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

Dog-safe Privacy Screen for Ocala, FL
June 25, 2015 - Am desperately searching for fast growing privacy that would be non toxic to dogs in Ocala, Florida (zone 9 I think). Wanted Leland cypress but due to toxicity it won't work.
view the full question and answer

Trees safe near walls from Rio Grande City
March 24, 2012 - What trees can be planted near the house that the roots won't break my walls?
view the full question and answer

Native holly (ilex) for Austin area
May 28, 2006 - Hi--my brother and his family live in Austin, TX--their german shepard "Holly" just died (she was 13)--I was throwing around the idea of sending them a holly plant of some sort to have in honor of H...
view the full question and answer

Soapberry Transplant shock symptoms
July 21, 2006 - Please suggest a cause & cure for general yellowing of the leaves of Western Soapberry when planted in the ground 20 miles NW of Austin (thin, poor clay over limestone). Trees still in containers are...
view the full question and answer

Allelopathy in Sassafras albidum
January 11, 2012 - Sassafras albidum description says "Sassafras is allelopathic and can discourage the growth of certain other plants within its root zone." My question is: WHICH plants are susce...
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 | STAFF
© 2015 Lady Bird Johnson Wildflower Center