Global threats from Phytophthora spp. (PHYTO-THREATS)

Understanding drivers of emergence and opportunities for mitigation through nursery best practice

Dieback of Japanese larch caused by Phytophthora ramorum

The PHYTO-THREATS project aims to address the risks to UK forest and woodland ecosystems from Phytophthora by examining the distribution and diversity of Phytophthoras in UK plant nursery systems. It also aims to provide the evidence base for the development of a set of enhanced nursery ‘best practice’ accreditation criteria to mitigate risk of further Phytophthora introduction and spread.

Research objectives

  • Examine the distribution, diversity and community interactions of Phytophthora in UK plant nursery systems
    P Ramorum on RhododendronThe distribution and diversity of Phytophthora species in water and plant samples collected from different UK plant nursery management systems, including those locations considered to be high risk in terms of importing new Phytophthoras, will be studied using state-of-the-art DNA sequencing technology. Water samples from streams and ponds in amenity environments will also be collected to investigate the wider distribution of nursery-associated Phytophthoras . This work will identify nursery practices resulting in the highest density and diversity of Phytophthora pathogens and the highest probability of onward spread into woodland or other natural ecosystems.
  • Provide the evidence base for a voluntary nursery ‘best practice’ accreditation scheme to mitigate further spread
    P Ramorum on Viburnum tinusData from the plant nursery survey (above objective) will provide evidence to guide the development of a UK-wide voluntary nursery accreditation scheme. Nurseries signing up to the scheme will adhere to a set of ‘best practice’ criteria designed to reduce the risks of importation and dissemination of Phytophthoras. Feasibility assessments will involve consultation with nursery managers, consumers and other stakeholders in order to identify economic and social opportunities and barriers, and attitudes towards implementation of such a scheme. We will also explore options to promote the visibility and legitimacy of the accreditation scheme to consumers such that there is an added advantage for nurseries to take part.
  • Identify and rank global Phytophthora risks to the UK
    SporangiaIdentifying future global Phytophthora threats and potential routes of entry will be essential in refining nursery ‘best practice’ and other national biosecurity measures. To do this, data on current known global distribution of Phytophthoras infecting woody species and biological characteristics that may affect establishment will be collated from databases and national surveys conducted in a broad range of countries. Models will identify those species occurring in locations resembling the UK’s climate and ecosystems and those species that are ecologically similar to Phytophthoras that have established in Europe, strengthening the evidence base for inclusion of pathogens in the UK Plant Health Risk Register. We will also look at the pathways of international trade and tourism and the risks of new Phytophthora introductions via these routes, identifying national focus points for biosecurity based on a raised risk that new Phytophthoras will arrive at these locations. Pathway analyses will be used to inform nursery managers and accreditation scheme criteria of the highest risk trade practices.
  • Gain a greater understanding of the evolutionary pathways of Phytophthoras
    Current practices are increasing the diversity of co-existing Phytophthoras in the environment, yet we have little understanding of the potential for new aggressive Phytophthoras to arise through hybridisation or other mechanisms of genetic exchange when new species meet. Whole genome sequences of Phytophthora species will be examined to determine the extent to which genetic exchange has occurred among Phytophthoras and related organisms, and how this might have enabled these pathogens to adapt on to tree species, change virulence or host range. This work will enhance our fundamental understanding of pathogen evolution.


Project will run from April 1st 2016 until March 30th 2019


Sarah Green

Funders and partners

Funded jointly by a grant from BBSRC, Defra, ESRC, the Forestry Commission, NERC and the Scottish Government, under the Tree Health and Plant Biosecurity Initiative.

Research partners

  • Forest Research (FR)
  • James Hutton Institute (JHI)
  • Centre for Ecology and Hydrology (CEH)
  • University of Edinburgh
  • University of Worcester
  • Animal and Plant Health Agency (APHA)
  • Science and Advice for Scottish Agriculture (SASA)
Forest Research logo The James Hutton Institute logo CEH Logo
University of Edinburgh University of Worcester logo APHA logo
SASA logo    

What's of interest


Press release

Would you like to participate in this project ?

We would like to work with industry to ensure healthy, high value plants. We are looking for plant nurseries and traders to participate in this project by sharing your expertise and experiences with us and by allowing us to sample water and plants at regular intervals during the course of the project.

We will provide you with information about your Phytophthora risk and work with you to reduce it.

All published data on nursery findings will be anonymous. Please see the participants information page. 

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