Assays of transmission of grapevine virus by pseudococcids.
In assays, the grapevine virus A (GVA) and type III virus associated with grapevine leaf curling (GLRaV-III) were transmitted by Planococcus citri from infected leaves of grapevine cv. Competição collected in Portugal, in 1991, to healthy cultivars Pinot noir and Cabernet Sauvignon. The ELISA technique showed that all Pinot noir and Cabernet Sauvignon plants used were infected with the viruses, approx. 6 months later and leaf curling symptoms and redness in infected grapevines were apparent 2 months later. Microscopic observations did not show the presence of the virus until 2 months later. This is the first report of GVA in Portugal.