Potato Y potyvirus (PVY) causes annual epidemics with 30 to 40% production losses in tomato crops of the Canary Islands in autumn. Two strains of the virus were diagnosed: PVY-0 and PVY-N. To identify hosts in areas where the virus is prevalent, and to establish the role of weeds in the epidemiology of this virus and its vector, plants were collected, chosen randomly and by viruslike symptom expression. Eighty-two samples of 30 plant species were tested for PVY-0 and PVY-N by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) with commercial antibodies made against PVY (INGENASA, Madrid), PVY-0/C (ADGEN, Auchincruive, UK), and PVY-N (BIOREBA, Reinach, Switzerland). Twenty-five weed species were found to be infected with PVY-0 and 12 plants were identified as new hosts (1) including the following: Argyranthemum gracile, Calendula arvensis, Convolvulus althaeoides, Foeniculum vulgare, Forsskaolea angustifolia, Hedypnois cretica, Hirschfeldia incana, Malva parviflora, Patellifolia patellaris, Sonchus oleraceus, Urospermum picroides, and Lavandula canariensis. Argyranthemum gracile and Lavandula canariensis were hosts only of PVY-N strain. References: (1) J. R. Edwarson. Fla. Agric. Exp. Stn. Monog. 5:96, 1974.