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As a plant pathologist responsible for assessing risks to UK/EU plant health from exotic plant pathogens (including Phytophthora ramorum and also Phytophthora kernoviae) I chose to attend this conference as I knew that there were many more Phytophthora species out there that might warrant a second look! I was not disappointed…
The meeting comprised five long days (and nights) of meetings with ca. 100 participants from all over the world with a strong North American contingent. A common theme throughout the meeting was the number of new species being discovered through surveillance in nurseries, forests and other situations. This was touched upon on day one with updates from representatives from Europe, Australasia and the Americas on the research and management of a range of Phytophthora spp. in the three continents. Clive Brasier (Forest Research, UK) speculated on the potential numbers of Phytophthora spp. that are ‘out there’, stating that in 1996 there were thought to be 54 species with another 50 described or being described by 2000, of which ca. 30 were nursery or tree pathogens. Water baiting has become a popular method for isolating P. ramorum and is used in surveillance work in the USA and the UK; this alone has led to 3 new species being described. Clive made a series of assumptions in his presentation and estimated that there are possibly 200 to 600 species of Phytophthora in total at the present time. If this proves to be true, the risk analyst and the Phytophthora specialist are faced with an insurmountable problem if we are to identify and manage the potential risks to the environment, the nursery and forestry industries.
Between day one and day five there were innumerable presentations and one poster session which illustrated the intense attention that the genus Phytophthora receives. This was my first genus-specific conference and it was very useful for identifying potential new threats to the UK and Europe. On the last day of the meeting I gave a presentation on the development of the Pest Risk Analyses (PRAs) for P. ramorum, P. kernoviae and P. lateralis. In the UK the Plant Health Service has been undertaking surveillance on nurseries and outdoors for P. ramorum since 2001 having been alerted to the problem posed by this organism in California and Oregon since the 1990s through a series of PRAs developed by CSL and Forest Research. This led to the first UK findings of P. ramorum in 2002 and to the discovery of P. kernoviae (as Phytophthora taxon C) in 2003. In updating the PRA for P. kernoviae this year I was concerned at the recent announcement that New Zealand had discovered this pathogen to be causing disease in an orchard of cherimoya (custard apple) since at least 2002 and wondered whether an unidentified Phytophthora known as the ‘Tokoroa Phytophthora‘ which had been isolated in the 1950s in NZ was in fact P. kernoviae; this was confirmed by a presentation given by Tod Ramsfield (Ensis, NZ) and has enabled me to develop the UK PRA as a result.
The meeting was located in the beautiful coastal area of Monterey Bay in the Asilomar Conference Grounds, with plenty of Monterey pines with pitch canker (to keep the pathologists happy). We were ideally located to make two field trips during the week to see the damage caused by P. ramorum in the Mittledorf Preserve and the Pfeiffer Big Sur State park. Our hosts guided us through the areas which had been chosen (respectively) to show a forest where P. ramorum had only recently entered and one where it had been there for more than ten years. Death of tanoak, one of the main hosts of P. ramorum was apparent and the fallen trees were left in situ with openings appearing in the canopy overhead. Giant redwood trees were also affected but thankfully only with shoot damage rather than the lethal stem cankers that this aggressive pathogen causes. As a risk analyst I spend much of my time writing about diseases that I never see so this was a fabulous opportunity to get a feel for what one of my target pathogens gets up to if left uncontrolled.
On the social side we were welcomed on our first day at a bonfire on the beach and finished the meeting with a very pleasant barbeque with music performed by some of the delegates on the penultimate night. Mid-week we were taken to the Monterey Bay Aquarium and were astounded by the beauty of the jellyfish displays, the cute sea otters and the newest inmate – a young great white shark! Being a pathologist, working with microscopic organisms throughout my career, it made me appreciate the world of the marine biologist. At least they can see a problem waiting to happen rather than after it arrives! We also managed to get to a commercial winery on the way home from the field trip to the Mittledorf Preserve.
I would like to congratulate the organisers (Janice Alexander, Elizabeth Fichtner, Susan Frankel, Ellen Goheen, Everett Hansen, Daniel Huberli, Katie Palmieri and Dave Rizzo) for an excellent meeting which has given me plenty of food for thought. I would also like BSPP, Defra Plant Health Division and CSL for supporting my attendance which will give risk analysts plenty of work for the foreseeable future!
Claire Sansford, CSL York