The recent discovery of the emerald ash borer in Portage doesn’t mean that all of the city’s 1,000-plus ash trees need to be chopped down.
But what city officials will do, particularly with the ash trees on public lands (such as parks and boulevards in front of houses), needs to be decided in the next few weeks.
Just weeks after the city of Portage was recognized, for the 20th consecutive year, as a Tree City USA, a Wisconsin Department of Natural Resources urban forester confirmed that at least two ash trees in Portage were severely infested with the larva of the emerald ash borer, a metallic-green insect that is about a half-inch long and about 1/16th-inch wide.
The larvae invade the area under the bark of the ash tree. The telltale signs of their presence include tiny D-shaped holes in the trees, serpentine patterns (called galleries) just beneath the bark where the larvae feed and excrete, and woodpecker flecking from a large number of wood-pecking birds that seek the insects in the tree.
Dan Kremer, the city’s manager of parks and recreation, said DNR officials spotted the infected tree, on city-owned boulevards near Franklin and Monroe streets, on April 27, and confirmed the presence of emerald ash borer larvae.
It’s not a surprise, Kremer said, because the emerald ash borer has been spreading throughout Wisconsin for the last several years. It was first spotted in Columbia County last July — in the town of Lodi (near Harmony Grove) and a few days later in the town of Dekorra.
Since then, Columbia County has been among the Wisconsin counties under an emerald ash borer quarantine, said Brian Wahl, regional urban forestry coordinator for the DNR. That means, he said, that no ash products, including lumber or wood chips, may leave the county, unless they’re going to another county that already is under quarantine.
The insects can travel up to 2 miles per year, Wahl said — so they’re spreading not by their own power, but in infected wood that’s being moved throughout Wisconsin.
“These little buggers are being transported in by people,” he said.
That’s why people need to buy wood where they’re camping, and burn it there, instead of transporting firewood in and out of particular areas, Wahl said.
Kremer estimated that there are between 800 and 1,000 ash trees on public property in Portage, and he said there’s no telling how many other ash trees are growing on private property.
George Koepp, agriculture agent for the University of Wisconsin-Extension Columbia County, said ashes have been popular trees in communities for many years, partly because they grow fast.
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Ironically, many ashes were planted to replace the Dutch elm trees that were wiped out by disease, noted Tim Zander, a Columbia County supervisor who is a member of the County Board’s Agriculture Land and Water Conservation Committee.
Wahl said the two trees in Portage where the ash borer infestation has been confirmed are goners, and will probably have to come down soon.
“These trees might leaf out this spring, but they won’t live very long,” he said.
But, while it’s almost certain that there are other ash trees in Portage that have the emerald ash borer, that doesn’t necessarily mean that all the infested trees will die or will have to be taken down.
Wahl said the emerald ash borer can be present in a tree for two to three years before the tree shows any symptoms of infestation, such as a thinning canopy of foliage.
In the early stages, Kremer said, infestations can be stopped with chemical treatment, either poured into the ground near the roots or injected by a professional arborist.
How many of the ash trees on city-owned property should be treated, and how many should be replaced with trees of a different species, remain to be decided by people in the city’s Parks and Recreation and Public Works departments, and by the Portage Common Council and city committees, boards and commissions.
Kremer said these groups will be talking in the next few weeks about options for dealing with the emerald ash borer, and city officials will post up-to-the-minute information on the city’s website, www.portagewi.gov.
Detailed information about the emerald ash borer is also available at datcpservices.wisconsin.gov/eab/index.jsp
People with ash trees on their private property can contact city officials if they think they have an infestation, but Kremer said the city workers can neither inspect nor treat trees on private property. There are, however, numerous certified arborists in the area, he said.
“It’s not like the trees are coming down tomorrow,” Kremer said. “We need to identify where the emerald ash borers are, and what we’re going to do.”
For a long-term response, both Wahl and Koepp have one word of advice: Diversify.
The best way to improve the long-term survival of urban trees, Koepp said, is to plant a variety of different species, rather than a lot of trees of the same species.
Wahl would take it one step further: “Plant the right tree in the right place. And if your next-door neighbor plants a tree, you plant something different.”