The New Zealand Grapevine Improvement Group (NZGVIG) is often approached by people regarding the establishment or purchase of a vineyard. Whilst it does not act as an advisory group for those wanting to enter the industry, it is happy to disseminate as much helpful information as possible regarding varieties and clones.

NZGVIG promotes the use of high health, virus tested planting material. Grapevine leafroll viruses can cause crop losses of up to 50% and the affected fruit produces low quality wines. To date nine different leafroll viruses have been detected in vines showing leafroll symptoms. These are named Grapevine leafroll-associated viruses (GLRaV), types 1 to 9.
GLRaV -1 is relatively uncommon in New Zealand , other than in Chardonnay Mendoza (which is 100% infected). On the other hand, GLRaV-3 has been found in most of the important grape clones growing in New Zealand. This strain of grapevine leafroll virus, GLRaV-3, has been demonstrated to severely reduce yield, delay ripening and lower juice quality.

Mealy bugs can transmit GLRaV-3 and the spread of this virus has been clearly demonstrated in several wine growing regions in New Zealand where this insect is present. The use of infected grafting material by nurseries is another factor although this is less common now that nurseries have access to reliable virus testing services.

The best steps to take in order to reduce the incidence of disease start with the establishment of a vineyard block. It is important that you do NOT plant vines infected with GLRaV-3.

NZGVIG advises growers to:

• source budwood only from nurseries that source budwood from blocks that are 100% ELISA tested for GLRaV-3 in the year of sale

• always remove infected vines before replanting

• do not plant new vines in close proximity to infected blocks

• avoid underplanting where disease is known to be present in existing vines.

NZGVIG and NZ Winegrowers are helping nurseries develop an industry-based standard for grafted vines that will in due course be refined to reflect the increasing availability of improved grafting material. This standard will initially prescribe minimum specifications for the health status of grafting material used by nurseries, and the physical conformity of the plant.