RE SEARCH Bacteria project completed? The Dutch four-year project ‘Bacteria-free potato seed cultivation – a challenge’ ended last autumn. A great deal about Erwinia was researched, but A great deal about Erwinia was researched, but much more still remained unexplained. much more still remained unexplained. The members of the project have therefore recommended a range of follow-up studies to solve current bacterial problems in the international potato sector. of the project group during those four years. After the first year of literature studies, grower surveys and a few initial field studies, the conclusion was then: ’First year of Erwinia project uncovers tip of iceberg.’ Today, four years later, we could use the same heading, because some questions have been answered, but others have come up. Four years of research has mainly resulted in an understanding of the various factors that relate to the Erwinia problems, is the conclusion of the project group itself. At least one of the objects of the project has been successful for them. We have not really found any concrete solutions, but we have drawn up recommendations for further research, says the project group. What that understanding is, has been specified in a report of which we received a brief overview. Together with reports written in the past four years, we look back on the final results of the project group. P Field monitoring must be more accurate One of the most fascinating questions of the Erwinia problems is: where and how does the very first infection really take place? The project group calls this the search for the initial infection. This is about questions such as: is the supposedly clean planting stock really free from bacteria? The testing of lots of mini tubers from 30 important varieties for the presence of Erwinia started in 2005. A year later, testing was repeated otato World magazine has closely monitored the activities and the planting stock of the traditional strains was investigated. It finally transpired that the planting stock for strain development – from both mini tubers and traditional strains – was free from contamination. This was an important outcome: the multiplication of strains could start with clean material. But it was not easy to also keep the subsequent crops clean, the field surveys showed. Three of the thirty varieties of mini tubers were monitored by about 50 to 60 growers in a few years of second growth. Varieties monitored were Désirée, Kondor and Spunta. This study into initial contaminations in the field showed that already after two second crops, a latent contamination with Erwinia was found. Where those contaminations came from, the researchers, unfortunately, cannot tell. Looking back, the study was too general to be able to find the mechanisms behind the contaminations, is what the summary says. Having learned from this limitation, the project group can only conclude that a possible follow-up study ‘will need a more accurate monitoring of the processes at a practical level’, to find the real cause of the contamination. Research should be much more focused, which also applies to the researcher/ grower contacts. Also important, according to the subsequent conclusion of the projects members, is that as much difference as possible was made between Erwinia strains at farm level. It is a pity that it was not possible to have a more accurate study. ‘The project was started with a series of research questions Potato World 2010 • number 1 17 Pagina 16
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