Onion is one of the largely cultivated vegetable throughout India and grown as kitchen garden crop in Himachal Pradesh. The bulbs as well as seeds of crop are used in a variety of culinary preparations and holds high nutritive and medicinal value. The commercial cultivation of onion is very successful because of its high demand and market value. The major constraint faced in the cultivation of onions is the incidence of biotic and abiotic factors. Among the various factors inflicting gap in production level, downy mildew is one of the most threatening diseases in the state during the crop period causing heavy economic losses.
