Inonotus Dryadeus – Oak Bracket

Inonotus is most commonly associated with oak trees, although it can also be found on horse chestnut, sweet chestnut, beech, London plane, elm and more rarely on conifers.

How do I recognise it?

The bracket, which can measure up to 30cm across and 8cm deep, is characterised by its uneven, lumpy appearance with pits or depressions which excrete thick yellow drops of liquid.  The surface of the fungi itself is pale yellow and turns darker to brown as it ages.


The fungus is usually seen only on large, old living trees and occurs predominantly near the base of the tree (and no more than a couple of meters above ground level) in early Autumn.

In the early stages of infection, the tree appears to have a dark brown “water soaked” area together with yellowish stripes of colour which become broader and lighter as the fungus develops. Finally, the whole wood becomes soft, and resembles paper pulp. Thick sheets of white mycelium (matted hair-like strands) are often present too, breaking up the decayed mass into sections.


Inonotus generally enters the tree through wounds so any precaution that would reduce injuries to the roots or base of the tree is advisable.

Remedial action may only require crown reduction as opposed to felling depending upon the degree of damage to the roots and therefore how stable the tree is. In its advanced stages, any decay in the heartwood and roots will affect the trees uptake of water and nutrients causing further dieback and weakness of the structure in general.

It is very important, particularly if the fungus is known to be present locally, to investigate the condition of the roots and determine the extent of any decay.

Since positive diagnosis is dependent on presence of the fungi, decay is usually well advanced at this time and in the most severe cases trees blown-down during rainstorms or windy periods is often the first and only indication of root rot.

In any event, since the fungus is progressive, eventual removal of the affected tree to avoid damage to surrounding property is recommended.


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