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

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

Leaves browning on non-native willow from in Cumbla PA
July 10, 2011 - We recently planted a willow tree. A lot of the leaves turned yellow and some turned brown, but it is also getting some new buds. my question is, should I take the dead leaves off or leave them there...
view the full question and answer

Care for California lilacs from Portland OR
January 16, 2014 - Hi There, We live in the Portland Oregon area, so temps are moderate and winters are wet. We have several California Lilacs that are about 7ft in height and have created the perfect screen. Love th...
view the full question and answer

Loss of leaves on yaupon in Austin
August 05, 2008 - Last winter I planted a Pride of Houston yaupon. Currently, the leaves at the tips of its stems are green and healthy, but the leaves along the stems are turning dark brown and falling off. Does...
view the full question and answer

Something killing evergreens on Long Island from Baldwin NY
June 06, 2011 - What seems to be killing so many of the evergreens on Long Island - see more and more dying each day - doesn't seem to be a rhyme or reason - can it be helped? Many thanks.
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