How to Manage Pests

Pests in Gardens and Landscapes

Neck rot (Botrytis bulb rot)—Botrytis spp.

Neck rot is a problem on onions and garlic and appears on bulbs near the time of harvest. A grayish mold may be seen between the scales and black spores on the neck of bulbs. Bulbs may appear discolored and water soaked. Infection occurs through the neck tissue or through wounds in bulbs.


Botrytis overwinters in the soil or in old plant debris and bulbs left in the garden and infects primarily bulbs that have not been harvested properly. Remove and destroy all plant debris at harvest. Be careful not to leave any bulbs in the soil. Allow plants to mature fully before harvesting and make sure the tops of plants are dried out. Lift or undercut mature plants. Avoid injury to plants and store bulbs in a dry area. No fungicides are recommended for neck rot. Plant with certified seed sets if available. Some resistant varieties may be available. Where neck rot has been a problem in the past, rotate out of garlic and onions.

Neck rot on garlic bulbNeck rot on garlic bulb

Statewide IPM Program, Agriculture and Natural Resources, University of California
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