Bulb yield and storage life are reduced by the plants becoming infected and the foliage dying.
Downy mildew (bulb vegetables) [Peronospora destructor]
Overwintering bulbs and crop residue are primary infection sources. Cool nights with dew condensation and moderately warm days favor the spread of the fungus.
Pattern of damage
Elongate-oval, light-gray infection sites which may be covered with a purple-gray layer of spores (Pictures 1 & 2). The foliage may die back completely (Pictures 3 & 4). Brown spots on infected bulb soil.