Fast transmission of grapevine 'Pinot gris' virus (GPGV) in vineyard

Grapevine 'Pinot gris' virus (GPGV) is a newly emergent virus associated with the appearance of grapevine leaf mottling and deformation disease (GLMD). The worldwide spreading of this virus, and sometimes of the associated disease, that has occurred in the last years, requests further epidemiological studies to verify the progress of natural infection in the field. In the present paper, GPGV infection and spatiotemporal spreading of GLMD, investigated in two vineyards with high disease occurrence, confirmed an elevated presence of the virus in vineyards of Northeastern Italy, and revealed an increasing of symptomatic plants over the time. At the same time, the progress of natural infection was monitored after the placement of new grafted plants near the symptomatic grapevines in the infected vineyards. After three years, 76 % of the plantlets that were initially GPGV-free became GPGV-infected, giving an evidence of the fast transmission of GPGV in the field. Only 14 % of the plantlets, all collocated inside a patch with diseased plants, showed typical GLMD-symptoms. Interestingly, some plantlets, which were already GPGV-infected with the "asymptomatic" GPGV variant before planting in the field, did not become infected with the "symptomatic" viral wild variant after three years and never showed GLMD symptoms.