Host an Event Volunteer Join Tickets

Support the plant database you love!

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

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 Diseases and Disorders Questions

Watering oaks in Houston, TX.
June 07, 2011 - Our yard (Real County, TX.) has many oak trees. We never water these trees, but I wonder if you recommend watering during this extreme drought. The trees look very stressed and are covered in ball m...
view the full question and answer

Why doesn't Diervilla lonicera bloom in Wisconsin?
June 11, 2015 - I have had a Diervilla lonicera in southeastern Wisconsin for at least 5 years. It has never bloomed. Why? It appears healthy.
view the full question and answer

Elaeagnus sudden death in Waxahachie, TX
May 11, 2015 - I live in North Central Texas and have eleagnus planted along my fence in full sun. Last year one dropped all it's leafs and died. The same is happening to one beside it this year. I have sprayed ...
view the full question and answer

Shy blooming non-native Crape Myrtle, in Littlestown Pennsylvania
July 25, 2011 - My Crape myrtle has been planted about three years, and reached a height of about 4'. It blooms late July and for the past two years, has only had one or two blooms on it. I have a lot of buds whic...
view the full question and answer

Live oaks dropping brown leaves
August 02, 2014 - We have three live oaks and one of them has been dropping quite a few brown leaves over the past two weeks. I looked at pictures of trees with oak wilt and ours do not look like the pictures. I als...
view the full question and answer

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