Contact Us Host an Event 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
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

Replacement for non-native Italian Cypress in Austin
July 10, 2011 - I would appreciate your assistance with some native plant options to replace Italian Cypress trees in the Arboretum area of Austin, TX. I have 12 of the trees on the north side of the house to obstru...
view the full question and answer

Oak bark problems from Stillwater OK
May 14, 2012 - In my clients large oak tree there is bark stripped from the limbs in small pieces. No piece is larger than 1 inch by 1 inch and occurs on limbs high in the canopy. It does not look like squirrel doin...
view the full question and answer

Will a gift yucca survive in Northwest Arkansas?
June 28, 2011 - Had received a yucca tree as a gift and wondering if it will survive in the ground here in northwest Arkansas. It has a complete tropical look compared to my regular yucca plants. I believe it's actu...
view the full question and answer

Why is my Ash drooping?
June 22, 2009 - Last spring, I bought a house in Austin, TX with a large Ash tree in the front yard. It looked fine last year, but has been looking funny since it leafed out this spring. It's as if the leaves are we...
view the full question and answer

Evergreen plants safe for horses in Louisville, Kentucky
May 16, 2010 - I have a horse farm in Louisville, Ky. I want to plant evergreen plants along the walls in front of the horse barns. What types of plants are not toxic to horses can I use? Thank you so much for all y...
view the full question and answer

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