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

Dying non-native St. Augustine grass from Austin
May 02, 2013 - Although we all know St. Augustine grass is not a good thing, I am stuck with it and am trying to save areas that appear to have take-all fungus. I have done much reading online and have tried peat m...
view the full question and answer

Leaf burn on hydrangeas
July 11, 2008 - What causes my leaves to burn on my healthy hydrangeas?
view the full question and answer

Oak Bark Loss in Arlington, TX
May 04, 2013 - I have multiple oak trees in my yard (in north texas) that have begun to lose their bark in small chunks. I'm in the middle of the city so their are no deer and yes it's been a dry 2 years but this...
view the full question and answer

Problems with Escarpment black cherry from Ponder TX
February 11, 2011 - I have an escarpment black cherry that is about three years old and about 9 feet tall. It was healthy until this last summer when its began to bark peel and sap run out at the base of the tree. The af...
view the full question and answer

Splitting bark on non-native mimosa from Buda TX
June 24, 2012 - What would cause my Mimosa tree to have splitting bark. I've only lived in this house for 8 months and am learning about this tree. The other tree seems fine. It looks as though it split and then ...
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