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
Not Yet Rated

Wednesday - July 25, 2007

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders
Title: Oak diseases as a result of wet, cool weather
Answered by: Damon Waitt

QUESTION:

The mature live oak trees in our back yard have been dropping leaves just like they do in March, but this is July! Small to medium spots on the leaves turn brown before they drop. The veins of the leaves are still green. The trees are growing on a well-drained slope in shallow soil over limestone here in the hill country just west of Austin. Asiatic jasmine grows under some, but not all, of the trees. This has never happened in the past 13 years. Does it have to do with the heavy rainfall? Will they survive? Do we need an arborist consult?

ANSWER:

It is our good fortune that James Houser, the Texas Forest Service Oak Wilt Technical Coordinator, recently addressed this question on the texasoakwilt.org website. You can click here to view a pdf version of his article with images.
"Abundant rainfall and cooler than normal temperatures this spring and summer, oak trees are infected with a variety of leaf diseases that cause significant discoloration of leaf tissues and defoliation. Symptoms include a spotting and/or yellowish mottling of the leaf tissue, blistering and deformity of the leaf margins, small twigs with brown leaves randomly distributed within the tree canopy, and small gold fruiting structures on the undersides of leaves. The trees are frequently shedding these leaves as the leaf disease matures.

Diseases that can be responsible for these problems include Actinopelte spp., Oak leaf blister, Diplodia spp., Anthracnose, and Oak rust among others. These problems are only confined to the leaf tissues, though with Diplodia spp. small twigs an inch or two long die. Branches remain alive and viable on the tree for new leaves to form. The trees are not dying. Fungicides are ineffective at this point as new infections do not occur with elevated night temperatures during the summer. Raking up and disposing of the leaves on the ground is a good strategy to remove the local inoculum. This is a natural occurrence during high rainfall years and the trees will recover on their own.

This is not oak wilt. Oak wilt leaf symptoms are completely different. Also a pattern of mortality in the stand of trees over time is not apparent, i.e. an infection center radiating out over the landscape for several years. Trees in Texas encounter many problems from our stressful weather conditions. Last year, drought was responsible for damage to the trees. This year too much moisture plays a role. Yet, trees, especially oaks, are tough. They go through these cycles of nature and keep on growing."

 

More Diseases and Disorders Questions

Oaks at Wildflower Center from Wimberley TX
September 05, 2012 - I know you have numerous Quercus fusiformis examples at the ladybird Johnson Wildflower Center. My question is, do you also have Quercus virginiana growing there? Also, is Oak Wilt a disease that ...
view the full question and answer

Non-native invasive carrot wood tree losing leaves in Alpine CA
April 22, 2014 - My carrot wood tree is losing all of its leaves. The tree is about 15foot high & 13 years old. Could it be gophers? The tree was trimmed 1 year ago.
view the full question and answer

Problems with Carolina Laurel Cherry from Pflugerville, TX
September 02, 2011 - In 2007 we planted 7 Carolina Laurelcherry (Prunus caroliniana)across our back fence. Everything was fine until this year. Three of the trees seemed to get sick and a local arborist said the roots ne...
view the full question and answer

Watering oaks in Houston, TX.
June 07, 2011 - Our yard (Real County, TX.) has many oak trees. We never water these trees, but I wonder if you recommend watering during this extreme drought. The trees look very stressed and are covered in ball m...
view the full question and answer

Leaves wrinkling on Tecoma stans from San Antonio TX
August 16, 2013 - My two year old esperanza (planted in the ground) froze back last winter, came back from the roots & has been doing well all summer. Recently one branch has leaves that are nice & green but very wrin...
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