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 IPM Pest Management Guidelines:
Onion and Garlic
R. M. Davis, Plant Pathology, UC Davis
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