Rent Shop Volunteer Join

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
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

Control of sooty mold from aphids in Crape Myrtle
February 25, 2007 - I have a crape myrtle in my front flower bed that has a sooty black substance on the leaves and trunk. I've done research and understand this is caused by aphids. My question is how do I get the bl...
view the full question and answer

Brown leaf problem with herbaceous blooming plants from Greenfield MA
May 28, 2014 - I have 3 plants cimicifuga brunette and lots of astile planted near each other. Suddenly the edges of leaves have turned brown and shriveled and spread to entire plant, all of them. It has not been ...
view the full question and answer

Problems with Blackeyed Susans in Philadelphia
May 26, 2009 - For 8 years I successfully grew Black Eyed Susans in a fairly large area in my garden. For the last two years,almost immediately upon pushing through the ground they develop black spots and then appe...
view the full question and answer

Failure of TX bluebonnets to thrive
May 28, 2015 - We have had extraordinary luck with bluebonnets growing in our driveway of decomposed granite--until last year and this year. The bluebonnets seem to be drying up and wilting away. The ones in other a...
view the full question and answer

Can Live Oak suckers be mowed during Oak Wilt spread season in Austin?
April 12, 2010 - I live in South Austin, not too far from the Wildflower Center. I have a Live Oak in my yard with a substantial amount of sucker growth from the roots. Can I mow them freely throughout the year, or ...
view the full question and answer

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