Common tree pests in NB and how to spot them?

New Brunswick's trees face several common pests that can cause significant damage if not caught early. The Maritime climate's high humidity and temperature fluctuations create ideal conditions for many insects and diseases, making regular monitoring essential for tree health.

Spruce budworm is arguably the most destructive pest in New Brunswick, particularly affecting balsam fir and white spruce. Look for reddish-brown caterpillars feeding on new growth in late spring, causing needles to turn brown and drop. Heavy infestations create a scorched appearance across entire tree crowns. The damage typically starts at the top of trees and works downward over several years.

Eastern tent caterpillars create distinctive silk tents in the crotches of deciduous trees, especially wild cherry, apple, and maple trees. These appear in early spring as small webs that grow larger as caterpillars mature. The hairy caterpillars emerge to feed on leaves during the day, returning to their tents at night. While unsightly, they rarely kill healthy trees but can weaken stressed ones.

Emerald ash borer has been detected in New Brunswick and poses a serious threat to all ash species. Early signs include D-shaped exit holes in the bark (about 3-4mm wide), S-shaped galleries under the bark, and crown dieback starting from the top. Woodpecker damage on the trunk often indicates borer activity underneath. This pest is fatal to ash trees and spreads rapidly.

Winter moth caterpillars emerge in early spring to feed on budding leaves of maple, oak, elm, and fruit trees. Look for small green caterpillars that drop on silk threads when disturbed. Heavy infestations can completely defoliate trees by late May. The damage appears as holes in leaves or completely eaten leaf tissue, leaving only the main veins.

Forest tent caterpillars differ from eastern tent caterpillars by not building tents. Instead, they create silk mats on tree trunks and branches where they rest. These blue caterpillars with white keyhole-shaped spots prefer aspen, birch, and maple. They can completely defoliate large areas of forest, though most trees recover if healthy.

Scale insects appear as small, waxy bumps on branches and needles of evergreens, particularly spruce and pine. Heavy infestations cause needle yellowing, branch dieback, and overall tree decline. Look for sticky honeydew on needles and branches, which often develops black sooty mold.

Early detection is crucial because most tree pests are easier and less expensive to control when caught early. Walk around your trees monthly during the growing season, looking for unusual discoloration, holes in leaves, webbing, or small insects. Pay special attention to new growth and the undersides of leaves where many pests hide.

For large or valuable trees, hire a certified arborist for proper diagnosis and treatment. Many pest problems require specific timing for effective control, and misidentification can lead to ineffective treatments. Professional arborists can also assess whether a tree is worth treating or should be removed to prevent spread to healthy trees.

Need help finding a qualified arborist or tree care professional? New Brunswick Landscaping can match you with certified tree care specialists in your area for proper pest identification and treatment recommendations.