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UK Risk Register Details for 'Candidatus Phytoplasma fraxini'

This record was last updated on 03/05/2023

Common Names

  • Ash yellows

Scenario and Pathways

Scenario for Risk Register

  • show / hide
  • Pest is introduced

Pathway Assessed for Entry to UK

  • show / hide
  • Plants for planting (except seeds bulbs and tubers)

Common Pathways

  • show / hide
  • Plants for planting (except seeds bulbs and tubers)

Risk Ratings and Current Mitigations

Unmitigated Risks

Likelihood [1 - 5] 3
Spread [1 - 5] 3
Impact [1 - 5] 4
Value at Risk [1 - 5] 5
Likelihood x Impact [1 - 25] 12
UK Relative Risk Rating [1 - 125] 60

Current Mitigations

  • show / hide

Key mitigation for pest

Prohibition of key pathway, regulated quarantine pest (Northern Ireland). Provisional quarantine pest (Great Britain).



Industry Scheme

Contingency Plan



Mitigated Risks

Likelihood [1 - 5] 2
Spread [1 - 5] 3
Impact [1 - 5] 4
Value at Risk [1 - 5] 5
Likelihood x Impact [1 - 25] 8
UK Relative Risk Rating [1 - 125] 40

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 (Limited)
United States Present (Limited)
South America
Chile Present (Limited)
Colombia Present (Limited)

Type of Pest

  • Phytoplasma

Host or Industry at Risk

  • show / hide

Broadleaved trees

Major Hosts

  • Acacia melanoxylon R.Br.
  • Croton L.
  • Eugenia L.
  • Fraxinus americana L.
  • Fraxinus angustifolia ssp. angustifolia Vahl
  • Fraxinus bungeana A.Dc.
  • Fraxinus excelsior L.
  • Fraxinus latifolia Benth.
  • Fraxinus nigra Marsh.
  • Fraxinus ornus L.
  • Fraxinus quadrangulata Michx.
  • Fraxinus syriaca Boiss.
  • Fraxinus tomentosa Michx.F.
  • Fraxinus uhdei (Wenzig) Lingelsh.
  • Fraxinus velutina Torr.
  • Gaultheria phillyreifolia (Pers.) Sleum.
  • Liquidambar styraciflua L.
  • Magnolia grandiflora L.
  • Myrtus ugni Molina
  • Paeonia L.
  • Pittosporum undulatum Vent.
  • Populus nigra L.
  • Prunus persica Batsch
  • Syringa diversifolia (S. x diversifolia) Rehd.
  • Syringa henryi (S. x henryi) Schneid.
  • Syringa josiflexa (S. x josiflexa) Preston
  • Syringa josikaea Jacq.F. Ex Reichb.
  • Syringa komarowii Schneid.
  • Syringa laciniata Mill.
  • Syringa meyeri Schneid.
  • Syringa nanceiana ( s. x nanceiana) Mckelvey
  • Syringa oblata Lindl.
  • Syringa persica (S. x persica) L.
  • Syringa pubescens Turcz.
  • Syringa sweginzowii Koehne & Lingelsh.
  • Syringa tomentella Bur. & Franch.
  • Syringa villosa Vahl
  • Syringa vulgaris L.
  • Syringa yunnanensis Franch.
  • Vitis vinifera L.
  • Fraxinus pennsylvanica
  • Quercus humboldtii Bonpl.

Threats to Protected Cultivation

Forest Tree Pests and Pathogens

  • Broadleaved

Further Information

PRA Availability

UK (2016)

Regulation and EPPO listing

  • show / hide

Provisional quarantine pest (Great Britain). Regulated quarantine pest (Northern Ireland)

Actions Indicated

  • show / hide


Statutory action on findings.

General Comments

Pathogen causing phytoplasma disease of certain tree species in the Americas. Regulation of hosts already provides some mitigation, but further regulation could be considered to include Syringa.