VIRULENCE ANALYSIS OF WHEAT POWDERY MILDEW POPULATION (ERYSIPHE-GRAMINIS F SP TRITICI) FROM THE REGION OF SLOVAKIA AND HUNGARY

In the year 1992 a total of 163 isolates of wheat powdery mildew were tested. The samples of mildew isolates were obtained by means of a mob ile spore catching apparatus. The populations from 4 regions of Slovak ia and 3 regions of Hungary were analyzed. The resistance due to Pm5, Pm8 and Ml-i genes at the observed locations has already been overcome . The resistance genes Pm1, Pm2 and a gene combination Pm2 + Pm6 ensur e the protection only against a part of the pathotypes of powdery mild ew population. Virulence corresponding to the Pm4b gene has been low s o far. The regional patterns of pathogen virulence are in good agreeme nt with the gene resistance spectrum by the cultivars grown regionally . Little differences in virulence among the populations from the regio ns of Slovakia and Hungary indicate that this part of Eastern Europe s hould be considered as an epidemiologic unit.