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
2 ratings

Wednesday - July 13, 2011

From: Harlingen, TX
Region: Southwest
Topic: Diseases and Disorders, Trees
Title: Treating suspected drought-stressed live oak
Answered by: Guy Thompson

QUESTION:

I have a live oak with excessive leaf drop - it was planted approx. 20 year ago surrounded by heavy pavers. very little grass - I did not plant the tree - I have noticed in the last few years the drop increases - the oaks I have in the back yard only shed during the winter, we have long hot summers. I can removed the pavers. Thank you

ANSWER:

There is no question that even old, well-established trees are going to need some extra help during the kind of drought we are having right now. If the pavers around your tree are set close together, water permeation may be sharply curtailed.  Mr. Smarty Plants recommends that you remove as many of the pavers as possible, right out to the drip line of the tree. Replace the pavers with 2-3 inches of mulch to slow the evaporation of soil water.

Many trees have been saved in past droughts by additional  watering in late summer. As the underlined article suggests, professional arborists suggest deep watering, and the amount of water applied would depend on your soil type, e.g., rocky or clay.  The trees might also benefit from additional fertilization.  Furthermore, trees suffering from drought stress are often more susceptible to insect and fungal attack.

This University of Illinois Extension website Dealing with the Drought affirms that watering even drought-resistant trees like the oak is essential. It points out that a 90 ft. oak tree will be a lot worse to lose than annual flowers or vegetables. We don't recommend watering at the base of the trunk, but watering farther out, with a hose or sprinklers, probably about every two weeks. An excerpt from this website will tell you why:

"Our 90-foot oak example could have roots at least 40 feet beyond the tree’s
drip-line. The same goes for most shrubs. So, apply water at the tree or
shrub’s drip-line, not at the trunk."

Those roots may be pretty deep, and part of the protection of the trees, but much of the root system is in the top 12 inches of the soil. So, putting the water out there helps to avoid fungus and rot at the base of the trunk.

 

From the Image Gallery


Escarpment live oak
Quercus fusiformis

Escarpment live oak
Quercus fusiformis

Escarpment live oak
Quercus fusiformis

More Trees Questions

Rhododendrons Hydrangeas in Indiana
December 13, 2007 - I live in very southern Indiana. Our home faces west and at the front of our home I have planted three rhododendrons. The furthest south is growing well the two to the north not so well. All three h...
view the full question and answer

Oak Selection in Austin
September 11, 2010 - The City of Austin is offering me two free trees to plant in my front yard. I live on the limestone shelf that is Northwest Austin, with only a few inches of topsoil that was brought in by the home b...
view the full question and answer

Would like a small tree for yard in Las Vegas, NV.
May 31, 2013 - would like a small tree with root system that grows down not spread on surface. Had raywood and medesto ash tree both died of desease. Diagnosed by arborist. Stated that these trees to big for my yard...
view the full question and answer

Is it wise to cut suckers from live oak branches in April in Austin
April 07, 2010 - My live oak branches are filling with suckers and I would like to cut them now, April. Is that wise?
view the full question and answer

Small Yard Tree for Washington DC
July 20, 2012 - What do you suggest for a tree or shrub in my front yard? The yard is small; 9 ft x 12 ft. Thank you.
view the full question and answer

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