En EspaŅol
Share

Ask Mr. Smarty Plants

Mr. Smarty Plants - Leaf Galls on Live Oak

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

Tuesday - March 20, 2012

From: Austin, TX
Region: Southwest
Topic: Pests, Trees
Title: Leaf Galls on Live Oak
Answered by: Becky Ruppel

QUESTION:

Hi - I have a live oak tree that always seems to have thinner foliage than our other two. Upon closer examination today I found small brown balls all over the mature leaves. The balls look and feel very much like peppercorns. What is this, and is this a danger to the tree? I did read the other post about Woody oak twig galls but based on that post I don't think that is what is going on here. Thank you for your time.

ANSWER:

The tree in question sounds like it has leaf galls formed by the Mealy Oak Gall Wasp Disholcaspis cinerosa.  This wasp forms both stem and leaf galls depending on the stage in its life-cycle.  Galls are formed when an insect (in this case a type of tiny wasp) lays an egg just under the surface of a stem or leaf.  A gall is formed because the tree is stimulated by the presence of the egg, and eventually the hatched larvae, to grow a structure around the wounded area.  Galls are very common in oaks and are not considered harmeful to the health of trees.

For more detalied information about Mealy Oak Gall Wasp see the Mr. Smarty Plants post by Nan Hampton that talks about the specifics of the wasp, its reproduction, life-cycle, and affect on trees. 

The links in that post appear to no longer work. Below are updated links for the information cited in that answer about Mealy Oak Gall Wasps. 

"The Mealy Oak Gall on Ornimental Live Oaks in Texas"

"Gall Making Insects and Mites"

 

More Pests Questions

Green cyst-like growths on Texas persimmon leaves
September 20, 2013 - We have a mature Texas persimmon. We just noticed some green cyst-like growths on the tops of some of the leaves. The undersides of those leaves have black spots where the growths are. They looks like...
view the full question and answer

Invasive native blackeyed susans from Warren OH
August 07, 2013 - In our demo garden we master gardeners in NE Ohio have been unable to get rid of black-eyed susans which have, like the other person, prevented or "killed" the other perennial plants. They are spre...
view the full question and answer

Removing yaupon hollies from yard in Austin
July 04, 2009 - We recently moved into a home w/ way too many and much too large (20-30') yaupon holly's in the back yard. I had some of them cut down, but they keep coming up from the roots of the old trees. How ...
view the full question and answer

Damage to ruellia in Monroe LA
October 26, 2009 - I have hundreds of Ruellia Brittoniana. Dwarf Katie White, Katie Blue and Katie Pink. I am finding holes in some of the leaves, Some just have notches chewed out of them. Some of the leaves have...
view the full question and answer

Infestation of flies around euonymus in summer
March 02, 2008 - I have 3 shrubs planted in my backyard. I think they are a type of euonymus (but I'm not sure). My question is why do they attract huge nasty flies. The first year we had them they didn't. But the l...
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