Emerald Ash Borer Discovered in Elm Creek Park Reserve

February 27, 2018

The first confirmed emerald ash borer (EAB) infestation within Three Rivers Park District was found in February 2018 in Elm Creek Park Reserve near the Chipmunk reservation picnic area. The infestation of this invasive species was discovered in three trees by Forestry staff during the annual hazard tree inspection. Forestry staff have surveyed ash trees in an extended area within Elm Creek Park Reserve, but have not found any other trees showing visible evidence of EAB.

Because the infestation was discovered in an active use area of the park, all of the ash trees in that immediate area must be removed. This includes the three infested trees and approximately 125 other ash trees. When EAB larvae infest a tree, it becomes brittle and portions of the tree can break off without warning posing a hazard for people in the area. When an infested tree is located in an active use area, the best course of action is to promptly remove it and any other potentially infested trees. This action also slows the spread of EAB to larger areas of the park. Forestry staff will continue to monitor the ash trees in Elm Creek and may start preemptive treatment on certain ash trees in other areas of the park reserve. 

It is impossible to determine exactly how EAB was spread to the infested area at Elm Creek Park Reserve, the most likely cause was through unintentional transportation of infested firewood to the picnic area. While there is very little that Three Rivers could do to prevent this insect from eventually spreading throughout the Park District, staff has been working for the last several years to decrease the impact and prepare for an infestation. Since 2010 the Park District has enforced a firewood policy prohibiting guests from bringing firewood onto any Three Rivers property unless it comes from an MDA approved vendor. 

Forestry staff has inventoried all of the Park District’s active use areas (e.g. picnic areas, campgrounds, play areas, etc.) to determine ash tree concentrations. To mitigate the eventual damage from this insect, staff have been preemptively removing up to 10 percent of the ash trees from these areas each year and have been replacing them with a variety of native, non-ash species.

EAB is an insect native to East Asia that was first discovered in the United States in the Detroit, Michigan area in 2002. EAB most likely arrived in Michigan on wood packing material carried by cargo ships or airplanes 5-10 years earlier. More information on EAB and its current status in Minnesota can be found on the Minnesota Department of Agriculture’s website.