Int.J.Curr.Microbiol.App.Sci (2020) 9(5): 2852-2857 2852 Original Research Article https://doi.org/10.20546/ijcmas.2020.905.327 Determination of the Effective Dose of Fungicide Mixtures against Pseudoperonospora cubensis causing Downy Mildew in Cucumber (Cucumis sativus L.) Rishu Sharma* and Binoy Gorai Department of Plant pathology, Bidhan Chandra Krishi Viswaviyalaya, Mohanpur- 741252, Nadia, West Bengal, India *Corresponding author ABSTRACT Introduction Cucumber (Cucumis sativus L.) is from Asiatic origin (De Candolle 1883). China is the world leader in cucumber production, accounting for approximately 62 per cent of the total production, followed by Turkey, Iran, Russian Federation and USA (Anonymous 2010). In India, a number of major and minor cucurbits are cultivated, which share about 5.6 per cent of the total vegetable production (Rai et al., 2008). Downy mildew of cucumber was first recorded Berkeley and Curtis in 1868. It is a International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 9 Number 5 (2020) Journal homepage: http://www.ijcmas.com Downy mildew is a common and serious disease in cucumber (Cucumis sativus L.), caused by the obligate fungus- Pseudoperonospora cubensi. The downy mildew disease causes abundant reduction in both quality and quantity of cucumber in countries around the world. In the present study, different doses of fungicide mixtures were used to determine the most effective dose for the management of the disease under the field conditions. The Experiment was conducted during the year of 2017-18 and 2018-19 at the University farm. The use of seven fungicide mixtures against the downy mildew pathogen were applied T1- T7 with T8 as control. The Average minimum Disease severity was found in 1 st year T3 (2.221) and T2 (2.246) followed by T6 (2.982), T1 (3.709), T5 (3.773), T4 (4.499) and T7 (4.931). The average maximum disease severity was found in T8 (7.888). Similarly, the Average minimum disease severity was found in 2 nd year T3 (2.184) and T2 (2.301) followed by T6 (3.079), T1 (3.684), T5 (3.824), T4 (4.628) and T7 (5.014). The maximum disease severity average was found in T8 (8.091). Thus, our studies concluded that these fungicide mixtures were effective in lowering the disease severity under the field conditions if used with recommendations. Keywords Cucumber, Downy mildew, Peronosporomycetes, Dimethomorph Accepted: 23 April 2020 Available Online: 10 May 2020 Article Info