The Public Works Department recently identified a tree infested with the Emerald Ash Borer (EAB) near the intersection of Stone and Cossitt Avenues. While the presence of the EAB was discovered last year in a trap, this is the first time a tree infested with the insect has been identified. The tree was removed due to its declining health as a result of the EAB.
The EAB insect is a small, metallic green, non-native invasive pest whose larvae feed underneath bark of the branch and trunks of ash trees thereby cutting off their ability to transport nutrients and ultimately causing the tree’s decline. Ash trees can be infested with EAB for a few years before the tree begins to demonstrate any signs of EAB infestation. Symptoms of EAB include canopy dieback, D-shaped exit holes, shoots sprouting from the tree trunks and S-shaped larval galleries underneath the bark.
La Grange has approximately 2,000 ash trees located in public parkways. Many more are located on private property. Based on its experience with controlling Dutch Elm Disease, the Village’s plan for managing the EAB is to remove the tree once the tree is discovered to be infested with the insect. Included in the Village’s five year capital program are funds to plant a replacement tree for every parkway ash tree that is removed.
At this time, the Village is not proposing any pre-emptive removal of existing ash tree species. Rather, the Village is of the opinion to retain affected trees until such time when declining health becomes evident and removal is required. This protocol will allow for staggered planting and re-growth of our urban forest.
There are several chemical applications to protect ash trees against the EAB, however the treatment of an ash tree does not guarantee that a tree will be fully protected against EAB infestation. When considering usage of insecticidal control for trees on private property, one should weigh the value of the tree against the cost of treatments. The Village will continue to assess the effectiveness of these treatments and their cost when developing its plan and budget for dealing with this insect for public parkway trees. Please refer to web links below for more information regarding treatments to protect against this insect.
Village staff members will respond to suspect sightings of EAB. If you suspect you may have found adult or larval forms of this insect, or trees that are showing symptoms of the insect, please contact the Village of La Grange’s Public Works Department at (708) 579-2328.
Additional information can be obtained by visiting the following links:
Upon request, the Public Works Department can provide a brochure with additional information on the Emerald Ash Borer.