Fungus spotlight: Ganoderma resinaceum (lacquered bracket)

I thought I’d share a little bit on the lacquered bracket, for those that may be interested. An interesting species of Ganoderma, particularly in the way in which is presents itself. Hopefully, for those interested in fungi, this post will be of use.

Common hosts

Frequently found colonising mature Quercus spp. (Mattheck et al., 2015; Rayner & Boddy, 1988; Watson & Green, 2011), though may also be found on other broadleaved species such as Acer pseudoplatanus (Deflorio et al., 2008a), Carpinus betulus (personal observation), Fagus sylvatica (Deflorio et al., 2008a; Schwarze & Baum, 2000), Platanus spp. (Schwarze & Ferner, 2003), and Robinia pseudoacacia (personal observation). Pseudotsuga menziesii may also act as a host (Deflorio et al., 2008a; Deflorio et al., 2008b). In colder areas, it may very rarely be found – even on its preferred hosts (Schwarze & Ferner, 2003).

A tier of dried-out Ganoderma resinaceum brackets upon a hornbeam (Carpinus betulus). These were located around 2.5m up the main stem.

Colonisation strategy

Entering through exposed heartwood surfaces, Ganoderma resinaceum will typically begin its life as a parasite. However, upon death of the host, it may persist as a saprophyte (Deflorio et al., 2008b; Mattheck et al., 2015). Upon entering into heartwood, it may begin to also colonise sapwood (Watson & Green, 2011).

Rot

The type of rot induced by Ganoderma resinaceum is not fully understood, though it is considered to selectively delignify its host (Deflorio et al., 2008a; Mattheck et al., 2015; Rayner & Boddy, 1988; Schwarze & Ferner, 2003; Watson & Green, 2011). Lonsdale (1999) remarks that it may oft be confused with Ganoderma lucidum, making differentiation of rot characteristics between the species difficult, though it is considered that Ganoderma resinaceum induces a more ‘complete’ rot that other Ganoderma species.

Areas affected

Decay is normally confined to the roots and buttress zone (Rayner & Boddy, 1988; Watson & Green, 2011), though may also – albeit rarely – extend further up the stem (Mattheck et al., 2015). The host species may perhaps play a role in the location of the decay, with Quercus spp. usually having rot confined to the roots and butt, whereas in Platanus spp. decay may extend some metres up the stem (Schwarze & Ferner, 2003).

A slightly stalked and now-inactive Ganoderma resinaceum sporophore emanating from the butt of a mature Quercus robur.

Significance

Because Ganoderma resinaceum can spread into sound sapwood (Watson & Green, 2011) by breaching the reaction zone (Schwarze & Ferner, 2003), in addition to the ‘complete’ delignification induced by the mycelium within not only the butt but also the roots (Lonsdale, 1999; Schwarze & Ferner, 2003), there is a potentially high level of risk associated with retention of a specimen with a full crown, where the target area is significant. Ductile fracturing will typically be induced at the root plate or near to the base of the host (Mattheck et al., 2015), when the decay has advanced significantly (Watson & Green, 2011). Schwarze & Ferner (2003) do however note that the extent of decay may be less than where decay has been caused by other Ganoderma species (such as Ganoderma applanatum).

A fresh sporophore growing at the base of a fairly large Quercus robur.

Treatment and prevention

Limiting the severity of pruning operations is likely to reduce the risk of decay by this fungus, though care where working around the base of potential hosts is also important – given the fungus will colonise around the root plate and butt region (Mattheck et al., 2015). If found to be colonising a tree, if the target area includes people and / or property, strong consideration must be given as to at least pruning the tree (even if only a small reduction). Investigations into determining wood strength can be supplemented with the use of a resistograph, ultrasound tomography, or a fractometer (Deflorio et al., 2008a; Mattheck et al., 2015). However, as Ganoderma resinaceum may colonise sapwood very easily when the barrier zone is breached by invasive devices (Schwarze & Ferner, 2003), careful consideration as to what type of decay-detection device that is to be used is mandatory.

References

Deflorio, G., Fink, S., & Schwarze, F. (2008a) Detection of incipient decay in tree stems with sonic tomography after wounding and fungal inoculation. Wood Science and Technology. 42 (2). p117-132.

Deflorio, G., Johnson, C., Fink, S. and Schwarze, F. (2008b) Decay development in living sapwood of coniferous and deciduous trees inoculated with six wood decay fungi. Forest Ecology and Management. 255 (7). p2373-2383.

Lonsdale, D. (1999) Principles of Tree Hazard Assessment and Management (Research for Amenity Trees 7). London: HMSO.

Mattheck C., Bethge, K., & Weber, K. (2015) The Body Language of Trees: Encyclopedia of Visual Tree Assessment. Germany: Karlsruhe Institute of Technology.

Rayner, A. & Boddy, L. (1988) Fungal Decomposition of Wood: It’s Ecology and Biology. UK: John Wiley & Sons.

Schwarze, F. & Baum, S. (2000) Mechanisms of reaction zone penetration by decay fungi in wood of beech (Fagus sylvatica). New Phytologist. 146 (1). p129-140.

Schwarze, F. & Ferner, D. (2003) Ganoderma on trees—differentiation of species and studies of invasiveness. Arboricultural Journal. 27 (1). p59-77.

Watson, G. & Green, T (2011) Fungi on Trees: An Arborist’s Field Guide. UK: The Arboricultural Association.