Editing Spruce (section)

=== Diseases ===
[[File:Fichtenstamm entrindet.jpg|thumb|Manually [[Debarking (lumber)|decorticated]] [[Tree#Trunk|trunk]] of a spruce as protection against [[bark beetle]]s]]
[[File:Древесина ели.jpg|thumb|Structure of spruce tree cells]]

==== ''Sirococcus'' blight (Deuteromycotina, Coelomtcetes) ====
The closely related species ''Sirococcus conigenus'' and ''Sirococcus piceicola'' cause shoot blight and seedling mortality of [[Pinophyta|conifers]] in North America, Europe, and North Africa.<ref>{{cite journal |last1=Rossman |first1=AY |last2=Castlebury |first2=LA |last3=Farr |first3=DF |last4=Stanosz |first4=GR |date=2008 |title=''Sirococcus conigenus'', ''Sirococcus piceicola'' sp. nov. and ''Sirococcus tsugae'' sp. nov. on conifers: anamorphic fungi in the Gnomoniaceae, Diaporthales |journal=Forest Pathology |volume=38 |pages=47–60 |doi=10.1111/j.1439-0329.2007.00529.x|doi-access=free }}</ref> Twig blight damage to seedlings of white and [[Picea rubens|red spruces]] in a nursery near Asheville, North Carolina, was reported by Graves (1914).<ref name="graves">{{cite journal |author=Graves, A.H. |year=1914 |title=Notes on diseases of trees in the southern Appalachians |journal=Phytopath |volume=4 |pages=63–72}}</ref> Hosts include [[White spruce|white]], [[Picea mariana|black]], [[Picea engelmannii|Engelmann]], [[Picea abies|Norway]], and [[Picea rubens|red spruces]], although they are not the plants most commonly damaged. ''Sirococcus'' blight of spruces in nurseries show up randomly in [[seedling]]s to which the fungus was transmitted in infested seed. First-year seedlings are often killed, and larger plants may become too deformed for planting. Outbreaks involving < 30% of spruce seedlings in seedbeds have been traced to seed lots in which only 0.1% to 3% of seeds were infested. Seed infestation has in turn been traced to the colonization of spruce cones by ''S. conigenus'' in forests of the western interior. Infection develops readily if conidia are deposited on succulent plant parts that remain wet for at least 24 hours at 10&nbsp;°C to 25&nbsp;°C. Longer periods of wetness favour increasingly severe disease. Twig tips killed during growth the previous year show a characteristic crook.

==== ''Rhizosphaera kalkhoffi'' needle cast ====
''Rhizosphaera'' infects white spruce, [[blue spruce]] (''Picea pungens''), and Norway spruces throughout Ontario, causing severe defoliation and sometimes killing small, stressed trees. White spruce is intermediately susceptible. Dead needles show rows of black fruiting bodies. Infection usually begins on lower branches. On white spruce, infected needles are usually retained on the tree into the following summer. The fungicide Chlorthalonil is registered for controlling this needle cast (Davis 1997).<ref name="davis">Davis, C. (24 September 1997) "Tree talk". ''The Sault Star''. Marie, Ontario. p. B2.</ref>

==== ''Valsa kunzei'' branch and stem canker ====
A branch and stem canker associated with the [[fungus]] ''Valsa kunzei'' Fr. var. ''picea'' was reported on white and Norway spruces in Ontario (Jorgensen and Cafley 1961)<ref name="jorg">{{cite journal |author=Jorgensen, E. and Cafley, J.D. |year=1961 |title=Branch and stem cankers of white and Norway spruces in Ontario |journal=For. Chron. |volume=37 |issue=4 |pages=394–400 |doi=10.5558/tfc37394-4|doi-access=free }}</ref> and Quebec (Ouellette and Bard 1962).<ref name="ouel">{{cite journal |author=Ouellette, G.B.; Bard, G. |year=1962 |title=Observations on a canker and resinosis in white and Norway spruce |journal=Can. Dep. For., for. Ent. Path. Branch, Ottawa ON, Bi-mo. Progr. Rep. |volume=18 |issue=2 |pages=2}}</ref> In Ontario, only trees of low vigour were affected, but in Quebec vigorous trees were also infected.