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Spirea-Powdery Mildew Cause Several fungi have been reported on spirea but only Podosphaera clandestina, P. tridactyla, P. minor var. longissima and P. spiraeae have been reported from the PNW. Podosphaera clandestina is also found on stone fruit trees su ...

Spruce (Picea spp.)-Heterobasidion Root Disease See: Fir, True (Abies spp.)- Heterobasidion Root Disease Note: Heterobasidion root rot is mostly a butt or trunk rot in spruce that becomes important when trees are 60 to 80 years old. ...

Spruce (Picea spp.)-Botrytis Blight See: Fir, Douglas (Pseudotsuga menziesii)- Gray Mold ...

Spruce (Picea spp.)-Bud Failure Cause A physiological disorder that affects the uppermost bud(s) on the terminal shoot (leader) of Colorado blue spruce (Picea pungens). Possibly caused by either a calcium deficiency or by high temperatures the previous gr ...

Spruce (Picea spp.)-Cytospora Canker Cause Cytospora kunzei (sexual: Valsa kunzei), a fungus that has not been reported in the Pacific Northwest but has been found by the OSU Plant Clinic. The disease is more common in the Northeastern United States. Rain ...

Spruce (Picea spp.)-Damping-off See: Fir, Douglas and True- Damping-off ...

Spruce (Picea spp.)-Needle Distortion Cause Unknown. Serbian spruce (Picea omorika) appears to sustain the most damage, but has been observed on a number of different spruce species and cultivars. Examinations of spruce, even before the bud cap has fallen ...

Spruce (Picea spp.)-Phytophthora Root Rot See: Hemlock (Tsuga spp.)- Phytophthora Root Rot Cause The fungus-like microorganisms Phytophthora cactorum and P. cinnamomi have been reported on spruce, but it generally is considered a tolerant plant and grows ...

Spruce (Picea spp.)-Rhizosphaera Needle Cast Cause Rhizosphaera kalkhoffii is the most prevalent cause although several other fungi (such as R. pini, Lophodermium sp., Lirula sp.) can cause needle cast diseases on spruce. The fungus overwinters in infecte ...

Spruce (Picea spp.)-Rusts See: Rhododendron- Rusts Cause Chrysomyxa sp., a fungus. Species reported from the Northwest include C. arctostaphyli (spruce broom rust, with kinnikinnick as the other host); C. ledicola (with labrador-tea, Ledum sp., as the oth ...