Conifer root and butt rot - Heterobasidion annosum

Prevent Heterobasidion annosum infection

Disease overview

H. annosum killing young pine

The basidiomycete fungus Heterobasidion annosum (formerly known as Fomes annosus) attacks the roots, butts and stems of many conifer trees – it is one of the most serious pathogens of commercial conifer forestry.

This resource will help you to select a management strategy to treat and protect your crop from H. annosum infection.

Disease details

Basidiospore released by H. annosum fruit bodyIn mainland Europe there are high levels of H. annosum: it affects up to 25 per cent of Norway spruce in Scandinavia and causes tree decay that results in losses of hundreds of millions of Euros every year.

But in Britain the problem is not so severe. British conifer stands have only been intensively managed for a relatively short period of time (100-200 years) and so H. annosum spores are relatively infrequent and infection levels remain lower than in Europe. However there is a risk that spore levels may increase over time.


  • Colonises stumps from recent thinning or clear-cutting operations
  • Fungus grows down through root stumps
  • If stump roots are in contact with roots of other trees, will infect living trees
  • Causes decay in the lower stems of many coniferous species – conifer root and butt rot
  • Kills pines on vulnerable sites

Stem decay in Norway spruce

 Prevent infection

  • Risk of infection depends upon soil type, climate and crop management
  • Prophylactic stump treatment prevents infection of standing crops
  • Fresh stump surfaces are sprayed with chemical or biological agents

Our research 

Stump treatment prevents H. annosum infection, and it accounts for 90% of all plant protection product use in British forestry. Forest Research are conducting field trials of two non-chemical treatments, PG Suspension, which is currently only registered for use on pine species, and Rotstop, which is registered in Scandinavia for use on Norway spruce and pine.

Find out more about our research on non-chemical protection against conifer root and butt rot  .


Dr. Kath Tubby                

What's of interest

PG Suspension

PG Suspension packaging
Forest Research produce this biological control agent that is based on Phlebiopsis gigantea