What's eating my wilson spruce?

Wilson Spruce (Picea wilsonii) is most seriously threatened by spruce spider mite, which thrives in cool weather and can defoliate branches before detection. Spruce aphids, pine needle scale, and bark beetles also attack stressed trees. Maintain tree vigour with adequate water and avoid wounding; treat mite outbreaks early with miticide or horticultural oil.

Needles turn from yellow-green to bronze-grey; fine webbing at branch bases; heavy infestations cause severe needle drop Apply horticultural oil or miticide in early spring and autumn when mites are active; avoid drought stress; knock mites off with forceful water spray

Needles turn yellow then drop, especially on inner and lower branches; sticky honeydew residue on foliage Spray with insecticidal soap or pyrethrum in late winter/early spring before populations explode; promote natural enemies

White elongated scale covers on needles; infested needles yellow and drop; heavy infestations weaken and kill branches Apply dormant oil spray; follow up with contact insecticide targeting crawlers in late spring; remove heavily infested branches

Entry holes with pitch tubes on bark; galleries under bark cause branch and top dieback; woodpecker activity may reveal infestation Remove and destroy infested wood promptly; keep trees well-watered to maintain resin flow which repels beetles; avoid mechanical wounding