The spruce cone rust, caused by the rust fungus ''Chrysomyxa pirolata'' Wint., affects spruces in 3 continents, including white spruce in Canada (Hiratsuka 1987).
[Hiratsuka, Y. 1987. Forest tree diseases of the prairie provinces. Gov’t Can., Can. For. Serv., Edmonton AB, Inf. Rep. NOR-X-286. 142 p.] Alternate hosts of the fungus are several species among 3 genera of wintergreen: ''Pyrola'' spp., ''Orthilia'' spp., and ''Moneses'' spp. (Ziller 1974, Sutherland et al. 1984).
[Ziller, W.G. 1974. The tree rusts of western Canada. Environ. Can., Can. For. Serv., Ottawa ON, Publ. 1329. 272 p.][Sutherland, J.R.; Woods, T.A.D.; Miller, G.E. 1984. Effect of selected insecticides and fungicides on germination of Douglas-fir and white spruce pollen. USDA, For. Serv., Tree Plant. Notes 35(1):22–24. (Cited in Coates et al. 1994).] Diseased cones open prematurely and orange-yellow
aeciospore
Aeciospores are one of several different types of spores formed by Rusts.
They each have two nuclei and are typically seen in chain-like formations in the aecium.
References
Fungal morphology and anatomy
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s are sometimes produced in such quantity as to color the forest floor and lake surfaces. Up to half of a cone crop can be affected, and most of the affected cones do not produce viable seed. Some localities commonly experience damage to 20% to 30% of cone crops (Hiratsuka 1987),
a factor to be considered in the siting of seed orchards.
References
Fungal plant pathogens and diseases
pirolata
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