After last year’s outbreak of Dutch elm disease, city forestry department workers are not taking any chances this summer when it comes to the beloved shade trees.
Crews have been putting in up to two hours of overtime each evening on Dutch elm disease patrol, cruising city streets on the lookout for the yellowing or wilting leaves that can signal the onset of the arboreal scourge.
So far, the news is relatively good, said Harold Hoover, Elmhurst superintendent of forestry.
“We feel that the situation is under control,” Hoover said. “Last year, Elmhurst lost 130 parkway trees and 125 back-yard trees to Dutch elm disease, our highest losses since the early 1980s. This year, we have lost about 65 parkway elms and 65 back-yard elms, which is closer to what are considered normal loss levels.”
The latest crop of casualties includes a large American elm in Wilder Park that is slated for removal, said Michael Penckofer, assistant forestry superintendent. However, not all diseased elms are doomed.
“If the disease is only in the crown of the tree, sometimes we can have a cherry picker aerial unit go out and prune out the diseased part,” Hoover said. “But if the disease is in the trunk, the tree is what we call a goner–a bona fide removal.”
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To determine if the Dutch elm fungus has spread to the trunk, foresters remove a piece of bark to reveal what is called the cambium layer of the tree, Penckofer said.
“On a healthy tree, the cambium layer is creamy white,” Penckofer said. “If there are brown streaks, the tree has Dutch elm disease.”
When Dutch elm disease is discovered in a tree on private property, Hoover said, the homeowner is compelled by village ordinance to have the tree removed.
Last year’s excessive losses were attributed in large part to the unusually hot and dry summer of 1995, which weakened elms throughout the area and left them more susceptible to the beetle-borne fungus.
“We believe (last year’s high loss rate) was a fluke, but once you have a bad year you want to dig in your heels and do everything you can to save the elms,” Hoover said.
Dutch elm disease has wiped out more than 50 million American elms since 1930 and continues to claim as many as 400,000 elms annually, experts have estimated.