Agriculture: Onion and Garlic Pest Management Guidelines

Garlic Mosaic

  • several viruses in the potyvirus group
  • Symptoms and Signs

    Symptoms of garlic mosaic include:

    • Small, angular, light-green-to-yellow discolored regions of tissue arranged in a mosaic pattern among darker tissue
    • Irregularly shaped, light-green blotches among normally colored tissues
    • Striping and streaking of leaves.

    Symptoms are usually more pronounced in young leaves. Infected plants are stunted, and bulb size is reduced.

    Comments on the Disease

    Because garlic is vegetatively propagated, several viruses are commonly present in all garlic. The label "garlic mosaic" has been applied to a number of different viruses in different countries and this has caused some confusion. However, there is a trend toward referring to garlic mosaic as a disease caused by one or more viruses belonging to the potyvirus group (garlic yellow stripe virus, leek yellow stripe virus, and several others). In addition to being spread by vegetative reproduction, these potyviruses can also be transmitted by various aphids.


    Purchase virus-free stocks produced from meristem tip culture and multiplied in areas free of commercial garlic to prevent reinfection by insects (aphids) that carry the viruses. Use of such stock can result in substantially higher yield.

    Text Updated: 02/19