Cucurbit powdery mildew (CPM) is mainly caused by two obligate ectoparasites, Golovinomyces orontii s.l. (Go) and Podosphaera xanthii (Px), that are highly variable in virulence. Various independent systems of CPM race determination and denomination have been used in recent decades. We recently developed new tools to enhance research of CPM virulence variation. Diversity models were applied to analyses of virulence variation of Go and Px populations (115 Czech isolates) from 2010 through 2012. Diversity within and distances between Go and Px populations and each other in spatio-temporal context and with regard to original host plant species were analyzed, based on virulence patterns of individual isolates (races) on a set of 21 melon (Cucumis melo L.) race differentials. Significant differentiation among the Go and Px pathogen populations was revealed. The results clearly demonstrate that the set of differential C. melo genotypes is well composed because of significant differentiation capacity for both species. There were no significant differences between Go isolates from different host plant species due to high variability, but there was significant host-specific differentiation among Px isolates. This approach was used to evaluate virulence variation of CPM populations in other European countries, South Africa and Asia (Thailand). Preliminary results obtained for Px showed enormous virulence variation in other European countries outside of Czech Republic, as well as in South Africa. Px isolates from Netherlands that originated from wild Cucumis species, grown in greenhouse however expressed lower virulent variation than the isolates from other countries. A Px isolate from Momordica charantia in Thailand differed in virulence compared with isolates from other countries. The approach used in this study provides revealed complex virulence structures of CPM populations of diverse origins, and when completed by race determination and denomination on melon, it may serve as a base to understand virulence variation of both CPM species on a global perspective.