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
1 rating

Friday - October 19, 2012

From: Houston, TX
Region: Southwest
Topic: Pests, Trees
Title: Are fuzzy oak leaf galls harmful to post oak trees?
Answered by: Nan Hampton

QUESTION:

Are the fuzzy balls on the undersides of our post oak trees harmful?

ANSWER:

The fuzzy balls are galls formed by the tree leaf in response to the feeding of the larvae hatched from an egg deposited by a tiny gall wasp in the Family Cynipidae, Genus Andricus.  Here are photos of Andricus quercusflocci galls that form on leaves of Quercus alba (white oak) and Quercus prinus (chestnut oak).  Andricus pattoni is reported to be the species that lays eggs on postoaks, but I could find no photos for that species of gall wasp.  Here is a link to an article about other Oak Cynipid Galls from the Department of Entomology, University of Minnesota.  You can see other types of galls in this article from the University of Wisconsin-Milwaukee and here is more information and photos from the University of PennsylvaniaHere is a link to an article on Randy Lemmon's Gardenline on KTRH radio about galls on oak trees in Houston in 2010.

In general, the galls are not harmful to the trees and there is really no insecticide that is effective since the wasps are tiny and not easily seen, plus the larvae are well-protected from pesticides within the galls.  Additionally, insecticides applied are very likely to be harmful to beneficial insects.

 

More Trees Questions

Pruning an oak tree in Missouri in February
February 09, 2009 - Can I prune an oak tree in Missouri in February?
view the full question and answer

Is there a recommended list for Texas Eastern Cross Timbers?
August 29, 2011 - Is there a recommended list for Texas Eastern Cross Timbers?
view the full question and answer

Safe branch length of oaks in Clayton NC
November 06, 2011 - I have 2 very large oak trees in my yard and I am concerned about the length of the branches over the house and driveway. Most seem larger than 4" in diameter. What is a safe length for these branc...
view the full question and answer

Loss of bloom on Fremontodendron californicum in California
June 11, 2009 - The flowers on my Flannel Bush all died at once I have noticed a sappy substance at the base of the trunk. There are still some flowers on bush but most are dead. It has been blooming since Feb. Is ...
view the full question and answer

Recovering neglected garden space from Grapevine TX
March 22, 2014 - I live in Grapevine TX (Dallas). I just moved into a house where almost the entire large backyard is covered by oak trees that shed tons of leaves throughout our mild falls/winters. The yard has not...
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