Ash trees under attack
A deadly insect that has killed hundreds of millions of ash trees across the East, a scourge that makes the cankerworm look pleasant, is edging toward Charlotte.
The emerald ash borer is an Asian beetle that was first spotted in North Carolina in 2013, in three counties near the Virginia line. The bug has invaded most eastern states, including Virginia and Tennessee, since it was first detected in the U.S. in 2002.
Experts compare the beetle’s lethal potential to the blight that wiped out chestnut trees a century ago and to the insect that is now steadily killing hemlocks across the Southern Appalachian mountains.
And it’s encircling Charlotte, where green and white ash grow naturally and are planted in landscapes. Green ash can make up 30 percent or more of forests in floodplains and wetlands of the Southeast. Here’s how to identify the trees.
Trees in Gaston, Lincoln, Catawba and Iredell counties, west and north of the city, have already been attacked, the North Carolina Forest Service reports. None have been found in Charlotte yet, but city tree officials are preparing for the beetle’s arrival.
“It’s on our doorstep,” said city arborist Tim Porter.
The Charlotte-based Catawba Lands Conservancy has found the borer at its Sally’s YMCA and Catawba Springs preserves in Lincoln County and at the Seven Oaks Preserve in Gaston County.
Volunteer crews from power tool maker Husqvarna cut down 30 dead trees at the Sally’s preserve last fall. Another crew, from Heartwood tree company, will take out more Friday to keep them from falling on hikers.
“We’re essentially seeing genocide for these trees,” said Heartwood owner Patrick George. “This is a bad situation, and we really have a fleeting opportunity to have a direct impact on our local population.”
Little can be done for ash groves in forests. Homeowners have two choices, George said: Treat individual trees with insecticides to prevent infestations, and continue treatments, or count on taking those trees down when they die.
“By the time you see them, they’ve been here for at least a year,” George said.
Heartwood has “adopted” and will treat a large ash tree near the band shell in Freedom Park. The company will also donate treatment of a grove of 17 large ashes near the Charlotte Nature Museum.
Kills in 2 to 5 years
The beetle, which is about the size of a cooked grain of rice, was first detected in Michigan 15 years ago and has slowly worked its way south. It invades new locations by flying or hitching rides on firewood and ash tree wood.
North Carolina, in an effort to slow the insect’s spread, imposed a statewide quarantine in mid-2013 that banned shipments of firewood and ash tree into out-of-state areas where it has not been found.
Here’s how the bug kills:
Adult beetles lay eggs on the bark of ash trees. Larvae emerging from the eggs bore into the bark and feed on tissues through which nutrients and water move, girdling and eventually killing the tree. The larvae then emerge as metallic green beetles between April and June.
Attacks take two to five years to kill a tree. Signs of an infestation start at the top of the tree, with thinning and loss of leaves.
Other clues include tunnels under the tree’s bark where larvae have fed. Sprouts, a defensive response by the tree, often emerge from the base of the trunk. Woodpeckers may busily hammer the tree to feed on insects beneath the bark.
Concord-based Carolina Tree Care has offered preventative treatments for four years. Annual treatments, which consist of soil injection or bark and canopy sprays, cost about $200 for a medium to large tree. Trees that have lost up to half their leaves to the insect may still be treated.
“I am letting (customers) know it’s around and is probably here,” said master arborist John Maurice. “If they have an ash tree that’s of significant value or of some emotional attachment, lets start protecting that now.”
Federal scientists hope to use biology to control the beetle. They’re evaluating three Chinese species of parasitic wasps that prey on it. Wasps have been released in Granville and Wayne counties.
Emerald ash borer in North Carolina
The state’s native ash species are white, green, Carolina and pumpkin ash. Green ash is widely used as a landscape tree. Mountain ash, which is not a true ash, is not susceptible to attack. State agriculture officials ask that the presence of insects suspected of being borers be reported to to (800) 206-9333 or firstname.lastname@example.org.