What's eating my white spruce?

White Spruce faces its most serious pest in the spruce budworm (Choristoneura fumiferana), a native caterpillar capable of killing trees during outbreaks. Cooley spruce gall adelgid causes pineapple-shaped galls on shoot tips. Spruce spider mites cause bronzing in summer, and white pine weevil kills the leader shoot of young trees.

Caterpillars consume new needles and shoot tips in spring; repeated defoliation over 2–5 years kills trees; major outbreak pest across northern North America. Apply Bacillus thuringiensis var. kurstaki (Btk) targeting young larvae in late May to June; aerial Btk is used in forestry; maintain tree vigour with adequate water; remove severely damaged trees.

Pineapple-shaped green to purple galls at shoot tips in spring; galls dry and distort growth; rarely kills established trees but disfigures ornamentals. Apply horticultural oil or insecticidal soap to dormant buds in early spring before adelgids lay eggs; remove and destroy galls before they open.

Needles stipple and bronze from June onward; webbing visible on branch undersides; heavy infestations cause needle drop, worst in dry summers. Spray with miticide or neem oil in early summer when populations build; water trees during drought; predatory mites provide natural suppression.

Adults girdle and lay eggs in the leader shoot; larvae feed beneath the bark, killing the terminal leader and causing a characteristic 'shepherd's crook' droop. Prune out and destroy infested leaders before adults emerge in July; train a strong lateral branch to replace the lost leader; apply preventive insecticide to the leader in early spring.