En Español

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?


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
4 ratings

Wednesday - May 12, 2010

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders
Title: Red-backed bugs on mountain laurel (Sophoro secundiflora)
Answered by: Nan Hampton


I found red-backed bugs (in fact two end-to-end like the east Texas love bugs) on my mountain laurel which has been losing leaves. Are these bugs the culprit?


Sophora secundiflora (Texas mountain-laurel), according to the US Forest Service "...are primarily pest-free, except for infestations by caterpillars of a moth in the family Pyralidae."  The moth is Uresiphita reversalis (Pyralid moth or Genista broom moth).  You would see the caterpillar and its damage from chewing on the leaves if they were infesting the plant.  Obviously the bugs aren't the caterpillars and since there don't seem to be any other serious insect pests I don't think the bugs are the culprit.  The Forest Service site does mention that the mountain laurels are especially susceptible to phenoxy herbicides.  One of the commonest of these phenoxy herbicides is 2,4-D.  These particular herbicides are used against broadleaf weeds on grass lawns, pastures or in grain fields.  The problem is that they are very volatile and can drift for miles with the wind and effect plants far from their application. They have been especially detrimental to grapevines.  If you or your neighbors have been using any of these on your lawns, it is possible that some has landed on your mountain laurel and is causing the problem. 

Another possibility is that you have had some environmental change where the plant is growing.  Mountain laurels like well-drained soil to grow in.  They don't like having 'wet feet'.  Has the drainage in its vicinity changed?  Is there the possibility that the soil has become compacted by a lot of traffic—foot or vehicle?  If you think that this has happened, you need to remedy this by stopping the traffic and adding a hardwood mulch over the soil surrounding the tree.  It will help protect the roots and eventually work its way into the soil and relieve the compaction. Better yet, you could carefully work some of the mulch into the soil so that when the tree does get water (from rain or supplemental watering) the water gets to the roots and doesn't stand on top of them.  Whatever you do, don't fertilize the tree. In the first place, native plants don't need fertilizing and a plant under stress (as yours seems to be) should never be fertilized.


More Diseases and Disorders Questions

Effect of heavy rains on Lindheimer Muhly
May 04, 2015 - It is April 2015, in San Antonio we've had very heavy rains recently. My Lindheimer muhly, which was looking beautiful, has now turned brown all over. Is this normal or is this a problem?
view the full question and answer

Beneficial earthworms attacked by fire ants
August 04, 2006 - Is there a right way or a trick to releasing earthworms? I have a friend who has an abundance of earthworms in their soil so I took advantage of the situation. I released them in my freshly tilled gar...
view the full question and answer

Potted Plumbago, struggling with the heat, in Spring Texas
June 29, 2011 - Why do some of the leaves of my plumbagos that are grown in large, well-draining planters turn brown? The brown starts on the tips, then extends to the whole leaf. They get several hours of west aft...
view the full question and answer

Failure to thrive of Lantanas
August 06, 2008 - Here at work we have 4 beautiful yellow Santanas(should I say had), the leaves have started to turn brown and no longer blooming. Appears to have a fungus or disease. Please help!
view the full question and answer

Iris Changing Color?
April 03, 2015 - I have some iris planted under a very tall tree and they bloom nicely every February. The original bulbs were given to me when I moved here to Arizona 30 years ago. They have always bloomed white. I h...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2016 Lady Bird Johnson Wildflower Center