Native Plants

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

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

rate this answer

Not Yet Rated

Tuesday - October 27, 2015

From: Center Point, TX
Region: Southwest
Topic: Diseases and Disorders, Herbs/Forbs
Title: What is the black stuff growing on my thoroughwort?
Answered by: Jimmy Mills

QUESTION:

What is the black stuff on my thoroughwort plant's leaves that is killing the plant?

ANSWER:

There are several species of plants that have the common name of thouroughwort, and I suppose most of them are susceptible to this “black stuff” that is probably an infection of sooty mold.

The sooty mold is a fungus that is living on the honey dew on the leaves which is excreted by aphids and other sap-sucking insects living on the plants such as scale. As honeydew is excreted by the sucking insects, it becomes airborne and falls and coats any surface upon which it lands in the area.

I'm including three links that will tell you more about aphids, honey dew, and sooty mold.

aphids, UC IPM

Sooty mold, UC IPM

Sooty mold, USDA

More Herbs/Forbs Questions

Evergreen for sunny, dry area under a maple in Connecticut
October 10, 2015 - I have a sloped, very sunny, dry area under a maple. I was wondering if Sweet Fern would be a likely candidate for this area. I would like it to be evergreen and to be able to survive under mounds of...
view the full question and answer

Making Ruellia nudiflora thicker in pot from Tucson AZ
June 25, 2012 - Can Ruellia Nudiflora be propagated in the same pot as the parent plant? Can it be cut back to stimulate a denser plant? I have plants in several pots and would like to 'thicken' the plant. Tha...
view the full question and answer

Raised beds over lateral lines in Solgohachia AR
January 02, 2010 - I would like to build raised flower beds over my lateral lines. They would be planted with strawberries and perennials. Will this cause any problems with the absorption into the ground or not lettin...
view the full question and answer

Nativity of Salvia coccinea (scarlet sage)
September 14, 2011 - Is Salvia coccinea native to Florida? In wikipedia they say it is native to Mexico.
view the full question and answer

Caterpillars devouring Blue Wild Indigo in Jesup GA
September 05, 2011 - I have a false blue indigo growing in my garden. Every spring it gets defoliated by Genista moth caterpillars. It usually doesn't put out new growth until the next spring. This summer, it has put ...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.