How to Manage Pests

UC Pest Management Guidelines

Onion and Garlic

Onion Yellow Dwarf

Pathogen: Onion yellow dwarf virus

(Reviewed 1/07, updated 1/07, corrected 6/09)

In this Guideline:


The first symptoms of onion yellow dwarf in young onions are yellow streaks at the bases of the first true leaves. All leaves developing after these initial symptoms show symptoms ranging from yellow streaks to complete yellowing of leaves. Leaves are sometimes crinkled and flattened and tend to fall over. Bulbs are undersized.

This virus is part of the virus complex that causes GARLIC MOSAIC.


The onion yellow dwarf virus is a potyvirus that has a narrow host range (onions, garlic, shallots and a few ornamental alliums). It survives in bulbs and sets and therefore can be transmitted during vegetative reproduction. Although the virus is not spread to the seed, seed from infected plants is of poor quality. It can survive in volunteer onions. It is spread from plant to plant by the green peach aphid, Myzus persicae, and other aphids in a nonpersistent manner.


Controlling the aphids does not prevent the disease, because they quickly transmit the virus as they move through the crop in search of preferred hosts. Use true onion seed rather than sets. Use virus-free planting stock (in garlic, indexing for the virus and meristem tip culture eliminates the virus). Rouge infected plants.

There is no chemical control for this disease.


[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Onion and Garlic
UC ANR Publication 3453


R. M. Davis, Plant Pathology, UC Davis
B. J. Aegerter, UC Cooperative Extension, San Joaquin County
T. Turini, UC Cooperative Extension, Fresno County
A. Ferry-Abee, UC Cooperative Extension, Tulare and Kings counties

Acknowledgment for contributions to Diseases:
F. F. Laemmlen, UC Cooperative Extension, Santa Barbara and San Luis Obispo counties
R. E. Voss, Vegetable Crops, UC Davis

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