Rent Shop 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
Not Yet Rated

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

Cultivar of Cercis Canadensis from Haskell OK
May 16, 2012 - We have a Hearts of Gold Redbud that first had dark edges to many of its leaves (about 2 weeks after planting). It now has multiple leaves w/ medium-dark brown spots on them. Are we looking at some ...
view the full question and answer

Prickly pear doing poorly on Long Island NY
December 27, 2012 - First, thanks for your reply on 11-3-12, re.Can a prickly pear cutting from Harker Heights, TX find happiness in Long Island, NY. The plants were set before a southern window in the attic, temp. ra...
view the full question and answer

Demise of Flameleaf Sumac in Austin, TX.
July 31, 2012 - My Flameleaf Sumac suddenly died. Beetles came out around the trunk when I cut it down. How can I prevent this on the other sumac?
view the full question and answer

Smarty Plants on mockoranges
May 25, 2005 - I live in Colorado where it is common to have 1 or 2 late frosts. I planted 4 littleleaf mockoranges (Philadelphus Microphyllus) 2 years ago and they are pretty much in full sun most of the day. I h...
view the full question and answer

Ground Arizona ash wood suitable for mulch?
April 23, 2015 - We cut down a 40 year old Arizona ash tree and had the stump ground into mulch. Can we use this mulch in our vegetable garden and flower beds
view the full question and answer

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