devil's River in Val Verde county, but more common in Mexico. Now planted widely as a landscape tree.

The leaves are simple, alternate, 2" to 5" long, highly variable, but often with several shallow lobes or teeth towards the tip. Leaves are thick, leathery, and semi-evergreen, with distinct raised veins on the yellowish underside. New leaves in spring are peach-colored and in colder climates the leaves are late-deciduous and turn yellow-brown.

oak_mexican150.jpg

The Native Plant Database lists this tree as Monterrey Oak as well as Mexican white oak and Netleaf white oak.

Your comment about the root flare is a potential problem. Soil and mulch should not be mounded up around the trunk higher than the root flare.  Howard Garrett, The Dirt Doctor has information and images on his website about Root Flare Management that may be of help to you in determining if your tree is planted too deeply.

 

From the Image Gallery


Mexican white oak
Quercus polymorpha

Mexican white oak
Quercus polymorpha

Mexican white oak
Quercus polymorpha

Mexican white oak
Quercus polymorpha

More Diseases and Disorders Questions

Problems with red tip photinia in San Antonio
March 29, 2009 - I have a red tip photinia that's about 20 years old and about 20 feet high--it is big! I noticed last summer the highest leaves looked droopy all the time even with deep watering and now that portion...
view the full question and answer

Brown spots in St. Augustine grass
July 05, 2008 - Mr. Smarty Plants, My husband and I are in the Air Force and were recently moved to Cibolo Texas. We built a home and hired a landscaper to finish the yard May 07 (with irrigation system). We laid d...
view the full question and answer

Red maple a casualty of Hurricane Ike in Houston
November 21, 2009 - We have a 3 year old Drummond Red Maple, between the sidewalk and the street in front of our house, that fell during Hurricane Ike. We replanted it. I recently noticed that the bark is severely cracke...
view the full question and answer

Hibiscus plants being attacked by powdery mildew, or maybe mealy bugs in Austin, TX.
August 10, 2011 - I have three hibiscus plants planted outside about a foot apart from each other. The one that gets most of the sunlight is the worse off of the three. However, all three of them have white powdery stu...
view the full question and answer

What is eating the plants in my garden?
August 08, 2008 - I have both purple and yellow coneflowers. Something is coming into my garden and eating the flowers off the stems. We don't have deer but may have other small animals that can get into our yard. Do ...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.