Insects & Disease


BackgroundOn March 26, 2009, the Illinois Department of Agriculture field staff viewed and confirmed Emerald Ash Borer (EAB) damage and positively identified EAB larva on June Terrace parkway trees in Lake Forest. Since that time the City’s Forestry section has confirmed that EAB is present in trees throughout the whole city, putting every ash tree within the City at risk. Symptoms of EAB are slow to appear and by the time it is identified it is estimated that it has already been present for 3-5 years. Unless a tree is chemically treated to protect it from EAB, infested ash trees typically succumb to EAB and ultimately die.  It is estimated that EAB has been in Lake Forest for 6-8 years and is likely on the verge of an exponential increase.

Impacts On Lake ForestThe City of Lake Forest’s urban forest is comprised of over 30,000 parkway trees, and hundreds of acres of additional trees on park, golf course, cemetery, and other city owned properties.  Based on an older tree inventory, approximately 20% of the parkway trees are ash.  Beyond parkway trees, it is estimated that other city properties may have three to five times this number.  In addition, there is countless more ash located on private property throughout the City. Obviously, the magnitude of this situation will have major implications for the City and its 20,000 residents.

EAB Management – Public Property TreesThe Forestry section is working with a plan that will consist of a number of procedures that will focus on maintaining a healthy urban forest and diversifying our overall tree inventory.  Due to the rapid spread of EAB in other states before us, early and quick action will be vital to the operation of a successful program. Our goal will be to act as soon as possible and as budgetary constraints allow.

It is critical that a diversified species tree planting program occurs on public & private property. Not every tree removed can be replaced due to several factors including underground and overhead utilities and location of other private property and public property trees. The City of Lake Forest will continue to pursue diverse tree planting throughout the City where possible.

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