ABSTRACT: The efficacy of three water plant extracts ie; Mint (Mentha villosa), Basil (Ocimum basilicum )and Aloe vera (Aloe barbadensis) with three concentrations (2 , 4 and 6 ml/ L) and plant essential oils of three plants Castor (Ricinus communis), Thyme ( Thymus vulgaris) and Mint  (Mentha villosa) with three concentrations (2.5 , 3.5 and 4.5 ml/L) were studied under greenhouse conditions during two successive seasons (2019-2020 and 2020-2021) on cucumber downy mildew disease management. The obtained results indicated that, application of plant extracts and essential oils significantly reduced the disease severity and increase the yield production (number of fruits / plant and average fruit yield production / plant). For the water plant extracts the Alo vera (6 ml/L concentration) was the best treatment, while the Basil (2 ml/L concentration) showed the lowest effect. For the essential oils, Castor oil (4.5 ml/L) gave the highest effect on decrease the disease severity and increase the yield while the Mint oil (3.5 ml/L) showed the minimum effect.