Native Plants
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.
Did you know you can access the Native Plant Information Network with your web-enabled smartphone?
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.
rate this answer
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.
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
More Diseases and Disorders Questions
Problems with a Cercis (Redbud)
August 25, 2014 - Half of my redbud tree is pooped out looking. On two places on the bark are areas where a few layers of bark have pulled back. In these areas there are white growths.
view the full question and answer
Fungus type problem on native blackeyed susans in Ohio
August 20, 2008 - I have black eyed susans that have recently developed a black fungus type problem in the bottom and on the leaves. The flowers are now wilting and dying. What is this and how can I stop it from possib...
view the full question and answer
Safe Concrete Planters For Plants?
February 24, 2015 - We are building low concrete walls around a patio (in Washington, DC). Can we create the walls to act as planters or will the lime leaching make the soil too inhospitable for most plants?
view the full question and answer
Need help with powdery mildew and mites in Bastrop, TX
July 26, 2011 - I tend to flower beds for the city. I have noticed a powdery mildew in 2 beds. It is on the Pavonia and Turks caps. I now notice mites. What should I do?
view the full question and answer
Need help for diseased Cherry Laurel tree in Houston
October 19, 2015 - A couple of weeks ago the leaves on my decade old cherry laurel began to turn brown. Now they are entirely brown. I have not changed the way in which I cared for it, but about three days ago I noticed...
view the full question and answer
| Support the Wildflower Center by Donating Online or Becoming a Member today. |