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Symptoms
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Young Norway spruces show distortions of the current years leading shoots (more rarely of lateral shoots) in summer and autumn. Mostly in the center of the shoot the bark surface is discolored red-brown to black-brown up to several cm in length, showing also cracks and resin flow. At first only limited loss of needles, later on dieback and in the following year death of the whole shoot, which is meanwhile defoliated and grey; before the shoot breaks, mostly at the initial stage of defoliation, a lateral shoot begins to take over the role of the leader. Therefore, repeated infection causes branching anomalies of the top, which can be intensified by growth of other microfungi as Sirococcus conigenus or species of Phomopsis into older branches or the stem.
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Impact
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A rust fungus with host alteration between Norway spruce and species of Prunus; on spruce, normally only the cones are infected, on which develop high numbers of aecidia below the scales instead of the seeds, the spores of which infect young leaves of Prunus (mostly Prunus padus in vicinity to the spruces). In the Prunus leaves small, violet and rectangular spots develop in summer (producing Uredo-spores and infecting further Cherry leaves. These spots can be easily mistaken for infections by Blumerella jaapii. On the litter a third type of spores are produced (Teleutospores, which infect spruce cones or shoots in the following spring. Shoots of spruces can be infected as well, but only on humid sites. One characteristic feature is that infections of spruce shoots tend to be repeated for years, leading to intense branching anomalies. After several years, the trees seem to grow out of the infection level (6-8m) and the branching becomes regular again. This disease is rather common in Austria, but up to now always localized and may cause some economic devaluation of the trees, but is mainly a striking phenomenon.
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Control
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Removal of Prunus padus from the vicinity of young afforestations of Norway spruce
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| Hosts |
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Spruce;
Cherry;
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| Affected plant parts
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Leaf;
Needle;
Shoot/Twig/Branch;
Stem;
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Spruce: shoots with necroses by Pucciniastrum areolatum
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Spruce. Dieback of shoots by Pucciniastrum areolatum
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Spruce cones with sporocarps of Pucciniastrum areolatum instead of seeds
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Cherry: leaf spots of Pucciniastrum areolatum
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Cherry: spore bearing structures of the Uredo-form in leaf spots
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Cherry: Teleutoform on leaves in the litter
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