Tree careTree diseasesSt Louis oak galls

What are Oak Galls?

Has your oak tree suddenly started struggling? Did you look up and see brown, bulbous growths on the branches? If so, it’s time to take some action!
What you are looking at are known as oak galls and they are a huge issue we are having all over St. Louis. We are especially seeing them in Maryland Heights, Creve Coeur, Overland, and St. Ann. These galls are abnormal growths of plant tissue found on twigs and branches. They are caused by a non-stinging wasp which produces a chemical that induces the tree to produce large, woody galls.
A couple oak galls here and there is just a nuisance and unpleasant to look at. But a severe infection will bring about the decline and death of your tree. Oak galls suffocate the vascular system of the tree, not allowing it to function properly.

A Certified Arborist’s Approach to Oak Galls 

Minor Infestation – With a minor infection, your tree can be deadwooded and those twigs disposed of properly. If you find twigs on the ground with these galls be sure to pick them up and dispose of them rather than leave them on the ground or throwing them in woods or compost. These pests overwinter in twigs, branches, and leaves, so it’s important to clean up any debris from the tree every fall to prevent an increased population come spring. Additionally, have a certified arborist and plant health care specialist out to assess the infestation. Oak galls can be treated with an injection treatment proven highly effective in the control of oak gall wasps. The oak gall treatment kills off the wasps however, this process does take time as there are eggs within the tree not yet visible. It is recommended to repeat this treatment in 2 years.
In the case of a minor infestation or a tree that has not yet exhibited oak galls, we recommend our oak gall preventative treatment. This trunk injection is best applied between the months of March and November. For minor infections, limbs that carry oak galls will still need to be dead wooded. However, an oak gall trunk injection will protect it from future infestations.
Major Infestation – If your tree is extremely infested, our certified arborist will recommend a couple of options. If you are trying to get shade out of the tree for as long as possible, they will recommend deadwooding to prolong the life as much as possible. However, if he believes that your tree won’t make it much longer, then deadwooding may be a waste of money. In that case, we recommend removal of the entire tree. 
Oak galls are a frustrating situation for any homeowner as they often affect our biggest and stateliest trees. Don’t hesitate to contact us as soon as you see any sign of oak galls for a free assessment.

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