Phytophthora in forests and natural ecosystems

Phyto-threats attendance at the 8th Meeting of the International Union of Forest Research Organisations Working Party (IUFRO) 7.02.09, Phytophthora in forests and natural ecosystems.

Sapa, Vietnam 18-25th March 2017

Sarah Green (Forest Research) attended the 8th meeting of IUFRO working party 7.02.09, ‘Phytophthora in forests and natural ecosystems’ held in SaPa, Vietnam at the end of March 2017. This meeting, which was attended by ~100 forest Phytophthora researchers from around the world, began with a two-day pre-conference field tour which was spent visiting forest nurseries and plantations of Eucalyptus and Acacia affected by Phytophthora cinnamomi.  The nursery operations viewed during the tour were less than optimal in terms of Phytophthora management but moves are afoot in the country to educate nursery managers and improve disease management practices.

During a conference session on Dispersal Pathways/Urban Horticulture, Sarah presented an overview of the Phyto-threats project, including a series of slides prepared by Louise Barwell and Beth Purse (CEH) on the global Phytophthora risk modelling approaches they intend to take, finishing up with a request for researchers to contribute their Phytophthora records for the development of global niche models. Several Phytophthora researchers from a range of countries have already contributed data, or are planning to do so, and resultantly the Phyto-threats modelling team are having good success in pulling these distribution data together (more than 7000 records to date).

In a closely parallel project, Peter Scott of Scion, New Zealand, demonstrated his modelling approaches to predict global Phytophthora diversity and biosecurity risk. His time series models predict up to four times more Phytophthora species than those currently described. Peter and his group are also modelling Phytophthora invasiveness traits to predict global risk. Given the degree of overlap in the two projects, and thanks to a surprisingly good wifi connection, a successful Skype meeting was held one evening between the New Zealand/Australian Phytophthora modelling team (plus Sarah) located in a hotel bedroom in northern Vietnam and Phyto-threats modellers’ Beth Purse and Louise Barwell located in an Oxford office!. Future meetings are now planned between the two groups to scope out potential areas for collaboration. This may include sharing of Phytophthora traits databases independently developed by both groups with a proposal to produce a combined traits database for every known Phytophthora species that will be published online and managed and updated through a collaborative effort.

Another major conference topic of interest to the Phyto-threats project was the use of metabarcoding to detect Phytophthora species in soil and water in a range of different ecosystems around the world, including plant nurseries. Some Phytophthora species appear to be ubiquitous across highly differing environments, and as the global picture continues to develop it may be possible to see (and hopefully understand) patterns in species distribution and diversity.  Miguel Redondo based in Uppsala, Sweden, reported on a study of Phytophthora communities in eight nurseries, 16 rivers and 14 forests in Sweden, and undertook modelling to identify functional traits associated with establishment. Their approach was particularly interesting for having included both highly managed and less disturbed sites in a single study, and the authors observed large differences in the composition of Phytophthora communities in the three environments. David Cooke (JHI), who leads Phyto-threats work package 1, gave a presentation on methods used for sampling Phytophthora diversity which highlighted some of the pitfalls of using the multi-copy ITS region for Phytophthora identification. David described a bioinformatics pipeline developed by project colleagues’ Leighton Pritchard and Peter Thorpe (JHI) which uses different clustering algorithms to address within-species sequence variability in species assignations. This pipeline, a key output from the Phyto-threats project, will soon be made publically available for metabarcoding analyses.

In terms of Phytophthora management in nurseries, a critical link in the dissemination of Phytophthoras globally, Laura Sims of the University of California presented a nicely contrasting ‘before and after’ study showing how a series of changes to nursery management practice can dramatically reduce Phytophthora detections. Similarly, Agnes Simamora of the University of Nusa Cendana in Indonesia showed how P. boodjera infections in a containerised production nursery can be eliminated by steam-sterilizing the re-used seedling trays. Such evidence of the effect of relatively straightforward management changes on reduction in disease load will be useful in upcoming engagement activities with UK nursery managers planned as part of the Phyto-threats project this year.