These conference reports are written by the beneficiaries of our travel fund.
Click here to read more about the fund and apply yourself
Fourth Sudden Oak Death (SOD) Science Symposium, June 15-18th 2009, Santa Cruz, California.
The first Sudden Oak Death (‘SOD’) Symposium was held in California in December 2002; since that time, meetings have been held in 2005 and 2007 with an online symposium in 2003. Despite working on assessing the risks to the UK from Phytophthora ramorum (the cause of SOD in California and Oregon) since 2001, I had never attended this important international meeting. So, I was delighted when the organisers of ‘SOD IV’ accepted my offer of an oral presentation of the Pest Risk Analysis (PRA) for P. ramorum for the European Union (EU), the key deliverable from the EU Sixth Framework Project. SOD IV was based at the Hilton Hotel, Scotts Valley; some 20 minutes drive inland from the coastal resort of Santa Cruz, California. There were more than 200 delegates, principally from North America, with a few Europeans including a handful of Brits, plus one Chilean scientist.
The first day of the meeting was dedicated to a field trip to the 20,000 acre Santa Lucia Preserve, Carmel, California. SOD was first confirmed there in 2004 and is currently distributed in coastally-influenced mixed evergreen forest and canyons in the western part. Because P. ramorum is not subject to strict eradication in California, within the preserve it is being managed collaboratively between landowners, staff of the preserve, and tree care professionals. It was useful to see how engaged the landowners were in trying to conserve the ecosystem in which they resided. The main problem is choosing what to replant after clearance of infected trees/shrubs; this is because P. ramorum has such a wide host list (currently at least 130 species based upon European and North American host lists).
The rest of the meeting was held at the hotel. The opening session was used to give participants an update of the status of P. ramorum in the USA (principally California and Oregon with nursery/waterway findings elsewhere), Canada, Europe, and the UK. Dave Rizzo, UC Davis, reminded us that the first isolation of the then ‘unknown’ Phytophthora as the possible cause of SOD since the mid-1990s in California was exactly 9 years earlier. Considerable research and management work has been done since that time, but sadly the pathogen has spread further, on both sides of the Atlantic. Its origin is still uncertain despite the Phytophthora hunts that have been undertaken in Asia (suspected source) by various scientists. Sandra Denman, Forest Research, presented the European situation, principally from the RAPRA databases but also from the EU Member State Surveys, P. ramorum is now in 19 EU countries as well as Norway and Switzerland, but it is still subject to official control.
My colleague, Keith Walters (Fera), presented the details of the 2008 Defraled (Defra, Forestry Commission and Welsh Assembly Government) public consultation on future management of Phytophthora ramorum and Phytophthora kernoviae as well as the outcome: a 5-year Defra-funded Fera programme for both pathogens, which began on 1 April 2009. This new programme includes further R&D, an awareness and behavioural change programme and, disease control through clearance of host plants in high-r isk areas. As for my talk, given in the ‘predicting risk’ session, this proved to be quite a challenge. In February 2009, myself and Alan Inman (Fera) completed the RAPRA PRA using the EPPO PRA scheme. We had worked on it almost solidly since August the previous year.
Having offered to present it, I discovered that each speaker had been allocated ten minutes to talk; but the PRA is 311 pages long, and represents the findings of a 39-month project undertaken by 9 partner institutes in 6 countries. Clearly all that I could do was to give an overview. Nevertheless, the talk was well-received and it was reassuring from the feedback of participants, that the PRA was being used by other countries as a resource, as well as a model for assessing risks and determining risk management options for exotic plant pathogens and pests.
Other highlights included the talk given by Clive Brasier on his exotic trips to Asia with fellow scientists to hunt for the origin of a range of Phytophthora spp. Although he revealed some fascinating information I think I’d best leave it to him and his co-workers to publish! Nevertheless, the origin of introduced pathogens is vital information when undertaking PRAs as without this it is difficult to determine risk management options for future pathways of entry. The jury is still out as to whether P. ramorum has a functional mating system (with viable progeny) but presentations by the Belgians (who have found the only known A2 isolates in Europe) suggests potential for sexual reproduction with one of their isolates. But, this seems unlikely to be a common natural event.
Matteo Garbelotto, UC Berkeley, gave a presentation on the use of genetic analysis of populations of P. ramorum in understanding patterns of spread. He suggested that there had been at least ten introduction events in California.
Worryingly, the pathogen appeared to have a bimodal spread pattern of 0-600m in the absence of wind and 1 to 5km with strong winds. This has implications for containment of outbreaks outside of nurseries, which as we know, at least in parts of the UK, will rely on removal of potential sporulating hosts. Various presentations were given on the detection of P. ramorum in waterways in various US states; this has to be accounted for in any risk management programme.
Taking a break from P. ramorum, the Chilean scientist, Rodrigo Ahumada, gave a very interesting presentation on Phytophthora pinifolia – a relatively recently-discovered pathogen of Pinus radiata in Chile. P. pinifolia was a potential candidate for a PRA for EPPO, but as plants of Pinus are prohibited entry into the EU from non-European countries, the only potential pathway is either timber or seed. The data presented showed that there was no apparent risk from timber; Rodrigo’s team are still investigating seed.
Measurement of impac ts f rom Phytophthora spp. that affect natural as well as nursery and managed garden situations still plagues those of us responsible for weighing-up the costs and benefits of risk management programmes; this remains an area that requires data. Risk management options were reviewed with some interesting data on the potential for commercial algicides to control P. ramorum in waterways as well as the usual review of the efficacy of phosphonates to protect/cure tree infections, something that is undertaken on local-scale in the US but still subject to investigation in the UK. Finally, something we do not have to tolerate is the fire risks associated with dead and dying trees in US west-coast forests; a secondary impact of this damaging pathogen, with its own session at the symposium.
A jam-packed programme means there is far more to convey to the reader of BSPP news, but the information that I gleaned to support my ongoing work in PRA and consultancy for Phytophthora spp. in the UK was invaluable. The opportunity to meet old and new colleagues with common concerns is more valuable than email exchange, so despite the distance travelled I was pleased to be able to attend SOD IV with the support of BSPP and Fera, to whom I am grateful.
Dr Claire Sansford, Fera, York
