Sitka Spruce (Picea sitchensis) Diagnostic Tables | UC Agriculture and Natural Resources

Crown and Needle Symptoms

Symptom	Possible Causes	Visual
Crown yellowing, often with top-down decline and distress crop	Armillaria root disease (Armillaria spp.)
Defoliation and yellowing of older needles. Older trees will be towards the lower crown, young trees near the top	Green Spruce Aphid (Elatobium abietinum)
Crown Dieback and defoliation of needles leading towards eventual death	Heterobasidion Root Disease (Heterobasidion occidentale)	Example of Heterobasidion Root Disease on Pines (spruce example coming soon)

Symptom	Possible Causes	Visual
Butt swelling on older trees, presence of brown rot in heartwood when cored, presence of velvety, brownish layers of cushion-like fruiting bodies at base of tree or on lower trunk	Velvet polypore/Dyer’s polypore (Phaeolus schweinitzii)
Black shoestring-like cords and white fans of fungal tissue running up the first few meters of the trunk (under bark), sometimes resin bleeds near base of tree, possible presence of epicormic sprouts	Armillaria root disease (Armillaria spp.)
Yellowing needles with branch defoliation and dieback of older needles AND/OR Dead or dying older needles covered in sooty mold, not affecting new growth	Green Spruce Aphid (Elatobium abietinum)

Symptom	Possible Causes	Visual
Medium to large velvety, brownish (lighter on margins when fresh) layers of cushion-like fruiting bodies at or near base of tree or on lower trunk	Velvet polypore/Dyer’s polypore (Phaeolus schweinitzii)
Clusters of tannish mushrooms present at the base or near trees, stringy yellowish to white rot with hard black plates present in the roots and lower trunk of downed trees	Armillaria root disease (Armillaria spp.)
Laminated or stringy white rot with oval pits or black flecks in decayed areas AND/OR Presence of hard, small, white fruiting bodies near root collar AND/OR Fully-developed flat to bracket-like fruiting bodies in or on nearby stumps and snags. Mature fruiting bodies hard, brown with white margin on top and white to faintly orangish below with irregularly shaped pores	Heterobasidion Root Disease (Heterobasidion occidentale)