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

Brown dead spots on arborvitae in Hillsboro OR
October 12, 2009 - Hello. I live in Hillsboro, OR and have several mature arborvitae as a privacy screen in my backyard. They are on our side of a black chainlink fence separating our yard from a drainage area maintaine...
view the full question and answer

Leucophyllum Resistant to Verticillium Wilt
March 25, 2015 - I need to know which large shrubs are resistant to verticillium wilt? I believe that a few of our Elaeagnus have succumbed to this disease, but being over 15 years old, I am not positive. I am thinki...
view the full question and answer

Changing bloom color from Tulsa OK
June 27, 2011 - How do you change the bloom color?
view the full question and answer

Oak leaf fall causing ivy damage
August 28, 2007 - I read the A/Q in the Austin American-Statesman Saturday, August 25, regarding the leaves falling now from the live oaks. I am experiencing the same thing, but it is the leaves of my post oaks that a...
view the full question and answer

Red oaks that didn't drop leaves in Austin
April 04, 2012 - I have a number of Red Oaks on land that did not drop leaves this past fall. Now these same trees seem to be dead? It seems there's some type of mold/fungus on the trees. Some trees have small patche...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP | STAFF
© 2016 Lady Bird Johnson Wildflower Center