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July / Aug 2016


My oak tree has some round ball things attached to the underside of some leaves.  Do you have any idea of what this is and how I should control it?  Will it kill the tree?



 The problem is a gall.  Galls can be caused by insects or diseases, but more commonly on oaks they are insects. They can be very showy—some even have red polka dots.  They come in all colors and sizes and if only on the leaves I would not worry about them.  There is an oak gall that can attack some trees that can cause damage, but it gets on small stems and twigs, not on the leaves. We saw a lot of galls early this season, so I am not surprised some have lingered.


September 2012

QuestionIf the bark is falling off from a part of a tree does that mean the tree has to be cut down because it is dying? Could it just be pruned up to remove the damaged part and the tree be saved?


AnswerIt depends on what is causing the bark to fall off, and the overall health of the tree. Sometimes lightning can hit a tree and cause bark to slough off—damage can be minor or deadly. Many oaks around the state are dying in part due to drought stress, but that can also cause hypoxylen canker to kick in. When this disease takes over, the outer bark usually falls off in patches, exposing either a dry gray substance or a black tarlike one. Usually by the time the bark falls off, the tree is either dead, or almost there. Damage from a weed-eater or lawn mower can also cause bark damage, but usually too close to the ground to cut out without cutting down the tree. Once bark begins to fall, you can’t stop it, but you can clean the wounded area and try to keep the tree overall healthy with proper watering .

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