Emerald Ash Borer in South Carolina: A Looming Crisis

Emerald ash borer (EAB), the invasive beetle that has killed hundreds of millions of ash trees across the eastern United States since its arrival from Asia, has been confirmed in South Carolina. For Upstate homeowners with white ash, green ash, or pumpkin ash trees in their landscape, the question is no longer "if" but "when" — and what you should do about it now.

What EAB Does

The adult emerald ash borer is a small (½-inch) bright metallic green beetle. The destructive life stage is the larva, which feeds in galleries just under the bark of ash trees. The galleries disrupt the tree's vascular system, eventually girdling and killing the tree. Once an ash tree has visible EAB symptoms, death within 2–4 years is almost certain without treatment.

EAB has no natural predators in North America. Native woodpeckers and a few introduced parasitoid wasps provide some pressure, but nowhere near enough to control populations once established.

The Statistics Are Sobering

Since EAB's arrival in Michigan in 2002, it has spread to 36+ states and killed an estimated several hundred million ash trees. In heavily-affected regions, ash mortality has approached 99% in some forest stands. The Upstate's ash population is relatively limited compared to Midwestern forests, but every individual ash tree is at risk.

How to Identify Ash on Your Property

Ash trees are characterized by:

- Opposite branching (branches and buds in pairs across the stem) — a distinguishing feature in North American trees, shared mainly with maples, dogwoods, and a few others.
• Compound leaves with 5–11 leaflets per leaf.
• Diamond-pattern bark on mature trees.
• Seeds in canoe-paddle-shaped samaras (single-wing helicopter seeds).

If you're not sure whether you have an ash, send a photo to us at quotes@greenvilleelitetree.com — we'll identify it for free.

Early Warning Signs

EAB infestations often go unnoticed for 2–3 years. Early signs include:

- D-shaped exit holes in the bark (about 1/8 inch, distinctly D-shaped) — the most diagnostic sign.
• S-shaped galleries visible if bark is removed.
• Crown dieback starting at the top of the tree and progressing down.
• Epicormic sprouting (new shoots from the trunk and large branches as the tree tries to compensate).
• Increased woodpecker activity stripping bark to access larvae.
• Bark splitting vertically over galleries.

By the time you see exit holes, the infestation is typically 2+ years old.

Treatment Options

For high-value individual ash trees, treatment is possible and effective when started before significant decline. Two approaches:

1. Trunk injections. Systemic insecticides (emamectin benzoate is the gold standard) are injected directly into the trunk. Effective for 2–3 years per treatment. Best for high-value specimens. Must be performed by a licensed pesticide applicator.

2. Soil drench. Imidacloprid applied to soil around the root zone, taken up systemically. Less effective than trunk injection but cheaper and doesn't require professional application.

Treatment economics work best for healthy ash trees with less than 30% canopy decline. Trees beyond that point typically can't be saved even with aggressive treatment.

When to Remove and Replace

Ash that already shows significant decline (40%+ canopy loss, multiple dead branches, bark splitting) should be planned for removal. Dead ash deteriorates structurally fast — much faster than most hardwoods — and dead ash trees over structures become hazards within 1–3 years of death.

For replacement, choose any of the native trees we recommend in our planting guide. Diverse plantings (different species, not just one replacement type) protect against the next pest crisis.

What About Untreated Healthy Ash?

If you have ash trees and you're not going to treat them, the responsible action is to plan their removal proactively — within the next 1–3 years. Removing a standing healthy ash now is cheaper, safer, and less stressful than removing a dead ash later. It also lets you control timing and replacement planting rather than reacting to an emergency.

This is a hard conversation to have with homeowners who love their ash trees. The reality is that the EAB front is advancing, and unmitigated ash in an EAB-infested area will be dead within a few years. The only question is whether you remove it on your schedule or on EAB's schedule.

Reporting EAB

If you see what you think is an EAB infestation, report it to Clemson University's Department of Plant Industry (864-646-2140). Verified detections help track the leading edge of the infestation and inform statewide management.

Free Ash Inspection

We provide free ash tree identification and EAB risk assessment for any Upstate property. If you have ash trees, this should be on your calendar this year. Call (864) 555-0174 for a no-pressure inspection and an honest assessment of your options.