Two years ago, the First European Powdery Scab Workshop was held in Aberdeen, Scotland, July 20-22. On the last day, key components of an integreated management of powdery scab and PMTV were defined and gaps in our knowledge identified. This formed the basis of a collaborative research project under the guidelines of the 5th EU framework. The proposal included field and pot trials to investigate the relationships between cultivar x environment and cultivar x pathogen. In the workshop it became obvious that there are many different tuber infection scoring systems in use. Therefor a standard scoring scale was needed for both tuber and root infection assessment.
Ruedi Schwaerzel from the Swiss Federal Research Station in Changins (RAC) initiated a field trial at their Spongospora screening site La Frétaz. It was planned to plant 10 cultivars with different susceptibility to powdery scab and mop top virus infection in repeated plots.Unfortunately Brussels then rated the Spongospora project not high enough and it was not accepted. Nevertheless the trial was planned so the potatoes were planted in spring 2002.
Then Ueli Merz from the ETH in Zurich sent an announcement to all the coordinators of the proposal to invite them to participate in a workshop as the standardization of the scoring scale is still an important issue. Eleven professionals (managers and researchers from the private sector and state organisations) from 6 European countries registered and attended the workshop which was held in La Frétaz, August 26-27. The location is nicely embedded in an alpine landscape on the jurassic hills and our hotel was located on the top of Mount Chasseron (1600m aSl) a scenic place with an impressive view over the french-swiss midlands towards the alps.
We started with field work digging out all the tuber and root samples and discussing the difficulties of assessing root galling in situ. We developed a standard visual scoring scale and tested it on the tuber samples. We compared powdery scab symptom pictures from different countries and once again came to the decision that a photographic documentation of verified symptoms should be established because of the high variation of symptom expression. Possibilities for future collaboration were also discussed and a standard list of 10 reference cultivars with different powdery scab susceptibility was created. These cultivars should be included in field screening trials if possible. Thus comparision of their behaviour in different environments will become possible, an important information still missing.
A big Thankyou to all participants who made this workshop a success.