Pathogens: Botrytis allii (Munn) Yohalem, B. aclada (Fresen.) (55) of the primary onion neck rot species of Botrytis, B. aclada (Fresen.). Descriptions and articles about Botrytis allii in the Encyclopedia of Life. Includes Wikipedia. Botrytis allii Munn, Bulletin of the New York Agricultural Experimental Station: () [MB#].
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Botrytis neck bottytis of alliums, caused by the fungus Botrytis alliiaffects onions,garlic, leeks and shallots. This pathogen is different from the bortytis that causes Botrytis leaf blight.
Botrytis neck rot primarily appears after harvest in onions and garlic that are not cured or stored correctly. The most common causes of severe losses are excessive nitrogen application, which delays crop maturity and curing, irrigation or rain late in the season, inadequate or improper curing, and improper storage.
The pathogen is soil- and seed-borne. In onion, the disease is more apparent after harvest, while bulbs are in storage.
Pest & disease factsheet – Botrytis (Onion neck rot)
Initially, soft neck tissue will become water-soaked and a yellow discoloration will move down from the neck into the leaf scales. Bulbs break down to a soft mass.
A gray mold develops between the onion scales, later producing small to large black sclerotia overwintering structureswhich develop as a solid layer around the neck. Extensive development of sclerotia is best seen on maturing bulbs just before and during harvest. In garlic, the disease usually appears first on necks near the soil line, and may occur any time after spring greenup when weather is conducive for disease development. The disease causes the most losses when it starts early in the season.
The fungus moves rapidly into the succulent tissue of the bulb neck, producing a water-soaked appearance. A gray mold develops on the surface of or between garlic scales, later producing black sclerotia around the neck. Secondary infections by other organisms may follow. Botrytis allii overwinters in the soil on bulb residue or as sclerotia, dense masses of mycelia surrounded by a weather-resistant black rind that can survive long-term in soil.
In the spring, sclerotia germinate and directly infect bulbs or produce asexual spores, which are dispersed in the air. Spores and sclerotia that come in contact with tissue of susceptible hosts may initiate new infections, especially if the tissue is wounded. Under prolonged moist conditions, the pathogen can also produce spores on infected dead or dying leaves.
After harvest, topped onions and garlic can become infected if the cut edge comes in contact with spores or soil containing sclerotia. Often, plants will become infected in the field but will remain symptomless until they are in storage. For more general information on proper harvesting, topping, and curing of onions, please click here. For more general information on proper harvesting, topping, and curing of garlic, please click here.
Botrytia are several fungicides labeled for neck rot control, and fungicides applied to control Botrytis leaf votrytis may also decrease neck rot incidence. For information on chemical control of this disease in onion, please see the New England Vegetable Management Guide website. Hazzard, information form Oregon State Extension. North American Amphibian Monitoring Program. North American Aquatic Connectivity Collaborative.
Back to top Alliums, Botrytis Neck Rot. Onions For more general information on proper harvesting, topping, and curing of onions, please click here. Practice a crop rotation of at least 3 years. Plant only disease-free seed. Most seed produced in the US is from arid environments and does not usually carry B.
Seed produced in Europe is more likely to be infested.
Follow growing practices that hasten curing: Allow tops to mature well at least half of leaves brownthen lift or undercut the onions. In dry weather, cure onions on the ground days.
Destroy crop residues after harvest. Be sure onions are well dried and necks tight i. Botrytis can move through green tissues into bulbs but cannot move through dry tissue. Minimize bruising and mechanical injury in topping and storage. Garlic For more general information on proper harvesting, topping, and curing of garlic, please click here.
Plant disease free cloves. Botryytis frequent and excessive irrigation.
Inspect garlic for symptoms and signs of the disease during the season and at harvest. A hand lens can help botryits this. Allow the tops to mature well, then lift or undercut the garlic. Pulling bulbs out when they are tight in the ground can open wounds at the stem-bulb junction.
Vegetable: Alliums, Botrytis Neck Rot | UMass Center for Agriculture, Food and the Environment
Minimize bruising during harvest and topping. If dry weather prevails, cure garlic on the ground for days. When topping, minimize bruising and mechanical injury. Destroy crop residues after harvest Chemical Control There are several fungicides labeled for neck rot control, and fungicides applied to control Botrytis leaf blight may also decrease neck rot incidence.
Crops that are affected by this disease: