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Ash trees are a common variety in Midwestern US cities, where they can survive cramped sidewalks, harsh winters and road salts. Pic phys.org
Emerald Ash Borer devastation continues in North America. The Emerald Ash Borer targets ash trees and once a tree is affected it is doomed, usually dying within 5 years.
Ash is a common variety of tree used in Midwestern US cities, where it can survive cramped pavements, harsh winters and road salts. The trees of St Louis are the latest victim of the beetle with the forestry commission making the tough decision to cut down trees before they succumb. Over the next two years crews in St Louis will cut down nearly one out of every five ash trees, that’s almost all of the city’s 14,000 ash (about 17 per cent of the total trees) which will alter its leafy landscape for at least a generation.
Forestry commissioner Skip Kincaid is managing the city’s huge mission of dealing with the invasive pest and the destruction it is expected to cause in the next few years.
“I’m trying as best I can to enlighten the public about how devastating it is going to be,” Kincaid said.
Scientists have discovered a pesticide treatment that can keep the insect from killing trees. But Kincaid said that wasn’t an economically feasible solution, as it must be repeatedly applied every other year.
A blue medallion pinned to an ash tree in Chicago, indicating it has been treated with pesticide to kill the Emerald Ash Borer, on June 29, 2016
The forestry expert surveyed the value of each tree, quantifying the benefits they provide in terms of property values, reducing storm water runoff, and reducing energy costs through natural cooling.
Only 1,000 made the cut. The rest will be removed and replaced with a variety of species, but it will be years before they reach the size of the Ash trees. “This is something where quite honestly, we really have no other choice,” Kincaid said.
Scientists estimate that about 30 million trees have already succumbed to the beetle, and by the time its path of destruction concludes, hundreds of millions more will be dead, brittle, and ready to fall during a storm. While scientists have begun trials to find successful natural predators and studies to create something of a biological balance, these parasitic controls are in their very early stages and could take decades or even a century to have an effect.
Kincaid points out that one of the key lessons of the Ash Borer invasion in cities is that too much of one tree is not a good thing. In St Louis he plans to replace ash trees with a far more diverse range so that no one insect can wreak mass havoc again.
“We’re in a world now where every year it’s a different invasive pest. That’s why it’s critical to have this diversity of species. So if something moves in… you won’t wipe out 17 percent of your street trees.”
Source: phys.org
