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 is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

rate this answer

Monday - June 25, 2012
From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders, Watering, Shrubs
Title: Yellowing of leaves in Texas Mountain Laurel from Austin
Answered by: Barbara Medford
QUESTION:
I planted a Texas Mountain Laurel in my Austin, TX yard this January. The tree was good sized (about 5 feet tall) when I planted it. Recently the leaves of the tree have started to turn yellow along the veins of the leaves, with some of the lower leaves turning a pale mottled yellow color. This is in distinct contrast to the dark glossy green of other established mountain laurels in my neighborhood. The tree receives full sun from mid-morning until evening. I have been watering the tree to help it become established. Am I overwatering the tree, or not providing enough water? Do I need to provide some shade until the tree is established? So far there hasn't been any leaf loss, but I am concerned that unless I do something the tree will not survive.ANSWER:
We are assuming that the leaves of the mountain laurels in your neighborhood are on trees that were not planted so recently. The difference in yours, although you planted it when we recommend for woody plants, in Winter, may be transplant shock.
Yellowish leaves could indicate chlorosis, or lack of iron being taken up by the tree from the soil. This is often caused by poor drainage and/or dense clay soil, which causes water to stand on the roots. Again, this could be a problem caused by planting, perhaps without any organic material added to hole, or damage to the tiny rootlets that take up water and trace elements, including iron, from the soil.
Please read this article from the University of Illinois Extension on chlorosis. Note the comment that the presence of chlorosis is often due to high alkalinity in the soil. You can be pretty sure that your soil is alkaline, but the Mountain Laurel is native to that soil and ordinarily would be happy in it.
Among the steps we would recommend are to use some sort of iron supplement, not too much, as Sophora secundiflora (Texas mountain laurel) does not ordinarily care for fertilizer. Water less, because we believe the main problem is lack of drainage in the hole dug for the shrub. Watering once a week should be adequate. Water by pushing a hose down into the soil around the tree and letting it dribble until water comes to the surface. Finally, using a good quality organic mulch, spread the mulch over the root area without allowing it to touch the trunk area. This will protect the roots from heat and cold and, as the mulch decomposes, will add some material to the soil to assist in drainage.
From the Image Gallery
More Diseases and Disorders Questions
Fasciation in Houston.
March 29, 2008 - I live in Houston and have had a rather large flower garden for many years. Most of the flowers are just gorgeous but over the last two or three years I have noticed that occasionally some of the flo...
view the full question and answer
Verticillium wilt in catalpa and maple
July 17, 2008 - On Monday - July 07, 2008, you answered a question about a catalpa and maple with the same problem--an entire branch died, and then more of the tree died. And both trees came from the same nursery. Th...
view the full question and answer
Yellow in pin oak leaves from Allen TX
May 25, 2012 - I have two pin oaks and one is completely yellow - a sign of iron deficiency and the other is starting to turn completely yellow as well. I've a proposal for iron deficiency but it is quite expensiv...
view the full question and answer
Oaks at Wildflower Center from Wimberley TX
September 05, 2012 - I know you have numerous Quercus fusiformis examples at the ladybird Johnson Wildflower Center. My question is, do you also have Quercus virginiana growing there?
Also, is Oak Wilt a disease that ...
view the full question and answer
Possible causes for plant problems in East Texas
September 06, 2007 - I have been an avid gardener for over 35 years in Texas.I love the wildflowers and use them extensively in my 2 acre plot here in East Texas. There is something really bad going on with my garden: pl...
view the full question and answer
Support the Wildflower Center by Donating Online or Becoming a Member today. |