2 rootstock potentially resistant to grapevine fan leaf virus currently being trialled

or a few years now, Mercier nurseries have been studying in Vix, Vendée, two new nematode-resistant rootstock stemming from Professor Andy Walker’s selection at the University of California, Davis – UCD GRN-1 and UCD – GRN-3. They display fairly broad-ranging resistance to nematodes of a number of species and phylloxera. And they could potentially be resistant to Xiphinema index, one of the two nematodes that spreads the grapevine fan leaf virus. In some of the areas where the virus has been located in the United States, they are proving to be satisfactory.

“The two rootstock were imported in 2020. They have been through quarantine and are currently being registered, with the process due to be finalised next year. They are currently being assessed in France and in Spain. In France, they are being trialled in two vineyards in Champagne – on around three hundred vines at two customers’ – and in our controlled greenhouse”, explains Olivier Zekri, deputy director of the Novatech laboratory, the Mercier group’s R&D subsidiary.

“Rootstock UCD GRN-1 is a crossing of Vitis Rupestris x Muscadinia rotundifolia and has very broad-ranging resistance to the root-knot, ring and lesion nematodes and to phylloxera. It shows low to moderate vigour. The UCD – GRN-3 rootstock is a complex hybrid including V. champinii. It provides good resistance to phylloxera and root-gall nematodes”, notes Zekri.

At the moment, adds Zekri, it is still too soon to comment on their potential. “At this stage in France, we have not yet confirmed that the two rootstock provide resistance to grapevine fan leaf virus nematodes. And we must remain very cautious. But potentially, they could add diversity to the range of rootstock”.