With few of the North Shore’s once plentiful collection of ash trees expected to survive the Emerald Ash Borer infestation that began in 2007, tree specialists are planning for the future to avoid similar disasters.
“We didn’t learn our lesson with Dutch elm disease and this is a much worse problem,” said Evan Shorr, a district manager for Davey Tree Experts and an EAB specialist. “There were areas where you could hardly see the sky and now there are no trees.”
Municipalities and private individuals are replacing dead and dying ash trees with a variety of species to avoid the wholesale attack on one type of tree, which has gone on against the North Shore’s ash trees for the last nine years.
Approximately 30 to 35 percent of all trees in the Chicago area are ash, according to Shorr.
Shorr said the key to replacing the ash trees is spacing different types of trees in a row so if a disease hits one, the others will survive.
The EAB infestation has been more costly than the aftermath of Dutch elm disease.
“The Emerald Ash Borer has cost billions and billions of dollars,” Shorr said. “With Dutch Elm disease it was in the millions.”
The exact count of the ash trees lost from Wilmette and Glenview on the south through Lake Bluff on the north is hard to calculate, according to Shorr. He said different tree care companies do not share information with each other and some homeowners have used the do-it-yourself method.
Davey Tree Experts has removed approximately 1,600 from private property in 2014 and 2015 alone, according to Shorr.
Municipalities know how many have been treated or cut down in parks and on parkways owned by the communities. In Lake Forest, the city owned approximately 30,000 trees at the start of 2009 when it began a program to deal with EAB, according to Chuck Myers, the city’s supervisor of parks and forestry.
Myers said 7,300 of those trees were ash and 6,000 have come down. Of the 1,300 remaining, he said treatment will continue but he only expects about 200 to survive but not over the long term.
“Eventually the Emerald Ash Borer will overtake them too,” Myers said.
Replacement of the ash trees with other species is an ongoing project in Lake Forest, according to Myers. He said city personnel is planting oak, hackberry, linden and hybrid elm trees.
“We won’t replace ash with ash. We’re looking at trees that are native to the area,” Myers said. “If we have too much of one thing we could be in serious trouble,” he added referring to the potential of another pest or disease in the future.
Lake Bluff has been dealing with the same issues. Jake Terlap, the village’s public works supervisor, said 200 ash trees have been removed leaving 400 getting treatment or currently healthy. He did not give an estimate of how many might ultimately be left but said 20 to 25 new trees are planted each year as potential replacements.
Like Lake Forest, no new ash trees will be planted in Lake Bluff, according to Bob Hertel, the village arborist. He said a selection of ginkgo, oak, sycamore and elm trees are going in.
When people are checking trees on their property to determine if they are ash, Schorr said they should look for ones with branches sticking out at 180-degree angles with one 90-degree angle on each side. The limbs are right next to each other and not spaced along the trunk.
If one of those trees has approximately 30 percent dead branches, particularly on top, they are most likely infected, according to Shorr.
“If it’s more than 30 percent, you’re not going to be able to save that tree,” Shorr said.
Property owners can find some treatments at hardware stores, which should work — unless the infestation is too severe, in which case professional help is necessary, especially for tree removal, according to Shorr. “They get brittle when they’re dead and can fall,” he said. “It’s a safety issue.”
He also suggested replacement with a variety of tree species, such as oak and linden among others.