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
4 ratings

Wednesday - August 08, 2012

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders, Trees
Title: Pecan leaves falling off the trees in Austin, TX.
Answered by: Jimmy Mills

QUESTION:

Why are the pecan tree leaves turning black, sappy and falling off the trees, in great quantities? This has happened since the recent rains, all through the Allandale area.

ANSWER:

Austin is presently experiencing an onslaught of honeydew. Honeydew is a waste-product of aphids and other sap-sucking insects 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. Pecan trees are only one of several kinds of trees and shrubs that are being attacked by the aphids.

This article from University of Minnesota Extension, another from the University of Kentucky College of Agriculture,  and a third from the University of California Davis give a rather thorough explanation of honey dew and aphids, and their effects on plants. The blackening of the pecan leaves is because of an infestation of sooty mold that grows on the honeydew. This article from the USDA tells how to recognize and control sooty mold.
Another problem is that the sticky sap gets all over cars. This link has information about sap removal.

 

More Diseases and Disorders Questions

Will Mountain Laurels be harmed by juglones from my pecan tree?
May 06, 2009 - Hi. I just bought a house. It has a big pecan tree at the edge of the front lawn next to the street. I guess it's about 25 feet from the front of the house. I was thinking of planting mountain la...
view the full question and answer

Problems with yaupon from San Angelo TX
April 08, 2012 - We have a 3-yr-old yaupon holly entering its 3rd summer. We have put store-bought wood-chips under the tree several times since it was planted. A plant has grown under the tree, possibly out of the ...
view the full question and answer

Large oak with possible Laetiporus fungus
November 29, 2011 - We have a huge oak tree in front of our new house. After the first rain this fall a large fungal growth appeared in an old knothole of the tree and I would guess that it is Laetiporus. A neighborho...
view the full question and answer

Need help diagnosing a problem with Bur Oak in Plano, TX
April 28, 2010 - I planted a bur oak 8 or 9 years ago. It has grown beautifully until this year. When opening, the leaves are very small (a couple inches) and there are lots of seeds (catkins?). I would hate to los...
view the full question and answer

Problems with red tip photinia in San Antonio
March 29, 2009 - I have a red tip photinia that's about 20 years old and about 20 feet high--it is big! I noticed last summer the highest leaves looked droopy all the time even with deep watering and now that portion...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP | STAFF
© 2016 Lady Bird Johnson Wildflower Center