Botrytis Neck Rot
Botrytis neck rot is a post-harvest storage disease. However, infection occurs in the field but remains latent. The disease is found worldwide. Yield losses can range from 30% up to 100% in severe cases.
Botrytis aclada and B. allii are airborne, soilborne and seedborne. Sclerotia (fungal survival structures) can survives on onion debris in the soil for several years. Spores can be spread by wind and rain. Infection of leaf and neck tissue occurs during moist and warm conditions but no symptoms develop (latent infection). If the neck area is still moist during harvest, the fungus colonizes the tissue and then moves into the bulb. Symptoms in bulbs are visible after 4-8 weeks in storage.
- No symptoms in the field
- In storage; discoloration of bulbs starting in the neck area
- Bulb rot
Curing onions by undercutting onions at maturity. All roots need to be severed. If it is wet during harvest artificial drying with forced, heated air (about 93°F) can be used followed by cool storage.