Disease name: SNEED (Sudden needle drop)
Pathogen name: Setomelanomma holmii (not confirmed) (fungus)
Hosts: Norway spruce (Picea abies), white spruce (P. glauca), Colorado blue spruce (P. pungens), and black hills spruce (P. glauca var. densata) are hosts for SNEED, also known as Spruce Needle Drop and Sudden Needle Drop.
SNEED is a health issue that arises from both environmental and fungal factors.
The fungus associated with SNEED is Setomelanomma holmii. Its pathogenicity has not been confirmed, but it has frequently been found with symptomatic trees. Known fungal pathogens that have also been associated with symptomatic trees include Phomopsis and Cytospora.
Other factors identified with symptomatic trees are excess soil moisture and nutrient deficiencies.
Symptoms
The symptoms of SNEED include a needle growth pattern that is easily noticed in the landscape.
The needles of the current growing season, at the tips of branches, remain green and attached to the branches. Green, yellowing, or yellow older needles in the canopy’s interior drop prematurely.
Most spruce trees typically hold needles from the past three to four years.
Needle drop causes the canopy to develop a thin appearance. The pattern of the needle drop can occur throughout the canopy with little directionality.
Fungal fruiting bodies that look like black specks of pepper can be found on the bark of the affected branches and twigs.
Disease Cycle
Very little is known about SNEED.
Two-year-old and older needles begin to yellow and turn brown during the growing season. Both discolored and green needles begin to drop off of the trees in the autumn.
Setomelanomma holmii can be found and isolated from diseased and healthy branches.
Management
Cultural Management
Maintain overall tree health and vigor. Encourage good airflow in the canopy to keep needles and branches drier. Ensure the trees are getting the appropriate amount of water for the tree species, soil type, and topography. Spruce trees do not grow well in wet or saturated soils, so modify drainage to drain away from spruce trees. Have soil and foliar nutrient testing performed and fertilize the tree as needed.
Plant non-host species: These include Serbian spruce (Picea omorika), Oriental spruce (P. orientalis), black spruce (P. mariana), firs (Abies), pines (Pinus), arborvitae (Thuja), and yew (Taxus).
Chemical Management
No chemical treatments are available at this time.
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