Explore Plants

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
    
 

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
Not Yet Rated

Monday - April 01, 2013

From: Katy, TX
Region: Southwest
Topic: Diseases and Disorders, Pests, Trees
Title: Growths on Shumard Red Oak leaves from Katy TX
Answered by: Barbara Medford

QUESTION:

Our beautiful Shumard Red Oak has developed lots of light green grape like growths on the leaves. Please inform us what this could be and how we should treat it?

ANSWER:

Quercus shumardii (Shumard oak) is, according to this USDA Plant Profile Map, native to Harris and Ft. Bend Counties, which means it is growing in the right place.

We learned in this article from Cornell University, Department of Plant Pathology that Quercus shumardii (Shumard oak) can develop oakleaf blister. This is a fungus and red oaks (which the Shumard Oak is) can be most susceptible to it. The pictures in that article don't look much like what you are describing so we will look further.  From Texas A&M AgriLIFE Extension, Texas Plant Disease Diagnostic Lab here is an article on Oakleaf Blister

Insects that attack the Shumard Oak are June beetles, striped oakworms. cankerworms, forest tent caterpillars, yellow-necked caterpillars, variable oakleaf caterpillars and red-hum[ed oakworms. Shumard oak acorns are subject to attack by acorn weevils. If you suspect any of these, you can search on the Internet for any of them for pictures and more information.

However, we suspect oaks galls. Here is an article from the University of Kentucky Extension Service on Oak Galls. It has no pictures at all, so we will try to find more information. From Google, we found Images of Leaf Galls, some of which look very like what you are describing. If you click on one of those pictures it will show you an enlargement, and if you click on it again, it will take you to the website from which the picture was copied.

Since we are neither entomologists nor plant pathologists, we suggest you consult a trained, licensed arborist for what to do next. It could be that, though unsightly, the problem is no serious threat to the tree.

 

From the Image Gallery

More Diseases and Disorders Questions

Oak tree with browning leaves in Brenham TX
August 16, 2011 - I have a large oak tree in my small back yard. I also have a sprinkler so the tree has been receiving some water. Nevertheless, some of the leaves are turning brown in patches. Would drip watering ...
view the full question and answer

Trees and shrubs turning brown in Dripping Springs TX
October 31, 2011 - Due to the extended drought - a number of trees and shrubs in our Dripping Springs area property have turned brown. Specifically: Live Oak; Agarita; Ash Juniper; Cedar Elm. Is this a dormant stag...
view the full question and answer

What to do about volunteer trees growing beneath a large live oak tree in Austin, TX
January 08, 2013 - We have a large live oak tree. Several volunteer trees are growing directly underneath it and into its branches. I want to cut them down if they are going to hurt the long term health of the live oak....
view the full question and answer

Bulging trunks on post oak
August 05, 2011 - I have a huge post oak with a codominant trunk that is bulging between the two main trunks. The bulging is causing the trunks to spread apart, so one of the trunks is getting much too close to the ho...
view the full question and answer

What to do about powdery mildew on Pavonia lasiopetala?
June 02, 2009 - My Pavonia lasiopetala seems to have gotten mildew this spring. I was hoping that warm weather would get rid of it. Instead it has spread to most of the plants which are located in widely separated b...
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.