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14th International Sclerotinia Workshop, Wilmington, North Carolina, USA
The International Sclerotinia Workshop is held every 4 years and this year’s was hosted by the University of North Carolina. Most plant pathologists will be familiar with Sclerotinia diseases, as both S. sclerotiorum and S. minor have a wide range of hosts (virtually no dicot is safe) and S. sclerotiorum (which predominates in the UK) is an increasing threat on many crops such as oilseed rape, lettuce and carrot. The Americans take Sclerotinia diseases very seriously and in 2004, they set up the government-funded National Sclerotinia Initiative with the aim of conducting a ‘coordinated research strategy to minimize the devastating effects of S. sclerotiorum on soybeans, canola, sunflowers, dry edible beans, and the pulse crop group consisting of dry peas, lentils, and chickpeas’ www.whitemoldresearch.com. There were therefore many workshop delegates from the US and Canada with only a few from Europe and elsewhere.
Day one saw sessions on population biology, host-parasite interactions, biocontrol and general disease control. I was lucky enough to be the first speaker on the first day and my keynote presentation (another first) on populations of S. sclerotiorum on agr icultural hosts and meadow buttercup was well received and stimulated some discussion on the role of wild hosts in Sclerotinia epidemiology and population diversity. Serena McCoy (Nebraska) then demonstrated the importance of characterising S. sclerotiorum isolates for effective screening for resistance while Steve Koike (California) showed how something as simple as increasing bed widths in lettuce production has led to greater levels of S. sclerotiorum compared to S. minor. This was because conditions had become more conducive to apothecial production for the former species. In the host-parasite interactions session there was some emphasis on developing tools to study this relationship. Steven Clough (I l l inois) showed how I lumina ‘sequencing by synthesis’ technology was being used to generate small RNA and gene transcripts expressed in the S. sclerotiorum-soybean interaction with the aim of understanding the role of small RNA in the regulation of host and pathogen genes. Martin Chilvers (Michigan) showed how use of the 454 pyrosequencing platform produced over 40Mb of sequence data associated with the S. sclerotiorum-pea interaction which will help identify genes involved in pathogenicity and resistance.
However, it seems that some progress still needs to be made with analysing these large data sets to sort out the most interesting genes from both host and pathogen. In the biocontrol and disease control sessions, it was clear that Coniothyrium minitans is still the biocontrol agent of choice for Sclerotinia with two presentations (Wenting Zeng, Michigan; Guoqing Li, Wuhan) showing how best to apply it and integrate it with other treatments. It was interesting that although in the past C. minitans has been targeted at sclerotia, it also has some activity in suppressing infection by ascospores and can degrade oxalic acid, a pathogenicity factor for S. sclerotiorum. In other presentations (Helene Dillard, New York; Alexander Putman, Connecticut) there was also concern about fungicide insensitivity in S. sclerotiorum and S. homoeoc arpa highlighting the importance of sensible use of existing actives and other control methods.
Day two was an all day field trip and because of the sub-tropical climate of North Carolina it was hot (>30°C) and unfortunately there was no opportunity to see any Sclerotinia disease as it was the wrong time of year. However, we did see some local blueberry production, visit the Moore’s Creek National Battlefield (a patriot victory here in the American Revolution) which included a demonstration of musket firing and finally we were taken for a swim on Wrightsville Beach followed by a cold beer. A good day to revive !
The final day of the Workshop was devoted to a general poster session and further oral presentations on host resistance. I presented a poster in collaboration with Caroline Young (ADAS) on forecasting Sclerotinia disease in lettuce but still had time to visit the other posters. Of particular interest to me was a diversity study of S. sclerotiorum in the US by Laura Aldrich-Wolfe (North Dakota) who is using some of the same microsatellite markers as in my studies. We hope therefore to compare some of our data in the future so that we can establish any relationships between UK and USA populations. The final session on host resistance showcased both conventional and transgenic approaches in sunflower (Thomas Gulva, North Dakota), peanut (Jiahuai Hu, Virginia) and bean (Shree Singh, Idaho). It was clear from these presentat ions that appropriate screening methods are critical in identifying plant resistance and in the case of bean, repeated inoculations of a plant genotype without disease developing was convincing evidence of resistance.
The Sclerotinia Workshop was therefore a fruitful meeting, not only in providing an international platform to present my own work but also allowing me to strengthen existing contacts and meet new colleagues with whom there may be potential collaboration opportunities.
I would therefore like to thank the BSPP for the opportunity to attend. The next Sclerotinia Workshop will be in China, either pre- or post- the International Congress of Plant Pathology in 2013.
For anyone interested in Sclerotinia, there is an International Working Group (http://entoplp. okstate. edu/iswg/).
John Clarkson, University of Warwick-HRI
