- Worldwide distribution. On onion, leek, Welsh onion (Japanese bunching onion), Chinese chive, shallot. A cosmetic disease.
- On the lower parts of the outer leaves and neck, in patches or rings.
- Spore masses with long stiff hairs. Spots on leaves turn to blights under wet warm conditions.
- More serious rots occur if onions harvested wet and stored moist >20°C.
- Causes a seedling damping-off.
- Spread occurs in wind-driven rain.
- Cultural control: well-drained soil; clean seed and healthy transplants; avoid harvesting in wet weather; cure bulbs quickly and store cool and dry; plant those with coloured outer scales; 2-3-year crop rotations.
- Chemical control: possibly, mancozeb, or chlorthalonil.
