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Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

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Thursday - July 04, 2013

From: Katy, TX
Region: Southwest
Topic: Diseases and Disorders, Trees
Title: Chlorotic disease in scrub oak from Katy TX
Answered by: Barbara Medford

QUESTION:

Please tell me how to treat my scrub oak as it has chlorotic disease. Parts of the tree are fine and others have yellow leaves. It has not been injured in any way.

ANSWER:

There are four plants native to North America with the common name "scrub oak." The map link following each plant name refers to the USDA Plant Profile Map on that plant showing to what states it is native. In the case of the two native to Texas, the map indicates the Texas counties in which a scrub oak grows natively.

Quercus dumosa (Coastal sage scrub oak) - endemic (growing natively nowhere else) to California (Map)

Quercus ilicifolia (Bear oak) Also known as  Scrub Oak (Map). Not reported as growing natively in Southwest U.S. at all.

Quercus mohriana (Mohr oak)  Also known as shin oak, scrub oak. (Map) West Texas and Panhandle.

Quercus turbinella (Sonoran scrub oak) (Map) El Paso, Hudspeth and Brewster Counties in Big Bend Area of far West Texas.

None of these sound very likely to be garden plants in Harris, Ft. Bend and Waller Counties, in southeast Texas. Is it possible that you got the wrong common name? As long as it is a member of the Quercus (oak) genus, it probably doesn't matter. Chlorosis in the Quercus genus is usually a product of being grown in incompatible soils.

Please read this previous Mr. Smarty Plants answer on chlorosis in another species of oak, Quercus palustris (Pin oak). We hope this helps you establish what your tree is and the best ways to deal with chlorosis.

 

From the Image Gallery


Coastal sage scrub oak
Quercus dumosa

Mohr oak
Quercus mohriana

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