Downy Mildew of Onion: Epidemiological Aspects

Fungal airspora over onion field was monitored for two consecutive cropping seasons (Nov. 2013 to Apr. 2014 and Nov. 2014 to Apr. 2015) using Rotorod Air Sampler. 24 fungal types belonging to 5 different subdivisions of fungi constitute the airspora over onion field. Monthly variation of Peronospora destructor and its impact on downy mildew disease (PDI) were observed. Occurrence of downy mildew disease depend on conducive weather parameters. Correlation of meteorological parameters with disease incidence and percentage contribution of P. destructor were significant (p< 5%).