Contact Us Host an Event Volunteer Join

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
1 rating

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

Why is my Mountain Laurel in distress?
November 26, 2008 - We have planted our 2nd Texas Mountain Laurel in the same spot (after fresh berm built with sandy loam) and it is not looking good in less than 2 weeks. We have an identical berm on the other end of...
view the full question and answer

Spots on just-emerging Zexmenia in Austin
April 02, 2010 - My zexmenia is just coming up from the ground after a cold winter in Austin. The leaves are all spotted with tiny holes as if something is munching on them before they even leave the ground or just as...
view the full question and answer

Live oak leaves yellowing from Denton TX
January 26, 2012 - In autumn of 2010 I planted 10 live oaks about 6 to 7 ft. tall. I have see that during the month of Dec. 2011 to Jan. 2012 they are showing some yellow leaves. What can I do to help them?
view the full question and answer

Palm plant with lower inches browning in Alexandria VA
July 21, 2009 - Palm plant 10 years old, about 5' tall, single trunk approximately 1" diameter, reddish green leaves about 12 to 14 inches long, original owner. All leaves on the lower 2 inches of plant leaves are ...
view the full question and answer

Old oak tree dropping leaves in Hazlet Township NJ
July 08, 2013 - I am 84 yrs old and have a 50 year old pin? oak. No more acorns, but the leaves are falling in clumps and are still alive. Every day I fill a huge garden bag with them. I live on a fixed income and...
view the full question and answer

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