Concerning effects of the tested extracts on controlling the powdery mildew disease caused by Sphaerolheca fuligi'nea on cucumber plants results indicate that, the most effective extract for controlling the disease incidence was Narcissus sp. which exerted efficacy of 37.7% against the disease incidence followed by Chenopodium album which resulted in 19.17% efficacy The rest extracts ranged between 0.0 to 8.5%, while the fungicide (Rubigan) reduced the disease incidence with 62.61% efficacy. The results showed that germination of the fungal conidial spores was partially inhibited by contacting to the tested extracts after 24 hours of incubation, treatments with C. album, Narcissus sp. and the fungicide (Rubigan) were the most effective against germination of the fungal conidial spores and decreased the number of the germinated spores with 90% comparing to the control. Meanwhile, the least effective extract was Conyza dioscoroides which exerted 50% efficacy. After 48 hours of incubation, the most suppressive treatments were with (ML-can), Narcissus sp. and C. album which decreased the germinated spores with efficacy (90.42, 84.92 and 79.45%), respectively. However, the least effective extract on spore germination was C. dioscoroides, which exerted only 15 05, efficacy.