DeKALB – The sidewalk was strewn with dead or hobbling emerald ash borers Friday on Normal Road near Northern Illinois University's school of nursing building.
It was an unusual sight even for Scott Schirmer, Illinois Department of Agriculture emerald ash borer program manager. His house is located near a field with at least nine ash trees that have been affected by the green Asian beetle.
"I've never seen this," Schirmer said while studying emerald ash borers on the sidewalk. "I don't know what's causing this."
The emerald ash borer, a tiny green beetle native to China, is responsible for the decay and eventual death of thousands of ash trees in DeKalb County. First spotted in the U.S. in 2002 and in Illinois in 2006, the beetles' larvae start at the top or canopy of the tree and work their way down to the trunk over a few years, feeding on the tree's water and nutrients.
Local municipalities have been treating or removing affected ash trees to combat the problem in programs costing thousands of dollars. Sycamore the removes and replaces affected trees, rather than using a chemical treatment because their trees are at a point in which chemical treatment would do no good, Sycamore Public Works Director Fred Busse said.
DeKalb uses a chemical treatment because it is timely and cost-effective, said DeKalb Public Works Director T.J. Moore.
The borer lays eggs underneath the trees' bark in the cambium layer, the layer between the bark and wood of ash trees. When the larvae hatch, they feed on the cambium, disrupting the tree's ability to transport water and nutrients. Effects of the beetle can easily be seen when tearing off the bark, exposing a maze of chewed-away tunnels. Adult emerald ash borers leave D-shaped exit holes on tree barks when they are finished feeding on ash trees.
The city of DeKalb's current treatment program, a yearly application called soil drench, costs the city $25,000 a year, money that comes from the special projects line item in the city's general fund support budget.
DeKalb has removed almost a quarter of the nearly 1,300 ash trees that once stood on city property and parkways, said Mark Espy, DeKalb Public Works assistant director. The city will pay to treat 865 trees starting July 1 with the soil drench chemical treatment, which involves pouring a solution around the base of the tree.
More than 120 trees that have already been damaged because of strong winds or were heavily pruned will be slated for removal, Espy said.
"Our parkways are showing signs of decline," Espy said. "Without any treatment program, 100 percent death is certain."
Determining whether a tree will be chemically treated or removed depends on the four D's: dead, dying, diseased or dangerous. Dead trees pose public safety concerns because they could fall and injure people or damage vehicles, Moore said.
Residents can educate themselves on the emerald ash borer by visiting agr.state.il.us/eab/.
DeKalb has opened bids for its treatment program this year and will present the bids Monday to the City Council.
As for Sycamore, city officials have already removed about 70 affected ash trees this year, making them more than halfway finished with removing affected trees, Busse said.
Sycamore Public Works has been busy working on street projects but will remove ash trees on city parkways in a few weeks, Busse said.
"We have another three years' worth of trees to remove at this rate until we're done," Busse said.
When a tree is removed from a Sycamore parkway, a resident pays half of the cost to replace the tree, which generally costs about $125 to $150 for the resident. A local landscaper plants a new tree, such as a maple, oak, lindenwood or pear tree, in the parkway or on the resident's front lawn. Sycamore will start replacing trees in September.
Meanwhile, experts are researching ways to create a hybrid ash tree that would be resistant to the emerald ash borer's effects. Ash trees in Asia could provide answers since they have co-evolved with the emerald ash borer and have built a resistance, Schirmer said.
In the meantime, local municipalities will continue to treat and remove the trees. Residents should contact their local public works department when considering whether to remove an ash tree on their property.
"Until it's their tree in their backyard, they're not really aware it's a problem," Moore said. "By the time they are aware it's a problem, it can almost be too late."
For more information
The emerald ash borer is responsible for the decay and eventual death of thousands of ash trees in DeKalb County. Residents can educate themselves on the emerald ash borer by visiting agr.state.il.us/eab/.