The oak tree on our lot has many branches that have dark, long, hard cylinders around the smaller portions of the branches. They are four to six inches long and about 1/2 to 1 inch in diameter. Is this something that should concern me?

What you are describing seems to indicate an infestation of a gouty oak gall. They are small wasps that lay eggs on new twigs in early spring, and when the latvae begin to pupate, the branches form a woody gall as a nest site. These can kill a branch. If this tree is not an oak, you may be seeing "black knot" on a wild cherry tree. You can click here to schedule a visit from one of our experts.

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