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?


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
Not Yet Rated

Friday - October 02, 2009

From: Georgetown, TX
Region: Southwest
Topic: Pests, Shrubs
Title: Purple sage with black residue on leaves in Georgetown TX
Answered by: Barbara Medford


I have 2 very healthy tx. purple sage that have developed a black residue on some leaves, and is a "sticky" substance..any ideas what this is and how to treat???


The Curse of the Common Name has struck again. You see, there are two very dissimilar plants that carry the common name "purple sage." One is Leucophyllum frutescens (Texas barometer bush), which we call cenizo and which is native to Central Texas. Four others are members of the genus salvia, a herbaceous blooming plant: Salvia dorrii (purple sage), Salvia dorrii ssp. dorrii (purple sage), Salvia dorrii ssp. dorrii var. incana (purple sage) and Salvia leucophylla (San Luis purple sage). While none of them are native to Texas, they could probably have been purchased from area nurseries.

In this case, which plant it is doesn't really matter because we think you have aphids, which are usually small and difficult to see, and the black stuff is a sooty mold which has grown on the sticky exudate of the aphids, called honeydew. This University of California Integrated Pest Management article on Aphids gives you information on control.  Neither the aphids nor the sooty mold are likely to cause real damage to the plant but are unsightly. When you read the article you will learn that a good stream of water on the plant will wash many of the offending little bugs off, and they can't get back up there after they are washed off. 

From our Native Plant Image Gallery:

Leucophyllum frutescens

Salvia dorrii

Salvia dorrii ssp. dorrii

Salvia dorrii ssp. dorrii var. incana

Salvia leucophylla




More Pests Questions

Loss of leaves from globe willows in Utah
July 26, 2008 - I have four globe willows that have been in my back yard for the past 6 years. For the past month they have been losing their leaves from the bottom up. We had aphids in some of our other trees and ...
view the full question and answer

Fungus Spots on Native Bush Honeysuckle
December 03, 2010 - My native bush honeysuckle plants that I have along my back fence have leaves that are turning yellow with spots. It appears to be a type of fungus, but not powdery mildew. Any suggestions as to what ...
view the full question and answer

Controlling sandburs from Austin
February 24, 2013 - Hello, What is the best way to prevent sticker burrs from growing in a rocky bed with no grass. There are many other plants we want to preserve and a drip line to keep them watered. We have 2 small k...
view the full question and answer

Bugs eating new growth on Mountain Laurel shrubs from Dripping Springs TX
April 02, 2013 - What is eating the new growth on my mountain laurel shrubs? One plant has red bugs and the other has black (could they be love bugs?). Is there something I can do to preserve the new growth?
view the full question and answer

Will Canada geese eat Asclepias tuberosa from Cape May Court, NJ
May 20, 2014 - Will Canada geese eat my butterfly milkweed (Asclepias tuberosa)? I know this plant is deer resistant. I really want to plant some on sandy bank near pond in my back yard, but I fear the geese will ...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2015 Lady Bird Johnson Wildflower Center