Almost all vines planted today are grafted onto an American rootstock. This is because the wine louse, the phylloxera, is still present in the soil. The American vine is immune to phylloxera, but not the European one. The wine grower can choose from different rootstocks, depending on the soil type and grape. But in fact, most people choose the same.
In France, 72 % of the growers use only five different varieties, although there are over 30 different ones to choose from.
The most common is called SO 4 and has nearly a quarter of the market. The biggest four after SO 4 is 110 Richter, 3309 Couderc, 41B MGT and Ruggeri. SO 4, actually Sélection Oppenheim 4, comes from a cross between Vitis berlandieri and Vitis riparia.
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