The Usefulness of Late-Blight Resistant Sarpo Cultivars - a Case Study

Sarpo potato varieties, bred in Hungary, are being selected in Wales and elsewhere for commercial suitability by the Sarvari Research Trust. Sarpo varieties have expressed very high resistance to both foliage and tuber blight in the field as exemplified by progressions of the disease in field trials in Wales in seasons 2005 and 2006. Similar trials in the very wet years of 2007 and 2008 were inoculated with a new strain of blight, Blue-13, which is now the predominant strain in UK and parts of northern Europe. An unexpected loss in resistance by several varieties, included as resistance standards, can be explained by the high aggressiveness of the new strain. Although Sarpo clones became infected more in 2007 and 2008, they showed a slow-blighting phenotype in the presence of the heavy blight pressure of strain Blue-13 over more than 50 days. 'Sarpo Mira', included as a resistance standard in field trials in five countries has retained high resistance in the period 2005-2008. The acceptability of Sarpo cultivars is discussed.