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Mr. Smarty Plants - Galls on live oak tree in Austin

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Thursday - December 12, 2013

From: Austin, TX
Region: Southwest
Topic: Pests, Trees
Title: Galls on live oak tree in Austin
Answered by: Nan Hampton

QUESTION:

I live in Austin, and have a 13 year old live oak in my yard. It has developed little spheres, kind of like green peas, on the underside of the leaves. What is it? Is it harmful? Is there something I should be doing to get rid of them?

ANSWER:

Mr. Smarty Plants is going to refer you to the answer to a recent question from someone else in Central Texas with the same, or at least similar, problem.  The little spheres are galls made by the trees tissue in response to the developing larva of an insect feeding on the leaf.  The galls are rarely injurious to the tree and there isn't really a method (such as spraying) to kill the larva inside the gall.  Here is a copy of the answer:

"They are galls caused by the trees reaction to insects laying their eggs in the leaves. The tree's tissues expand and grow around the developing egg and the resulting larvae that feeds on the plant tissue before emerging as an adult.  The galls may not be aesthetically attractive but they are not especially deleterious to the trees.  There is really no way to "treat" them since the insect is safely ensconced within the gall and won't be reached by any insecticide.  Here are some articles related to galls from Texas A&M Texas Plant Disease Diagnostic Lab and from Texas A&M AgriLife Extension.  Here are photos of oak leaf galls caused by Belonocnema tratae and more photos of oak galls from the Central Texas Gardener blog."

 

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