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Preventing and Identifying Oak Wilt

Posted by Sharon Rosshirt on Sunday, April 9th, 2017 at 1:03pm.

Now that the weather is warming up and beautiful weekends become commonplace many of you will be looking to complete some yard work. Before diving in though you should be aware of Oak Wilt and the problems that it can lead to for you and your neighbor's trees.  Oak Wilt is caused by the fungus Ceratocystis fagacearum and is a destructive disease affecting live oaks and red oaks in Central Texas.  This fungus can spread tree to tree through roots or by beetles moving spores between trees. Your trees will become vulnerable to infection whenever your oaks have new, open wounds like when you are pruning off unsightly branches.

How Can I Tell If I Have Oak Trees?

In Central Texas, our oak trees are predominately live oaks and red oaks.  A live oak is an evergreen tree (hence “live”) while a red oak is deciduous and will lose it’s leaves and change color in the fall and winter.  Oak leaves have a “lobe and sinus” pattern that makes them very easy to identify.  The lobes are typically pointed with a rounded sinus connecting the leaves to one another.
It can be easy to mistake Red Oak leaves for Maple leaves, the main difference is when they will begin to change color and drop their leaves. Maples will show their colors earlier in the season and will have mostly fallen by the time Red Oaks begin this process.

How can I prevent Oak Wilt?

Fortunately, you can help prevent the spread of this destructive disease with just a little bit of extra caution.
  • Always paint fresh wounds on oaks, including pruning cuts and stumps, with a wound dressing or latex paint immediately after pruning or live tree removal at all times of the year.
  • Clean all pruning tools with 10% bleach solution between sites and/or trees.
  • If possible avoid pruning or wounding of oaks during the spring (currently defined as February 1 through June 30)

You may read on gardening or tree care sites about wound paints or sealers being toxic to trees or a bad, old school idea, but oak trees in Central Texas where oak wilt is prevalent are a clear exception to that assertion.

Regardless of the reasons or time of year, proper pruning techniques should be used. These techniques include making proper pruning cuts and avoiding injurious practices such as topping or excessive crown thinning. If you are uncertain about any of this information, you should consult with a Texas Oak Wilt Certified arborist, ISA Certified Arborist, or an oak wilt specialist from a city, county or state government agency such as the Texas A&M Forest Service or Texas A&M AgriLife Extension Service.

More Information

If you are interested in learning more or need to find an expert to help with a potential problem visit
If you suspect that your trees may be suffering from oak wilt visit this website to walk you through identification of the disease and steps to treat it.

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