Onion Yellow Dwarf

The first symptom of onion yellow dwarf in young onions is the appearance of yellow streaks at the bases of the first true leaves. After this initial symptom, all developing leaves show symptoms ranging from yellow streaks to complete yellowing of the leaves. Leaves are sometimes crinkled and flattened and tend to fall over; bulb size is reduced.

In combination with other viruses, this virus probably contributes to GARLIC MOSAIC symptoms.

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. The green peach aphid, Myzus persicae, as well as other aphids, spreads the virus from plant to plant in a nonpersistent manner. The virus can also survive in volunteer onions.

Although the virus is not spread to the seed, seed from infected plants is of poor quality.

Use true onion seed (rather than sets) and use virus-free planting stock. In garlic, indexing for the virus and meristem tip culture eliminates the virus. Rogue (remove) infected plants.

No pesticides control this disease. Controlling aphids also does not prevent the disease because they retain the virus for a very short period of time and quickly transmit the virus as they move through the crop in search of preferred hosts.