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NHNCT HomeNHNCT News - Oak Wilt


Oak Wilt Disease in Dallas Co.

Oak Wilt is considered to be one of the most destructive tree diseases in the United States. Over 10,000 trees have already died of oak wilt in the Austin area alone.

This disease affects live oaks and red oaks (a group of several oaks) in our state but not oaks in the white oak family. As we have increased in our knowledge of this disease, we have become increasingly aware of its presence in the Dallas area.For more information and pictures please access the The Cooperative Oak Wilt Suppression Project web page.

The linked map below (see the Acrobat link below) shows the locations of all the known and confirmed oak wilt centers in the immediate Dallas area. There are certainly other "spots" that have not been reported yet. As they are confirmed, we will add them to the map.

-Courtney Blevins, TFS Dallas



Oak Wilt Update for D/FW

By the time the newsletter is mailed out in July (1998), at least 30 new Oak Wilt infection centers will be detected since March 1st of this year and added to the previous list of over 150 documented cases in Tarrant and Dallas Counties. An Oak Wilt "center" may only be one tree or a grouping of oak trees. That makes the actual number of trees lost this year just in these two counties very substantial, ...especially to those homeowners and the neighborhoods around them that have lost trees.

Oak Wilt is a fungus that clogs up the part of the tree where water travels from the root system to the leaves. Except for the fruiting part of the fungus which occurs on red oak trees in the spring, you cannot "see" the fungus, only the symptoms of the fungus. Live oak trees and red oak trees (blackjack, Spanish, and Shumard oaks) are the trees that are susceptible to this disease. Oak trees in the white oak family such as post oaks and bur oaks do not die from the disease in our area. Insects spread the disease in the spring from infected red oaks to wounds on healthy trees. It is also spread tree to tree by connected or grafted root systems which is an often occurrence on these species.

  
When a live oak tree has Oak Wilt it may die in 3-6 months. Some of the leaves on the tree and those shedding on the ground will have a pattern where the veins are highlighted a different color from the leaf. They will look as if they have a halo or as if you tried to inject a die into the veins. When red oak trees have Oak Wilt, they may die in 1-3 months. Their leaves actually go through a stage of looking wilted on the tree (which began on May 1st of this year in our area), then to a color of bronzy green then brownish-red hanging on the tree awhile before they eventually fall. Also, laboratory tests can confirm the existence of the disease.

Prevention of the disease includes minimizing wounds on trees (especially from February 1 to June 1), painting fresh wounds as they occur, and covering fresh cut firewood with a clear plastic or buying seasoned firewood. Suppression of the disease once a center is started may mean removing infected red oaks, trenching to cut connecting root systems to isolate the disease from surrounding trees, and injecting highest value trees with the fungicide Alamo. Alamo can protect individual trees but the disease will continue to spread to connected and unprotected trees.

If you suspect you may have Oak Wilt or if you have further questions, please call the Texas Forest Service, Texas Agricultural Extension Service, or your local city forester for help.

Jan Davis
Staff Forester
Texas Forest Service



Oak Wilt Map
(See HELP for obtaining free Acrobat reader software.)


Common Questions About Oak Wilt Texas Forest Service site.