En EspaŅol

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
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
 
rate this answer
1 rating

Monday - June 15, 2009

From: Leander, TX
Region: Southwest
Topic: Diseases and Disorders, Trees
Title: Problems with Mountain Laurel in Leander TX
Answered by: Barbara Medford

QUESTION:

My 13 yr old Mountain Laurel tree is sick. It has lost most of its leaves after blooming this spring. The twigs seem to still be pliable so I assume alive. I saw no moth worms or bags this year, just the loss of leaves. Shall I just have patience and it will return to its glorious state?

ANSWER:

Sophora secundiflora (Texas mountain-laurel) is truly one of the treasure native plants of Texas. It is puzzling that it would have done so well up until it bloomed this Spring, and then began to decline. We did some research trying to find a clue to what has happened and didn't come up with the perfect answer. All we can do is give you some questions to ask yourself about something that has or has not happened recently that might have caused this. First of all, a Texas mountain laurel will not tolerate compacted soil. Over time, has the soil around this tree's roots been walked on a lot, maybe some vehicle is being parked nearby and perhaps over the roots? If so, stop whatever has been causing the compacting, and spread a good quality shredded hardwood mulch over the root area. This will shade the roots, protect the ground surface and, as it decomposes, add to the drainage capability of the soil. We are sure you already know that this plant cannot tolerate wet feet, and needs a well-draining alkaline soil. We found no pests nor diseases of "any major concern" of this plant. The Genista caterpillar can chew the leaves, but said you found no indication of insect damage. You should also know you should not ever fertilize this plant. Most native plants are so well-adapted to their area the don't need fertilizer, and this is certainly one of those plants.

Finally, and we sure hope this is not what happened, the Texas mountain laurel is very susceptible to phenoxy herbicides. These are herbicides used for killing broad-leaf plants, weeds, and usually applied by spraying. The Sophora secundiflora is, of course, a broad-leaf plant. Is there any possibility that a herbicide was applied in the area by you or a neighbor? Perhaps a landscaper putting down "weed and feed" fertilizer? That fertilizer feeds the grass, which is a monocot, and kills the broad leaf plants, which are dicots. Application on a windy day (of which we have plenty in Central Texas) could cause the dissemination of the herbicide beyond the target area. If that happened, we're not at all sure the tree can be saved.

Obviously, for whatever reason, the plant is stressed. Although it has been in the ground for 13 years, about all we know to suggest is that you treat it as though for transplant shock. Trim off the upper 1/4 to 1/3 of the plant. Make sure the drainage of the soil around it is still good, then water it deeply but infrequently. This is a tough desert plant, well-adapted to our conditions in Central Texas, and we can hope it will pull through. 


Sophora secundiflora

Sophora secundiflora

Sophora secundiflora

Sophora secundiflora

 

 

More Diseases and Disorders Questions

Leaves falling off recently transplanted mature Mountain Laurel
July 05, 2006 - I have recently purchased a Mountain Laurel for my backyard landscaping. It is a fully matured ML standing over 9 feet tall by 6 feet wide. Since it was planted (about 6 weeks ago) it has been losin...
view the full question and answer

Salvia farinacea and rust fungus from Kerrville TX
February 22, 2014 - Are Henry Duelberg salvias (Salvia farinacea)susceptible to rust fungus?
view the full question and answer

Huisache tree is not thriving in Kerr County, TX.
May 18, 2011 - Our landscaper planted a Huisache tree in our back yard (Kerr County). It was planted about 3 years ago. It has grown considerably (about 15 feet tall)but it has never flowered and is always late in...
view the full question and answer

My Mock Orange fails to flower in Redmond, WA.
July 06, 2011 - I planted a Mock Orange shrub about 5 years ago. The first few years, it only produced leaves but no blossoms. Then, last year, it finally produced 4-5 blossoms on 2 of the branches. This year, it a...
view the full question and answer

Transplant shock in Vacccinum corymbosum (highbush blueberry)
June 28, 2007 - Blueberry plants - We planted Northland and Blue Crop, 2 of each. All 4 plants have some leaves that are turning brown. This starts at the tip of the leaf, eventually encompasses the entire leaf, a...
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP | STAFF
© 2015 Lady Bird Johnson Wildflower Center