• Leaves - yellow and dieback
• Roots - rotten & base of the bulb covered with a watery or grey fungal growth
• Numerous small black spherical sclerotia are produced

Mode of spread and survival:

• Sclerotia persists in soil for eight years
• Pathogen has no direct sporulation stage and it is not air borne
• Sclerotia are transported from field to field by flood water

• Long rotation of 8 to 10 yrs
• Good drainage
• Use of healthy planting materials
• Destruction of wild onion and leeks
• Seed dressings-benomyl/carbendazim