Why are oak trees dying in Ocean County, NJ?

Usually a combination of stresses: bacterial leaf scorch, spongy moth defoliation, drought and root damage, followed by the twolined chestnut borer, which attacks weakened oaks. Oak wilt has not been recorded in New Jersey, according to Rutgers.

Dying Ash & Oak Trees in Ocean County, NJ

Q: Is emerald ash borer in Ocean County?

Yes. As of the 2024 New Jersey Forest Health Highlights, all 21 New Jersey counties have emerald ash borer detections.

Short version: a healthy, valuable ash can often be protected with treatment; a dead ash should come down before it gets brittle. Oaks usually decline over several years from a mix of stresses, so get a diagnosis before you decide.

Emerald ash borer is everywhere in New Jersey now

The emerald ash borer (EAB), an invasive beetle from Asia, was first found in New Jersey in Somerset County in 2014. According to the 2024 New Jersey Forest Health Highlights, all 21 New Jersey counties now have EAB detections, Ocean County included. The beetle attacks true ash trees (and also white fringetree). The larvae feed under the bark and cut off the tree's water and nutrient flow. The NJ Department of Agriculture says tree death typically comes three to five years after infestation.

Pines and oaks dominate most Ocean County yards, but green and white ash are planted along streets and in yards, especially in older neighborhoods.

Signs of emerald ash borer

The NJ Department of Agriculture lists these signs:

Canopy dieback starting at the top of the tree and moving down until the tree is bare.
Sprouts growing from the roots and trunk.
Split bark with S-shaped tunnels underneath.
D-shaped exit holes about an eighth of an inch across.
More woodpecker activity, leaving large patches where they dig out larvae.

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Treat or remove an ash?

NJDEP forest health says systemic pesticide treatments are effective at protecting individual ash trees, should be applied by a licensed pesticide applicator, and work best on healthy trees. In practice:

Healthy, valuable ash (good shade tree, little or no dieback): ask a NJ Licensed Tree Expert about treatment. It has to be repeated on a schedule.
Ash with major dieback, or dead: plan removal. Dead ash dries out and arborists widely report it gets brittle quickly, which makes climbing riskier and can mean a lift or crane.
Don't move ash firewood. NJDA asks people to use local firewood and burn it where they buy it, because firewood spreads tree-killing pests.

Why oaks decline here

Oaks rarely die from a single cause. According to Rutgers NJAES fact sheet FS1392 (2026), the pests and diseases affecting oaks in New Jersey include:

Bacterial leaf scorch (BLS), caused by a bacterium that clogs the water-conducting tissue. Leaves look scorched at the edges, often in late summer, and the canopy declines over years, sometimes more than ten, before the tree dies. It's easy to confuse with drought.
Spongy moth (formerly gypsy moth), whose caterpillars defoliate oaks in late spring and early summer (Rutgers spongy moth fact sheet). Repeated defoliation weakens trees.
Anthracnose and other leaf problems after cool, wet springs, which are usually cosmetic.

Weakened oaks then attract the twolined chestnut borer. The USDA Forest Service says it mainly attacks oaks stressed by drought, root injury, soil compaction or defoliation. Its first sign is wilted brown leaves on scattered branches in late summer that stay attached for weeks. Trees can die in the first year, but death usually follows two to three years of attack.

What's not here (yet)

Rutgers notes that oak wilt and sudden oak death have not been recorded in New Jersey. Oak wilt has been confirmed in Pennsylvania. Because BLS, oak wilt and drought can look alike, Rutgers recommends sending oak leaf and branch samples to the Rutgers Plant Diagnostic Laboratory for a proper diagnosis (Rutgers NJAES fact sheet FS1392 (2026)). Separately, the 2025 New Jersey Forest Health Highlights reports beech leaf disease was found in Ocean County in 2025, so dark striping between the veins of beech leaves is worth reporting too.

When to prune or remove oaks

For disease prevention, Rutgers advises that oaks should not be pruned, trimmed or felled during the growing season. The best and safest time is December through February (Rutgers NJAES fact sheet FS1392 (2026)). Dead or dangerous oaks are the exception: safety comes first. Check your town's permit rules before removal; many waive fees for dead or hazard trees. See the permit guide and our hazard tree assessment guide.

Is emerald ash borer in Ocean County, NJ?

Yes. The 2024 New Jersey Forest Health Highlights report says all 21 New Jersey counties have emerald ash borer detections.

Can an ash tree with emerald ash borer be saved?

Often, if it's still healthy. NJDEP says systemic treatments by a licensed applicator are effective and work best on healthy trees. Trees with heavy dieback usually can't be saved.

When should oaks be pruned in New Jersey?

Rutgers advises December through February, avoiding the growing season, for disease prevention. Dangerous limbs are the exception.

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Last updated October 18, 2026. Prices and rules come from the cited third-party and municipal sources and can change. They aren't quotes or legal advice. Free referral service, not a tree company. Your request goes to one independent local tree company, which may pay us for the referral.