Area of mlo-varieties grown in western and central Europe: there are no exact data available. Several national variety offices publish data on cultivar areas grown for seed certification. From these approximately the percentage of mlo-varieties actually grown can be estimated. Not all sown seed is certified, but this uncertaneity is with both mlo- and non-mlo-cultivars . The following table summarises the data available till now. Data form mediterranean countries and east baltic states are not included, since mildew is there usually not a problem and these areas are epidemiologically quite different from central and western Europe