Recent test results from Washington State University Puyallup Plant & Insect Diagnostic Laboratory confirmed the first case of Dutch Elm Disease (DED) in the core area of the Washington Park Arboretum.  The tree, a 45 year old Guernsey Elm (Ulmus minor ‘Sarniensis’), had been suffering from mechanical injury to the root crown and annual infestations of the Elm Leafminer, an insect that that feeds on elm leaves.