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Q. Who is Mr. Smarty Plants?

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Thursday - July 14, 2011

From: Salado, TX
Region: Southwest
Topic: Diseases and Disorders, Trees
Title: Care of a live oak with decay and perhaps fungus on trunk
Answered by: Guy Thompson

QUESTION:

I have a huge live oak on my property in Salado that just lost a very large branch. The branch had decay in the center and also has a variety of bugs in it, espeically since it has been on the ground for a few days now. what can I do for this tree to help it survive. I'm not sure how much rot is in this tree, but can see a darkend vein down one side ? Also, there is a type of white substance on the bark on one side that is hardened and on the ends of bark outcrops or projections. I've never seen anything like it. Otherwise, the tree looks perfectly healthy all leaves green even on the branch that broke off.

ANSWER:

Decay in the center of a branch or the center of the tree's trunk involves the heartwood, which is already dead.  The important part of the trunk is the cambium, which is the layer a few inches thick (depending on the tree's size) under the bark.  That is the living part of the trunk.  If your tree's trunk has a cavity filled with soft decayed wood, carefully remove it, making sure not to damage the more solid wood.  Until recently it was recommended to fill the cavity with some impervious material like concrete to provide strength to the trunk.  That is now thought to be harmful, and experts suggest leaving the cavity unfilled.  The darkened vein down one side of your oak should not be treated with wound paint or other material.  The white substance on the side of the trunk may be a fungus.  This web site will give you information on fungi infesting oak trees.  If it appears that your tree does have a fungal infection, Mr. Smarty Plants would recommend that you contact your local county extension agent for help in treatment.  Large oaks like yours are too precious to risk losing.

 

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