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

Saturday - August 30, 2008

From: Boerne, TX
Region: Southwest
Topic: Compost and Mulch, Diseases and Disorders, Soils, Trees
Title: Yellow, pale green leaves on Cedar Elms in Texas
Answered by: Barbara Medford

QUESTION:

I have had several cedar elms of various sizes planted in our yard over the last 10 years. Only the largest has dark green, healthy looking leaves. All the others have yellowish, pale green leaves. The poor color look is more pronounced this year than before. Do you believe this is a soil problem?

ANSWER:

The diagnosis is that the leaves on the smaller elms are chlorotic, or not having enough chlorophyll in the leaves. Chlorosis is caused by the failure of the tree roots to absorb enough iron from the soil for the creation of chlorophyll, with which the plant manufactures food. Ulmus crassifolia (cedar elm) prefers moist to dry, alkaline soil. In Boerne, in the Texas Hill Country, you have the alkaline soil, but not necessarily the moist soil. But even for a plant preferring a slightly alkaline soil, the Central Texas soils can be too alkaline to permit the plant to take up iron in the soil. In excessively wet or poorly drained soils, the chemistry of the soil changes and iron becomes unavailable. 

Here are some things to try to prevent chlorosis. Improve the soil-work compost in around the roots, this will also help make the soil drainage better. Apply iron sulfate, blending with organic matter like compost and concentrate the mix in soil near plant roots. Apply iron chelate-these organic compounds keep iron soluble and available to roots. Scatter the dry granules within plant's drip line, then water thoroughly. Leaves should start to green up in 2 to 3 weeks. 

The website Ulmus crassifolia (USDA Forest Service) mentions that Elm leaf beetles and aphids can infest the Cedar Elm. The elm leaf beetle can seriously defoliate a tree, but is not a cause of yellowing, and defoliation is usually not too severe. Aphids also may suck fluids out of the leaves, causing them to yellow; again, not a big threat. Aphids can usually be identified by the honeydew they deposit on the undersides of leaves, which often hosts sooty mold, turning the leaves dark gray or black. Another disease that has yellowing leaves as a symptom is Dutch Elm Disease (USDA Forest Service. This disease is usually fatal, and there are other more compelling symptoms on the tree besides yellowing leaves. 

In answer to your question, is this a soil problem, yes, we believe the alkalinity of the soil and/or poor drainage is probably the reason the leaves are turning yellow. If only the smaller trees are showing these symptoms, it is probably because their roots are not getting good enough drainage to permit them to draw on the minerals in the soil. See the first paragraph for compost around the roots and drainage improvement. 


Ulmus crassifolia

Ulmus crassifolia

Ulmus crassifolia

 

 

 

 

More Trees Questions

Oak roots damaged by ax from Austin
July 03, 2013 - Hello. I am attempting to create my own tiny copy of the Wildflower Center within my yard. I'm using all native, drought tolerant plants. My front yard is full of live oaks. I used a sod cutter la...
view the full question and answer

Problems with fruit of Mexican Plum from McKinney TX
May 19, 2013 - MY Mexican plum tree (about 5 years old) has small fruit on it. Some of them are severely deformed, and look rotten almost. They are bumpy and ragged looking. Or they are pasty white,rotten and dried ...
view the full question and answer

Sticky film on oak tree leaves from Whitney TX
September 04, 2012 - What is the sticky film that is coating leaves on our oak trees?
view the full question and answer

Are brown junipers (Juniperus ashei) dead?
November 08, 2011 - If the cedar/junipers in our area are brown, will they ever come back green? Or just clear them out as dead. There are many of them due to the drought. Thank you.
view the full question and answer

Trees that are non-toxic for horses
May 02, 2008 - I live in Ponder, Tx. We have some acreage and horses and wish to plant trees to afford some shade for the horses. Can you tell me what trees are toxic to horses.
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