Symptoms- Onions appear healthy when growing but bulb scales become softer after 8-12 weeks in store. Brown, sunken lesions and a fluffy gray mold develop in the neck. The upper part of the bulb is soft when pressed, with brownish black discoloration under the dry outer leaves. Onion neck rot spreads downward through the bulb, which in severe cases may decay completely and be covered with fluffy gray mold. Sides and base of bulbs are rarely affected unless outer scales have been damaged before or during harvest.

Prevention and Control- Buy seed and sets from reputable suppliers. Use wide spacing  during growth to allow are movement around the crops. Avoid damage before or during harvest, and allow tops to fall over naturally. Dry well in an airy warm dry atmosphere until the onion skins rustle. Do not store damaged bulbs. Store in cool, dry, airy conditions and remove bulbs that develop that develop symptoms as they occur. Use a crop rotation of at least 4 years. Do not apply nitrogen fertilizer after mid-July and be sure that slow release nitrogen fertilizers are not applied too late in the season. As harvest time approaches discontinue irrigation to allow tops to dry down, reducing the chance of onion neck rot..

Fungicidal Control- applications such as BI-CARB Old Fashioned Fungicide OMRI listed, is a fungicide containing micro-encapsulated potassium bicarbonate. It is a contact fungicide, and works by disrupting the potassium ion balance in the fungus cell, causing it to collapse and die..

Oxidate uses peroxygen chemistry – rapid oxidation that kills a wide range of bacteria and fungi on contact. With this OMRI-listed weapon, organic farmers can fight Botrytis and other such disease causing pathogens. A wide variety of crops that suffer from these can now be treated safely and repeatedly to prevent continuing outbreaks. Because of its mode of action, there can be no resistance developed to OxiDate’s continued use. It is exempt from pesticide residue considerations and is EPA registered.

Cease™ is a contact biological fungicide that contains a patented strain of the bacterium Bacillus subtilis. It controls common fungal diseases such as Botrytis(pathogen causing onion neck rot). Cease™ works two ways. First, the bacterial spores occupy space on the plant surface and compete with the pathogens; then active compounds called lipopeptides produced by each bacterium disrupt the germination and growth of invading pathogens. Due to this, resistance is not likely to develop. Cease™ can be used in combination and/or rotation with other products and as part of an effective resistance management program.