Symptoms
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Young maple trees (mostly Acer pseudoplatanus, more rarely Acer platanoides, BHD up to 30cm) with up to several meters long fissures in lower stem parts, usually not connected to the collar, often with distinct callusing; xylem in cross section greenish, later greyish discolored (sectors reaching the heart wood); depending on the extension of the fissure crown thinning and dieback.
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Impact
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Though the symptoms resemble Verticillium-wilt, this pathogen is rarely found: agents causal for the wood discoloration and the bark cracking seem to be Fusarium species (F. sambucinum and others); the phenomenon is locally common, distinct weakening factors are unknown, though drought could likely play a role by disposing the trees to attacks by the fungi; acc. to literature there are commonly bark beetles involved.
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Control
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Removal of the most heavily affected trees (risk of breakage)
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Hosts |
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Maple;
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Affected plant parts
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Stem;
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