Ambrosia Beetle Infestation #153453 - Ask Extension

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Ambrosia Beetle Infestation #153453

Asked September 19, 2013, 4:27 PM EDT

I have an ambrosia infestation on a white oak. I have read your article "Ambrosia Beetles in Maryland" and want to make sure that I am understanding it correctly. Once the frass is coming out from the tree, is it too late to spray? I have one tree guy who says to spray now and another who says to wait. What do you say? This tree is losing lots of branches and will most likely die in the next couple of years, but I am hoping to get a little more life from it still.

Anne Arundel County Maryland

Expert Response

Just to be sure, we would mention that multiple insects can cause frass to be pushed out of trees. It is the small, toothpick-thin type of frass projections that indicate ambrosia beetles.
You are correct in that once you see these frass projections, the insects that caused them are already in there and it's too late to prevent their boring. You can help the tree from future generations of the insect by timing the application of a protective spray. The best timing for a bark spray application is early March. You need to have it on by mid-March. If the tree is large, you should hire an arborist with the equipment that is able to apply it completely and safely so that you are not in the position of trying to apply pesticides over your head, which can be dangerous.
Thank you so  much - your expertise is very much appreciated and helpful.
The Question Asker Replied September 21, 2013, 1:04 PM EDT

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