Explore Plants
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.
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
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
Why are our Euphorbia myrsinites plants dying in Soquel, CA?
August 02, 2010 - Some of our Euphorbia myrsinites die in our garden for reasons we cannot understand. Do you have any explanation or suggest area we should be looking for?
view the full question and answer
Juniper-apple rust galls
April 24, 2010 - I have Red Cedar trees in my yard. I have just noticed something that looks like a reddish brown squid-like bloom about the size of a small orange. Is this normal or is it a fungus?
view the full question and answer
Why isn't my recently planted Mexican Redbud growing in Georgetown, TX?
April 11, 2010 - I planted a container-grown Mexican Redbud in early March. As of April 5th, it is showing no signs of buds or leaves. Other redbuds in the area (possibly Texas redbuds) have been blooming for severa...
view the full question and answer
Live oak leaves yellowing from Denton TX
January 26, 2012 - In autumn of 2010 I planted 10 live oaks about 6 to 7 ft. tall. I have see that during the month of Dec. 2011 to Jan. 2012 they are showing some yellow leaves. What can I do to help them?
view the full question and answer
Why is my recently planted Esperanza doing poorly in Texas City, TX?
May 28, 2010 - I have an Esperanza I planted about 2 months ago. It has been doing well, except today all but one stem of the plant is wilting and the leaves are rolling. I see no bugs on the plant. Any idea what...
view the full question and answer
 |
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. |
