Symptoms and Signs
Apium virus Y causes cilantro leaves to have mottled or mosaic patterns, cleared veins, and slight distortions. Affected plants can be stunted. Under experimental conditions, inoculated parsley can develop slight chlorosis and distortions of leaves; however, in the field, parsley infected with ApVY appears to be mostly symptomless.
Comments on the Disease
Apium virus Y has only recently been reported in California and is thus far documented only in the Central Coast region. In addition to cilantro and parsley, this virus has been found in the field on celery, and the weed poison hemlock (Conium maculatum). This virus is carried by the aphids and transmitted to plants as the aphids feed. Seed-borne transmission has not been reported.
Elimination of weed hosts like poison hemlock appears to be important, as most Apium virus Y cases occur where this weed is widely distributed. Avoid planting cilantro or parsley in fields with a history of this disease.
Organically Acceptable Methods
Use cultural controls in an organically certified crop.
Pesticides are not effective against plant viruses. Insecticides should be used for managing the vectors, though such sprays do not prevent the aphids from transmitting the virus.