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Wednesday - June 20, 2012

From: New Braunfels, TX
Region: Southwest
Topic: Diseases and Disorders, Pruning, Trees
Title: Trimming oaks and elms from New Braunfels TX
Answered by: Barbara Medford


I would like to trim my live oaks and elm trees at the same time, if possible. I think they are American Elms. When is the best time to do this and avoid oak wilt and Dutch elm disease? Should all cut branches be treated with tar or black spray paint?


If you are bringing in professional licensed arborists to trim your trees at the same time, that is a good idea. If you are planning to have them trimmed before November, that is a bad idea. Sometimes woody shrubs with blooms can be trimmed at other times of the year to enhance blooming, but as a general rule planting and pruning should be done in cold weather when the plants are dormant.

The Live Oak is a very special case. You are definitely in the Oak Wilt danger area in Central Texas, which means touch-it-not until November at the earliest. We suggest that anyone caring for Live Oaks in this area go to oakwilt.org and read all the dos and don'ts of oak care. In answer to your question on painting cut areas, yes, we do recommend painting any cut area bigger around than your thumb with a paint specifically formulated for tree wounds. There is no cure for Oak Wilt, and prevention is the only way to go. The best prevention is to avoid any kind of wound to the oak bark, such as banging it with motorized equipment (lawn tractor) or cutting with a weedeater. Any break in the bark will result in exuding of sap, which will attract the nitidulid beetle, who loves the sap and may have the fungus that causes Oak Wilt on his body from an already diseased Live Oak from which he got his last snack.

On pruning Ulmus americana (American elm): Since you are particularly concerned about Dutch Elm Disease, we found this article from the USDA Forest Service on How To Save Dutch Elm Diseased Trees by Pruning. From eHow, here is an article on When to Prune Elm Trees. Frankly, we still think the best idea would be to bring in professionals with the know-how and right equipment and do the pruning all at once.


From the Image Gallery

Escarpment live oak
Quercus fusiformis

Escarpment live oak
Quercus fusiformis

Escarpment live oak
Quercus fusiformis

American elm
Ulmus americana

American elm
Ulmus americana

American elm
Ulmus americana

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