Monday, November 24, 2014

Deconstructing the Masseto vineyard: Disease and virus management

Masseto is one of the the world's leading Merlot wines and its 6.63 ha vineyard is ensconced within the confines of the larger Ornellaia vineyard in Bolgheri, Tuscany. It has been difficult to obtain information on the details of this vineyard so I have undertaken the task of deconstructing it using data from publicly available sources as well as reasoned assumptions. I began with the soils and then assessed the cultivar and rootstock. I now turn to virus and disease management.

One of the key issues that we need to be concerned about is ensuring that the risks of grapevine viruses in the vine yard are minimized. Grapevine viruses:
  • Can affect both the rootstock and scion
  • Is spread by propagation
  • Is propagated both across the vineyard and to progeny of the current vines.
A list of grapevine viruses of concern in the Italian environment is presented in the table below.

Virus                         Manifestation                           Infection                       Impact
Grapevine Degenerative Complex* including:
  • Grapevine fanleaf virus

  • Other European NEPO viruses

  • Leaf deformation; yellow mosaic; vine banding

  • Poor fruit set
  • Short berries
Grapevine leafroll complex
        Red leaf color in fall
  • Grafting scion on rootstock wood
  • Feeding of mealy bugs
  • Delayed fruit maturity
  • Poor color
  • Reduced yield
Grapevine rugrose complex
        Rough or bark wood

Grapevine fleck disease

Phytoplasma-induced diseases

*Most dangerous group; transmitted by nematodes
Source: Maher Al Rwahni; Golino 1

The best insurance against virus infection and disease is the use of certified scion and rootstock selections. And that position is currently mandated by EU and Italian laws and regulations. The Italian schema divides plant material responsibility between initial propagation material and nursery-developed-material, with the nursery securing infection-free material from trusted sources and supplying certified material to the vineyards. Certified materials are so indicated by blue packaging while “standard material” – where no clone has been recorded – is provided in packaging with orange labels. Material in the blue packaging is certified free of all diseases and viruses included in the table above. I will assume that Masseto only plants certified stock in its vineyards.

In the event rootstocks and scions need to be procured from external sources, I assume that it will be sourced from Vivai Cooperative Rauscedo (Rauscedo, Italy) who, according to
- Is one of the biggest nurseries in the world
- Produces over 60 million plants/year with 4000 rootstock/scion combinations
- Has a renowned research center which has an intensive clone selection program.

Vivai Cooperative Rauscedo has the scale to increase likelihood of great diameter matching between scion and clone, one of the key factors considered when evaluating nurseries.

©Wine -- Mise en abyme

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