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
2 ratings

Sunday - February 25, 2007

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders
Title: Control of sooty mold from aphids in Crape Myrtle
Answered by: Joe Marcus

QUESTION:

I have a crape myrtle in my front flower bed that has a sooty black substance on the leaves and trunk. I've done research and understand this is caused by aphids. My question is how do I get the black sooty substance off the tree and what do you recommend for getting rid of the aphids?

ANSWER:

Sooty mold is a fungus, or more commonly a complex of two or more fungal species, that grows on honeydew or on plant exudates. Honeydew is a waste-product of aphids and other plant-sucking insects. As honeydew is excreted by sucking insects, it falls and coats any surface upon which it lands. Sooty mold fungi invade and live upon this sugary coating. These fungi do not infest the leaf ifself. Thus, sooty mold may often be found growing on any exposed surface beneath aphid-infested trees and shrubs. Sooty mold can cause great harm to plants, however, by blocking sunlight to the leaf surface below and diminishing photosynthesis.

Sooty mold can often be successfully removed by rinsing with water from a garden hose. However, this will be most effective after the aphids or other honeydew-producing insects are destroyed. Sometimes sooty mold development is so severe and persistent that only time and exchange of leaves through the growing seasons will remove it all.

Aphids are not especially difficult to control and non-chemical methods are usually very effective. Insecticidal soaps are often the remedy of choice for many gardeners. Various brands of insecticidal soaps may be found at just about any retail nursery or garden center. Be sure to read and carefully follow all label directions when using any pesticide, organic or chemical.

 

More Diseases and Disorders Questions

Failure to thrive of Tex-ash in Tucson AZ
December 02, 2011 - I planted a mature (15') Tex-Ash about a year ago. Lately more and more leaves seem to be browning and it has never filled out. I am concerned I am going to lose it if I don't get it something befor...
view the full question and answer

Replacement Yaupon holly doing poorly in Pflugerville, TX
May 09, 2012 - I had to replace quite a few shrubs after the drought last year. I live in Austin, TX. I have planted 3 dwarf yaupon holly bushes in the exact same place where the previous three same type of shrubs...
view the full question and answer

Is it normal for the bark to fall off an oak tree in Austin, TX
May 02, 2013 - Is it normal for live oak bark to fall off when touched? I am afraid to get near them?
view the full question and answer

Wax myrtle problems from Driftwood TX
September 04, 2010 - We planted 27 wax myrtles on the perimeter of our property last year and were diligent about watering them throughout the drought. They are in very rocky soil (we had to use a jackhammer to dig the ho...
view the full question and answer

Old oak tree dropping leaves in Hazlet Township NJ
July 08, 2013 - I am 84 yrs old and have a 50 year old pin? oak. No more acorns, but the leaves are falling in clumps and are still alive. Every day I fill a huge garden bag with them. I live on a fixed income and...
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
© 2014 Lady Bird Johnson Wildflower Center