VIRUS DISEASES OF OLIVE: AN OVERLOOK
There are a few diseases affecting Olea europaea L., reported from several countries, likely to be caused by viral agents. Several viruses were mechanically transmitted to indicator plants and, of the seven that were subsequently identified, four belong to the nepovirus group: strawberry latent ringspot (SLRV), cherry leaf roll (CLRV), arabis mosaic (AraMV) and olive latent ringspot (OLRV); one belongs to the cucumovirus group: cucumber mosaic virus (CuMV) and two others have not been assigned to any of the existing groups: olive latent virus-1 (OLV1) and olive latent virus-2 (OLV-2). Sometimes virus are detected in Olea plants that show symptoms, as severelly distorted leaves and mishapen fruits - which are particularly evident in infected Negrinha cv. in Portugal and in Ascolana tenera cv. in Italy - double nodes, fasciation of stems and tree decline. Often, however, viruses occur symptomless. The recent application of DAS-ELISA test to plant organs as roots, leaves and fruits, proved it to be sucessfull in diagnosing SLRV, CuMV and CLRV in those tissues. This made possible to show that fruit deformations in Negrinha cv. appear closely associated to the presence of SLRV, as has been shown to occur in Ascolana tenera cv. exhibiting similar symptoms. Our studies, carried out in Portugal over the last three years, on diagnosis of SLRV, CuMV and, to a lesser extent, CLRV, showed that 20 out of 30 different cvs. of portuguese, spanish, italian, french and turkish origins, were virus infected. SLRV was diagnosed in 20% and CuMV in 10% of ca. 300 samples and CLRV in 5% of 100 samples. In a few cases, multiple infections were detected. These results stress the need for the production of virus-free propagative material to use in new plantations.
da Clara Henriques, M. I. E. (1994). VIRUS DISEASES OF OLIVE: AN OVERLOOK. Acta Hortic. 356, 379-385
Olea europaea L., nepovirus, cucumovirus, ELISA