Oak tree carbunkles

[gsable]

I have 20 or so large (over 80 feet tall), old growth oak trees that have hard carbunkle like growths on the outer most limbs. These are generally round, hard, wood like growths.

My questions are, what are they, do they hurt the tree, if harmfull how do I correct the problem.

I've attached photo.

 

[John Paul Sanborn]

It is a twig gall cause by insect larvae, usualy a wasp.

There is a control for it if the problem is severe. If notit is just an aesthetic problem. The treatment has a narrow window of application and uses some strong products, like Orthene.

 

[gsable]

Thank You!!!
The problem is wide spread. The affected trees are 80+ ft in height so the application of chemicals won't occur anytime soon.

Since they don't negatively affect the tree, it's probably better to let them fall of via normal attrition.

Thanks again!!

 

[John Paul Sanborn]

The applications do not make the current ones go away, it reduces the populations in new twigs. Wonce wood is wounded it can only be covered up by new tissue or shed.