SURROUNDINGS
By Michelle Cassell
task editor
ORANGE COUNTY — Experts believe an ash tree on an Orange County property is dead or dying due to an invasive insect called the emerald ash borer.
“Most ash trees in Orange County are already infested or will be infested soon,” said Kelly Oten, an assistant professor at North Carolina State University.
Forest experts in Orange County discovered the insect in 2016. Since then, the beetle has spread rapidly and trees have gone untreated, leading to the beetle’s massive destruction of native Orange County ash trees.
“If someone has an ash tree on their property, consider treating it because right now that’s the only successful way of telling people to try to save their trees,” Oten said.
Once emerald ash borers start attacking a tree, they die after three to five years. Oten said the poorer the tree’s health, the less effective insecticides are.
“If you have a tree that you want to save, you should start treatment as soon as possible,” she said.
Damage left by emerald ash borers under tree bark. Photo courtesy of Kelly Oten.
The insect is a small metal-green beetle native to much of Asia and has evolved into North America’s most destructive invasive species. The insect was first spotted in Michigan in 2002 and has since spread to 35 states and five Canadian provinces, killing millions of ash trees, according to a North Carolina state fact sheet.
The beetle larvae feed on the inner bark of ash trees, disrupting the flow of water and nutrients, and ultimately killing the tree. The adult beetles feed on leaves, lay their eggs on the bark and reproduce rapidly. It can be difficult to notice damage to a tree until it’s too late.
“In large ash trees, with all of their canopy high, they usually lay their eggs high up in the tree wood, and those eggs hatch. And it’s the larvae that start digging their galleries under the bark and destroying the tissues under the bark, and that’s what kills the tree,” said Craig Nishimoto, founder of Treeist Tree Service in Chapel Hill and certified Master arborist, adding that the damage is not great deep on a tree is visible, it is probably too late.
When it was first discovered, the beetle spread so rapidly across the United States that firewood was quarantined because it might harbor beetles.
“Property owners would see this decaying ash tree in their yard and may not know that the EAB is a problem,” Oten said. “So they cut down the tree, cut it up for firewood, and if they went camping next weekend, they might have brought it with them.” So these bugs stay in that forest, and when they’re brought to a new location, they show up and infest the ash trees at the new location. This causes the beetle to move hundreds of miles, or however many miles, much faster than its natural range allows for.”
This led to a firewood ban in many North Carolina state parks, which has since been lifted after the ban was found to be no longer effective due to the spread of the insects.
“Unfortunately, at Chapel Hill, it’s probably too late to start treatment,” Nishimoto said. We would be very optimistic if people had known about it three years ago. At the moment. We are very pessimistic about the success rates.
Most of Nishimoto’s Chapel Hill treatments for ash trees began two years ago. His arborists return for the second or third round of treatments on the same trees. The injections must be done every few years to ward off the pests.
“The EAB population has exploded,” he said. So they are everywhere and just devour everything. We would be shocked to find a tree in Chapel Hill that the EAB has not yet damaged.”
According to the NC Extension Gardener Plant Toolbox, the North Carolina ash or white ash or Biltmore ash can be identified by their opposite branching pattern and compound leaves, which typically have 5 to 9 leaflets. The leaves of this tree are dark green above and light green below, with a serrated margin. The bark of old trees is gray and grooved with diamond-shaped patterns. The tree produces winged seeds called samaras in the fall. The North Carolina ash is a tall deciduous tree that can grow up to 80 feet tall.
Nishimoto said arborists should be able to identify ash trees for property owners.
Typically, Nishimoto tells people they have a problem because the arborist sees the ash trees on their property and says, “Hey, look out.”
“There is a lot of information from sources that have no interest in making money. Most tree services should provide free estimates for identifying your trees,” he explained. Nishimoto explained.
Many communities have residents who know how to identify trees or garden clubs as resources.
If a tree is too far away, Nishimoto recommends letting it die and decay on its own as long as it doesn’t pose a threat to surrounding structures. However, removing decaying ash trees in densely populated areas is expensive and requires specialized equipment.
For trees that can still be saved, Oten pointed out developing a treatment according to guidance from the North Carolina Forest Service.
“It’s called soil drench,” Oten said. “You could go to a big store like Lowe’s or Home Depot, buy this chemical, mix it up, and then soak it around the base of the tree.”
The tree absorbs the chemical mixture that is toxic to the beetles, but also prevents the tree from becoming a habitat for non-invasive insects.
The prospects are bleak, but scientists are not giving up.
“I have a Ph.D. “Student studying this phenomenon called residual ash,” Oten said. “When the emerald ash borer comes through an area and kills 99.9% of the ash trees, you will occasionally see that only 0.1% are left. They dubbed this find “Remaining Ashes,” she explained.
Researchers believe the survivors possess genetic resistance to the insect, which could offer a way to breed trees for replanting.
Another possibility of control is biological. Entomologists and researchers are looking for native species that could be used to control the insects. Oten said a dozen species show promise so far.
thelocalreporter.press
https://thelocalreporter.press/an-invasive-insect-has-conquered-orange-countys-ash-trees/
