But one facet of the traceability is probably not as well known as many of the others, and that is the certified quality of the grapevines themselves.
Back in 2006 NZW established the Grafted Grapevine Standard (GGS) to provide certainty for those purchasing vines; that they were not only certified true to the varietal level, but met vine physical specifications, had associated management systems and most importantly of all, were free of the devastating Leaf Roll Associated Virus III.
The necessity for such a standard became apparent when the virus began showing up in increasing numbers in New Zealand.
Leaf Roll Virus can decimate vineyards, particularly those with red varieties. Its impact on the quality of wine has been well documented. There is no cure. The only remedy is to remove all infected vines and replant.
Having clean planting material is the basis for a virus free future. It’s no good spending millions of dollars on virus elimination, if the replant material is not confirmed as being virus free. Which is where the GGS comes in.
There hasn’t been much new vineyard development since 2008, but some growers and wineries have been replanting with new varietals or top grafting.
It’s this area that Ben Wickham, Chair of the Vineyard Nursery Association (VINA) believes needs some addressing. VINA has been working alongside NZW to implement GGS and they are concerned that unless testing of the mother material and budwood is carried out prior to grafting, there is a risk of virus being spread into the new vines.
Leaf Roll Virus doesn’t tend to be obvious in white varietals like Sauvignon Blanc but that doesn’t mean it isn’t present. If a red varietal is grafted onto potentially infected Sauvignon Blanc mother material, the virus will take hold – quickly. The only guarantee is that whatever virus the mother material contains, it will be passed onto the grafted vine.
In other words top grafting may initially be a cheaper option, but unless the mother material and budwood is confirmed as being free of virus, the potential long-term cost is high.
It is important that all vines purchased for planting or development are Leaf Roll Virus free. So far four New Zealand nurseries have GGS accreditation, a fifth one is about to join their ranks. Externally audited, they are the only ones that can provide guarantee of traceability and confirmation that the vines are not virus infected.
They are a direct result of the implementation of GGS and the forward thinking of New Zealand Winegrowers. But to reach the future goal of an industry free of Leaf Roll Virus, every member has to ensure the vines they choose for planting, or the mother material they are using for top grafting meets the criteria outlined under the Grafted Grapevine Standards. ν
