EARLY ASSESSMENT OF ADULT-PLANT REACTION OF WHEAT (TRITICUM-AESTIVUM L) TO POWDERY MILDEW (ERYSIPHE-GRAMINIS F-SP TRITICI) AT THE 5-LEAF SEEDLING STAGE

An original procedure leading to the early prediction of adult plant r eaction to powdery mildew infection at a seedling stage was defined. S eedlings of eight wheat lines were inoculated at the two- and five-lea f stages with various inocula (either clones or synthetic mildew popul ations) overcoming their major specific resistance genes. The mean mil dew score (MMS) and the mean time for first sporulation (MTFS) proved to be strongly correlated. For each line tested, the mildew reaction o f adult plants was closely predicted by that of vernalized, five-leaf seedlings. Using inoculations on five-leaf vernalized seedlings, we ca n predict the adult stage mildew reaction of a line, where the specifi c resistance should be overcome. Using this method, it is possible to study the genotypes, the specific resistance of which are still effect ive in the field, thus preventing assessment of their possible non-spe cific adult plant resistance in the field.