Phylloxera

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Phylloxera can be controlled by chemical treatment of the earth around the vine, but this is very expensive. Until the end of WW II, Romanee-Conti vines grew on their native roots and were not grafted to American root stock. They were kept healthy with chemical treatment, which was no great problem for a wine as expensive as Romanee-Conti. However, because of shortages of needed chemicals during the war, the vines remained untreated for a considerable time and were invaded by Phylloxera. The vineyard had to be completely replanted after the 1945 vintage. There was no Romanee-Conti for many years after that. The rich owners of Romanee-Conti could afford such a loss, but they likely were extremely unhappy about it. Owners of vineyards producing less expensive wines often can not afford to take such risks.

There are a few small pockets of vines around Europe that were not infected by Phylloxera. Tiny amounts of Champagne still come from grapes on vines with native roots. A tiny amount of port is made from vines on native roots. Colares in Portugal is made from grapes from ungrafted vines. The vines are planted in very deep sand by the ocean, and the Phylloxera pests apparently can not live in the dry sand at some stage of their life cycle. The roots of the vines go very deep to seek water, and the pests do not go deep enough to reach the moist area.

There was much experimentation with different root stocks to see which gave the best wine as well as resisted the pests. Apparently proper selection of rootstock for grafting does influence the quality of the wine. For a very long time after grafting over to American rootstock, a favorite topic of wine discussion concered the quality of pre-Phylloxera wine compared to wine made after grafting became common.

European wine grapes have been planted without grafting in some areas of North and South America that were free of Phylloxera. However, in some of these cases, Phylloxera moved in and the vines had to have expensive treatments or be grafted over to American rootstock.