This investigation was conducted for two successive seasons (2013 and 2014) in a private vineyard located at 64 Km of Cairo-Alexandria desert road to study the possibility of using organic products to reduce powdery mildew, which it is reflect in reducing yield and fruit quality of King Ruby grapevines. The chosen vines were ten-years-old, grown in a sandy loam soil, spaced at 1.5 X 3.0 meters apart and irrigated by the drip irrigation system, trained to bilateral cordon with spur pruning, and trellised by the "Y" shape system. The vines were pruned during the last week of January with bud load of (60buds/vine). Application of different biocontrol agents Trichoderma harziamum, Trichoderma viride, Bacillus subtilis as well as blight stop a commercial biocide which contains different isolates of Trichoderma forms in Arabic gum and potassium soap) were obtained kindly from central lab. of organic agriculture, ARC. Giza, in an attempt reduces powdery mildew of the plants.
The results showed that all vital bioagents treatments significantly were reduced the powdery mildew disease compared with micron sulphur and control in both season. However, spraying mixture of Trichoderma harziamum + Trichoderma viride and blight stop gave the least disease incidence and severity which it is reflect to increase yield, achieve the best physical characteristics of bunches as well as improving the physical and chemical properties of berries.