Should we treat our ash tree for emerald ash borer if it looks healthy?
No, treatments that begin before emerald ash borers are detected within 10 to 15 miles of you are a waste of money, and the use of insecticides can have other negative effects. Here is a good up-to-date link about protecting trees: Insecticide Options for Protecting Ash Trees from Emerald Ash Borer.
Do you know where the nearest instances currently are of Emerald Ash Borer? I.e., how can we best track when it is within 10 to 15 miles of us? (We're near the 50th and France intersection of Edina)
I live in SW MN so I'm sorry if I'm not familiar with your exact location. You may be within 10-15 miles of an infestation.Here is a link to info about emerald ash borers with links to help you find out. Good luck! http://www.extension.umn.edu/garden/insects/find/emerald-ash-borer/#where