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Forest Health in New Jersey
State Forestry Services surveys New Jersey's forests both from the ground and the air for various insects and diseases. While hundreds of insects and diseases damage our forests, foresters suppress only those that spread quickly and will not weaken on their own. Often the worst pests and diseases are non-native and introduced to our forests accidentally. Without their native predators, these pests will thrive and spread.


Southern Pine Beetle
(Dendroctonus frontalis)


Southern Pine BeetleSouthern Pine BeetleDetails
This fast-moving bark beetle killed over 14,000 acres of southern NJ pines in 2010 alone.

Susceptible Species
SPB attacks all species of pine including pitch, shortleaf, Virginia, white, loblolly, and red.

Signs of Infestation
Pitch tubes, exit holes, fading crown, S-shaped galleries under bark

Affected Areas
Pine forests in southern New Jersey

More information Southern pine beetle from State Forestry Services

spb

Gypsy Moth
(Lymantria dispar)
Gypsy Moth


Details
Larvae feed from May-June. Often confused with Eastern tent caterpillar. The high gypsy moth population in New Jersey can be attributed to reduced activity of the fungal parasite Entomophaga maimaiga. The reduced activity is due to lack of precipitation.

Susceptible Species
Prefers oaks and but also attacks many deciduous trees and shrubs

Signs of Infestation
Defoliation, oval egg masses, caterpillars

Affected Areas
Statewide

More information Gypsy moth from the US Forest Service

Hemlock Woolly Adelgid
(Adelges tsugae) Hemlock Woolly Adelgid


Details
Nymphs and adults feed on sap from the tree's twigs. This insect has infested all 26,000 acres of Hemlock stands to some degree in New Jersey. Some hemlock stands have been destroyed, while others have only low HWA infestations.

Susceptible Species
Eastern hemlock

Signs of Infestation
Egg masses, dying limbs

Affected Areas
Statewide

More information Hemlock woolly adelgid from the US Forest Service

Eastern Pine Looper
(Lambdina pellucidaria)Pine looper


Details
After overwintering in the soil beneath the host tree, moths emerge in May and June to lay eggs on the tree's needles. By mid-summer, the larvae hatch and eat notches out of the needles.

Susceptible Species
Pine species

Signs of Infestation
Brown needles, defoliation

Affected Areas
Ocean and Eastern Burlington Counties

Emerald Ash Borer
(Agrilus planipennis)


Emerald Ash Borerd-shaped EAB holeDetails
The invasive destructive insect, Emerald Ash Borer, has been found in nearby states Maryland, New York, and Pennsylvania.

Susceptible Species
White ash, green ash

Signs of Infestation
D-shaped exit holes, woodpeckers

Affected Areas
Not yet found in NJ

More information Emerald ash borer from the US Forest Service

Asian Longhorned Beetle
(Anoplophora glabripennis) ALB


Details
The larvae of this invasive species feeds on the heartwood

Susceptible Species
maples, willows, poplars, ash, horse chestnuts, elm, and buckeye trees

Signs of Infestation
3/4" to 1 1/4" adults, 3/8" exit holes, oozing sap, sawdust

Affected Areas
Union and Middlesex Counties

More information Asian longhorned beetle from the US Forest Service

Sudden Oak Death
(Phytophthora ramorum)
Sudden Oak Death


Details
Plant pathogen found in CA, OR, WA, FL, GA

Susceptible Species
75 Species including many oaks

Signs of Infestation
Brown leaves, large bleeding cankers

Affected Areas
Not yet found in NJ

More information Sudden oak death from the USDA APHIS

Bacterial Leaf Scorch
(Xylella fastidiosa)
Bacterial Leaf Scorch


Details
The bacterium is transmitted to healthy trees by feeding leafhopper and spittlebug insects moving from diseased herbaceous plants, such as goldenrod, blackberries, and clover, to healthy trees. This disease continues to be a serious health threat to urban shade trees in NJ.

Susceptible Species
Red, pin, and scarlet oaks, sycamore, elm.

Signs of Infestation
Brown discoloration along leaf margins.

Affected Areas
South-western New Jersey

More information Bacterial leaf scorch from the US Forest Service

Beech Bark Disease
(Nectria coccinea)


Beech bark diseaseBeech bark diseaseDetails
Fungus invades through bark wounds created by aphid-like insects

Susceptible Species
American Beech, European Beech

Signs of Infestation
Sparse foliage, woolly scales, ooze on trunk, small red fungal fruiting bodies

Affected Areas
Northern New Jersey

More information Beech bark disease from the US Forest Service

Scarlet Oak Sawfly
(Caliroa quercuscoccineae)
sawfly


Details
Repeated defoliation may affect vigor or kill the tree

Susceptible Species
Red and white oaks

Signs of Infestation
Skeletonized or transparent leaves, defoliation starting in upper crown, larvae feeding on leaves

Affected Areas
Northern New Jersey

More information Scarlet oak sawfly from the USDA Forest Service

Thousand Cankers Diseasethousand cankers disease


Details
A tiny bark beetle, the walnut twig beetle when combined with the Geosmithia fungus result in tree dieback and mortality. Found as close as Bucks County, PA.

Susceptible Species
Black walnut

Signs of Infestation
Branch dieback, many small cankers on branches and bole, tiny bark beetles, circular or oblong cankers under bark, tiny entrance and exit holes

Affected Areas
Not found in NJ yet

More information Thousand cankers disease from the USDA Forest Service

 

 

 

 

 

 

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