RE SEARCH Possibility of detecting Erwinia in seed potatoes increased Number of infected (sub)-samples of random tubers and waste tubers in studies carried out in 2012 and 2013. Ten sub-samples of 20 tubers from each lot were tested. 2012 Lots 1 2 3 4 5 6 7 8 9 10 Total sub-samples infected Number of (sub)-samples infected from random tubers 0 0 3 0 0 0 3 1 3 0 10 Plant Research International (PRI) Number of infected (sub)-samples of random tubers and waste tubers in study carried out in 2013. From each tuber the navel end or the whole tuber was tested. Ten sub-samples of 20 tubers from each lot were tested. Random tubers Lots 1 2 3 4 5 6 7 8 9 10 Total sub-samples infected Navel end 0 0 2 2 1 4 4 0 0 1 13 Plant Research International (PRI) Whole tubers (vacuum) 11 3 10 10 2 18 6 0 9 4 73 Navel end 4 5 5 2 1 19 10 2 5 3 56 Waste Whole tubers (vacuum) 15 23 18 8 5 22 15 0 15 15 136 Number of (sub)samples infected from waste tubers 1 0 5 1 0 1 16 7 9 6 46 Number of samples infected from random tubers 0 0 2 2 1 4 3 0 0 1 13 2013 Number of samples infected from waste tubers 4 5 5 2 1 19 10 2 5 3 56 Waste tubers examined In order to increase the probability of finding infected tubers, Plant Research International in Wageningen has been checking whether waste tubers contain a higher percentage of infected tubers than a random sample from a lot. Waste tubers are rejected seed potatoes that show infections, are deformed, or cut. In the 2012 and 2013 studies, the navel ends of waste tubers and those of random tubers from 10 lots, categories E and A, were tested. From each lot, ten mixed samples of 20 tubers were tested by grinding the navel end of each tuber and incubating this in the PEB medium. In 2012 as well as in 2013, the researchers found considerably more infections in the waste than in the random sample. More infection in whole tubers In the 2013 study, another method was examined, which had been developed within the Erwinia Deltaplan at an earlier stage. This method not only tested the navel end but the entire 20 Potato World 2015 • number 1 Pagina 19
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