I have been treating DED trees in my yard for at least thirty years. Now I am...
I have been treating DED trees in my yard for at least thirty years. Now I am down to two, one large and the other very large. I did it myself for a couple of years. Now the professional charges have gone progressively up and the newest wrinkle is the recommendation is to treat every two years (instead of three). Is there evidence as to how often is required?
Olmsted County Minnesota
Thank you for the question. There are many factors that determine how often a tree needs treatment, and I cannot find a definitive answer. All research based publications that I have read state that treating every 1-3 or 2-3 years might be advisable as a prevention to Dutch elm disease but each case must be evaluated individually. You might try calling several certified arborists and see what they say. Here's a link to information on finding reputable certified arborists: How to Hire a Professional Arborist to Help Care for Your Landscape Trees.
Here is a link to 2014 information from the University of Minnesota regarding Dutch elm disease: Dutch Elm Disease
Here are 3 more links if you care to read more.
Thank you for contacting Extension.