Alfalfa (lucerne) mosaic

Potato plant with 'calico' disease
caused by alfalfa mosaic virus


Alfalfa mosaic virus (alfamovirus).


Symptoms can vary depending on the host, but nearly always involve a yellow-green mosaic pattern or bright yellow blotches on leaves. As the plant matures, these areas may become more intense in colour and cover large areas of the leaves.

How does it spread

Aphids spread the virus from plant to plant, needing only very short feeding times for transmission. Many aphid species are able to transmit the virus, including the green peach aphid (Myzus persicae), the pea aphid (Acyrthosiphon pisum), the bluegreen aphid (Acyrthosiphon kondoi) and the spotted alfalfa aphid (Therioaphis trifolii). Annual crops are most likely to become infected when planted near perennial hosts such as lucerne and clover that often have a high level of infection.

Crops affected

Alfalfa mosaic virusoccurs worldwide and has a wide range of hosts among legumes and other broad-leafed plants. Natural hosts of the virus include lucerne, clover, potato (calico disease), tomato, capsicum, lettuce, soybean, bean, sowthistle (Sonchus oleraceus) and nightshades (Solanum).

Control options

The level of alfalfa mosaic infection in vegetable crops is usually not sufficient to cause serious losses. Adequate control is possible by not planting susceptible crops adjacent to stands of lucerne and clover.

Chemical registrations and permits
Check the Australian Pesticides and Veterinary Medicines Authority chemical database and permit database for chemicals registered or approved under permit to treat this disease on the target crop in your state or location. Always read the label and observe withholding periods.