decay (external signs in trees)

Direct evidence of decay in trees consists of exposures of rotten wood and cavities, and the presence of fungal fruiting bodies. Signs of root rot in the crown include small, sparse or pale leaves, premature discoloration of foliage and defoliation, and die-back. There is a chance of decay in the aerial part wherever there are old wounds, stubs, dead bark etc., including wounds that have been completely occluded. Structural weakness (not just due to decay) can be inferred from various features of adaptive growth, while bleeding from the bark may be caused by bacterial wetwood.

This definition is abridged from A – Z of tree terms: A companion to British arboriculture.
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