Emerald Ash Borer
Who should I contact to look at a Green Ash tree in my yard for possible Green Ash Borer.
Adams County Iowa
You should look for a certified arborist in your area. They are often listed in the Yellow Pages. This article may provide some tips: http://www.extension.iastate.edu/forestry/care_maintenance/arborists.html You might also contact your county extension agent to see if they have a list of certified arborists in your area.
For treating a specimen ash tree, you may want to call several arborists to get some idea on pricing for preventive treatment which is injected into the trunk every two years. However, once a tree is infested there is no reliable treatment.