Home Garden Disease Controls
The Pennsylvania State University
Cooperative Extension
Bulb Crops: Onions, Leeks, and Garlic
How important are diseases on bulb crops in gardens?
Leaf spots may develop by mid-late summer, and can be significant.
What diseases can affect bulb crops?
Listed below are several diseases that most frequently occur on bulb crops. Symptoms are described briefly. Colored pictures of disease symptoms can be seen in the publication Identifying Diseases of Vegetables.
Leaf Spots and Blights
Spots appear on leaves and the leaves die. Control: Grow bulb crops in a sunny, well-drained area. Practice at least a 2-year rotation. If needed, especially for storage onions, use of fungicides as labeled will help.
Storage Rots
Dry and wet rots develop in storage. Control: Grow bulb crops in a sunny, well-drained area. Practice at least a 2-year rotation. To allow adequate pre-storage drying of onions, promote early maturity by planting early, provide adequate space to grow the plants, and avoid excessive nitrogen fertilization. For onions, use of labeled fungicides for control of leaf spots and blights may help. At harvest time, undercut onions and later windrow until neck tissue is dry. If necessary, dry onions in artificial heat (90-120 degrees Fahrenheit for 2 or 3 days); then, if possible, use thick-necked bulbs immediately, and store adequately dried bulbs in an area that is dry and cool (32-34 degrees Fahrenheit).
Note: Where trade names are used, no discrimination is intended
and no endorsement by the Cooperative Extension Service is implied.
Information provided is intended for consideration by the user, but is not
intended to be a recommendation. Production decisions should be based on
consideration of many types of information (scientific, experiential, economic,
legal, etc.) available to the user.
