The amazing Cabernet franc

2016-05-04 07:44

The amazing Cabernet franc...
DNA sequence analysis performed on the oldest South African grapevine rootstock cultivar has now revealed that the long sought-after identity of its Vitis vinifera parent could be the ancient European cultivar, Cabernet franc! This is very good news for grapevine breeders in the future if they want to produce a good South African disease-resistant grapevine variety. Its disease-resistance qualities are derived from its other parent, a North American 'wild' Vitis species called Vitis aestivalis or 'the Summer grape'.

The Jacquez grapevine has had a colourful history (since the phylloxera outbreak). It is a red grapevine cultivar that has been used literally for centuries as both a wine grape (so-called direct-producer) as well as a fairly successful rootstock that saved many a vineyard from the initial ravages of the mildew diseases and later the phylloxera in both Europe and America. The European viticultural industry was eventaully saved from the root-sucking phylloxera insect by grafting vinifera varieties onto American hybrid rootstocks such as Jacquez and others which were 'immune' to that insect. 

We now have 'evidence' that Jacquez was naturally generated from hybridization events involving the Vitis vinifera cultivar, Cabernet franc, with a 'wild' Vitis aestivalis grapevine species that took place at some point in early colonial America (around the middle of the 18th century). One possible reason why Cabernet franc was more successful than other European cultivars in growing reasonably successfully at that time in the eastern American colonies could be because it is one of the most cold-hardy Vitis vinifera varieties known. This fact most likely played an important 'role' in that region that resulted in the eventaul hybridization event that gave rise to the 'amazing' Jacquez cultivar.

However, the Madeira Islands (Portuguese archipelago in the north Atlantic Ocean) played an equally important pivotal role in the propagation and dissemination of this early rootstock to the New World (e.g. America, South Africa and Australia).Although we suspect that the Jacquez (also known as Black Spanish or Lenoir) cultivar was rescued by some early French or Portuguese settlers in America (either from South Carolina or Georgia), Americans were, initially, not aware of the importance of Jacquez in combating the aforementioned ravages to the European vineyards. The result was that Jacquez was brought to the Madeira islands by some settlers returning to Europe due to their dissatisfaction with the viticultural failures in those Eastern American colonies. The rest of the story is history...the European viticultural industry was 
well on its way to being rescued...

Aside from the fact that 'Jacquez' was one of the first 'natural' direct-producers (bearing varieties) to have been used on European soil (because of its relatively 'good' resistance to the mildews), even today, some 150 years later after the outbreak of the 

phylloxera epidemic in Europe, Jacquez and other hybrid rootstocks containing Jacquez 'genes' have been successfully used in South Africa and elsewhere, supplementing the rootstock arsenal in the fight against the phylloxera pest which has never really permanently left our vineyards.

All this drama...thanks to Cabernet franc!
by Dr Jerry Rodrigues (May, 2016)

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