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Saturday - July 26, 2014

From: Houston, TX
Region: Southwest
Topic: Pruning, Trees
Title: Pruning Post Oaks
Answered by: Anne Van Nest

QUESTION:

I live in Houston and have two post oaks. One is right by my house. I'd like to trim them but was told they are sensitive and might die if I trim them. Is this true? What is the right course of action?

ANSWER:

Post oaks, botanically known as Quercus stellata are the most common oak in Texas and like to grow in sandy or gravel soils. The Lady Bird Johnson Wildflower Center Native Plant Database has the following information about the post oak:

Post oak is the most common oak throughout Texas. The typical places to see it are sites with sandy or gravelly soils. Its acorns are an important food source for deer, squirrels, wild turkeys and other wildlife. Larval host for several butterfly species. This plant is common in the central and southern forest regions, where it is a medium-sized tree. This is the ultimate drought resistant tree, but also grows in soggy, flatwoods soils. In dry portions of the western part of its range it is smaller. Its roots are extremely sensitive to disturbance. Not often used in landscape situations. Slow-growing and long-lived.

White oaks (the group to which post oak belong), are resistant to the oak wilt fungus and rarely die from this disease. Pruning, through the creation of open wounds, is a factor in the spread of the disease. Perhaps this is why you were told that trimming your tree would be harmful. Even though this tree is not hugely susceptible to oak wilt, it is a good idea to follow the same protocols to prevent new infections. Do not prune from February through June and paint all wounds and pruning cuts immediately.

One good resource about these trees is the article, The Care and Feeding of Post Oaks in Denton County by John Cooper, Denton County Extension Horticulturist. While it doesn't specifically address pruning, it has a lot of great information about keeping these trees healthy including feeding and steps to preserve the roots.

The USDA had an excellent factsheet on the post oak and does discuss pruning with the following statements: "needs little pruning to develop a strong structure" and the branches "droop as the tree grows, and will require pruning for vehicular or pedestrian clearance beneath the canopy; showy trunk; should be grown with a single leader."

 

From the Image Gallery


Post oak
Quercus stellata

Post oak
Quercus stellata

Post oak
Quercus stellata

Post oak
Quercus stellata

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