How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS

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.

COMMENTS ON THE DISEASE

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.

MANAGEMENT

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.

PUBLICATION

UC IPM Pest Management Guidelines: Onion and Garlic
UC ANR Publication 3453
Diseases
R. M. Davis, Plant Pathology, UC Davis
B. J. Aegerter, UC Cooperative Extension, San Joaquin County
Acknowledgment for contributions to Diseases:
F. F. Laemmlen, UC Cooperative Extension, Santa Barbara/San Luis Obispo counties
R. E. Voss, Vegetable Crops, UC Davis

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