Effect of two types of vegetable oils (neem and soybean), two types of plant extracts (bougainvillea blossoms and Garlic), KH₂PO₄ and salicylic acid (SA) as inducers and Eminent fungicide on sugarbeet powdery mildew disease, were tested to study their effect in vitro and in vivo against Erysiphe betae the causal pathogen of Sugarbeet powdery mildew. The reduction of spore germination was increased with concentration increasing in vitro. Most effective concentration was studied on powdery mildew disease of three varieties of sugar beet in greenhouse, all treatments had a significant effect in reducing disease severity compared to control Untreated plants, bougainvillea blossoms extract and Eminent fungicide were the most effective treatments. Enzymes, phenols, sugars, proteins and chlorophyll contents of leaves were evaluated. Bougainvillea blossoms extract exhibited high contents of sugars, phenols, protein, pigments and antioxidant enzymes.