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 of 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 Trees Questions

Black walnut herbivory
June 13, 2005 - We moved to Texas just about a year ago and have loved it here. This past January we visited the Wildflower Center and obtained some black walnut seeds. Up until last night the tree was doing well p...
view the full question and answer

Live oak wobbling in the ground from Austin
May 02, 2012 - I have a live oak that was not planted firmly in the ground by the subdivision builder's landscapers. The entire tree is wobbly to the touch and it has come close to dying as result of windy condit...
view the full question and answer

Juniper as host of cedar-apple rust
July 17, 2007 - Thanks for the helpful advice on the Eastern Red Cedar. I was wondering if you could ease my mind about a potential problem. I have read up on some of the native plants in my area in a very good book ...
view the full question and answer

How many native trees in U.S. from Clarkson MI
May 18, 2011 - Does anybody have any numbers on how many native trees there are in the entire United States?
view the full question and answer

Privacy hedge for Dallas area
February 21, 2010 - We live in the Park Cities area of Dallas, and our neighbors are right on top of us. Our lot is small, but I'm looking for a privacy hedge or small tree to plant along the side of the fence. It needs...
view the full question and answer

Smarty Plants's Facebook profile 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.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center