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UK Risk Register Details for Heterobasidion occidentale

This record was last updated on 03/05/2023

Common Names

Scenario and Pathways

Scenario for Risk Register

  • show / hide
  • Pest is introduced

Pathway Assessed for Entry to UK

  • show / hide
  • Non-squared wood

Common Pathways

  • show / hide
  • Plants for planting (except seeds bulbs and tubers)
  • Non-squared wood
  • Bark
  • Wood packaging material

Risk Ratings and Current Mitigations

Unmitigated Risks

Likelihood [1 - 5] 2
Spread [1 - 5] 3
Impact [1 - 5] 3
Value at Risk [1 - 5] 5
Likelihood x Impact [1 - 25] 6
UK Relative Risk Rating [1 - 125] 30

Current Mitigations

  • show / hide

Key mitigation for pest

Prohibition on key hosts. Provisional quarantine pest (Great Britain).



Industry Scheme

Contingency Plan



Mitigated Risks

Likelihood [1 - 5] 1
Spread [1 - 5] 3
Impact [1 - 5] 3
Value at Risk [1 - 5] 5
Likelihood x Impact [1 - 25] 3
UK Relative Risk Rating [1 - 125] 15

Proposed Actions

Proposed Actions



Management By Industry

Targeted Survey


Contingency Plan



Distribution and Pest Details


Country / Territory Status Notes
United Kingdom Absent
North America
Canada Present
Mexico Present
United States Present

Type of Pest

  • Fungus

Host or Industry at Risk

  • show / hide


Major Hosts

  • Abies Miller
  • Abies amabilis (Dougl. Ex Lood) Dougl. Ex Forbes
  • Abies concolor var. concolor (Gord. & Glend.)Lindl. Ex Hild.
  • Abies fraseri (Pursh) Poir.
  • Abies grandis (D.Don) Lindl.
  • Abies lasiocarpa var. lasiocarpa (Hook.) Nutt.
  • Abies nordmanniana (Stev.) Spach
  • Abies procera Rehder
  • Abies religiosa (H.B.K.) Schlecht.
  • Picea A.Dietr.
  • Picea breweriana S.Wats.
  • Picea engelmannii Parry Ex Engelm.
  • Picea sitchensis (Bong.) Carr.
  • Pseudotsuga menziesii var. menziesii (Mirbel) Franco
  • Sequoiadendron giganteum (Lindl.) J. Buchholz
  • Tsuga Carr.
  • Tsuga heterophylla (Rafin.) Sarg.
  • Tsuga mertensiana (Bong.) Carr.

Threats to Protected Cultivation

Forest Tree Pests and Pathogens

  • Coniferous

Further Information

PRA Availability

UK (2016)

Regulation and EPPO listing

  • show / hide

Provisional quarantine pest (Great Britain).

Actions Indicated

  • show / hide


Statutory action against findings.

General Comments

Fungal pathogen from North America which can affect tree vigour and timber production for a number of conifer species, including those commonly grown for forestry purposes in the UK. Management practices (such as stump treatments) carried out against native fungal species may be helpful in controlling this non-native species if introduced, although such practices may not be carried out for those tree species known to be tolerant (e.g. Abies grandis) to the native species.

Risk Records for this Pest