| Abstract | Powdery mildew caused by Sphaerotheca fuliginea (Schlecht. Ex Fr.) Poll. Is a major problem in cucumbers grown under greenhouse conditions. Culture filtrates of certain biocontrol agents (Epicoccum nigrum ES1, Epicoccum minitans ES2, Epicoccum sp ES3, Trichoderma harzianum ES4, Trichoderma viride ES5 and Bacillus pumilus ES6) were evaluated alone and in combination with penconazole against powdery mildew in cucumbers. The results showed that most of the culture filtrates of the tested microbial isolates in combination with the fungicide were more effective against powdery mildew than the fungicide alone at the recommended concentration level. The antifungal activity of the tested culture filtrates against powdery mildew was due to the presence of known antifungal compounds identified by GC-MS analysis. The results revealed that culture filtrates can be regarded as an effective control method for powdery mildew in cucumbers |