Most conifers planted in the UK during the past 100 years (a period of intensive afforestation) are susceptible to root and butt-rotting attacks by the basidiomycete fungus Heterobasidion annosum (formerly known as Fomes annosus).
This decay fungus infects coniferous crops by colonising the recently cut stumps created in thinning or clear-cutting operations. The fungus grows down through the stump roots and across into any roots of nearby living trees which happen to be in contact. It can result in killing of pines on vulnerable sites, and decay in the lower stems of many other coniferous species.
Importance of stump treatement
Infection of the standing crop can be prevented by prophylactic (but not remedial) stump treatment whereby fresh stump surfaces are sprayed with chemical or biological agents that inhibit infection by airborne basidiospores of the pathogen.
In Britain, these pathogen spores are present all year round but because conifer stands in the UK have only been intensively managed for a relatively short period of time (100-200 years), spores are relatively infrequent and infection levels in most stands are low.
Over time however, and without the practise of stump treatment, the fungus can be expected to increase to levels currently experienced in mainland Europe. For example, in Scandinavia, up to 25 per cent of Norway spruce may be affected and decayed, resulting in losses which run into hundreds of millions of Euros per year.
It is therefore very important that we use stump treatment wherever necessary.