Emerald ash borer
The emerald ash borer is a small, metallic green beetle from Asia. Its larvae tunnel under the bark of ash trees and cut off the flow of water and nutrients. It was confirmed in Hamilton County in 2013, when Chattanooga's urban forester trapped it near the city's rail lines. It has since spread across much of the state.
Signs
- Thinning leaves and dead branches starting at the top of the tree
- Small D-shaped exit holes in the bark, about an eighth of an inch across
- Bark splitting or woodpeckers stripping patches of bark
- Clumps of new sprouts along the trunk
What to do
A healthy ash in a spot you value can be protected with insecticide treatments from a licensed professional, repeated on a schedule. An ash that has already lost a third or more of its crown is usually past saving. Dead ash wood gets brittle quickly, and dead ash trees are known for dropping limbs and snapping without warning. They also get more dangerous and more expensive to remove the longer they stand. See dead and hazard tree removal.
Hemlock woolly adelgid
Eastern hemlocks grow in cool coves and along streams on Signal Mountain, Walden's Ridge and Lookout Mountain. The hemlock woolly adelgid, a tiny aphid-like insect, has been killing them across the southern Appalachians. Signal Mountain has fought it for years with a hemlock task force, chemical treatments and releases of beetles that eat the adelgid.
Signs
- White, cottony tufts on the underside of twigs at the base of the needles, easiest to see in late fall through spring
- Graying needles that drop early
- No new growth at the branch tips
What to do
Treatment works best on hemlocks that still have most of their needles. Soil-applied or trunk-applied systemic insecticides can protect a tree for several years per treatment. A hemlock that's mostly gray and bare is usually beyond help and becomes a falling hazard as it dies.
Pine bark beetles
Southern pine beetles and their smaller cousins, Ips engraver beetles, attack pines that are already stressed by drought, crowding, lightning or root damage. Once beetles get established in one pine, they can spread to the pines around it.
Signs
- Pitch tubes: small, popcorn-like blobs of resin on the bark
- Reddish sawdust in bark crevices and at the base of the tree
- Needles fading from green to yellow to reddish brown, sometimes in just a few weeks
What to do
Beetle-infested pines generally can't be saved. Removing them promptly, before the next generation of beetles leaves, helps protect the pines nearby. Keep the rest of your pines healthy by avoiding root damage and watering during long dry spells if they're near the house.
Don't move firewood
Many tree-killing insects spread to new places in firewood. Burn wood close to where it was cut, and buy firewood near where you'll burn it. Tennessee keeps a quarantine on firewood brought in from other states. See what to do with the wood after a removal.
Get a dying tree looked at
If a tree is declining and you're not sure why, an ISA Certified Arborist can diagnose it. If it's already dead or past saving, call (423) 356-6500 or use the form below, and we'll connect you with a local crew to take it down safely.
Common questions
Is the emerald ash borer in Chattanooga?
Yes. It was confirmed in Hamilton County in 2013, first found near Chattanooga's rail lines, and has since spread through much of Tennessee. Most untreated ash trees in the area are at risk.
Can an ash tree be saved?
Sometimes. Healthy, high-value ash trees can be protected with insecticide treatments applied by a professional, repeated every few years. Once a tree has lost much of its crown, treatment usually doesn't work and removal is the safer choice.
What are the white cottony spots on my hemlock?
Most likely hemlock woolly adelgid, a small invasive insect that feeds at the base of the needles. It's well established on Signal Mountain and Walden's Ridge. Treatment can protect hemlocks for years if it starts before the tree is badly declined.
Why are my pine trees turning brown?
Drought, root damage and bark beetles are the most common causes. Small blobs of resin on the bark, called pitch tubes, and fine sawdust in bark crevices point to beetles. Infested pines usually can't be saved and should come down before they spread beetles to nearby pines.