There are many types of oak trees that are native to Texas and all of America, and there are many diseases that are specific to and affect oak trees.  Galls are one such form of disease that affects oaks.  However, before you think of worst-case scenarios regarding your oak trees, there are some interesting facts pertaining to galls that you should know.  Let‘s examine them here.

First, what is a gall?  A gall is a growth which can be found on several parts of trees, including the leaves, twigs, flowers, and roots.  This growth is produced when certain species of insects deposit their eggs into any of these parts of the tree.  (Galls may also be produced by fungi or bacteria).  Commonly known insects who do this include wasps, mites, and flies.  The galls are formed as a result of a chemical reaction between the larvae and the tree, and their onset is most commonly seen during the spring when budding begins.  Once the gall is formed, the larvae feed on the tissue contained within it until they are fully developed and emerge as adults.

It is difficult to say how to treat galls, as they can be produced by several variety of organisms.  Since they are well-hidden within the confines of the gall, identifying the organism residing therein is equally as difficult.  Some research indicates that preventative spraying may help.  However, the insects responsible for the galls may vary from year to year.  This can make knowing which chemical repellent to use equally as difficult. 

Another interesting and rather puzzling fact regarding galls is that although they are technically categorized as a tree disease, affected trees are generally unscathed by them.  In other words, the presence of galls will not typically kill a tree.  In fact, the presence of galls hardly warrants any efforts to control at all.  Perhaps the most common repercussion of galls is that a large number of them on a particularly weak anatomical location, such as a leaf or a small twig, may cause it to fall from the tree.  Often, it is the loss of leaves at an unconventional time that is one’s first indication a tree may be “sick.”  To reiterate, the onset of galls is typically during spring, and seasonal shedding of leaves is not common until autumn.  Once one takes notice of the falling leaves and investigates further, the galls, which typically appear on the underside of the leaves, are discovered.

Galls can be removed by hand.  They are also often easily removed by the elements, such as wind and rain, after the bulk of it is removed as a result of the larvae’s feeding and certainly after the organism emerges as an adult.  If the galls are particularly unsightly to you, consider contacting an Austin tree trimming specialist, who may be able to assist you aesthetically. 

Galls that are brown in color, hollowed, and dried out are so from providing nourishment to its inhabiting organism.  Once the adult has emerged, galls will contain small holes through which the adult insect emerged.  These are signs that the gestational cycle involving the gall is complete.

If you have a tree that you believe is affected by galls, but aren’t quite certain, contact an Austin tree removal professional.  If your tree is affected by galls, chances are any damage will be minimal.  However, if your tree is affected by something else, it is best to have a professional diagnose the disease as quickly as possible so corrective measures can be taken and your investment can be preserved. 

About the Author: Andrew Johnson is the owner of Central Texas Tree Care, a leading provider of Austin tree services in Central Texas. Certified ISA Austin arborist services including: tree trimming, tree removal, tree care and stump removal. For more information on Austin tree service please visit

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