What's eating my red fir?

Red Fir (Abies magnifica) faces the greatest threat from bark beetles, particularly fir engravers (Scolytus spp.), which attack stressed or damaged trees. Balsam woolly adelgid and western spruce budworm also cause serious damage in its native Sierra Nevada and Cascade range. Maintaining tree vigour through adequate water is the primary defence.

Pitch tubes and resin bleeding on bark; J-shaped egg galleries under bark; crown dieback progressing from top down; eventual tree death Prevent drought stress with deep watering during dry seasons; remove and destroy infested trees or logs promptly; avoid creating wounds; no chemical cure once infestation is established inside bark

Woolly white masses on bark nodes; gouting of shoots; branch and crown dieback in moderate to severe infestations Soil-applied imidacloprid provides systemic protection; horticultural oil or insecticidal soap applied directly to infested bark kills crawlers on contact

New shoot tips and developing needles chewed and killed in spring; defoliated branch tips turn reddish-brown; repeated infestations severely weaken trees Bacillus thuringiensis var. kurstaki (Btk) applied at egg hatch is effective and safe for non-targets; spinosad as an alternative; large infestations in forests are sometimes managed by aerial application