Field surveys were conducted in Greek olive orchards from 2017 to 2020 to collect information on the sanitary status of the trees. Using a high-throughput sequencing approach, viral sequences were identified in total RNA extracts from several trees and assembled to reconstruct the complete genomes of two isolates of a new viral species of the genus Tepovirus (Betaflexiviridae), for which the name olive virus T (OlVT) is proposed. A reverse transcription–polymerase chain reaction assay was developed which detected OlVT in samples collected in olive growing regions in Central and Northern Greece, showing a virus prevalence of 4.4% in the olive trees screened. Sequences of amplified fragments from the movement–coat protein region of OlVT isolates varied from 75.64% to 99.35%. Three olive varieties (Koroneiki, Arbequina and Frantoio) were infected with OlVT via grafting to confirm a graft-transmissible agent, but virus infections remained latent. In addition, cucumber mosaic virus, olive leaf yellowing-associated virus and cherry leaf roll virus were identified.

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Zucchini yellow fleck virus (ZYFV), genus Potyvirus, is the causal agent of a disease of cucurbits. The genome sequences of seven ZYFV isolates of different origin were determined, two of which were reconstructed from a squash (Cucurbita sp.) collected in 2017 in Greece, while the others, accessions from the DSMZ Plant Virus Collection, were from samples collected in Italy, Greece, and France in the 1980s and 1990s. A high level of molecular diversity, well dispersed along the genome, was observed, but this was within the limits for assignment of the virus isolates to the same species. P1 was the most diverse gene, and isolates from squash contained an insertion in this gene.

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