Race and mating type identification of powdery mildew on cucurbits in Greece

Sphaerotheca fusca was confirmed, by the formation of cleistothecia on artificially inoculated detached cotyledons of melon in Petri dishes, as the main powdery mildew pathogen on Cucurbitaceae in Crete during 1993–94. Among 41 single‐spore isolates of S. fusca from Cucumis sativus, C. meto, Cucurbita pepo and Cucurbita sp., two races (1 and 2) were identified, in an approximately equal ratio, by using four melon differential lines. All 41 single‐spore isolates of S. fusca were grouped into two mating types, indicating that the fungus is bipolarly heterothallic and that both mating types are present in Greece. By examining mycelial and conidial features, one single‐spore isolate of powdery mildew from C. pepo was identified as belonging to Erysiphe cucurbitacearum.