Downey mildew
Crop: Onion Disease: Fungal Pathogen: Botrytis allii
SYMPTOMS AND SIGNS
DISEASE DEVELOPMENT
DISEASE MANAGEMENT
- Shriveled neck tissues of infected bulbs. Bulb scales soften and turn brown. A gray mold grows on the surface of the bulb and between bulb scales. Masses small black sclerotia grow on the outer scales around the neck. Affected internal parts of the bulb are brown, water-soaked and spongy.
- Small black sclerotia may develop on the outer scales around the neck. Bulbs are usually first affected at the neck, although the decay can spread downwards to affect the whole bulb. Occasionally, symptoms develop at the side or the base of the bulb if there has been physical damage at this point. Scales of diseased bulbs become soft and brown, giving them a ‘cooked’ appearance.
- Affected internal parts of the bulb are brown, water-soaked and spongy. Infected tissues gradually dry up so that the bulb suffers from a dry rot and eventually becomes sunken and mummified.