Busy Summer for Invasive Tree-Killer: Emerald ash borer detected in 11 new counties since May

by | Jul 19, 2019

Summer is often full of plans, but no one has been busier this year than the emerald ash borer. Although small, this invasive beetle is killing countless ash trees across the state. Since May, it has been confirmed in 11 additional counties within North Carolina, bringing the statewide total to 48 as of mid-July.

Newly-infested counties include (in order of confirmation): Polk, Rowan, Lenoir, Chatham, Davie, Caldwell, Nash, McDowell, Burke, Watauga and Yadkin.

Craig Lawing (N.C. Forest Service, Forest Health Branch) examines emerald ash borer galleries beneath the bark of an infested ash tree in Yadkin County.

Prior to 2019, the emerald ash borer was previously detected in Alamance, Avery, Buncombe, Cabarrus, Caswell, Catawba, Davidson, Durham, Forsyth, Franklin, Gaston, Graham, Granville, Guilford, Halifax, Haywood, Iredell, Jackson, Johnston, Lincoln, Macon, Madison, Mecklenburg, Mitchell, Orange, Person, Randolph, Rockingham, Surry, Swain, Transylvania, Vance, Wake, Warren, Wayne, Wilson and Yancey Counties.

Unfortunately, emerald ash borer is a death sentence for our ash trees unless they are protected with an insecticide. For landscape and ornamental trees, there are many options available to protect or save lightly infested trees, with professionally-applied emamectin benzoate and do-it-yourself applications of imidacloprid being the most popular.

What does an infested tree look like? Overall, they exhibit general decline in tree health. The canopy thins and whole branches die. In addition, there could be sprouts growing from the base of the tree, vertical splits in the bark, or increased woodpecker activity. When any combination of these symptoms is noticed, a closer inspection for direct evidence of the beetle should occur. The most obvious sign of the beetle is the ¼” D-shaped exit holes in the bark, caused when the adult beetle emerges from the tree. Upon removing the bark from the tree, winding, S-shaped larval galleries can be seen.

A dead ash tree in Yadkin County, killed by the emerald ash borer.

This year’s range explosion is second only to 2015, when 14 new counties were declared positive for the beetle, prompting the entire state of N.C. to be quarantined for the pest. This quarantine regulates the transportation of ash material and hardwood firewood to reduce the accidental movement of it from one place to another. Because this wood-boring pest can easily hide within wood, not only will the quarantine help reduce its spread, but North Carolinians are encouraged to burn firewood within 50 miles of where it is cut. These are your forests to protect: buy local firewood, burn local firewood!

The N.C Forest Service’s emerald ash borer range map is regularly updated to provide the most up-to-date known whereabouts of this tree killer and help you make the best treatment decision for your ash. If you suspect you have emerald ash borer in an uninfested county, contact your N.C. Forest Service county ranger or your county extension agent.

The emerald ash borer is now known to occur in 48 counties within North Carolina. Map created July 18, 2019.