Abstract
In the years 1974-79 in Skierniewice and in 12 other places Erysiphe cichoracearum DC (imperfect stage) was observed on cucumbers in 1979 both A. cichoraceum and Sphaerotheca fuliginea were found in Skierniewice, Zielonka and Gołębiewo. Then were distinguished in the conidial stage mainly on the basis of differences in conidial germination and the presence or absence of fibrous bodies, and in the perfect stage on the basis of the number of asci in peridia and the number of spores per ascus.