EPPO Platform
on PRAs

Pest categorisation of Melampsora farlowii


Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest categorisation of Melampsora farlowii, a well‐defined and distinguishable fungus of the family Melampsoraceae. Mfarlowii is the causal agent of a leaf and twig rust of hemlocks (Tsuga spp.) in eastern North America. The pathogen is regulated in Council Directive 2000/29/EC (Annex IAI) as a harmful organism whose introduction into the EU is banned. Mfarlowii is not reported to be present in Europe and could enter the EU via host plants for planting and cut branches. Cones and fruits are listed as plant parts that can carry the pest in trade and transport, but are not regulated. The pathogen could establish in the EU, as climatic conditions are favourable and Tsuga spp. have been planted as ornamentals and in plantations in several EU countries. Mfarlowii would be able to spread following establishment by human movement of host plants for planting and cut branches, as well as natural spread. Should the pathogen be introduced in the EU, impacts can be expected on Tsuga spp. plantations, ornamental trees and especially nurseries. Hemlock rust is considered a destructive rust attacking Tsuga spp., particularly Tsuga canadensis in nurseries. The main uncertainties concern whether the impact of the pathogen in plantations under European conditions could be different than observed in eastern North America, whether fruit/cones of Tsuga can be a pathway of entry, and the dissemination potential of the pathogen under European conditions. However, Mfarlowii is found in North America in most of the natural distribution range of Tcanadensis, suggesting little dispersal limitation of the pathogen. The criteria assessed by the Panel for consideration as a potential quarantine pest are met, whilst, for regulated non‐quarantine pests, the criterion on the pest presence in the EU is not met.


  • Melampsora farlowii


  • Tsuga
  • Tsuga canadensis


Type File Size
Pest Risk Analysis Link to file

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