Diseased pin oak
I have a pin oak tree and it has knots growing on all the branches. How can I save this tree.
Woodford County Kentucky
The problem you are referring to is called gouty oak gall or the horned oak gall – both cause the type of woody stem galls in the picture. Unfortunately, there is no effective control with either systemics or contact sprays.
Some arborists are willing to try several years of systemic treatments but there is no evidence that this works. If a small number of galls are present, then removal of infested twigs or branches (if practical) may slow the increase some but will not solve the problem. The wood galls ultimately girdle stems and twigs, killing them. Promoting tree health may prolong survival of the trees for a few years longer.
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